WO2019160961A1 - Aqueous digital inkjet ink - Google Patents

Abstract

An aqueous digital inkjet ink containing a water dispersible polyester-based pigment dispersion, a high boiling point humectant, and a polyurethane. The composition may also contain antimicrobials, surfactants, wetting agents, dispersants, leveling or slip aids, or defoamers. The compositions provide benefits of adhering to substrates, such as textiles, without the need to pretreat the substrates.

Description

AQUEOUS DIGITAL INKJET INK

RELATED APPLICATION

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application Serial Number 62/630,472, filed on February 14, 2018, the contents of which are incorporated in this application by reference.

TECHNICAL FIELD

[0002] The present invention relates to an aqueous-based pigmented ink formulation useful in digital applications and the method of use thereof. In particular, the invention relates to a formulation containing a water dispersible polyester-based pigment dispersion, a high boiling point humectant, and a polyurethane dispersion.

BACKGROUND OF THE INVENTION

[0003] Digital printing refers to methods of printing from a digital-based image directly to a variety of media substrates. It usually refers to professional printing where small-run jobs from desktop publishing and other digital sources are printed using large-format and/or high-volume laser or inkjet printers. Inks employed in such applications are referred to as“digital inks.”

[0004] Aqueous pigmented digital inks traditionally have to straddle a balance between printability (i.e., getting the pigment through the printhead nozzle) and performance on a substrate. Digital inks must maintain low viscosity in order to get the ink properly through the nozzle. At the same time digital inks must maintain high humectancy in order to prevent the ink from drying and thereby clogging the nozzle when the nozzle is open for a time. Increased humectancy increases the viscosity of the ink. In addition, additives necessary for increased substrate performance also increase viscosity. [0005] As increased viscosity decreases the likelihood that the ink will fire from the nozzles, there is limited formulation space available for humectants and substrate performance additives in aqueous pigmented digital inks. Because increased humectancy is also required in order to prevent the ink from drying and thereby clogging the nozzle when the nozzle is open for a time, the limited formulation space is typically taken up by the humectants. As a result, digital inks typically lack substrate performance additives, which limits the utility of digital printing methods compared to traditionally applied analog printing methods (e.g., screen printing) in certain applications.

[0006] One such application where analog printing methods are better than current digital printing methods is textile applications. In textile applications, crockfastness and washfastness properties of analog printing methods are currently unachievable with digital printing methods. This is because current digital inks cannot include enough substrate performance additives, such as resin to adequately adhere the pigment to the substrate, without clogging the print nozzles. As analog printing methods are not restricted by print nozzles, they do not suffer from the same printability problems.

[0007] This digital printability problem has typically been addressed by utilizing in-situ polymerization of acrylates onto particle surfaces to make low viscosity dispersions by covalently linking the stabilizing molecule onto the surface of the particle. This has the drawback of limiting stabilization to acrylates (or other in-situ polymerizable systems) and limits the total amount of material that can be used to stabilize the particle due to limited anchor points for that covalent linkage. Thus, many of these systems do not have long-term shelf-stability and so the printability of the ink degrades over time. [0008] The on-substrate performance issues have attempted to be addressed by the incorporation of polyurethanes or other materials that adhere to the substrate. The issue with polyurethane systems is twofold. First, the polyurethane adds viscosity, so formulations are limited in the amount of urethane that can be put in the system before the nozzles start clogging. Second, because all of the formulation space (i.e., excess viscosity) is used for the polyurethane, there is no room to add humectants. Thus, urethane-containing inks have been found to clog inkjet nozzles due to the nozzles being left open for a time.

[0009] Other means of adhering inks to substrates include solubilization of resin materials in a solvent-based ink or using radiation-curable inks to cure the ink to the substrate following printing. In the solvent case, the resin is loaded at a high enough concentration to allow film formation upon deposition onto the substrate surface but that film is soluble in the ink itself and so nozzle clogging is limited. These systems however have the disadvantage of inherently being environmentally unfriendly due to their solvent use. In the radiation-curable case, monomers are polymerized using radiation following deposition on the surface, again forming a film that is somewhat difficult to remove. These materials present heat and light stability issues from a storage perspective. They also present health and safety issues for the substrate, particularly if it will be brought into direct contact with skin.

[0010] Colorants may be dispersed in a water dispersible polyester using methods known to those skilled in the art. For example, the dispersing steps may utilize a 2-roll mill, media mill, ball mill, attritor or microfluidizer.

[0011] Colors may also be measured mathematically. For example, the Hunter L, a, b color space describes all perceivable colors in three dimensions: L for lightness, a for green-red, and b for blue-yellow. FIG. 1 depicts the Hunter L, a, b color scale. In the Hunter L, a, b color space, the L axis runs from top to bottom. The maximum for L is 100, which would be a perfect reflecting diffuser (i.e., the lightest white). The minimum for L would be 0 which would be a perfect absorber (i.e., the darkest black). The a and b axes have no specific numerical limits. Positive a is red. Negative a is green. Positive b is yellow. Negative b is blue.

[0012] One of the most important attributes of the Hunter L, a, b model is device independence. This means that the colors are defined independent of their nature of creation or the device they are displayed on. The L* value of the Hunter L, a, b color scale can be obtained using any HunterLab color measurement instrument and is calculated using the formula:

L = 100

wherein Y is the CIE tristimulus value and Y_n is the tristimulus value for the illuminant. The Hunter L, a, b model permits the quantification of how dark a product actually is. The darker the product, the more pigment that has actually adhered to the substrate.

[0013] Thus, there is a need for a printable, rewettable aqueous ink that doesn’t clog inkjet nozzles while enhancing the on-substrate performance of the ink, approaching that of conventional analog printing methods without the need to pretreat the substrate.

BRIEF SUMMARY OF THE INVENTION

[0014] The present invention employs an aqueous-based ink formulated with a water dispersible polyester-based pigment dispersion, a high boiling point humectant, and a polyurethane. In certain embodiments, the polyurethane is an aqueous-based polyurethane dispersion. Not wishing to be bound by a particular theory, it is believed that the polyester stabilizes the pigment dispersion. It is also believed that at the conditions used for fixation, the water dispersible polyester and the polyester-based polyurethane are hydrolyzing and cross- linking with each other, covalently bonding the pigment to the polyurethane resin being used to bind to the substrate. Furthermore, fixation/drying of printed textiles may occur at elevated temperatures and pressures depending on the type of substrate. As a result, the polyesters are further susceptible to hydrolysis, particularly at elevated temperatures, if the polymer linkages are exposed to significant amounts of water. Such an interaction does not involve film formation across a substrate and trapping of the pigment to the surface underneath a film, but rather involves covalently linking the pigment to the formed film. This is one reason why the performance of this particular composition is superior to the performance of traditional compositions with similar amounts and types of polyurethane.

