METHOD THAT USES WATER-BASED HIGH-SPEED INKS WITH ALCOHOL-TOLERANT LATEXES

Description

[0001] The present application claims priority to U.S. Provisional Patent Application No. 62 / 534,891 filed July 20, 2017.FIELD OF THE INVENTION

[0002] The invention disclosed herein is directed to the field of method of high speeding printing of printing inks, and in particular to water-based inks. The inks for use in the invention are printed by flexo or gravure printing.BACKGROUND OF THE INVENTION

[0003] State of the art solvent based inks typically contain slow solvents such as glycol ethers, which keep the ink from drying before it contacts the substrate. However, these solvents cause adverse plate swelling and diminish long term runnability at high speeds (e.g., 2000 feet per minute (fpm) or greater).

[0004] Advantageously, water-based ink formulations are less flammable than solvent-based inks. The flash point of a water-based ink should be less than that of a solvent based ink. This eliminates a potential safety hazard encountered during printing operations. Further, water is a significantly cheaper solvent than the commonly used organic solvents. However, water-based inks known in the art are not suited for high speed printing.

[0005] An opaque water-based ink obtains its opaqueness through the inclusion of a white pigment material in the ink formulation. Titanium dioxide (TiO 2 ) and zinc sulfide (ZnS) are examples of white pigment materials that may be included in an ink. Opaque ink formulations are used to obscure, hide and / or cover underlying ink layers and / or the substrate on which the opaque inks are printed. Opaque ink is also used to enhance the appearance of an ink printed on over the opaque ink. For example, a colored ink printed over an opaque ink will exhibit brighter color and cleaner appearance. Water-based opaque inks are often used in this manner, that is, as first down inks.

[0006] Representative publications showing state of the art formulations include CN105062208, CN102649889, CN103819962, CN104672982, JP2017002266, CN104693888, CN102382510, US8709288, CN104710876, DE102004051019, IN2015MN03487, AU5257799, CN102605678, AU5941200, AU4237702, GB1578859 and US 2015 / 0197649.

[0007] US 2015 / 0197649 describes an alcohol-based printing ink that is based on a polyurethane-urea resin and an alcohol content of at least 50%. US2014 / 015912A1 relates to an aqueous ink composition includes at least 60% water by weight, an acrylic latex polymer suspension, a polyurethane suspension, a polyethylene wax suspension, and an organic solvent that comprises about 10% to about 30% of the ink composition. US5127948A relates to water-based chemical compositions and is concerned, in particular, with water-based inks and varnishes, such as are used in flexographic and gravure printing and other specialised printing and overprinting processes. JPH0741719A relates to a method for the production of water-based printing ink. JPH07126562A relates to water-based gravure printing inks. CN105038402A relates to an aqueous gravure metal gold regulating oil, in particular to an environmentally friendly, water-based gravure metal gold regulating oil suitable for high speed gravure printing and a preparation method thereof. CN100575433C relates to water-based ink and its preparation method, in particular to water-based high-gloss abrasionresistant gravure ink and its preparation method, the ink is suitable for packaging in the field of flexible packaging mainly including food, beverage, medicine, health care products, daily chemical products print.SUMMARY OF THE INVENTION

[0008] The invention is defined by the appended claims. Described herein is a method of flexographic printing and a method of gravure printing a water-based ink that comprises water, a water miscible solvent having a boiling point of about 56°C to about 98°C, wherein in combination, the water and the water-miscible solvent are present in the ink in an amount of 15wt% to 40wt%; and a latex, wherein the latex is present in an amount between 25wt% and 40wt%. The resin particles in the latex increase 0 to 15% in particle size in the presence of a 25wt% aqueous solution of ethanol, wherein the particle size increase is the increase in the size of the resin particles of a latex material upon exposure to a 25wt% aqueous solution of ethanol at a temperature of 25°C for 10 minutes, as determined in a particle size analyzer by dynamic light scattering at 25°C. Flexographic printing is performed on a flexographic press at ≥600 meters / minute. Gravure printing is performed on a gravure press at ≥200 meters / minute. In one aspect, the water miscible solvent comprises about 10wt% to about 30wt% of the inks (based on the total weight of the inks).

[0009] Described are printing methods in which articles are printed with the water-based inks described herein, at high printing speeds.

[0010] The water miscible solvent for use in the invention comprises an alcohol.

[0011] The water miscible solvent for use in the invention comprises an alcohol or a mixture of alcohols.

[0012] In another aspect, the water miscible solvent for use in the invention is an alcohol or a mixture of alcohols.

[0013] The water miscible solvent for use in the invention comprises ethanol.

[0014] In another aspect, the water miscible solvent for use in the invention is ethanol.

[0015] In another aspect, the latex for use in the invention comprises polymeric resin particles, that when exposed to a 25wt% aqueous solution of ethanol at a temperature of 25°C for 10 minutes, undergo a particle size increase of 0% to 10%, preferably 0% to 5.0%, more preferably 0% to 3.0%, and even more preferably 0% to 1.0%.

[0016] In another aspect, the latex for use in the invention comprises acrylic resin particles.

