WO2025023924A1

WO2025023924A1 - Inkjet inks for side shoot printing

Info

Publication number: WO2025023924A1
Application number: PCT/US2023/028393
Authority: WO
Inventors: Greg DUNCAN; Yuta Matsumoto
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2023-07-21
Filing date: 2023-07-21
Publication date: 2025-01-30
Anticipated expiration: 2026-01-21

Abstract

An inkjet ink that 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 is provided for side shoot printing. The inkjet ink is characterized by extended decap times at a range of environmental conditions even when printing on vertical surfaces, and furthermore has good running stability and dry time. A method of forming a printed image with a thermal inkjet printhead by side shoot printing is also provided.

Description

TITLE

INKJET INKS FOR SIDE SHOOT PRINTING

[0001]

BACKGROUND OF THE INVENTION

TECHNICAL FIELD

[0002]

The present invention relates to inkjet inks for side shoot printing, specifically inkjet inks formulated with a fatty acid, two linear alkane 1,2-diols, and an organic solvent.

DESCRIPTION OF THE RELATED ART

[0003]

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

[0004]

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

[0005]

However, industrial marking and coding regularly requires the printing of essential information — such as personal information, labels, codes, dating (e.g., expirations dates), and traceability information (e.g., manufacturing lot) — onto substrates that may be vertical or at an angle. Such printing by shooting the ink horizontally may be known as “side shoot printing.” Industrial settings may furthermore require side shoot printing on a variety of substrates, such as parcels and bottles. This printing may occur in a variety of environmental conditions, for instance, printing in a cold room to label refrigerated food products, or printing in a warm outdoor environment to mark lumber products. Additionally, thermal inkjet printing can be troubled by poor reliability after periods of inactivity. For example, some inkjet inks suffer from short decap times, in which solvent losses due to prolonged exposure to air within an uncapped printhead leads to clogging/plugging of printhead nozzles, and thus unreliable ink jetting and image quality erosion over time Since side shoot printing involves emitting the ink sideways, residual ink can accumulate more easily on the printhead. Thus, the degradation in image quality from short decap times tends to be more aggravated by side shoot printing. Poor image quality is unacceptable for many applications, but particularly so for marking and coding of essential information. For this reason, even despite the other advantages, TIJ technology has had only modest acceptance in marking/coding applications and is limited by environmental conditions and printing on horizontal substrates.

[0006]

U.S. Patent Application US20220064472 (also filed as JP-A-2022-037408) describes an ink composition and a treatment liquid composition. Both compositions are applied onto a printing medium by an inkjet method. The ink composition is a water-based composition containing a coloring material and a surfactant. The treatment liquid composition is a waterbased composition containing a flocculant and a surfactant. Each composition contains a silicone surfactant, and any one of the ink composition and the treatment liquid composition contains a nitrogen-containing solvent, a sulfur-containing solvent, or a cyclic ester. The patent application did not consider side shoot printing or decap time.

[0007]

U.S. Patent Application US20160333209 (also published as WO2015/125368), describes an ink composition contains an amide with a specific molecular weight, a colorant, a polymer having an SP value of 17 to 24, and water, in which there is a specific relationship between a log P value of the amide and an SP value of the polymer. An inkjet recording method involves jetting the ink composition onto a recording medium which may have been acid treated. The patent application did not consider side shoot printing or decap time.

BRIEF SUMMARY OF THE INVENTION

[0008]

In view of the foregoing, there is a need for inkjet inks for side shoot printing that have extended decap times, including across a range of temperatures and humidities.

[0009]

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

[0010]

It is another object of the present disclosure to provide novel methods of forming a printed image on a substrate by side shoot printing the inkjet inks onto the substrate and drying.

[0011] These and other objects, which will become apparent during the following detailed description, have been achieved by the inventors’ discovery of an inkjet ink for side shoot printing characterized by extended decap times at a range of environmental conditions and good running stability.

Thus, the present invention provides:

[0012]

(1) An inkjet ink for printing by shooting sideways onto a substrate with an inkjet printhead, the inkjet ink comprising:

[0013]

(A) a fatty acid comprising an unsaturated fatty acid;

[0014]

(Bl) a first linear alkane 1,2-diol having a carbon chain of 2 to 4 carbon atoms;

[0015]

(B2) a second linear alkane 1,2-diol having a carbon chain of 5 to 14 carbon atoms;

(C) an organic solvent, and

(D) water, wherein the first linear alkane 1,2-diol (B l) and the second linear alkane 1,2-diol (B2) are each present independently in an amount of 0.1 to 10 wt%, based on a total weight of the inkj et ink.

[0016]

(2) The inkjet ink of ( I), wherein the organic solvent (C) comprises dimethyl sulfone or 2-pyrrolidone, and the dimethyl sulfone or 2-pyrrolidone is present in the inkjet ink in an amount of 2 to 20 wt%, based on a total weight of the inkjet ink. [0017]

(3) The inkjet ink of (1) or (2), wherein the organic solvent (C) comprises dimethyl sulfone.

[0018]

(4) The inkjet ink of any one of (1) to (3), wherein the water (D) is present in an amount of 40 to 80 wt%, based on a total weight of the inkjet ink.

[0019]

(5) The inkjet ink of any one of (1) to (4), wherein the fatty acid (A) is present in an amount of 0.1 to 5 wt%, based on a total weight of the inkjet ink.

[0020]

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

[0021]

(7) The inkjet ink of any one of (1) to (6), wherein the first and second linear alkane

1.2-diol combined ((B 1 )+(B2)) are present in the inkjet ink in an amount of 5 to 20 wt%, based on a total weight of the inkjet ink.

[0022]

(8) The inkjet ink of any one of (1) to (7), wherein the first linear alkane 1,2-diol (Bl) is

1.2-propanediol, and wherein the second linear alkane 1,2-diol (B2) is 1,2-hexanediol. [0023]

(9) The inkjet ink of (8), wherein a weight ratio of the 1,2-propanediol to the 1,2- hexanediol is from 1 :1 to 10: 1.

[0024]

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

[0025]

(11) The inkjet ink of (10), wherein the alkanolamine (E) is present in an amount of 0.01 to 5 wt%, based on a total weight of the inkjet ink.

[0026]

(12) The inkjet ink of (1 ) or (1 1 ), wherein the alkanolamine (E) is at least one selected from the group consisting of ethanolamine, propanol amine, isopropanolamine, diethanolamine, and triethanolamine.

[0027]

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

[0028] (14) The inkjet ink of any one of (1) to (13), wherein the inkjet ink further comprises (G) a colorant

[0029]

(15) The inkjet ink of (14), wherein the colorant (G) is present in an amount of 0.1 to 30 wt%, based on a total weight of the inkjet ink.

[0030]

(16) The inkjet ink of any one of (1) to (15), wherein the inkjet ink further comprises one or more glycol ethers (H) present in a total amount of 0.1 to 5.0 wt%, based on a total weight of the inkj et ink.

[0031]

(17) A method for forming a printed image on a substrate by side-shoot printing, the method comprising:

[0032] applying the inkjet ink of any one of (1) to (16) sideways onto the substrate with a thermal inkjet printhead; and

[0033] drying the inkj et ink.