[0015] The ink formulation may also contain antimicrobials, surfactants, wetting agents, dispersants, defoamers, slip and leveling agents, and other ink components known to those skilled in the art.

[0016] The colorants used may include soluble and insoluble colorants, such as - but not limited to - organic pigments, inorganic pigments, carbon black and carbon nanotubes. Surface active agents may also be used to increase the dispersibility of the colorant prior to incorporation with the water dispersible polyester.

[0017] The water dispersible polyester may be chosen from a carboxylated, sulfonated, phosphate, or phosphonated polyester. The glass transition temperatures for such polymers may range from about 0 °C to about 90 °C. Furthermore, the charge densities may range from about 0.2 meq/g to about 1.0 meq/g. In one embodiment, the water dispersible polyester is a sulfonated polyester with a glass transition temperature of about 55 °C and a charge density of about 0.66 meq/g. [0018] The ratio of pigment to water dispersible polyester may range from about 5% to about 65% by dry weight of the two components. In such embodiments, the pigment and the water dispersible polyester are present at a ratio from about 5:95 to about to about 65:35 by weight. In other embodiments, the pigment and the water dispersible polyester are present at a ratio from: about 10:90 to about to about 60:40 by weight, about 15:85 to about to about 55:45 by weight, 20:80 to about to about 50:50 by weight, from about, 25:75 to about to about 45:55 by weight, 30:70 to about to about 40:60 by weight.

[0019] Humectants may be ethylene glycol, glycerol, dipropylene glycol hexylene glycol, butylene glycol, alpha hydroxy acids, glyceryl triacetate, sorbitol, xylitol, maltitol, sugar alcohols, aloe, or mixtures thereof.

[0020] Polyurethanes used may be nonionic or anionic. In addition, they can be polycarbonate-based polyurethanes, polyester-based polyurethanes, or polyether-based polyurethanes. In one embodiment, the polyurethane is U6100 supplied by Aberdingk-Boley.

[0021] The water dispersible polyester may further provide the ability to formulate an ink with a low viscosity (5-15 cP at 25 °C) pigment dispersion at pigment concentrations of 3-10 percent. This may allow for formulations using high viscosity components necessary for printing performance (e.g., humectants) or performance on the substrate (e.g., binders).

[0022] In one embodiment, the ink is created by first combining a pigment, a water dispersible polyester, and optionally a surfactant to create a concentrate having a viscosity of from about 10 cP to about 100 cP at 25 °C with a pigment volume of from about 10 to about 26 percent. Next, the concentrate is diluted with water to create a polyester dispersion having a viscosity of from about 2 cP to about 10 cP at 25 °C and a pigment volume of from about 3 to about 10 percent. Finally, the polyester dispersion is mixed with a humectant having a boiling point greater than about 240 °C, and an aqueous-based polyurethane dispersion to create the ink.

[0023] The viscosity of the composition may be measured in any manner known by those skilled in the art. Such as, on a Brookfield Viscometer LVF model, using the small sample adapter with spindle size 18, sample chamber 13R at 30 RPM.

[0024] The compositions disclosed herein also exhibit increased stability with regard to particle size. In certain embodiments particle size range from: about 80 to about 200 nm, about 100 to about 180 nm, or about 100 to about 140 nm. Changes of greater than or less than 20% are not deemed to affect composition stability. In certain embodiments, particle size measurements may be conducted with a Malvern Zetasizer NanoZS particle analyzer from Malvern Instruments Ltd, Malvern, UK. In certain embodiments, the particle size of the composition when stored at 60 °C does not change by more than 20% for at least about 6 weeks, about 8 weeks, about 10 weeks, or about 12 weeks.

[0025] A method of applying the ink via an inkjet printer that is responsive to digital data signals is also disclosed. In such embodiments, the printer is loaded with both the disclosed ink and a substrate to be printed. In certain embodiments, the ink is loaded before the substrate. Conversely, the substrate may be loaded before the ink. Indeed, the ink and substrate may also be loaded at approximately the same time. Digital data signals including a design and execution instructions are transmitted via wired or wireless communication to the printer. In response, the printer, prints the design onto the substrate using the ink and the crocking of the ink, as measured using an AATCC method described in the Example section below is greater than 4.0.

[0026] It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention. BRIEF DESCRIPTION OF THE DRAWING

[0027] The invention is best understood from the following detailed description when read in connection with the accompanying drawing. Included in the drawing are the following figures:

[0028] FIG. l is a diagram of the Hunter L, a, b color space.

[0029] FIG. 2A is a commercially available ink printed using a Dimatix DMP printer following 2 weeks of heat aging at 60 °C.

[0030] FIG. 2B is one embodiment of the disclosed ink printed using a Dimatix DMP printer following 2 weeks of heat aging at 60 °C.

[0031] FIG. 3 is a graphical depiction of the stability characteristics of one embodiment of the of the disclosed ink as compared to two commercially available inks.

[0032] FIG. 4 is an image comparing dry (A) and wet (B) crocking results for one embodiment of the disclosed ink (1) as compared to a commercially available product (2).

[0033] FIG. 5 is an image comparing the L* and crockfastness of the disclosed ink (A) printed on untreated cotton fabric and an ink made exactly the same way as the disclosed ink, except with a nonionic surfactant (BYK190) as the pigment stabilizer rather than the water soluble polyester printed on the same fabric (B), and the modified available ink printed on cationically pretreated fabric.

[0034] FIG. 6 is a graphical depiction of the number of unclogged nozzles when embodiments with varying amounts and types of humectants are open and exposed to the atmosphere for a number of days.