[0017] In another aspect, the latex for use in the invention comprises resin particles of acrylic homo- or co-polymers, for example, co-polymers of styrene-acrylic, styrene-butadiene, vinyl-acrylic, and acrylic-vinyl acetate.

[0018] In another aspect, the water-miscible solvent is present in the inks for use in the invention in an amount of about 10 wt% to about 30wt%, preferably about 10 wt% to about 20wt%.

[0019] In another aspect, the water-based inks for use in the invention further comprise one or more additional resin components, such as for example, a vinyl, a rosin, a polyamide, and mixtures thereof.

[0020] In another aspect, the water-based inks for use in the invention further comprise a surfactant.

[0021] In another aspect, the water-based inks for use in the invention further comprise a defoamer.

[0022] In another aspect, the water-based inks for use in the invention further comprise a dispersant.

[0023] In another aspect, the water-based inks for use in the invention further comprise a wax.

[0024] In another aspect, the water-based inks for use in the invention further comprise colorants, such as white pigments (e.g., TiO 2 ) and colored organic and inorganic pigments.

[0025] The inks for use in the invention are high speed printing inks.

[0026] In one aspect, the inks for use in the invention are flexographic printing inks.

[0027] The inks for use in the invention are printable on a flexographic press at speeds of greater than or equal to (≥) 600 meters / minute.

[0028] In another aspect, the inks for use in the invention have a dynamic surface tension of about 25 dynes / cm to about 35 dynes / cm.

[0029] In another aspect, the inks for use in the invention have a flash point of about ≥40°C, preferably about ≥60°C, and more preferably about ≥80°C.

[0030] In one aspect, the inks for use in the invention contain a colorant. The colorant may be a pigment. The colorant may be a white pigment or a color pigment.

[0031] In one particular aspect, described herein is a water-based high speed flexographic printing ink for use in the invention comprising a water miscible solvent having a boiling point of 56°C to 98°C in an amount of about 10wt% to about 30wt%, water, wherein in combination, the water and the water-miscible solvent are present in the ink in an amount of 15wt% to 40wt%; and an alcohol tolerant latex, wherein the latex is present in an amount between 25wt% and 40wt%;. In a preferred embodiment of the water-based high speed flexographic printing ink for use in the invention, the water miscible solvent is present in the range of about 10wt% to about 20wt% and / or the alcohol tolerant latex is present in the range of about 20wt% to about 50wt%. The amounts are based on the total weight of the ink.

[0032] The water miscible solvent of the water-based high speed flexographic printing ink for use in the invention comprises an alcohol.

[0033] The water miscible solvent of the water-based high speed flexographic printing ink for use in the invention comprises an alcohol or a mixture of alcohols.

[0034] In another aspect, the water miscible solvent of the water-based high speed flexographic printing ink for use in the invention is an alcohol or a mixture of alcohols.

[0035] The water miscible solvent of the water-based high speed flexographic printing ink for use in the invention comprises ethanol.

[0036] In another aspect, the water miscible solvent of the water-based high speed flexographic printing ink for use in the invention is ethanol.

[0037] In another aspect, the latex of the water-based high speed flexographic printing ink for use in the invention comprises polymeric resin particles that when exposed to a 25wt% aqueous solution of ethanol at a temperature of 25°C for 10 minutes, undergo a particle size increase of 0% to 10%, preferably 0% to 5.0%, more preferably 0% to 3.0%, and even more preferably 0% to 1.0%.

[0038] In another aspect, the latex of the water-based high speed flexographic printing ink for use in the invention comprises acrylic resin particles.

[0039] Described herein to assist understanding of the invention are articles that are printed or coated with the water-based high speed flexographic printing ink for use in the invention described herein. The articles comprise a substrate that is printed or coated with the water-based inks for use in the invention that are described herein.

[0040] Described are printing methods in which articles are printed with the water-based high speed flexographic printing ink for use in the invention described herein.

[0041] The water-based high speed flexographic printing inks for use in the invention are printed on a flexographic press at speeds of greater than or equal to (≥) 600 meters / minute.

[0042] Described herein is a water-based high speed gravure printing ink for use in the invention comprising a water miscible solvent having a boiling point of 56°C to 98°C in an amount of about 10wt% to about 30wt%, water, wherein in combination, the water and the water-miscible solvent are present in the ink in an amount of 15wt% to 40wt%; and an alcohol tolerant latex, wherein the latex is present in an amount between 25wt% and 40wt%. In a preferred embodiment of the water-based high speed gravure printing ink for use in the invention, the water miscible solvent is present in the range of about 20wt% to about 30wt% and / or the alcohol tolerant latex is present in the range of about 20wt% to about 30wt%. The amounts are based on the total weight of the ink.

[0043] The water miscible solvent of the water-based high speed gravure printing ink for use in the invention comprises an alcohol.

[0044] The water miscible solvent of the water-based high speed gravure printing ink for use in the invention comprises an alcohol or a mixture of alcohols.

[0045] In another aspect, the water miscible solvent of the water-based high speed gravure printing ink is an alcohol or a mixture of alcohols.