[0034]

(18) The method of (17), wherein a line along the shortest distance between a nozzle of the thermal inkjet printhead supplying the inkjet ink and the substrate forms a smallest angle in a range of 70° to 90° with the direction of gravity. [0035]

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]

A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

Fig. 1 A illustrates an inkjet nozzle after side shoot printing with a common inkjet ink.

Fig. IB illustrates an inkjet nozzle after side shoot printing with the inventive inkjet ink.

Fig. 1C illustrates an inkjet nozzle after side shoot printing with the inventive inkjet ink.

[0037]

Fig 2A illustrates an initial side shoot printing of a typical inkjet ink with the arrow added to indicate the direction of the printing.

[0038]

Fig. 2B illustrates a subsequent side shoot printing with the typical inkjet ink, 30 minutes after the printing in Fig. 2A and without wiping the printhead.

[0039]

Fig. 3 A illustrates an initial side shoot printing of an inventive inkjet ink with the arrow added to indicate the direction of the printing.

[0040]

Fig. 3B illustrates a subsequent side shoot printing with the inventive inkjet ink, 30 minutes after the printing in Fig. 3 A and without wiping the printhead. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041]

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

[0042]

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

[0043]

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

[0044] As used herein, the words “about,” “approximately,” or “substantially similar” may be used when describing magnitude and/or position to indicate that the value and/or position described is within a reasonable expected range of values and/or positions. For example, a numeric value may have a value that is +/- 0.1% of the stated value (or range of values), +/- 1% of the stated value (or range of values), +/- 2% of the stated value (or range of values), +/- 5% of the stated value (or range of values), +/- 10% of the stated value (or range of values), +/- 15% of the stated value (or range of values), or +/- 20% of the stated value (or range of values). Within the description of this disclosure, where a numerical limit or range is stated, the endpoints are included unless stated otherwise. Also, all values and subranges within a numerical limit or range are specifically included as if explicitly written out.

[0045]

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

[0046]

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

[0047]

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

[0048]

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

[0049]

As used herein, the term “fatty” describes a compound with a long-chain (linear) hydrophobic portion made up of hydrogen and anywhere from 8 to 30 carbon atoms, which may be fully saturated or partially unsaturated.

[0050]

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

[0051]

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

[0052] The term “(meth)acrylate” is used herein to refer to both acrylate and methacrylate groups. Tn other words, this term should be read as though “meth” is optional. Further, the term “(meth)acrylate” is used generally to refer to both acrylic acid-based compounds and acrylic ester-based compounds.

[0053]

Throughout the specification, the term “boiling point” (b.p.) refers to the boiling point of a liquid measured at sea-level atmospheric pressure (i.e., 760 mmHg or 1 atm), also called the nornial boiling point, unless specified otherwise. The term “melting point” (m.p.) refers to the melting point of a solid measured at sea-level atmospheric pressure (i.e., 760 mmHg or 1 atm).

[0054]

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

[0055]

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

[0056]

Some of the problems to be solved by the invention are staining during continuous printing and short decap times. These two features may be linked to each other but could be caused by different factors.

Of the first, staining during continuous printing is caused by ink accumulation around the nozzle Without being bound by any particular theory, it is assumed that the anionic moiety of elaidic acid or fatty acid which is liquid at 25°C adsorbs to the nozzle surface so that the hydrophobic part is oriented outward. This makes the nozzle surface hydrophobic, and in turn causes the aqueous ink to be less wettable. Thus, it is more difficult for the ink to wet and spread onto the nozzle surface. Without the ink wetting and spreading, the nozzle surface is kept clean. For instance, Fig. 1A shows the ink build up on a nozzle surface after printing with a common inkjet ink, while Fig. IB shows a clean nozzle surface free of ink build up after printing with the inventive inkjet ink. Although this is not certain, it is assumed that the solvent has an influence to the orientation of the unsaturated fatty acid that was achieved in relation to the first diol. Since the second diol (B2) may be more hydrophobic than the first diol (B2), it can be considered that the addition of a large amount of the second diol would have reduced the activity of the oleic acid and no effect was seen.

The decap time may be improved (i.e., lengthening the decap time) by adding dimethyl sulfone or 2-pyrrolidone to the inkjet ink composition as a drying inhibitor. The second diol may be more hydrophobic than the first diol, and therefore, more biased toward the ink-air interface, and has a higher boiling point, thus inhibiting excessive evaporation of water (capping agent). It is assumed that the best performance is obtained by these factors working together. In addition, since the performance is also affected by ink stains around the nozzle, it is assumed that the results are somewhat linked to the stain evaluation results.

[0057]

Inkjet inks of the present disclosure generally include the following components: (A) an unsaturated fatty acid; (Bl) a first linear alkane 1,2-diol having a carbon chain of 2 to 4 carbon atoms; (B2) a second linear alkane 1,2-diol having a carbon chain of 5 to 14 carbon atoms; (C) an organic solvent, and (D) water The first and second linear alkane 1 ,2-diols (Bl, B2) may each be present independently in an amount of 0.1 to 10 wt%, based on a total weight of the inkj et ink.

[0058]

The inkjet inks of the present disclosure may also optionally include one or more of (E) an alkanolamine, (F) a surfactant, (G) a colorant, and (H) a glycol ether.

(A) Fatty Acid

[0059]

Inkjet inks of the present disclosure are formulated with a fatty acid (A). Typically, from the viewpoint of running stability at side shooting and long decap time, the fatty acid (A) is employed preferably in an amount of 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, at most 5.0 wt%, at most 4.5 wt%, at most 4.0 wt%, at most 3.5 wt%, at most 3.0 wt%, at most 2.5 wt%, at most 2.0 wt%, at most 1.5 wt%, at most 1.2 wt%, at most 1.1 wt%, at most 1.0 wt%, at most 0.75 wt%, at most 0.50 wt%, at most 0.45 wt%, at most 0.40 wt%, at most 0.35 wt%, at most 0.30 wt%, at most 0.25 wt%, at most 0.20 wt%, at most 0.15 wt%, relative to a total weight of the inkjet ink.

[0060]

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), linoelaidic 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 a further embodiment, the inkjet inks are formulated with an unsaturated fatty acid as the fatty acid (A), and further comprise a saturated fatty acid, including but not limited to stearic acid (18:0), margaric acid (17:0), palmitic acid (16:0), pentadecylic acid (15:0), myristic acid (14:0), tridecylic acid (13:0), lauric acid (12:0), undecylic acid (11 :0), capric acid (10:0), pelargonic acid (9:0), and caprylic acid (8:0). In one embodiment, where both an unsaturated fatty acid and a saturated fatty acid are present in the inkjet ink, a weight ratio of the unsaturated fatty acid to the saturated fatty acid is in a range of preferably 1 :1 to 100:1, preferably 5: 1 to 50:1, more preferably 10: 1 to 30: 1 , more preferably 15: 1 to 25: 1

[0061]

Preferably, from the viewpoint of running stability at side shooting and long decap time, the fatty acid is liquid at room temperature, for instance, the fatty acid has a melting point of no greater than 25 °C. In one embodiment, from the viewpoint of running stability at side shooting and long decap time, the fatty acid comprises oleic acid and/or linoleic acid, which each have melting points of 25 °C or less. The oleic acid may be obtained as Lunac® O-V, available from Kao Chemicals. In one embodiment, the fatty acid comprises elaidic acid. From the viewpoint of running stability at side shooting and long decap time, in a preferred embodiment, the fatty acid (A) comprises oleic acid.