PET ATT ED DESCRIPTION OF THE INVENTION

[0035] Embodiments of the present invention include an aqueous-based ink comprising, consisting essentially of, or consisting of a colorant, water dispersible polyester-based dispersion, a high boiling point humectant, and a polyurethane. The ink formulation may also contain antimicrobials, surfactants, wetting agents, defoamers, slip and leveling agents, and other ink components known to those skilled in the art. Furthermore, the polyurethane may be an aqueous-based polyurethane dispersion.

[0036] As used in the specification and claims, the singular form“a”,“an” and“the” include plural references unless the context clearly dictates otherwise. For example, the term“a monomer” includes a plurality of monomers, including mixtures of monomers.

[0037] As used herein, the term “comprising” is intended to mean that the defined compositions and methods include the recited elements, but not necessarily exclude others. “Consisting essentially of’ when used to define compositions and methods, shall mean to exclude other elements of any essential significance to the combination. Thus, a composition consisting essentially of the elements as defined herein would not exclude trace contaminants from the isolation and purification methods. “Consisting of’ shall mean to exclude more than trace elements of other ingredients. Embodiments defined by each of these transition terms are within the scope of this invention.

[0038] The term“polymer” refers to a molecule composed of repeating structural units. Such repeating units are building blocks provided by polymerized monomers. Unless specifically excluded, the term“polymer” is a mixture of molecules composed of repeating structural units. Further, unless specifically excluded, the term“polymer” also refers to copolymers.

[0039] The term“substrate” refers to any material onto which a liquid ink is applied. For example, when referencing textiles the substrate may be: cotton, polyester, nylon, cotton/poly blends, and nylon/lycra blends. [0040] The phrase“water based” when referring to a polymer means that the polymer is in a stable, homogeneous phase with water. The polymer may be dissolved in water, or the polymer may be in a stable suspension in water, or the polymer may be a stable solution in water, or the polymer may be a stable dispersion in water.

[0041] The term“mixture” refers to any composition that comprises more than one substance. The term refers to both a homogeneous and heterogeneous mixture. The term refers to any composition that comprises more than one substance, regardless of the morphology of the substances or the phase thereof. Thus, the term includes a solution, a suspension, a dispersion, a solid, a foam, a gel, an amalgam, an alloy, and like.

[0042] The name of an element when used to refer to a substituent or to a portion of a molecule or a polymer means that one of more atoms of that element are incorporated within the structure of that molecule, regardless whether the atom is found in the molecule as defined by the class the molecule or not. For example, the nitrogen in the phrase“a nitrogen-containing acrylamide” refers to both the nitrogen which is a part of the amide group, and to any nitrogen- containing groups that may be a substituent on the acrylamide.

[0043] The name of an element, or a group of elements, when used to refer to a substituent or to a portion of a molecule or a polymer, is used regardless of the oxidation state of that atom. For example, the term“a halogen” includes within its definition a halide.

[0044] Water Dispersible Polyester

[0045] The instant compositions include at least one water dispersible polyester. In some embodiments, the water dispersible polyester may be a carboxylated, sulfonated, phosphate, or phosphonated polyester. These exemplary polyesters may be formed by condensation polymerization. [0046] A carboxylated polyester may comprise any water-soluble or water-dispersible polyester material or materials having thereon carboxyl groups or salts thereof. The term “carboxylated polyester’ is meant to include mixtures of various types of carboxylated polyesters, as well as individual types of carboxylated polyester. The carboxylated polyesters may be homopolymers or copolymeric in nature.

[0047] The term“carboxyl group” as used herein is meant to encompass carboxylates as well as their corresponding salts with various metals. Carboxylate groups have generally the formula — M(RCOO)n, wherein M is hydrogen or any metal atom or ion and n is 1, 2, 3, etc. Carboxylate salts in embodiments may be based on alkali metals such as Li, Na, K, Cs, and alkaline earth metals such as Mg, Ca, Sr, Ba. In addition, in some embodiments, carboxylated salts may be based on transition metals or rare earth metals.

[0048] A sulfonated polyester may comprise any water-soluble or wnter-dispersible polyester material or materials having thereon sulfonate groups or salts thereof. The term“sulfonated polyester” is meant to include mixtures of various types of sulfonated polyesters, as well as individual types of sulfonated polyester. The sulfonated polyesters may be homopolymers or copolymeric in nature.

[0049] The term“sulfonate group” as used herein is meant to encompass sulfonates as well as their corresponding salts with various metals. Sulfonate groups have generally the formula— S0₃M, wherein M is hydrogen or any metal atom or ion. Sulfonate salts in embodiments may be based on alkali metals such as Li, Na, K, Cs, and alkaline earth metals such as Mg, Ca, Sr, Ba. In addition, in some embodiments, sulfonate salts may be based on transition metals or rare earth metals. [0050] The sulfonate groups may also he present in a polyester in the form of aryl or hetero aryl sulfonate species or moieties. Exemplary aryl sulfonate species or moieties that may be present in the sulfonated polyester include, by way of example, phenyl sulfonates, naphthyl sulfonates, biphenyl sulfonates, diphenyl ether sulfonates, diphenyl thioether sulfonates, diphenyl alkyl ene sulfonates, bisphenol sulfonate, and other aryl sulfonates.

[0051] In some embodiments the sulfonated polyesters comprise condensation polymer products of diester monomers and glycol monomers, one or both of which may include one or more sulfonate group thereon. Aryl sulfonate groups that may be present in diester and/or glycol monomers include aryl sulfonate species or moieties that may be present in the sulfonated polyester include phenyl sulfonates, naphthyl sulfonates, biphenyl sulfonates, diphenyl ether sulfonates, diphenyl thioether sulfonates, diphenyl alkylene sulfonates, and like aryl sulfonate species as noted above. Monomers containing unsulfonated aryl groups may also be present in copolymer compositions.

[0052] A phosphate polyester may comprise any water-soluble or water-dispersib!e polyester material or materials having thereon phosphate groups or salts thereof. The term“phosphate polyester” is meant to include mixtures of various types of phosphated polyesters, as well as individual types of phosphated polyester. The phosphated polyesters may be homopolymers or copolymeric in nature.