[0046] The water miscible solvent of the water-based high speed gravure printing ink for use in the invention comprises ethanol.

[0047] In another aspect, the water miscible solvent of the water-based high speed gravure printing ink is ethanol.

[0048] In another aspect, the latex of the water-based high speed gravure printing ink for use in the invention comprises polymeric resin particles that, when exposed to a 25wt% aqueous solution of ethanol at a temperature of 25°C for 10 minutes, undergo a particle size increase of 0% to 10%, more preferably 0% to 5.0%, even more preferably 0% to 3.0%, and still even more preferably 0% to 1.0%.

[0049] In another aspect, the latex of the water-based high speed gravure printing ink for use in the invention comprises acrylic resin particles.

[0050] Described herein to assist understanding of the invention are articles that are printed or coated with the water-based high speed gravure printing ink for use in the invention described herein. The articles comprise a substrate that is printed or coated with the water-based inks for use in the invention that are described herein.

[0051] Described are printing methods in which articles are printed with the water-based high speed gravure printing ink for use in the invention described herein.

[0052] The water-based high speed gravure printing inks for use in the invention are printable on a gravure press at speeds of ≥200 meters / minute.

[0053] The inventors have discovered that in printing operations, such as on flexo and gravure presses, the water-based inks described herein reduce if not eliminate plate swelling. A further advantage is that they do not include slow solvents (e.g., glycol ethers). Still further, the inventors have found that at high speeds, the described inks for use in the invention print as well as if not better than solvent-based inks, particularly on flexo and gravure printing presses. That the described inks for use in the invention print successfully at high speeds on flexo and gravure printing presses, is a particularly important milestone attained by the inks described herein. It is believed that effective high speed water-based inks have not been previously available.

[0054] Also, since the present inks for use in the invention perform better or as well as state of the art high speed solvent-based inks and contain relatively low amounts of volatile organic compounds (VOCs), their use reduces workplace hazards and leads to a healthier workplace environment (e.g., lesser amounts of evaporating volatiles in the environment to breath in, thereby improving workplace air quality and reducing the possibility of contracting illnesses. Further, the risk of combustion is reduced when using a low VOC ink).

[0055] While state of the art first down water-based white ink may currently be run on gravure or flexo presses, which may reduce solvent emissions and have low flammability risk, these inks print at slower speeds and do not adhere well to many polymeric substrates.

[0056] Applicants have found that the inks for use in the invention described herein can be printed on various different substrate materials, such as, for example, polyethylene, polypropylene, polyethylene terephthalate, and polyamides.BRIEF DESCRIPTION OF THE DRAWINGS

[0057] FIG.1 is a bar graph plotting the particle size increase of a latex that can be used in the present water-based inks and the particle size increase of other latexes in neat and 10% isopropyl alcohol solutions.DETAILED DESCRIPTION OF THE INVENTION DEFINITIONS

[0058] As used herein, the use of the singular includes the plural unless specifically stated otherwise. For example, the singular forms "a," "an" and "the" are intended to include the plural forms, unless the context clearly indicates otherwise.

[0059] As used herein, the terms "comprises" and / or "comprising" specify the presence of the 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. Furthermore, to the extent that the terms "includes," "having," "has," "with," "composed," "comprised" or variants thereof are used in either the description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprising."

[0060] As used herein, ranges and amounts may be expressed as "about" a particular value or range. "About" is intended to also include the exact amount. For example, "about 5 percent" means "about 5 percent" and also "5 percent." "About" means within typical experimental error for the application or purpose intended.

[0061] As used herein, the terms "polymer" and "polymers" includes copolymers unless indicated otherwise.

[0062] As used herein, the terms "inks and coatings," "inks," "compositions" and "fluids" are used interchangeably.

[0063] Throughout this disclosure, all parts and percentages are by weight (wt% or mass% based on the total weight) and all temperatures are in °C unless otherwise indicated.

[0064] Described herein are water-based inks that comprise a water miscible solvent having a boiling point of 56°C to 98°C, water, and a latex. In one aspect, the water miscible solvent comprises about 10wt% to about 30wt% of the inks (based on the total weight of the inks).

[0065] The water miscible solvents include alcohols. The water-miscible solvents comprises ethanol. Ethanol may be used alone or in combination with another water-miscible solvent, e.g., isopropyl alcohol.

[0066] The amount of water miscible solvent in the inks may be about 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, about 30wt%, and fractions of these values. These ranges apply to all combinations of water miscible solvents described herein.

[0067] Alternatively, the water miscible solvent range may be about 10wt% to about 30wt%, about 11wt% to about 29wt%, about 12wt% to about 28wt%, about 13wt% to about 27wt%, about 14wt% to about 26wt%, about 15wt% to about 27wt%, about 16wt% to about 26wt%, about 17wt% to about 25wt%, about 18wt% to about 24wt%, about 19wt% to about 23wt%, about 20wt% to about 22wt%, and fractions of these values. These ranges apply to all combinations of water miscible solvents described herein.

[0068] As used herein, a "latex" is a stable dispersion of polymer microparticles in an aqueous medium.