(B) Linear alkane 1,2-diol

[0062]

In one embodiment, the inkjet ink comprises a first linear alkane 1,2-diol (B l) and a second linear alkane 1,2-diol (B2) which is different than the first. The first and second linear alkane 1,2-diols may each be employed independently, from the viewpoint of running stability at side shooting and long decap time, preferably, in amounts of 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 1 east 3 5 wt%, at 1 east 4 0 wt%, at 1 east 4 5 wt%, at I east 5 wt%, at 1 east 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, at most 10 wt%, at most 9.5 wt%, at most 9 wt%, at most 8.5 wt%, at most 8 wt%, at most 7.5 wt%, at most 7 wt%, at most 6.5 wt%, at most 6 wt%, at most 5.5 wt%, at most 5 wt%, at most 4.5 wt%, at most 4 wt%, at most 3.5 wt%, at most 3.5 wt%, at most 2.5 wt%, at most 2 wt%, at most 1 wt%, relative to a total weight of the inkjet ink.

In a preferred embodiment, the first linear alkane 1,2-diol (Bl) is present in an amount of 0. 1 to 10 wt%, and the second linear alkane 1,2-diol (B2) is present in an amount of 0. 1 to 10 wt%, based on a total weight of the inkjet ink.

[0063] In one embodiment, from the viewpoint of running stability at side shooting and long decap time, the first and second linear alkane 1 ,2-diols may be present in the inkjet ink at a combined concentration ((B1)+(B2)) of, preferably, at least 5 wt%, at least 6 wt%, at least 7 wt%, at least 8 wt%, at least 9wt%, 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%, relative to a total weight of the inkjet ink.

[0064]

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

[0065]

In a preferred embodiment, from the viewpoint of running stability at side shooting and long decap time, the first linear alkane 1,2-diol (B l) is 1,2-propanediol, and the second linear alkane 1 ,2-diol (B2) is 1 ,2-hexanediol Tn a preferred embodiment, from the viewpoint of running stability at side shooting and long decap time, 1,2-propanediol is present in the inkjet ink at a concentration of, 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%, relative to a total weight of the inkjet ink. In a preferred embodiment, from the viewpoint of running stability at side shooting and long decap time, 1,2-hexanediol is present in an amount of, 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%, relative to a total weight of the inkjet ink.

[0066] In one embodiment, from the viewpoint of running stability at side shooting and long decap time, the first linear alkane 1 ,2-diol (Bl) is 1 ,2-propanediol, and the second linear alkane 1,2-diol (B2) is 1,2-hexanediol, and a weight ratio of the 1,2-propanediol to the 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, preferably at most 10:1, at most 9:1, at most 8:1, at most 7:1, at most 5: 1.

In one embodiment, a weight ratio of the 1,2-propanediol to the 1,2-hexanediol in the inkjet ink is preferably from 1: 1 to 10: 1, preferably 1.5:1 to 9:1, more preferably 1.7: 1 to 8: 1, more preferably 1.7: 1 to 2:1

(C) Organic solvent

[0067]

In many printing processes that utilize solvent-based inks, in particular thermal inkjet printing, the selection of an appropriate organic solvent may impact the reliability of the printing process, the properties/appearance of the printed ink product, and the overall printing process efficiency For example in thermal inkjet printing, the choice of organic solvent may 1) aid bubble formation during the jetting process resulting in reliable ink jetting, 2) affect the stability/volatility of the inkjet inks by changing the interaction dynamics between the organic solvent(s) and the various inkjet ink components and thus the decap behavior, kogation, and/or drop trajectory, 3) impact the adhesion, rub and scratch resistance, and optical density properties of the printed image through the interactive forces between the organic solvent and the other inkjet ink components even though the organic solvent(s) may no longer be present, or may be present in reduced amounts, after drying, 4) influence the drying time after application or the equipment needed to dry the applied ink, and/or 5) impact droplet dynamics.

[0068] In one embodiment, the organic solvent (C) may include one or more of the glycol cosolvent, dimethyl sulfone, or 2-pyrrolidone.

The glycol co-solvent may contain at least 2 carbon atoms, preferably at least 3 carbon atoms, and up to 10 carbon atoms, preferably up to 8 carbon atoms, more preferably up to 6 carbon atoms, even more preferably up to 5 carbon atoms, yet even more preferably up to 4 carbon atoms. Preferred organic solvents (C) are those containing two hydroxyl groups attached to adjacent carbon atoms (i.e., vicinal diols).

Examples of the organic solvent (C) include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, 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 can be used singularly or in combination.

In preferred embodiments, the organic solvent (C) is at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, 1 ,2-butanediol, 1 ,3 -butanediol, 1 ,4-butanediol, and 2,3- butanediol, with ethylene glycol, propylene glycol, or both, being more preferred.

In terms of improving inkjet ink performance, e.g., decap performance, print quality, etc., without considerably lengthening ink dry times, preferred organic solvents (C) are those which have a boiling point of from 188 °C to less than 250 °C, preferably less than 240 °C, preferably less than 230 °C, preferably less than 220 °C, more preferably less than 210 °C, more preferably less than 200 °C. Tn light of the above, preference is given herein to ethylene glycol, propylene glycol, or both.

When employed, the organic solvent (C) may be present in the inkjet inks in an amount of 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. %, yet even more preferably at least 17 wt. %, and up to 40 wt. %, preferably up to 38 wt. %, preferably up to 36 wt. %, preferably up to 34 wt. %, preferably up to 32 wt. %, preferably up to 30 wt. %, preferably up to 28 wt. %, preferably up to 26 wt. %, more preferably up to 24 wt. %, even more preferably up to 22 wt. %, yet even more preferably up to 20 wt. %, based on a total weight of the inkjet ink.

In addition to those solvents mentioned above, the solvent system may also optionally include one or more other organic solvents.

Examples of other organic solvents include, but are not limited to, polyols (other than trimethylene glycol (B), and 1,2-hexanediol (C), described previously) such as glycerol, and mixtures of two or more thereof.

[0069]

From the viewpoint of long decap time, the amount of the organic solvent (C) present in the inkjet inks 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 at most 20 wt%, at most 19 wt%, at most 18 wt%, at most 17 wt%, at most 16 wt%, at most 15 wt%, at most 14 wt%, at most 13 wt%, at most 12 wt%, at most 11 wt%, at most 10 wt%, at most 9 wt%, at most 8 wt%, at most 7 wt%, at most 6 wt%, relative to a total weight of the inkjet ink.