[0053] The term“phosphate group” as used herein is meant to encompass phosphates as well as their corresponding salts with various metals. Phosphate groups have generally the formula — P0_4. Phosphate salts in embodiments may be based on alkali metals such as Li, Na, K, Cs, and alkaline earth metals such as Mg, Ca, Sr, Ba. In addition, in some embodiments, phosphate salts may be based on transition metals or rare earth metals. [0054] A phosphonated polyester may comprise any water-soluble or water-dispersible polyester material or materials having thereon phosphonate groups or salts thereof. The term “phosphonate polyester” is meant to include mixtures of various types of phosphonated polyesters, as well as individual types of phosphonated polyester. The phosphonated polyesters may be homopolymers or copolymeric in nature.

[0055] The term“phosphonated group” as used herein is meant to encompass phosphonates as well as their corresponding salts with various metals. Phosphonated groups have generally the formula — C-PO(OH)₂ or C-PO(OR)₂ (where R = alkyl, aryl). Phosphonate salts in embodiments may be based on alkali metals such as Li, Na, K, Cs, and alkaline earth metals such as Mg, Ca, Sr, Ba. In addition, in some embodiments, phosphonate salts may be based on transition metals or rare earth metals.

[0056] The polyester may have a glass transition temperatures ranging from about 0 °C to about 90 °C.

[0057] The water dispersible polyester may also have a charge density ranging from about 0.2 meq/g to about 1.0 meq/g.

[0058] In one embodiment, the water dispersible polyester is a sulfonated polyester with a glass transition temperature of 55 °C and a charge density of 0.66 meq/g.

[0059] The water dispersible polyester may provide a low viscosity pigment dispersion. For example, before the addition of any humectants or polyurethanes the viscosity of the polyester dispersion may be from about 2 cP to about 10 cP at 25 °C with a pigment concentrations from about 3 to about 10 percent by weight. Such a low viscosity embodiment, allows for formulations using high viscosity components necessary for printing performance or performance on the substrate. [0060] The other difference between traditional dispersants (i.e. non-polyester dispersants) and the water dispersible polyester used as the dispersant in this invention is that there is an interaction between the water dispersible polyester and the polyurethane that may significantly increase abrasion resistance and bond strength to the substrate.

[0061] Colorant

[0062] The instant compositions include at least one colorant. The colorant may be, for example, a pigment.

[0063] Colorants may be dispersed in the water dispersible polyester using methods known to those skilled in the art. For example, the dispersing steps may utilize a 2-roll mill, media mill, ball mill, attritor or microfluidizer.

[0064] The colorants used include soluble and insoluble colorants, such as - but not limited to - organic pigments, inorganic pigments, carbon black and carbon nanotubes.

[0065] Surface active agents may be used to increase the dispensability of the colorant prior to incorporation with the water dispersible polyester. Such surface active agents may be anionic or nonionic. Anionic surface agents may be sulfate, sulfonate and phosphate esters or carboxylate- based surfactants. Nonionics surface agents may be ethoxylates, fatty acid esters, amine oxides, sulfoxides and phosphine oxides.

[0066] The ratio of colorants to water dispersible polyester can range from about 5% to about 65%.

[0067] In one example, the colorant is an aniomcally dispersed pigment. In another example, the anionically dispersed pigment is a dispersion including water, the pigment, and an anionic polymer that disperses the pigment. The dispersion may also include, for example, a co-solvent, such as 2 -pyrrol id one. [0068] The pigment may be any suitable organic and/or inorganic pigment. The pigment may be any color, including, as examples, a cyan pigment, a magenta pigment, a yellow pigment, a black pigment, a violet pigment, a green pigment, a brown pigment, an orange pigment, a purple pigment, a white pigment, a metallic pigment (e.g., a gold pigment, a bronze pigment, or a silver pigment), a pearlescent pigment, or combinations thereof.

[0069] Examples of suitable blue or cyan organic pigments include C.I. Pigment Blue 1, C.I. Pigment Blue 2, C.I. Pigment Blue 3, C.I. Pigment Blue 15, Pigment Blue 15:3, C.I. Pigment Blue 15:34, C.I. Pigment Blue 15:4, C.I. Pigment Blue 16, C.I. Pigment Blue 18, C.I. Pigment. Blue 22, C.I. Pigment Blue 25, C.I. Pigment Blue 60, C.I. Pigment Blue 65, C.I. Pigment Blue 66, C.I. Vat Blue 4, and C.I. Vat Blue 60.

[0070] Examples of suitable magenta, red, or violet organic pigments include C.I. Pigment Red 1, C.I. Pigment Red 2, C.I. Pigment Red 3, C.I. Pigment Red 4, C.I. Pigment. Red 5, C.I. Pigment Red 6, C.I. Pigment Red 7, C.I. Pigment Red 8, C.I. Pigment Red 9, C.I. Pigment Red 10, C.I. Pigment Red 1 1, C.I. Pigment Red 12, C.I. Pigment Red 14, C.I. Pigment Red 15, C.I. Pigment Red 16, C.I. Pigment Red 17, C. I. Pigment Red 18, C. I. Pigment Red 19, C.I. Pigment Red 21, C.I. Pigment Red 22, C.I. Pigment Red 23, C.I. Pigment Red 30, C.I. Pigment Red 31 , C.I. Pigment Red 32, C.I. Pigment Red 37, C.I. Pigment Red 38, C.I. Pigment Red 40, C.I. Pigment Red 41, C.I. Pigment Red 42, C.I. Pigment Red 48(Ca), C.I. Pigment Red 48(Mn), C.I. Pigment Red 57 ( ( a ) C. I. Pigment Red 57: 1, C.I Pigment Red 88, C.I. Pigment Red 1 12, C.I. Pigment Red 114, C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment Red 144, C.I. Pigment Red 146, C.I. Pigment Red 149, C.I. Pigment Red 150, C.I. Pigment Red 166, C.I. Pigment Red 168, C.I. Pigment Red 170, C.I. Pigment Red 171, C.I. Pigment Red 175, C.I. Pigment Red 176, C.I. Pigment Red 177, C.I. Pigment Red 178, C.I. Pigment Red 179, C.I. Pigment Red 184, C.I. Pigment Red 185, C.I. Pigment Red 187, C.I. Pigment Red 202, C.I. Pigment Red 209, C.I.

Pigment Red 219, C.I. Pigment Red 224, C.I. Pigment Red 245, C.I. Pigment Red 286, C.I.

Pigment Violet 19, C.I. Pigment Violet 23, C.I. Pigment Violet 32, C.I. Pigment Violet 33, C.I.