[0069] The water-based inks include a latex in which the polymeric resin particles in the latex, when exposed to 25wt% aqueous solution of ethanol at a temperature of 25°C for 10 minutes, undergo a particle size increase of 0 to 15%.Preferably the polymeric resin particles in the latex, when exposed to 25wt% aqueous solution of ethanol at a temperature of 25°C for 10 minutes, undergo a particle size increase of 0% to 10%, more preferably 0% to 5.0%, even more preferably 0% to 3.0%, and still even more preferably 0% to 1.0%. A "particle size increase" is defined herein as an increase in the size of the resin particles of a latex material upon exposure to a 25wt% aqueous solution of ethanol at a temperature of 25°C for 10 minutes, as determined in a Horiba particle size analyzer by dynamic light scattering at 25°C.

[0070] The latexes that exhibit limited (e.g., not exceeding 15%) to no particle size increase as described above are preferably included in the present water-based inks. Such latexes are considered to be "alcohol-tolerant latexes". The compositions of inks containing alcohol-tolerant latexes are uniform, have acceptable viscosities for the printing operation in question (e.g., flexo, gravure), and adhere well to substrates.

[0071] On the other hand, inks containing what may considered to be non-alcohol tolerant latexes, that is, latexes that increase more than 15% in particle size in the presence of 25wt% aqueous ethanol solution under the above-described conditions, have been found to have unacceptable print properties. For example, such inks have been found exhibit unacceptably high viscosities, making them difficult to run on a printing press. While this issue could conceivably be addressed by reducing the ink with further water and / or solvent, this has the effect of reducing the concentration of other components and the effectiveness and / or functionality of same. For example, solvent addition could reduce the opacity of a white ink due to pigment dilution.

[0072] The inventors have found several commercially available aqueous acrylic resin latexes that are alcohol tolerant. Among them are 2514 HV ™< Latex (Alberdingk Boley, Inc.), Joncryl ®< 74 (BASF), HydriPrint ™< 604, and Lucidene ™< 4045 Lucidene ™< 4045 is an aqueous styrene / acrylic emulsion available from Dow Chemical Company. The HydriPrint ™< 604latex is available from IMCD, Lakewood OH. HydriPrint ™< 604shows no increase in particle size in the presence of ethanol. 2514 HV ™< Latex and Joncryl ®< 74 show about a 5% increase in particle size in the presence of ethanol. Lucidene ™< 4045 does not undergo a particle size increase in the presence of ethanol.

[0073] One or more alcohol tolerant latexes are included in the inks described herein. The total amount of alcohol tolerant latexes included in the ink for use in the invention is 25wt% to 40wt%, preferably about 30wt% to about 40wt%.

[0074] The water present in the described inks may be supplied in whole or in part by the water present in the aqueous latexes that are included in the ink formulations. Water may also be added to the ink formulations apart from what is present in the aqueous latexes.

[0075] FIG. 1 shows that when the alcohol tolerant 2514 HV latex is exposed to a 10wt% aqueous solution of isopropyl alcohol, it underdoes 0% particle size increase, in relation the particle size of the "neat" latex. In other words, the alcohol tolerant latex maintains a constant particle size when exposed to the alcohol in the ink formulation.

[0076] In contrast, FIG. 1 also shows that the Joncryl ®< 60 and Joncryl ®< 80 latexes undergo substantial particle size increases when exposed to 10wt% aqueous solution of isopropyl alcohol, in relation to the "neat" forms.

[0077] The latex used herein may be comprised of different kinds of polymeric resin particles. In one aspect, the latex is an acrylic latex that contains acrylic resin particles. The acrylic resin particles may be acrylic homo- or co-polymer resin particles. Acrylic-vinyl resin particles are one example of resin particles that may be incorporated in the aqueous medium of the latex. Co-polymers include, for example, co-polymers of styrene-acrylic, styrene-butadiene, vinyl-acrylic, and vinyl acetate-acrylic.

[0078] In one aspect, the inks exhibit a dynamic surface tension of about 25 dynes / cm to about 35 dynes / cm, at a frequency of 5 / sec.

[0079] The inks are high speed printing ink suitable for printing on a flexo press at 600 m / min and / or a gravure press at 200 m / min.

[0080] The inks are printable on a flexographic press at speeds of ≥600 meters / minute.

[0081] In another aspect, the inks are gravure printing inks.

[0082] The inks are printable on a gravure press at speeds of ≥200 meters / minute.

[0083] Another advantage of the inks described herein is that the amounts of water-miscible solvents such as alcohols are reduced, while printing speed and printing quality is maintained. The reduction in solvent amount means that the inks have higher flash points, which reduces the likelihood of combustion and fire. For example, as noted above, the flash points of the inks may be about ≥40°C, preferably about ≥60°C, and more preferably about ≥80°C.

[0084] Also, the present inks contain lower volatile organic compounds (VOCs) than state of the art high speed solvent-based inks. The present water-based inks provide an alternative to solvent based inks, which generally have been the only option available for printing at high speeds, while advantageously eliminating the safety hazards associated with using inks that include large amounts of volatile components.