[0070]

In a preferred embodiment, from the viewpoint of long decap time, the organic solvent (C) comprises dimethyl sulfone and/or 2-pyrrolidone, preferably dimethyl sulfone. (D) Water

[0071]

In one embodiment, the inkjet inks comprise water (D). The water may be tap water, distilled water, bidistilled water, deionized water, deionized distilled water, reverse osmosis water, and/or some other water. In one embodiment the water is bidistilled or treated with reverse osmosis to eliminate trace metals. Preferably the water is bidistilled, deionized, deionized distilled, or reverse osmosis water, and at 25 °C has a conductivity of less than 10 pS cm preferably less than 1 pS cm ¹; a resistivity of greater than 0.1 M cm, preferably greater than 1 MQ cm, more preferably greater than 10 Mil cm; a total solid concentration of less than 5 mg/kg, preferably less than 1 mg/kg; and a total organic carbon concentration of less than 1000 pg/L, preferably less than 200 pg/L, more preferably less than 50 pg/L. Preferably the water is deionized water.

[0072]

Tn one embodiment, the amount of water present in the inkjet inks 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%, at most 48 wt%, at most 46 wt%, relative to a total weight of the inkjet ink.

(E) Alkanolamine [0073]

Tn some embodiments, the inkjet inks further comprise an alkanolamine (E). Alkanolamines are alkane-based compounds that contain both hydroxyl (-OH) and amine (primary, secondary, or tertiary) groups.

[0074]

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 up to 8 carbon atoms, up to 7 carbon atoms, up to 6 carbon atoms, or up to 5 carbon atoms. In a preferred embodiment the alkanolamine (E) has 3 carbon atoms.

[0075]

In preferable embodiments, the alkanolamine (E) used in the inkjet inks herein has the following general formula II:

[0076] where X, Y, and Z are independently selected from the group consisting of a hydrogen; a C1-C5 alkyl group, preferably a C₂-C₃ alkyl group; and an alkanol group, preferably a C₂-C₅ alkanol group, more preferably a C₃-C₄ alkanol group; and at least one of X, Y, and Z is an alkanol group (an alkyl substituent that bears at least one hydroxyl group).

[0077]

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

[0078] With respect to the one or more alkanol groups, the alkyl chain thereof may contain branching. Alternatively, the alkyl chain of the alkanol group may be linear (contains no alkyl branching). In preferred embodiments, the alkanol group(s) is based on a linear alkyl chain. Further, the hydroxyl bearing carbon of the alkanol group may be a primary, secondary, or tertiary carbon, preferably the hydroxyl bearing carbon is a primary or secondary carbon.

[0079]

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

[0080]

Suitable examples of the alkanolamine (E) include, but are not limited to, isopropanolamine, ethanolamine, N-methylethanolamine, N,N-dimethylethanolamine, N- ethyl ethanol amine, N-propylethanolamine, N-isopropyl ethanol amine, 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, diisopropanol amine, triisopropanolamine, 2-amino-2- methyl-1 -propanol, 2-amino-2-ethyl-l,3-propanediol, 4-amino-l -butanol, 2-amino-l -butanol, sec-butanolamine, and di-sec-butanolamine including the various stereoisomers thereof, as well as mixtures thereof. In preferred embodiments, the alkanolamine (E) comprises at least one selected from the group consisting of isopropanolamine, ethanolamine, propanolamine (3-amino-l -propanol), diethanolamine, and triethanolamine. Tn a preferred embodiment, from the viewpoint of ink stability and drying time, the alkanolamine (E) comprises triethanolamine.

[0081]

In some embodiments, from the viewpoint of ink stability and drying time, the alkanolamine (E) is present in the inkjet ink in an amount of, 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%, at most 0.05 wt%, relative to a total weight of the inkjet ink. In one embodiment, the alkanolamine (E) is present in the inkjet ink in an amount preferably in a range of 0.01 to 5 wt%, more preferably 0.2 to 2 wt%, even more preferably 0.3 to 1 wt%, even more preferably 0 4 to 0 6 wt%, based on a total weight of the inkjet ink

(F) Surfactant

[0082]

In one embodiment, from the viewpoint of ink stability and wetting on the substrates, inkjet inks may comprise one or more surfactants. The one or more surfactants are present in the inkjet inks at a combined concentration of 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%, at most 0.15 wt%, at most 0.1 wt%, at most 0.05 wt%, based on a total weight of the inkjet ink.

Example surfactants, include, but are not limited to,

[0083] anionic surfactants (based on sulfate, sulfonate, or carboxylate anions), for example, di octyl sodium sulfosuccinate (DSS), perfluorooctanoate (PFOA or PFO), perfluorooctanesulfonate (PFOS), sodium dodecyl sulfate (SDS), ammonium lauryl sulfate, and other alkyl sulfate salts, sodium laureth sulfate (SLS, and also known as sodium lauryl ether sulfate (SLES)), alkyl benzene sulfonate, soaps, and fatty acid salts;

[0084] polysiloxanes including organomodified silicones (e.g., alkyl, aryl, and/or arylalkyl modified silicones) such as COATOSIL 1211C and 3573, each available from Momentive;

[0085] silicone acrylate copolymers such as KP-541, KP-543, KP-545, KP-550, and KP-575 (acrylic polymers grafted with polydimethyl siloxane side chains, available from Shin- Etsu Chemical Co., Ltd.), and BYK-3550 (available from BYK Japan K.K.);

[0086] polyether modified silicones, including those which are block copolymers having a pendent graft structure formed from a linear or branched polydimethylsiloxane backbone containing one or more polyether side chains and optionally one or more fatty alkyl side chains. Polyether modified silicones include but are not limited to KF- 6013 (PEG-9 dimethicone, uncapped, HLB = 10.0), KF-6015 (PEG-3 dimethicone, uncapped, HLB = 4.5), KF-6017 (PEG-10 dimethicone, uncapped, HLB = 4.5), and KF-6038 (lauryl PEG-9 poly dimethyl siloxyethyl dimethicone, uncapped, TTLB = 3.0), each available from Shin-Etsu Chemical Co., and BYK-307 (poly ether modified poly dimethyl siloxane), available from BYK Additives & Instruments;

[0087] fluoropolymers such as FC-4430 and FC-4432, available from 3M Corporation;

[0088] photo-cross-linkable silicone acrylates or silicone polyether acrylates such as TEGO RAD 2100, TEGO RAD 2200, TEGO RAD 2250, TEGO RAD 2300 (silicone poly ether acrylate), each available from Evonik Industries, and BYK-UV 500 and 3530, available from BYK;

[0089] polyacrylates including polyacrylate copolymers and cross-polymers such as BYK- 381 and BYK-361N (polyacrylate copolymer), each available from BYK, PEMULEN F.Z-4U (acrylate/C10-C30 alkyl acrylate crosspolymer) and PEMULEN TR-2 (acrylic acid/C10-C30 alkyl acrylate crosspolymer), each available from Lubrizol;

[0090] acetylenic diol and acetylenic glycol-based gemini surfactants such as SURFYNOL SEF and DYNOL surfactants, available from Evonik Industries;

[0091] polysiloxane-based gemini surfactants such as TEGO TWIN 4100 and TEGO TWIN 4200, available from Evonik Industries;