Pigment Violet 36, C.I. Pigment Violet 38, C.I. Pigment Violet 43, and C.I. Pigment Violet 50.

[0071] Examples of suitable yellow organic pigments include C.I. Pigment Yellow 1, C.I. Pigment Yellow 2, C.I. Pigment Yellow 3, C.I. Pigment Yellow 4, C.I. Pigment Yellow 5, C.I. Pigment Yellow 6, C. I. Pigment Yellow 7, C.I. Pigment Yellow 10, C.I Pigment Yellow 11, C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow 16, C.I. Pigment Yellow 17, C.I. Pigment Y'eilow 24, C.I. Pigment Yellow 34, C.I. Pigment Yellow 35, C.I. Pigment Yellow 37, C.I. Pigment Yellow 53, C.I. Pigment Yellow 55, C.I. Pigment Yellow 65, C.I Pigment Yellow 73, C.I. Pigment Yellow 74, C.I Pigment Yellow 75, C.I. Pigment Yellow 77, C.I. Pigment Yellow 81 , C.I. Pigment Yellow 83, C.I. Pigment Yellow 93, C.I. Pigment Yellow- 94, C.I. Pigment Yellow 95, C.I. Pigment Yellow 97, C.I. Pigment Y'ellow 98, C.I. Pigment Yellow 99, C.I. Pigment Yellow 108, C.I. Pigment YYIlow 109, C.I. Pigment Yellow 1 10, C.I. Pigment Yellow 1 13, C.I. Pigment Yellow 1 14, C.I. Pigment Yellow 1 17, C.I Pigment Yellow 120, C.I. Pigment Yellow 122, C.I. Pigment Yellow 124, C.I. Pigment Yellow 128, C.I. Pigment Yellow 129, C.I. Pigment Yellow 133, C.I. Pigment Yellow 138, C.I. Pigment Yellow 139, C.I. Pigment Y ellow 147, C.I. Pigment Yellow 151, C.I. Pigment YYIlow 153, C.I. Pigment Yellow 154, C.I. Pigment Yellow 167, C.I. Pigment Yellow 172, C.I. Pigment Yellow 180, and C.I. Pigment Yellow- 185.

[0072] C’arbon black may be a suitable inorganic black pigment. Examples of carbon black pigments include those manufactured by Mitsubishi Chemical Corporation, Japan (such as, e.g., carbon black No. 2300, No. 900, MCI 88. No. 33, No. 40, No 45, No. 52, MA7, MA8, MAI 00, and No. 2200B); various carbon black pigments of the RAVEN® series manufactured by Columbian Chemicals Company, Marietta, Ga., (such as, e.g., RAVEN® 5750, RAVEN® 5250, RAVEN® 5000, RAVEN® 3500, RAVEN® 1255, and RAVEN® 700), various carbon black pigments of the REGAL® series, the MOGUL® series, or the MONARCH® series manufactured by Cabot Corporation, Boston, Mass., (such as, e.g., REGAL® 400R, REGAL® 33 OR, and REGAL® 660R); various black pigments manufactured by Evonik Degussa Corporation, Parsippany, N.J., (such as, e.g., Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black SI 50, Color Black SI 60, Color Black SI 70, PRINTEX® 35, PRINTEX® U, PRINTEX® V, PRINTER® 14QU, Special Black 5, Special Black 4A, and Special Black 4), and various carbon black pigments of the BLACK PEARLS® series manufactured by Cabot Corporation, Boston, Ma., (such as, e.g., BLACK PEARLS® 1300, BLACK PEARLS® 900, BLACK PEARLS® 800, BLACK PEARLS® 717, BLACK PEARLS® 4840, and BLACK PEARLS® 630). An example of an organic black pigment includes aniline black, such as C.I. Pigment Black 1.

[0073] Some examples of green organic pigments include C.I. Pigment Green 1, C.I. Pigment Green 2, C.I. Pigment Green 4, C.I. Pigment Green 7, C.I. Pigment Green 8, C.I. Pigment Green 10, C.I. Pigment Green 36, and C.I. Pigment Green 45.

[0074] Examples of brown organic pigments include C.I. Pigment Brown I, C.I. Pigment Brown 5, C.I. Pigment Brown 22, C.I. Pigment Brown 23, C.I. Pigment Brown 25, C.I. Pigment Brown 41 , and C.I. Pigment Brown 42.

[0075] Some examples of orange organic pigments include C.I. Pigment Orange 1, C.I. Pigment Orange 2, C.I. Pigment Orange 5, C.I. Pigment Orange 7, C.I. Pigment Orange 13, C.I. Pigment Orange 15, C.I. Pigment Orange 16, C.I. Pigment Orange 17, C.I. Pigment Orange 19, C.I Pigment Orange 24, C.I. Pigment Orange 34, C.I. Pigment Orange 36, C.I. Pigment Orange 38, C.I Pigment Orange 40, C.I. Pigment Orange 43, and C.L Pigment Orange 66.

[0076] A suitable metallic pigment includes a metal chosen from gold, silver, platinum, nickel, chromium, tin, zinc, indium, titanium, copper, aluminum, and alloys of any of these metals. These metals may be used alone or in combination with two or more metals or metal alloys. Some examples of metallic pigments include STAND ART® R0100, STAND ART® R0200, and DORADO® gold-bronze pigments (available from Eckart Effect Pigments, Wesel, Germany)

[0077] In one example, the pigment is dispersed by the anionic polymer. The total amount of pigment in the ink may range from about 1 wt % to about 10 wt % (based on the total wt % of the ink). The average particle size (D50) of the pigments may be less than about 200 nm. Indeed, the average particle size (D50) may range anywhere from about 40 nm to about 200 nm. In a non-limiting embodiment, the average particle size (D50) may range anywhere from about 80 nm to about 200 nm.

[0078] Humectant

[0079] The instant compositions include at least one humectant. The humectant prevents drying of the ink on the inkjet nozzle and ensures that the ink prints properly. This is done by ensuring that the resin components of the ink formulation are not allowed to dry on the inkjet nozzle and form a blockage.

[0080] In certain embodiments, water and the humectant may form an azeotrope. In one embodiment, the azeotrope may be a negative azeotrope, whereby the boiling point of the azeotrope is greater than the boiling point of any of its constituents. In one embodiment the azeotrope is comprised of 2, 3, 4, 5, or 6 components. [0081] In one embodiment, the humectant is a high boiling point humectant. For example, the boiling point of the humectant may be greater than 240 °C.