[0085] The inks of the present may also optionally comprise colorants, such as organic and inorganic pigments. Examples of inorganic pigments include such as Pigment White 6 (Titanium Dioxide), zinc sulfide (ZnS), Pigment Black 7 (carbon black), Pigment Black 11 (Black Iron Oxide), Pigment Red 101 (Red Iron Oxide) and Pigment Yellow 42 (Yellow Iron Oxide). Organic pigments include Pigment Yellow 1, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 37, Pigment Yellow 63, Pigment Yellow 65, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow 75, Pigment Yellow 83, Pigment Yellow 97, Pigment Yellow 98, Pigment Yellow 106, Pigment Yellow 114, Pigment Yellow 121, Pigment Yellow 26, Yellow 126, Pigment Yellow 136, Pigment Yellow 174, Pigment Yellow 176, Pigment Yellow 188, Pigment Orange 5, Pigment Orange 13, Pigment Orange 16, Pigment Orange 34, Pigment Red 2, Pigment Red 9, Pigment Red 14, Pigment Red 17, Pigment Red 22, Pigment Red 23, Pigment Red 37, Pigment Red 38, Pigment Red 41, Pigment Red 42, Pigment Red 112, Pigment Red 146, Pigment Red 170, Pigment Red 196, Pigment Red 210, Pigment Red 238, Pigment Blue 15, Pigment Blue 15:1, Pigment Blue 15:2, Pigment Blue 15:3, Pigment Blue 15:4, Pigment Green 7, Pigment Green 36, Pigment Violet 23 and others. Combinations of pigments may be used.

[0086] In a preferred aspect, the pigments included in the present inks are milled to a particle size that is less than 1 micrometer, and after milling, have a preferred particle size distribution of about 10nm to about 500 nm, more preferably about 10nm to about 350 nm, so as to provide the present inks with better transparency and a wide color gamut.

[0087] To incorporate the above-described pigments into the present inks, it is preferred that the pigments be manufactured and stably stored as pigment dispersions in water. This is may be achieved by dispersing the pigment into a water-soluble or water-dispersible resin using a water-soluble and / or a water-dispersible surfactant, which introduces hydrophilic functional groups into the surface of the pigment particles. Examples of such dispersing resins include but are not limited to polyvinyl alcohols, polyacrylic acid, acrylic acid-acrylonitrile copolymers, vinyl acetate-acrylate copolymers, acrylic acid-acrylate copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylate copolymers, styrene-alpha methyl styrene-acrylic acid copolymers, styrene-alpha methyl styrene-acrylic acid-acrylate copolymers, styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, vinyl naphthalene-acrylic acid copolymers, vinyl naphthalene-maleic acid copolymers, vinyl acetate-maleate copolymers, vinyl acetate-crotonic acid copolymers, and vinyl acetate-acrylic acid copolymers, and the salts thereof. The copolymers can be used in any form of random copolymer, block copolymer, alternating copolymer and graft copolymer. Examples of such resins include Joncryl ®< 67, 678, 8500, 586, 611, 680, 682, 683 and 69 available from BASF. Examples of the salts include sodium hydroxide, potassium hydroxide and salts of basic compounds such as ammonia, ethylamine, diethanolamine, triethanolamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutyl amine, diethanolamine, triethanolamine, triisopropanolamine, dimethyl ethanolamine, amino methyl propanol, and morpholine. The amount of the basic compound is not limited so long as the resin dispersant is equal to or more than the neutralization equivalent. Combinations of the above may be used.

[0088] The colorants may be included in the inks as water-based colorant dispersions comprising about 15wt% to about 60% pigment, about 5wt% to about 75wt% resin, and about 10wt% to about 60wt% water. These amounts are based on the total weight of the colorant dispersion. The water-based colorant dispersion may be a water-based pigment dispersion that includes a water-based acrylic resin. The water-based colorant dispersion component, if present in the inks, may be present in an amount of about 1.0wt% to about 50wt%, based on the total weight of the composition.

[0089] The inks of the present invention may optionally contain additional polymers and resins, such as to improve resistance properties, e.g., mar and rub resistance, and / or to improve printability or adhesion. Such resins may include but are not limited to styrenated acrylics, rosinated alkyds, melamine-formaldehyde resins, ureaformaldehyde resins, polyester-urethanes and urethanes.

[0090] Additives may be optionally included in the inks in order to improve and enhance various properties. A partial list of such additives includes, but is not limited to: adhesion promoters, silicones, light stabilizers, de-gassers, waxes, ammonia, flow promoters, crosslinkers, defoamers, antioxidants, stabilizers, surfactants, dispersants, plasticizers, rheological additives, and others.