[0092] non-ionic polyethers for example as substrate wetting surfactants such as TEGO WET 510 (hydrophilic polyether substrate wetting surfactant), available from Evonik Industries;

[0093] amides or monoalkanolamides of fatty acids, including alkoxylated monoalkanolamides of fatty acids such as coconut fatty acid monoethanolamide and coconut fatty acid monoethanolamide reacted with 2-20 moles of ethylene oxide, [0094] ethers, such as alkoxylated C1-C22 alcohols including alkoxylated fatty alcohols such as BIO-SOFT N-600 (C12-C13 alcohol ethoxylate), MAKON DA-4 (ethoxylated isodecyl alcohol), MERPOL SE (alcohol ethoxylate), and POLYSTEP TD-6 (ethoxylated tridecyl alcohol), each available from Stepan, ethylene oxide/propylene oxide copolymers, alkoxylated alkylphenols, and alkyl polyglycosides (APGs) such as those made from reaction between fatty alcohols and glucose;

[0095] fatty esters such as ethoxylated and/or propoxylated fatty acids (e.g., castor oil with 2 to 40 moles of ethylene oxide), alkoxylated glycerides (e.g., PEG-24 glyceryl monostearate), glycol esters and derivatives, monoglycerides, polyglyceryl esters, esters of polyalcohols, and sorbitan/sorbitol esters like sorbitan monolaurate (e.g., EMASOL L-10V, available from Kao) and polysorbates including mono-, bi- or trifatty acid esterified polysorbates such as TOXIMUE SEE-340 (sorbitan trioleate ethoxylate (20)), available from Stepan;

[0096] phosphate ester surfactants such as alcohol phosphates, alkyl phosphate esters, alcohol ethoxylate phosphates, tridecyl alcohol ethoxylate phosphate esters, oleyl alcohol ethoxylate phosphate esters, alkyl phenol ethoxylates, aryl phosphate ethoxylate esters, nonylphenol ethoxylate phosphate esters, salts of nonylphenol ethoxylate phosphate esters, organo phosphates, aliphatic phosphate esters, a phosphated nonylphenoxy polyethoxy ethanol, phosphate coesters of aliphatic alcohols, or a salt of ethyl-hexanol ethoxylated phosphate ester (“2EH-2EO”). In one embodiment, the phosphate ester surfactant is Dephotrope™ CAS-MF. In another embodiment, the phosphate ester 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 ester surfactant is Strodex™ PK-80A from Ashland, and [0097]

- glycosides of fatty alcohols such as PL ANTASENS NATURAL EMULSIFIER HE20 (cetearyl glucoside, sorbitan olivate), available from Clariant.

[0098]

In a preferred embodiment, from the viewpoint of ink stability and wetting on the substrates, the inkjet inks comprise a phosphate coester of aliphatic alcohols such as Strodex™ PK-80N, dioctyl sodium sulfosuccinate (DSS), and/or a siloxane-based gemini surfactant such as Tego Twin™ 4200.

(G) Colorant

[0099]

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

[0100]

The inks of the invention could also comprise dyes known in the art of inkjet printing. For aqueous-based ink compositions dyes suitable for use in the 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, anthrapyridone dyes, azo dyes, rhodamine dyes, solvent dyes and the like. Specific examples of dyes usable in the present invention are as follows: yellow dyes including: 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, 1 1 1 , 127, 131 , 135, 142, 162, 164, and 165; Direct Yellow 1 , 8, 1 1 , 12, 24, 26, 27, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 1 10, 132, 142, and 144; Reactive Yellow 1, 2, 3, 4, 6, 7, 1 1 , 12, 13, 14, 15, 16, 17, 18, 22, 23, 24, 25, 26, 27, 37, and 42; and Food Yellow 3 and 4; magenta dyes including: 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, 131, 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, 3 1, 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 Food Red 7, 9, and 14; cyan dyes including: 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, 1 12, 113, 117, 120, 126, 127, 129, 130, 131 , 138, 140, 142, 143, 151, 154, 158, 161, 166, 167, 168, 170, 171, 182, 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 249; 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 C I. Food Blue 1 and 2; black dyes including: 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, 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 19 IL which comprises 15 wt% Direct Black 19.

[0101 ]

In some embodiments, from the viewpoint of ink stability and optical density on the substrates, the inkjet inks comprise the colorant (G) at a concentration of 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%, at most, 0.5 wt%, relative to a total weight of the inkjet inks. In one embodiment, the colorant (G) may be present at a concentration in a range of 0.1 to 30 wt%, 15 to 28 wt%, preferably 20 to 25 wt%, relative to a total weight of the inkjet ink.

(H) Glycol ethers [0102]

Tn some embodiments, the inkjet inks further comprise one or more glycol ethers (TT) present at a combined concentration of 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%, at most 0.2 wt%, relative to a total weight of the inkjet inks. The one or more glycol ethers (H) may comprise aliphatic or aromatic glycol ethers such as an aromatic glycol ether like propylene glycol phenyl ether (e.g., Dowanol™ PPh glycol ether) or aliphatic glycol ether 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, di ethylene glycol mono-isopropyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, 1 -methyl- 1 -methoxybutanol, propylene glycol monomethyl ether (Dowanol™ PM), propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-isopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-isopropyl ether, propylene glycol mono-n-butyl ether, and dipropylene glycol mono-n-butyl ether; formamide, acetamide, dimethyl sulfoxide, sorbitol, sorbitan, glycerol monoacetate, glycerol diacetate, glycerol triacetate, and sulfolane; or combinations thereof. In one embodiment, from the viewpoint of dry time and wetting on the substrates, the one or more glycol ethers (IT) are employed as glycol ether DTI.

[0103]

(I) Additive

In some embodiments, the inkjet inks may comprise one or more additional ingredients or additives to improve various ink characteristics and performance.

[0104]

Resin Dispersion

In one embodiment, the inkjet inks may comprise a resin dispersion. The resin dispersion is not particularly limited as long as it is a resin dispersion in which the resin is dispersed in a dispersion medium as fine particles, and examples thereof include a dispersion, a suspension, and an emulsion.

[0105]

Examples of the resin dispersion, which are not particularly limited, include emulsions of urethane resins represented by a polyether-type urethane resin, a polyester-type urethane resin including an ester bond in the main chain, or a polycarbonate-type urethane resin including a carbonate bond in the main chain, and a (meth)acrylic resin emulsion, and a styrene-(meth)acrylic acid copolymer-based resin emulsion. Moreover, the above-described copolymers may be any form of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer.

[0106]

The resin dispersion may be used alone as one kind or may be used in a combination of two or more kinds.

[0107] By including a resin dispersion, the resin and the pigment of the ink composition fuse together upon drying. When this happens, the pigment is fixed on the fabric, or a resin film is fixed on the fabric, which advantageously increases the friction resistance and the washing fastness of an image portion of the recorded matter.