[0082] In another embodiment, the humectant may be selected from a group consisting of ethylene glycol, glycerol, dipropylene glycol hexylene glycol, butylene glycol, alpha hydroxy acids, glyceryl triacetate, sorbitol, xylitol, maltitol, sugar alcohols, aloe, or mixtures thereof. For example, the humectant may be glycerol.

[0083] Polyurethane Dispersion

[0084] The instant compositions include at least one polyurethane. In certain embodiments, the polyurethane is an aqueous dispersion or emulsion of a polymer containing urethane groups (e.g., polyurethane). Such embodiments may comprise a crosslinked polyurethane. The crosslinked polyurethane is combined with the water dispersible polyester and colorant to produce a stable ink that can be used to print on textiles. In certain embodiments, the crosslinked polyurethane has substantially all of its crosslinking completed prior to its addition to the other ink components.

[0085] In certain embodiments, the polyurethanes used are aqueous dispersions that may be nonionic or anionic. Furthermore, in other embodiments, the polyurethanes may be polycarbonate-based polyurethanes, polyester-based polyurethanes, or polyether-based polyurethanes. For example, the polyurethane may be a polyester-based polyurethane such as U6100 supplied by Aberdingk-Boley.

[0086] In certain embodiments, the polyurethane may provide a balance between modulus and abrasion resistance. This balance may prevent the abrasion resistance from being too high which may cause the material to crack upon washing. Conversely, if the abrasion resistance is too low, the ink may rub off in an unacceptable manner. [0087] Surfactants

[0088] Non-ionic, cationic, and/or anionic surfactants may be present in total in the aqueous- based ink in a range from about 0.01 wt % to about 5 wt %. As an example, the ink may include non-ionic, ionic, cationic, and/or anionic surfactants. Examples of nonionic surfactants include ethoxylates, fatty acid esters and sulfoxides. Examples of ionic surfactants include sulfate and sulfonate-based surfactants. In one embodiment, the composition may contain the non-ionic surfactant Surfynol 465. In another embodiment, the composition may contain the ionic surfactant Dowfax 2A1. The composition may also include a silicone-free alkoxylated alcohol surfactant such as, for example, TEGO® Wet 510 (Evonik Tego Chemie GmbH).

[0089] The surfactant component is optional and may be added at any stage of the ink production. For example, in one embodiment, a surfactant is added to the pigment/polyester mixture in an amount from about 0 to about 20 wt %.

[0090] Wetting Agents

[0091] In some embodiments, the aqueous-based ink may include a self-emulsifiable wetting agent. The wetting agent may be based on acetylenic diol chemistry (e.g., SETRFYNOL® SE-F surfactant from Air Products and Chemicals, Inc.). A total amount of the wetting agent in the aqueous-based ink may range from about 0.05 wt % to about 2 wt %.

[0092] Antimicrobials

[0093] Antimicrobial agents, such as biocides and fungicides, may be added to inhibit the growth of harmful microorganisms. Example antimicrobial agents may include the NUOSEPT® (Ashland Inc ), UCARCIDE™ or KORDEK™ (Dow Chemical Co ), and PROXEL® (Arch Chemicals) series, and combinations thereof. A total amount of the antimicrobial agents in the aqueous-based ink may range from about 0.05 wt % to about 1 wt % or from about 0.1 wt % to about 0.25 wt %.

[0094] Defoamers

[0095] The composition may also contain a defoamer. Examples of defoamers may include silicones, EO/PO-based defoamers, alkyl polyacrylates, or a combination thereof. The total amount of defoamers in the aqueous-based ink may range from about 0.05 wt % to about 1 wt % or from about 0.1 wt % to about 0.25 wt %.

[0096] Concentrate

[0097] The instant compositions may comprise a concentrate which is a highly loaded pigment dispersion that can be diluted with other components into a usable ink formulation.

[0098] In one embodiment, the color concentrate includes a water soluble polyester, a pigment and an optional surfactant. Pigment concentrations in the color concentrate can range from about 10 to about 26 wt%. Water soluble polyester concentrations in the color concentrate may range from about 0.5 to 17 wt%. The optional surfactant may range from about 0 to about 10 wt%. The rest of the color concentrate may be water, which may be deionized. The final viscosity of this color concentrate may ranges from about 10 to about 100 cP.

[0099] The color concentrate may be diluted into a final ink form. Such dilution may include mixing the color concentrate with various ink components, including a humectant, surfactant, polyurethane dispersion, antimicrobial, wetting agent, leveling or slip aid, or combination thereof. In one embodiment, when the color concentrate is diluted with only water, its viscosity may range from about 2 to about 10 cP at pigment concentrations from about 3 to about 10 wt%. Such an embodiment may show long-term shelf stability in oven tests. Such low viscosity compositions may provide significant formulation space for higher viscosity components that provide performance benefits, such as the humectant and polyurethane dispersion.

[0100] Application of Composition

[0101] The inks disclosed herein may be applied to a substrate via an inkjet printer that is responsive to digital data signals. In such embodiments, the printer is loaded with both the disclosed ink and a substrate to be printed. In certain embodiments, the ink is loaded before the substrate. Conversely, the substrate may be loaded before the ink. Indeed, the ink and substrate may also be loaded at approximately the same time. Digital data signals including a design and execution instructions are transmitted via wired or wireless communication to the printer. In response, the printer, prints the design onto the substrate using the ink.

[0102] Indeed, the inks disclosed herein may be used across a broad array of substrates. For example, cotton, polyester, nylon, cotton/poly blends, and nylon/lycra blends in textile applications. The composition also allows the use of the ink across other substrates, including thermoplastic and thermoset surfaces, glass, metals, ceramics and composites. Application areas for use include, but are not limited to, direct to garment digital printing and wide format digital printing.

[0103] Not wishing to be bound by a particular theory, it is believed that the polyester stabilizes the pigment dispersion. It is also believed that at the conditions used for fixation, the water dispersible polyester and the polyester-based polyurethane are hydrolyzing and cross- linking with each other, covalently bonding the pigment to the polyurethane resin being used to bind to the textile substrate. Furthermore, fixation/drying of printed textiles may occur at elevated temperatures and pressures depending on the type of substrate. As a result, the polyesters are further susceptible to hydrolysis, particularly at elevated temperatures, if the polymer linkages are exposed to significant amounts of water.