[0091] Defoamers may be included in the present inks. Defoamers prevent the formation of foam during manufacture of the inks and also during jetting. Defoamers are particularly useful when the inks are deposited through recirculating print heads. Examples of suitable defoamers include TEGO FOAMEX N, FOAMEX 1488, 1495, 3062, 7447, 800, 8030, 805, 8050, 810, 815N, 822, 825, 830, 831, 835, 840, 842, 843, 845, 855, 860, and 883, TEGO FOAMEX K3, TEGO FOAMEX K7 / K8 and TEGO TWIN 4000 available from Evonik. Available from BYK are BYK-066N, 088, 055, 057, 1790, 020, BYK-A 530, 067A, and BYK 354. DC62, DC65, DC 68, DC71 and DC74 are available from Dow Corning. Agitan 120, 150, 160, 271, 290, 298, 299, 350, 351, 731, 760, 761, and 777 are available from Munzing.

[0092] Surface control additives, also known as surfactants, can be included in the inks to adjust the surface tension of the ink. Surface control additives may also control the level of slip and scratch resistance of the inks. Examples of suitable surface control additives include but are not limited to TEGO FLOW 300, 370, and 425, TEGO GLIDE 100, 110, 130, 406, 410, 411, 415, 420, 432, 435, 440, 482, A115, and B1484, TEGO GLIDE ZG 400, TEGO RAD 2010, 2011, 2100, 2200N, 2250, 2300, 2500, 2600, 2650, and 2700, TEGO TWIN 4000 and 4100, TEGO WET 240, 250, 260, 265, 270, 280, 500, 505, and 510 and TEGO WET KL245, all available from Evonik. Available from BYK are BYK 333 and 337, BYK UV 3500, BYK 378, 347 and 361, BYK UV 3530 and 3570, CERAFLOUR 998 and 996, NANOBYK 3601, 3610, and 3650, and CERMAT 258. Available from Cytec are EBECRYL 350 and 1360, MODAFLOW 9200, and EBECRYL 341. From Sartomer the aliphatic silicone acrylate CN9800 may be used. Surfynol ®< 104, 420, 440, 465, 485, 61, 82, and 2502 are available from Air Products. Multiwet BD, EF, SU, SO, and VE are available from Croda. Capstone FS-30, 31, 34, 35, 50, 51, 60, 61, 63, 64, 65, and 3100 are available from Du Pont.

[0093] Other examples of surfactants include anionic surfactants such as alkane sulphonates, alpha-olefin sulphonates, alkyl benzene sulphonates, alkyl naphthalene sulphonates, acyl methyl taurinates, dialkyl sulfosuccinates, alkyl sulfates, sulfurized olefins, polyoxyethylene alkyl ether phosphates, polycarboxylic acids and mono glycerol phosphate, amphoteric surfactants such as alkylpyridinium salts and non-ionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkyl amides, glycerol alkyl esters and sorbitan alkyl esters. Examples include EFKA 1000, 4000, 5000 and 6000 series products from BASF, Tamol series products from Dow, and Solsperse 27,000, 40,000, 44,000, 46,000 and 47,000 from Lubrizol. Combinations of the above may be used.

[0094] De-aerators may also be included in the present inks. De-aerators may prevent the formation of air inclusions and pinholes in the printed inks after drying. Examples of de-aerators include the following products available from Evonik: TEGO AIREX 900, 910, 916, 920, 931, 936, 940, 944, 945, 950, 962, 980, and 986.

[0095] Methods of printing in accordance with the principles described in the present invention include printing the water-based inks described herein onto substrates, such as a polyethylene substrate. In one aspect, the printing methods are carried out at high speeds. High speed printing includes speeds of greater than or equal to 2000 feet per minute. For gravure printing, speeds include those greater than or equal to 200 meters / minute. For flexographic printing, speeds include those greater than or equal to 600 meters / minute.EXAMPLES

[0096] The following examples illustrate specific aspects of the present invention and are not intended to limit the scope thereof in any respect and should not be so construed.

[0097] The following test methods were employed : Opacity (Contrast ratio): Opacity is measured with a Technidyne BNL-3 opacity meter. Three (3) measurements are taken. The reported value is the average of the three results. Tape adhesion: 610 tape from 3M is place over an area and then removed. The test is then repeated over the same area. Three (3) measurements are taken. The reported value is the average of the three. Pass: ≤ 10% ink film removal. Heat resistance: Inks are printed onto green bond paper. The prints are heated at 20psi pressure for one minute. The reported temperature is the temperature is the failure temperature. Sutherland ®< rub: Printed sheets of green bond paper are rubbed for 500 cycles at speed 3 (88 cycles / minutes) on a Sutherland ®< rub tester with a 4 pound weight. A passing grade is minimal marking. Restrained Shrink Test: Hang a four (4) inch printed sheet in an oven at 345°F for 15 seconds. Check machine and cross directions, and observe for signs of cracking when stretched. Dry Crinkle: Place a sample of printed film between the thumb and index finger of each hand, spaced approximately 1 inch apart. Then, the grasped film is brought together and cycled back and forth in a circular motion similar to pedaling a bicycle. This test is performed with both 10 and 20 cycles. Once complete, the sample should be wiped to remove ink particles that have come loose. No ink removal should occur. Scratch resistance: A printed sample is placed over a resilient surface (e.g., a pad of paper) and is scratched 10 times with the fingernail of the index finger at an angle (so as not to "cut" the sample). The applied pressure is moderate pressure, and the swiping motion is fast. Pass: ≤ 10% ink film removal. Nestle bottle block: Individual Nestle water bottle labels are adhered to a jar. Overwrap print samples are then heat shrunk to the jar, ink to label using a heat gun. The print is removed and checked for ink transfer. Conventional block: Put in oven at these conditions: 120°F / 50psi / 80%rh / 16 hours / ink to film. Look for whether it blocks. Coefficient of Friction (COF): 0.2-0.4 ink to film. Test Protocol for Optical Microscopy Pinhole Analysis: Olympus BX-51: Bright field illumination / Magnification - 4x is used.