[0108]

Other additives include: pH adjusting agents, 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;

[0109] preservatives and/or fungicides including but not limited to sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-l -oxide, sodium sorbate, sodium dehydroacetate, and l,2-dibenzisothiazolin-3-one;

[01 10] an anti-kogation agent, a stabilizer, a humectant, a security taggant, some other resin, binder, tackifier, adhesive substance, rust inhibitor, or other inkjet ink additive(s) known by those of ordinary skill in the art; and the like, including mixtures thereof.

[0111]

In one embodiment, the additive (1) may comprise a surfactant in addition to or instead of the one or more surfactants (F). Example surfactants, include, but are not limited to,

[0112] polysiloxanes including amine modified silicones and organomodified silicones (e.g., alkyl, aryl, and/or arylalkyl modified silicones) such as COATOSTL 1211 C and 3573, each available from Momentive;

[0113] silicone acrylate copolymers such as KP-541, KP-543, KP-545, KP-550, and KP-575 (acrylic polymers grafted with polydimethyl siloxane side chains, available from Shin- Etsu Chemical Co., Ltd.), and BYK-3550 (available from BYK Japan K.K.);

[0114] polyether modified silicones, including those which are block copolymers having a pendent graft structure formed from a linear or branched polydimethylsiloxane backbone containing one or more polyether side chains and optionally one or more fatty alkyl side chains. Polyether modified silicones include but are not limited to KF- 6013 (PEG-9 dimethicone, uncapped, HLB = 10.0), KF-6015 (PEG-3 dimethicone, uncapped, HLB = 4.5), KF-6017 (PEG-10 dimethicone, uncapped, HLB = 4.5), and KF-6038 (lauryl PEG-9 polydi methyl si 1 oxy ethyl dimethicone, uncapped, HLB = 3 0), each available from Shin-Etsu Chemical Co., and BYK-307 (polyether modified poly dimethyl siloxane), available from BYK Additives & Instruments;

[0115] fluoropolymers such as FC-4430 and FC-4432, available from 3M Corporation;

[0116] photo-cross-linkable silicone acrylates or silicone polyether acrylates such as TEGO RAD 2100, TEGO RAD 2200, TEGO RAD 2250, TEGO RAD 2300 (silicone poly ether acrylate), each available from Evonik Industries, and BYK-UV 3500 and 3530, available from BYK;

[0117] polyacrylates including polyacrylate copolymers and cross-polymers such as BYK- 381 and BYK-361N (polyacrylate copolymer), each available from BYK, PEMULEN EZ-4U (acrylate/C10-C30 alkyl acrylate crosspolymer) and PEMULEN TR-2 (acrylic acid/C10-C30 alkyl acrylate crosspolymer), each available from Lubrizol;

[0118] acetylenic diol and acetylenic glycol-based gemini surfactants such as SURFYNOL SEF and DYNOL surfactants, available from Evonik Industries;

[0119] polysiloxane-based gemini surfactants such as TEGO TWIN 4100, available from Evonik Industries;

[0120] non-ionic polyethers for example as substrate wetting surfactants such as TEGO WET 510 (hydrophilic poly ether substrate wetting surfactant), available from Evonik Industries;

[0121 ] amides or monoalkanolamides of fatty acids, including alkoxylated monoalkanolamides of fatty acids such as coconut fatty acid monoethanolamide and coconut fatty acid monoethanolamide reacted with 2-20 moles of ethylene oxide;

[0122] ethers, such as alkoxylated C1-C22 alcohols including alkoxylated fatty alcohols such as BIO-SOFT N-600 (C12-C13 alcohol ethoxylate), MAKON DA-4 (ethoxylated isodecyl alcohol), MERPOL SE (alcohol ethoxylate), and POLYSTEP TD-6 (ethoxylated tridecyl alcohol), each available from Stepan, ethylene oxide/propylene oxide copolymers, alkoxylated alkylphenols, and alkyl polyglycosides (APGs) such as those made from reaction between fatty alcohols and glucose; [0123] fatty esters such as ethoxylated and/or propoxylated fatty acids (e.g., castor oil with 2 to 40 moles of ethylene oxide), alkoxylated glycerides (e.g., PEG-24 glyceryl monostearate), glycol esters and derivatives, monoglycerides, polyglyceryl esters, esters of polyalcohols, and sorbitan/sorbitol esters like sorbitan monolaurate (e.g., EMASOL L-10V, available from Kao) and polysorbates including mono-, bi- or trifatty acid esterified polysorbates such as TOXIMUL SEE-340 (sorbitan trioleate ethoxylate (20)), available from Stepan; and

[0124]

[0125]

An additive in any of the above list, including surfactants and resin dispersions, may be present in any of the inkjet inks of the present disclosure at a concentration of at least 0.0001 wt%, at least 0.0005 wt%, at least 0.001 wt%, at least 0.005 wt%, at least 0.01 wt%, at least 0.05 wt%, at least 0. 1 wt%, at least 0.2 wt%, at least 0.4 wt%, at least 0.5 wt%, at least 0.7 wt%, at least 1 wt%, at least 1.2 wt%, at least 1.5 wt%, at least 1.7 wt%, at least 2 wt%, 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%, and/or at most 35 wt%, at most 30 wt%, at most 25 wt%, at most 20 wt%, at most 16 wt%, at most 15 wt%, at most 12 wt%, at most 10 wt%, at most 9 wt%, at most 8 wt%, at most 7 wt%, at most 6 wt%, at most 5 wt%, at most 4.5 wt%, at most 4 wt%, at most 3.5 wt%, at most 3 wt%, at most 2.5 wt%, at most 2 wt%, at most 1.7 wt%, at most 1.5 wt%, at most 1.2 wt%, at most 1 wt%, at most 0.7 wt%, at most 0.5 wt%, at most 0.4 wt%, at most 0.2 wt%, at most 0.1 wt%, at most 0.05 wt%, at most 0.01 wt%, at most 0.005 wt%, at most 0.001 wt%, at most 0.0005 wt%, relative to a total weight of the inkjet ink.

[0126]

Alternatively, the inkjet ink may be free of or substantially free of an additive or compound in any of the above list, including surfactants, meaning that such additive or compound has a concentration in the inkjet ink of less than 1 wt%, less than 0.5 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.001 wt%, less than 0.0001 wt%, less than 0.00001 wt%, or 0 wt%.

In one embodiment, the inkjet ink comprises less than 5 wt% of 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-propane diol, lauric acid, and/or a resin.

Methods of Making

[0127]

Embodiments of the inkjet inks described herein may be prepared by any suitable technique known to those of ordinary skill in the art, for example by combining a fatty acid (A) comprising elaidic acid or a fatty acid having a melting point of no greater than 25 °C, a first linear alkane 1,2-diol (Bl) having a carbon chain of 2 to 4 carbon atoms, a second linear alkane 1,2-diol (B2) having a carbon chain of 5 to 14 carbon atoms, an organic solvent (C), and water (D) in any order and stirring, agitating, and/or homogenizing at a temperature between 20 and 100°C for a suitable amount of time to form a homogeneous solution.