[0104] It is believed that such an interaction does not involve film formation across a substrate and trapping of the pigment to the surface underneath a film, but rather involves covalently linking the pigment to the film. This is another reason why the performance of this particular composition is superior to the performance of a traditional compositions with similar amounts and types of polyurethane.

[0105] Composition Creation

[0106] In one embodiment, the composition is created in a number of ways. For example, the instant compositions may be made by mixing a pigment (carbon black, for example) with the water dispersible polyester-based dispersant, and optionally a surfactant. The humectant and polyurethane may be separately mixed with deionized water. These can be loaded up at concentrations (17-25% for the humectant, 5-9% for the polyurethane) that are not achievable with other heat stable dispersions at viscosities that can be jetted through inkjet nozzles. The two mixtures may then be combined.

[0107] Conversely, other embodiments of the compositions can be made by any method known to those skilled in the art. Other optional ingredients can be added during this mixing process or added to the mixture after the aforementioned mixing or to an individual component prior to the aforementioned mixing step.

[0108] The instant composition can also be made by adding each ingredient separately and mixing the ingredients prior to depositing on the substrate. In some embodiments, the mixing can be just prior to contacting the substrate. In other embodiments, one or more ingredients can be premixed in a separate step prior to bringing all of the ingredients together. [0109] The following examples are included to demonstrate the advantages of the present composition over compositions that contain a nonionic surfactant (BYK190) as the pigment stabilizer rather than the water soluble polyester. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventors to function well in the practice of the invention, and thus can be considered to constitute modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

EXAMPLES

[0110] The following examples are included to more clearly demonstrate the overall nature of the invention. Figs. 2A, 2B, 3, 4, 5, and 6 illustrate the improved results obtained by employing compositions of this invention. These examples are exemplary, not restrictive, of the invention.

[0111] For comparison purposes, a batch of the disclosed ink was prepared, containing about: (1) 5.0% carbon black (BLACK PEARL ® 800); (2) 6.1% sulfonated polyester (AQ55); (3) 20% humectant (Glycol); (4) 20 % polyurethane dispersion, 35% solids (U6100); (5) 2.0% surfactant (Surfynol); (6) 0.2% biocide (Promex 20S); and (7) the remaining volume (46.7%) deionized water.

[0112] The comparative ink, created in the same way as the disclosed ink except with a nonionic surfactant (BYK190) as the pigment stabilizer rather than the water soluble polyester were obtained. These comparative inks consisted of a carbon black dispersion stabilized with a nonylphenol ethoxylate surfactant and acrylic resin(s). The ink further contains a glycol (ethylene glycol or dipropylene glycol), polyethylene glycol and likely a small amount of ethoxylated surfactant and biocide.

[0113] First, the stability of the inks were tested. Specifically, the inks were held open at 60 °C for 12 weeks. Figures 2A and 2B shows a comparative ink (FIG. 2A) and the disclosed ink (FIG. 2B) printed using a Dimatix DMP printer following 2 weeks of heat aging at 60 °C. The disclosed ink print (FIG. 2B) is uniform due to extended shelf stability provided by the water dispersible polyester. The streaks observed in the comparative sample (FIG. 2A) are due to clogging of the inkjet nozzles by the ink used to print the ink. In addition, a Malvern NanoZS dynamic light scattering instrument was used to determine whether there was a change in particle size (i.e., whether the ink particles began to aggregate).

[0114] Figure 3 shows the stability of the disclosed ink versus two comparative samples. In Figure 3, DLS measurements were conducted with a Malvern Zetasizer NanoZS particle analyzer from Malvern Instruments Ltd, Malvern, UK at a wavelength of 633 nm from a 4.0 mW, solid-state He-Ne laser at a scattering angle of 173° and at 25 +/- 0.l°C. The D50 particle sizes reported are based on the intensity average diameter and are an average of three separate particle size measurements. As depicted in Figure 3, the disclosed ink outperform the comparative samples in all cases for cyan, magenta and yellow. The sample from comparative sample 2 does show similar stability for the black ink, however. Overall, the disclosed inks show greatly enhanced stability compared to inks that do not contain the water dispersible polymer.

[0115] Second, the dry and wet crocking was investigated. Specifically, Figure 4 shows dry (A) and wet (B) crocking results for the disclosed inks (A-l, B-l) versus a modification of the disclosed inks whereby BYK190 was used as a dispersant rather than the water soluble polyester (A-2, B-2). Each ink contains 7% polyurethane solids and 20% glycerine and was printed onto cotton fabric using a Dimatix DMP printer. The key difference is that the modified ink contains a traditional surfactant (BYK190) and so does not interact with the polyurethane in a similar way to the water soluble polyester dispersant. Crocking was conducted using AATCC Method TM116 Colorfastness to crocking - rotary vertical crock meter method. Both the wet and dry crocking results for the ink containing the water dispersible polyester are significantly better than the ink with the traditional surfactant.

[0116] Crocking was also investigated using AATCC Method TM116 Colorfastness to crocking - rotary vertical crock meter method for pre-treated and un-treated cotton poplin fabric. Specifically, wet and dry crocking of the disclosed ink was compared to the inks tested in Figure 3. Crocking is the transfer of color from one material to another when the materials are rubbed together. Higher values indicate less color transfer when the textile is rubbed (i.e., less crocking). As Tables 1 and 2 below outline, the disclosed inks outperformed the commercially available inks in all tests.

Table 1 : Average crockfastness measurement for each ink

Table 2: Average crockfastness measurement for each ink

[0119] Third, the fact that the disclosed ink does not require substrate pretreatment was demonstrated. Specifically, as Table 2 and Figure 5 show the disclosed ink printed on untreated cotton fabric (Sample (A)) is subject to less crocking than an acrylic-based commercially available sample printed on the same cotton fabric (Sample (B)) or an acrylic-based commercially available sample printed on a cationically pretreated fabric (Sample (C)). All samples were printed using a Dimatix DMP printer, 4-passes at 600 DPI. The commercially available sample has a slightly better dry crockfastness on pretreated fabric than on untreated fabric but the disclosed ink has significantly better dry crockfastness than either sample, even though the fabric was not pretreated. In addition, L* values were measured as 27.42 (Sample (A)), 34.03 (Sample (B)), and 31.44 (Sample (C)). These results confirm that the disclosed ink (Sample (A)) is darker (i.e., it has more initial color than the commercial samples), further emphasizing the improvement over commercially available inks.