[0098] Sample prints were evaluated at low magnification to capture larger field, which allows for better statistical sampling. All images were captured at 4x magnification. Image analysis software was used to count pin holes.Example 1: Flexographic White Ink

[0099] A flexographic white ink was prepared and evaluated in an over-wrap application. The ink components and ink preparation are described in Table 1. The ink displayed equal or better performance when compared to the standard bottle wrap ("BW") control ink (Sun Chemical Corporation code CRYFS1115933A), which is a solvent-based ink that includes a combined 35wt% of the volatile solvents propanol and propyl acetate, a white pigment, a urethane resin, and a nitrocellulose resin. Table 1 Material Wt% Surfynol ®< 104 PA 0.50 HydriPrint ™< 604 39.00 Mono ethanol amine (MEA) 0.50 Mix 5 minutes and add...Ethanol-SDA-3C (95 / 5 Ethanol / IPA) 8.00 Tap Water 4.00 Joncryl ®< Wax 4 (40% Solids) 1.00 Mix 5 minutes and add...TR-52 (TiO 2 pigment) 20.50 Mix 5 minutes and add...TR-52 20.50Ethanol-SDA-3C (95 / 5 Ethanol / IPA) 3.00 Tap Water 3.00 100.00

[0100] The performance attributes of inventive Example 1 ink as compared to the BW solvent-based control ink are set forth in Table 2 below. The "white" test results refer to the testing the print of a white layer. The "color trap" test results refer to a print layer of white over which a colored layer of solvent based ink is printed. The inks were printed onto corona treated polyethylene sheet. The results show that Example 1 ink possesses properties similar to those of the BW control ink. Table 2 White Color Trap Tests BW White (control) Example 1 BW White / BW Color Example 1 / BW Color Opacity (Contrast Ratio) 53.8754.8263.5666.47Adhesion Resistance PassPassPassPassGloss 79.178.680.381.2Rub Resistance slight removalPassPassPassScratch PoorPoorPoorPoorCOF (Kinetic) 0.360.420.280.30Heat Resistance 375°F475°F400°F475°FRestrained Shrink PassPassPassPassDry Crinkle PassPassPassPassBottle Block - Shrink film, ink to bottle label, around Glass Bottle PassPassPassPassConventional Block - Ink / Film PassSlight PickPassSlight PickWater Resistance - Initial --Slight PickOKWater Resistance - Aged Slight PickOKSlight PickOKBottle Block - Heat Seal - Plastic Bottle NA20% Ink Transfer80% Ink TransferNo TransferBottle Block - Heat Seal - Monoweb Label NAvery slight transferPassPass Bottle Block - Heat Seal - Monoweb Label - 300°F, 5", 10psiBottle Block - Heat Seal - Plastic Label - 425°F, 4", 10psi Example 2 - Water-Based White Gravure Ink

[0101] A water-based white gravure ink was prepared. The components and ink preparation are described in Table 3. Table 3 Wt.% MATERIAL & INSTRUCTIONS Gather and weigh the following materials, add to a clean mixing tub 20.00 HydriPrint ™< 399 5.50 Lucidene ™< 4045 0.90 Surfynol ®< 104PA Turn on mixer to low speed and adjust as needed to maintain acceptable vortex Then add the following while mixing 24.50 Ethanol-SDS-3C (95 / 5 Ethanol / IPA) When ethanol has been thoroughly mixed Then add the following while mixing... 23.40 TR-52 (TiO 2 pigment) Mix until pigment is well dispersed then add... 22.00 TR-52 Mix until pigment is dispersed and show Sample to QC for grind check. When ok add the following while mixing... 3.60 Tap Water 0.10 MEA 100.000 TOTAL

[0102] HydriPrint ™< 399 is a styrene acrylic resin solution.