[0128] In one example, the inkjet ink may be made by first combining the fatty acid (A), first and second linear alkane 1 ,2-diols ((Bl), (B2)), the organic solvent (C), water (D), and any optional resins, solvents, surfactants, or other additives in a vessel, followed by stirring for at least 10 minutes. The colorant (G) may then be added as the final component with continued mixing, and the solution may then be mixed for at least 10 minutes to afford the inkjet ink. The resulting inkjet ink may then be placed into a printing cartridge, such as e.g., a HP45Si printer cartridge made by Hewlett Packard, a FUNAI TIJ cartridge made by Funai Co., or some other suitable printhead.

[0129]

Properties

[0130]

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

[0131]

The inkjet inks disclosed herein may also be characterized by a long running stability (also known as ink longevity or print longevity). To test the inkjet inks for running stability, the head nozzle was visually observed after continuously printing 3,600 pages.

[0132]

The case with a large amount of ink accumulation (see, for example, Fig. 1 A using Ink-2) was evaluated as Not Good, “NG.” This ink accumulation results from dripping. The case with no ink accumulation at all (see, for example, Fig. IB using Ink-1) was evaluated as Good, “G.” The case with a slight accumulation of ink (see, for example, Fig. 1C using Ink- 17) was evaluated as Acceptable, “A”

Printed Article

[0133]

The printed article of this invention comprises a substrate and a dried form of the inkjet ink of this invention disposed on the substrate by side shoot printing.

[0134]

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

[0135]

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

[0136]

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

Method of Forming a Printed Image

[0137]

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

[01 8]

With side shoot inkjet printing, a desired printed image is formed when a precise pattern of dots is ejected horizontally from a drop-generating device, known as a printhead, onto a print medium.

[0139]

In one embodiment, a line along the shortest distance between a nozzle of the thermal inkjet printhead supplying the inkjet ink and the substrate forms a smallest angle in a range of 70° to 90°, preferably 80° to 90°, preferably 85° to 90°, or about 90° (perpendicular) with the direction of gravity. In this embodiment, it may be considered that the ink is shot sideways, horizontally, or perpendicular to gravity. In one embodiment, the substrate is positioned substantially vertically during the printing, meaning that a normal line from the substrate forms a smallest angle of the abovementioned ranges with the direction of gravity.

[0140]

The printhead has an array of precisely formed nozzles located on a nozzle plate and attached to an inkjet printhead substrate. The inkjet printhead substrate incorporates an array of firing chambers that receive inkjet ink through fluid communication with one or more ink reservoirs. Each firing chamber has a resistor element, known as a firing resistor, located opposite the nozzle so that the inkjet ink collects between the firing resistor and the nozzle. Each resistor element is typically a pad of a resistive material and measures, for example, about 35 pm x 35 pm. The printhead is held and protected by an outer packaging referred to as a print cartridge or an inkjet pen. Upon energizing of a particular resistor element, a droplet of inkjet ink is expelled through the nozzle toward the print medium. The firing of ink droplets is typically under the control of a microprocessor, the signals of which are conveyed by electrical traces to the resistor elements, forming alphanumeric and other image patterns on the print medium Since the nozzles are small, typically 10 pm to 40 pm in diameter, inks that minimize clogging are desired. In particular, since thermal inkjet (TIJ) printing uses an open atmosphere printhead design (the nozzle orifices are open to atmosphere and there is no valve seal at the orifice to allow ink pressurization), TIJ printing has historically suffered from poor performance during intermittent printing, where decap time (print idle time) causes premature drying of ink in and around the nozzles, especially in cold, dry environments. Decap times for printed images of acceptable quality decreases for typical inkjet inks in the context of side shoot printing. Here, the horizontal path of the ink allows for more ink accumulation and clogging around the nozzle. The present disclosure provides a method of forming a printed image by side shoot printing any of the inkjet inks of the present disclosure, in one or more of its embodiments, onto a surface of a substrate by a thermal inkjet printhead and drying the inkjet ink. Use of the inkjet inks described herein overcomes the problem of short decap time (rate of solvent loss is too fast) commonly associated with thermal inkjet processes, across a range of temperatures and humidities.

[0142]

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

[0143]

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

[0144]

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

[0145]

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

The following clauses are further illustrative of the embodiments of the inkjet ink , the method for forming a printed image on a substrate by side-shoot printing, and use of the inkj et ink. [0146]

The inkjet ink for printing by shooting sideways onto a substrate with an inkjet printhead, the inkjet ink comprising:

(A) oleic acid in an amount of 0.2 to 1.5 wt%, based on a total weight of the inkjet ink;

(Bl) 1,2-propanediol in an amount of 1 to 10 wt%, based on a total weight of the inkj et ink;

(B2) 1,2-hexanediol in an amount of O.lto 10 wt%, based on a total weight of the inkj et ink;

(C) dimethyl sulfone in an amount of 1 to 20 wt%, based on a total weight of the inkj et ink; and

(D) water, wherein a weight ratio of the 1,2-propanediol to the 1,2-hexanediol in the inkjet ink is from 1.7: 1 to 2: 1

[0147]

<2>

(Bl) 1,2-propanediol in an amount of 1 to 10 wt%, based on a total weight of the inkj et ink; (B2) 1,2-hexanediol in an amount of 0.1 to 10 wt%, based on a total weight of the inkjet ink;

(C) dimethyl sulfone in an amount of 1 to 20 wt%, based on a total weight of the inkj et ink;

(E) triethanolamine in an amount of 0.1 to 1 wt%, based on a total weight of the inkjet ink; and

(D) water, wherein a weight ratio of the 1,2-propanediol to the 1,2-hexanediol in the inkjet ink is from 1.7: 1 to 2: 1.

[0148]

<3>

A method for forming a printed image on a substrate by side-shoot printing, the method comprising: applying the inkjet ink of any one of <1 > to <2> sideways onto the substrate with a thermal inkjet printhead; and drying the inkj et ink.

[0149]

<4>

The use of the inkjet ink of any one of <1> to <3> for printing by shooting sideways onto a substrate with an inkjet printhead.

EXAMPLES

Materials [0150]

Glycol Ether DTI was obtained as DOWANOL EPh6 from Dow Chemical Company and is a polyethylene glycol phenyl ether having a major component with a molecular weight of 358 g/mol.

[0151]

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

[0152]

TEGO TWIN 4200 is a siloxane-based gemini surfactant, available from Evonik Industries.

[0153]

PELEX OT-P is dioctyl sodium sulfosuccinate (DSS), available from Kao Chemicals.

LUNAC O-V is oleic acid, available from Kao Chemicals.

[0154]

ORIENT 191L is a colorant solution comprising 15 wt% Direct Black 19 (water soluble dye). ORIENT 191 L is available from Orient Chemical Industries Co., Ltd.

Inkjet ink examples

[0155]

Example inkjet inks are given in Tables 1 to 8, with the Comparative Examples being indicated with an asterisk. The amount of each component is expressed in terms of weight percentage based on a total weight ( 100%) of the inkjet ink. The compound names of the tradenames are indicated above. The ORIENT 191 L indicated in Tables 1 to 8 is a 15 wt% aqueous solution of Direct Black 19. Preparation methods

[0156]

The inkjet ink was obtained by the following method: Dimethyl sulfone was mixed with water using a stirrer until the dimethyl sulfone completely dissolved. Then, co-solvents were added dropwise into the mixture and mixed for at least 15 min. The colorant was then added and mixed for at least 15 min to obtain the inkjet ink. The inks were then evaluated as described below, with the results summarized in each of the Tables 1 to 8.