[0120] Finally, the effects of varying amounts and types of the humectant in the disclosed ink was investigated. Figure 6 shows the disclosed ink with varying amounts and types of humectant. Specifically, the humectants either replaced or were replaced by deionized water. The figure shows that 17.5% glycerol had zero impact on the printability of an ink with 7% solid polyurethane. There was, however, some impact on printability for lower humectant concentrations (15%) or lower boiling point (and viscosity) humectants, such as 12% dipropylene glycol, which show clogged print nozzles when allowed to sit overnight uncovered.

[0121] Although illustrated and described above with reference to certain specific embodiments and examples, the present invention is nevertheless not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the invention. It is expressly intended, for example, that all ranges broadly recited in this document include within their scope all narrower ranges which fall within the broader ranges. It is also expressly intended that the steps of the methods of using the various compositions disclosed above are not restricted to any particular order.

Claims

CLAIMS What is claimed is:

1. An aqueous ink composition comprising:

a polyester dispersion, comprising:

a pigment;

a water dispersible polyester;

optionally a surfactant; and

water,

wherein, the polyester dispersion has a viscosity of from about 2 cP to about 10 cP at 25 °C, and a pigment volume of from about 3 to about 10 percent;

a humectant having a boiling point greater than about 190 °C; and a polyurethane.

2. The composition of claim 1, wherein the water dispersible polyester is a carboxylated, sulfonated, phosphate, or phosphonated polyester.

3. The composition of claim 1, wherein the water dispersible polyester has a glass transition temperature of from about 0 °C to about 90 °C.

4. The composition of claim 1, wherein the water dispersible polyester has a charge density of from about 0.2 to about 1.0 meq/g.

5. The composition of claim 1, wherein the water dispersible polyester is a sulfonated polyester with a glass transition temperature of about 55 °C and a charge density of about 0.66 meq/g.

6. The composition of claim 1, wherein the pigment and the water dispersible polyester are present at a ratio from about 5:95 to about to about 65:35 by weight.

7. The composition of claim 1, wherein the humectant is ethylene glycol, glycerol, dipropylene glycol, hexylene glycol, butylene glycol, alpha hydroxy acids, glyceryl triacetate, sorbitol, xylitol, maltitol, sugar alcohols, aloe, or mixtures thereof.

8. The composition of claim 1, wherein the polyurethane dispersion is a polycarbonate-based polyurethane, polyester-based polyurethane, or polyether-based polyurethane.

9. The composition of claim 1, further comprising at least one of

an antimicrobial element;

a surfactant;

a defoamer;

a slip or leveling aid;

and

a wetting agent.

10. The composition of claim 1, wherein the ink has a viscosity of from 5 cP to 15 cP at 25°C and contains from 20 to 25 percent humectants and from 4 to 10 percent polyurethane dispersion.

11. An aqueous ink concentrate comprising:

a polyester dispersion comprising:

a pigment;

a water dispersible polyester;

optionally a surfactant; and water,

wherein the polyester dispersion has a viscosity of from about 10 cP to about 100 cP at 25 °C with a pigment volume of from about 10 to about 26 percent.

12. The composition of claim 11, wherein the water dispersible polyester is a carboxylated, sulfonated, phosphate, or phosphonated polyester.

13. The composition of claim 11, wherein the water dispersible polyester is a sulfonated polyester with a glass transition temperature of about 55 °C and a charge density of about 0.66 meq/g.

14. The composition of claim 11, wherein the ratio of the pigment to the water dispersible polyester is from about 5:95 to about 65:35 by weight.

15. The composition of claim 11, wherein the polyurethane dispersion is a polycarbonate-based polyurethane, polyester-based polyurethane, or polyether-based polyurethane.

16. The composition of claim 11, further comprising at least one of:

a humectant

an antimicrobial element;

a surfactant;

a defoamer;

a slip or leveling aid;

and

a wetting agent.

17. The composition of claim 11, further comprising a humectant selected from the group consisting of ethylene glycol, glycerol, dipropylene glycol, hexylene glycol, butylene glycol, alpha hydroxy acids, glyceryl triacetate, sorbitol, xylitol, maltitol, sugar alcohols, aloe, and mixtures thereof.

18. The composition of claim 17, wherein the ink has a viscosity of from 5 cP to 15 cP at 25 °C a contains fromabout 20 to about 25 percent humectants and from about 4 to about 10 percent polyurethane dispersion.

19. An aqueous inkjet ink prepared by a process comprising the steps of:

combining a pigment, a water dispersible polyester, and optionally a surfactant to create a concentrate having a viscosity of from about 10 cP to about 100 cP at 25 °C with a pigment volume of from about 10 to about 26 percent; diluting the concentrate with water to create a polyester dispersion having a viscosity of from about 2 cP to about 10 cP at 25 °C and a pigment volume of from about 3 to about 10 percent; and

mixing the polyester dispersion with a humectant having a boiling point greater than about 240 °C, and an aqueous-based polyurethane dispersion.

20. The composition of claim 19, wherein, before any additional components are added to the polyester dispersion save for water, the polyester dispersion has a viscosity of from about 2 cP to about 10 cP at 25 ° C and a pigment volume from about 3 to about 10 percent.

21. A method for printing onto a substrate, comprising the steps of:

(a) providing an inkjet printer that is responsive to digital data signals;

(b) loading the printer with a substrate to be printed;

(c) loading the printer with an aqueous ink composition comprising:

a polyester dispersion, comprising:

a pigment, a water dispersible polyester,

optionally a surfactant, and

water,

wherein, the polyester dispersion has a viscosity of from about 2 cP to about 10 cP at 25 °C, and a pigment volume of from about 3 to about 10 percent;

a humectant having a boiling point greater than about 190 °C; and a polyurethane; and

(d) printing onto the substrate using the ink in response to the digital data signals;

wherein crocking of the ink measured using an AATCC method is greater than

4.0.