Inkjet ink evaluation methods

Printing sample preparation

[0157]

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

Decap time evaluation

[0158]

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

[0159]

- Printing mode: side shoot printing, where the print cartridge is set with the nozzle surface tilted approximately 90 degrees from the horizontal plane and printing is performed.

- Printing substrate: normal (non-coated) paper

- Printing resolution: 300 dpi x 300 dpi (vertical ^x horizontal)

- Print speed: 7 m/min - Pulse width: 1.8 ps

- Voltage: 8.6 V

- Pulse warming: OFF

[0160]

- Printing image: 100% duty (Monochrome bitmap) (see e.g., Figs. 2A-2B and 3A-3B). The images have a height of 1.2 cm and a length of 4.8 cm (0.5 in. * 1.9 in.).

[0161]

- Printing environment: 10 °C (50 °F) at 30% relative humidity or 35 °C (95 °F) at 85% relative humidity. Figs. 2A-2B and 3A-3B were printed in environments of 35 °C at 85% relative humidity.

[0162]

An image including a numeric sequence was printed to confirm that there were no missing or unclear lines included in the printed image (signifying plugged or missing nozzles). After confirming, the printhead was left decapped for a specific time (1 min, 3 min, 5, min, 10 min, 15 min, 30 min, 45 min, or 60 min), and then the same image was reprinted The reprinted image (after the specific time lapse) was checked to determine whether loss of lines/loss of line clarity occurred. If no loss of lines/loss of line clarity occurred, then the inkjet inks were given a “Good” (G) decap rating for that time interval. Fig. 3B is an example of an inkjet ink printing with a “Good” decap rating. If 1-10 lines were lost, or if clarity was lost at the tested time interval, but not enough to significantly affect the clarity or readability of the image at the tested time interval, then the inkjet ink was given an “Acceptable” (A) decap rating for that time interval. If more than 10 lines were lost, or if clarity and/or readability was significantly lost at the tested time interval, then the inkjet ink was classified as “Not Good” at that time interval.

[0163] Figs. 2A-2B and 3A-3B were printed in environments of 35 °C at 85% relative humidity. Figs. 2A and 2B were each printed with comparative example Ink-2, and Figs. 3A and 3B were each printed with inventive Ink-1. Fig. 2B shows an example of inkjet ink printing that would be classified as “Not Good.” Suitable/desirable inkjet inks are those which achieve an “Acceptable” or “Good” decap classification when decapped (z.e., exposed to air) for each of the tested time intervals and environmental conditions. For instance, Fig.

3B shows an example of an inkjet ink printing that would be classified as “Good.”

[0164]

Table 1. Inkjet ink compositions with running stability and decap results 1

G = Good

A = Acceptable

NG = Not Good Table 2. Inkjet ink compositions with running stability and decap results 2

Table 3. Inkjet ink compositions with running stability and decap results 3

Table 4. Inkjet ink compositions with running stability and decap results 4

Table 5 Inkjet ink compositions with running stability and decap results 5

Table 6 Inkjet ink compositions with running stability and decap results 6

Table 7 Inkjet ink compositions and Running stability and decap results 7

Table 8 Inkjet ink compositions and Running stability and decap results 8

Inkjet ink performance

[0165]

From Tables 1, 3, and 5 to 7, it can be seen that the combination of an unsaturated fatty acid, first and second linear alkane 1,2-diols, and an organic solvent resulted in remarkable effects in terms of running stability and decap times at different temperatures and humidities when side shoot printing (See Examples 1, 3, 4, 9, 11, 13, 15, and 17).

Conversely, inkjet inks formulated with 1,3 -propanediol or glycerol in place of one of the linear alkane 1,2-diols exhibited poor decap behavior and running stability (See Table 4, Comparative Examples 7 and 8). Inkjet inks formulated with lauric acid (melting point 43 °C) as the fatty acid (See Table 3, Comparative Example 5) exhibited poor performance as compared to the inkjet inks comprising equal weight percentages of oleic acid, linoleic acid, and elaidic acid (See Table 3, Examples 1, 3, and 4, respectively). Table 1, Examples 1 and 17 show that dimethyl sulfone or 2-pyrrolidone could be used as the solvent for advantageous effects of running stability and decap behavior.

Claims

1 . An inkjet ink for printing by shooting sideways onto a substrate with an inkjet printhead, the inkjet ink comprising:

(A) a fatty acid comprising an unsaturated fatty acid;

(C) an organic solvent; and

(D) water, wherein the first linear alkane 1,2-diol (Bl) and the second linear alkane 1,2-diol (B2) are each present independently in an amount of 0.1 to 10 wt%, based on a total weight of the inkj et ink.

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

3. The inkjet ink of claim 1 or 2, wherein the organic solvent (C) comprises dimethyl sulfone.

4. The inkjet ink of any one of claims 1 to 3, wherein the water (D) is present in an amount of 40 to 80 wt%, based on a total weight of the inkjet ink.

5. The inkjet ink of any one of claims 1 to 4, wherein the fatty acid (A) is present in an amount of 0. 1 to 5 wt%, based on a total weight of the inkjet ink.

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

7. The inkjet ink of any one of claims 1 to 6, wherein the first and second linear alkane 1,2-diol combined ((B1)+(B2)) are present in the inkjet ink in an amount of 5 to 20 wt%, based on a total weight of the inkjet ink.

8. The inkjet ink of any one of claims 1 to 7, wherein the first linear alkane 1,2-diol (Bl) is 1,2-propanediol, and wherein the second linear alkane 1,2-diol (B2) is 1,2-hexanediol.

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

10 The inkjet ink of any one of claims 1 to 9, wherein the inkjet ink further comprises (F.) an alkanolamine.

11. The inkjet ink of claim 10, wherein the alkanolamine (E) is present in an amount of 0.01 to 5 wt%, based on a total weight of the inkjet ink.

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

13. The inkjet ink of any one of claims 1 to 12, wherein the inkjet ink further comprises one or more surfactants (F) in a combined amount of 0 01 to 5 wt%, based on a total weight of the inkj et ink.

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

15. The inkjet ink of claim 14, wherein the colorant (G) is present in an amount of 0.1 to 30 wt%, based on a total weight of the inkjet ink.

16. The inkjet ink of any one of claims 1 to 15, wherein the inkjet ink further comprises one or more glycol ethers (H) present in a total amount of 0.1 to 5.0 wt%, based on a total weight of the inkj et ink.

17 A method for forming a printed image on a substrate by side-shoot printing, the method comprising: applying the inkjet ink of any one of claims 1 to 16 sideways onto the substrate with a thermal inkjet printhead; and drying the inkj et ink.

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

19. A use of the inkjet ink of any one of claims 1 to 16 for printing by shooting sideways onto a substrate with an inkjet printhead.