[0103] Opacity of the Example 2 white ink was 60, as measured on a BNL-3 opacity meter, indicating that the ink of this example is a high opacity ink. The Example 2 white ink was run on a rotogravure press at 900 ft / min with a 175 lip gravure cylinder. The Example 2 white ink did not pick off the ink it was applied to, and it did not bleed through ink that it came in contact with.Example 3 - Water-Based White Ink

[0104] The components and preparation steps for the Example 3 ink are described in Table 4. Table 4 Material Wt% HydriPrint ™< 604 (Tg -20°c) 36.00 TR-52 (TiO 2 pigment) 41.00 Joncryl ®< Wax 4 (40% Solids) 1.00 Surfynol ®< 104 PA 0.50 Ethanol-SDA-3C (95 / 5 Ethanol / IPA) 14.00 Tap Water 7.00 MEA 0.50 Total 100.00 Bulk Viscosity / cps 97

[0105] The white ink of Inventive Example 3 was compared to the standard bottle wrap ("BW") control ink, which is the solvent-based white ink described above in Example 1. The results appear below. Table 5 Bottle Overwrap Application Solvent Base White Ink Example 3 Contrast Ratio 57.0 60.0 BNL3 Opacity 54.0 56.0 % TI0 2 41.0 41.0 Dynamic Surface Tension 35.0 35.0 610 Tape Adhesion Resistance Good Good Fingernail Scratch Resistance Good Good Ice Water Crinkle Good Good

[0106] As shown the Example 3 ink is comparable in properties to the solvent-based white ink.Example 4 -Yellow Ink Composition

[0107] A yellow ink was included the following components, which were combined to form the ink: Table 6 Material Wt% Flexiverse ®< yellow base 50wt% Joncryl ®< 74 (60wt% water) 33wt% Ethanol 15wt% Wax 1.0wt% Surfynol ®< 104PA 1.0wt%

[0108] Flexiverse ®< yellow base is an organic pigment dispersion available from Sun Chemical Corporation, Parsippany NJ.

[0109] The ink was printed on corona-treated polyethylene with a lab proofer. When tested for high speed printing properties it matched a solvent based ink and the pinholing on the lab prints was comparable to that of a solvent based ink.Comparative Example A - Low Alcohol Ink Formulation

[0110] A white water-based ink with a 3wt% alcohol content was made as follows: Table 7Material Wt% Surfynol ®< 104 PA 0.50 HydriPrint ™< 604 39.00 Mono ethanol amine 0.50 Mix 5 minutes and add...Ethanol-SDA-3C (95 / 5 Ethanol / IPA) 3.00 Tap Water 4.00 Joncryl ®< Wax 4 (40% Solids) 1.00 Mix 5 minutes and add...TR-52 20.50 Mix 5 minutes and add...TR-52 20.50 Ethanol-SDA-3C (95 / 5 Ethanol / IPA) 3.00 Tap Water 8.00 100.00

[0111] Joncryl ®< Wax 4 is a large particle polyethylene wax.

[0112] When tested in comparison to standard solvent based ink on a corona treated polyethylene substrate, the ink had poor lay, as determined from a pinhole assessment.Comparative Example B -Ink Formulation Not Including Latex Example with solution resin

[0113] An ink was made as follows (latex replaced with solution resin) Table 8 Material Surfynol ®< 104 PA 0.50 HydriCryl ™< 345 39.00 Mono ethanol amine 0.50 Mix 5 minutes and add...Ethanol-SDA-3C (95 / 5 Ethanol / IPA) 8.00 Tap Water 4.00 Joncryl ®< Wax 4 (40% Solids) 1.00 Mix 5 minutes and add...TR-52(TiO2 pigment) 20.50 Mix 5 minutes and add...TR-52 20.50 Ethanol-SDA-3C (95 / 5 Ethanol / IPA) 3.00 Tap Water 3.00 100.00

[0114] HydriCryl ™< 345 is a styrene-acrylic resin solution available from Hydrite Chemical Co., Brookfield WI.

[0115] When tested in comparison to standard solvent based ink on a corona treated polyethylene substrate, the ink had poor adhesion and water resistance (determined by placing printed articles into a water bath and observing the removal of ink).Comparative Example C -Ink Formulation Including Non-Alcohol Tolerant Latex

[0116] An ink that includes a non-alcohol tolerant latex was made as follows: Table 9Material Surfynol ®< 104 PA 0.50 NeoCryl ®< 1171 - a non-alcohol tolerant latex 39.00 Mono ethanol amine 0.50 Mix 5 minutes and add...Ethanol-SDA-3C (95 / 5 Ethanol / IPA) 8.00 Tap Water 4.00 Joncryl ®< Wax 4 (40% Solids) 1.00 Mix 5 minutes and add...TR-52(TiO2 pigment) 20.50 Mix 5 minutes and add...TR-52 20.50 Ethanol-SDA-3C (95 / 5 Ethanol / IPA) 3.00 Tap Water 3.00 100.00

[0117] The ink was found to have a high viscosity (500 cps). The ink was reduced by 30% with a reducing solvent (50% water, 49% ethanol, 1% mono ethanol amine) to get to a final press viscosity of 80 cps. The resulting print had low opacity (47 vs. 58 for a standard solvent based ink. The NeoCryl ®< 1171 latex in the above ink was found to have about a 20% particle size increase in the presence of ethanol.

[0118] The present invention has been described in detail, including the preferred embodiments thereof. However, it will be appreciated that those skilled in the art, upon consideration of the present disclosure, may make modifications and / or improvements on this invention that fall within the scope of the invention.

Claims

1. A method of flexographic printing a water-based ink, wherein the water-based ink comprises: water miscible solvent having a boiling point of 56°C to 98°C, wherein the water miscible solvent comprises ethanol; - water; wherein in combination, the water and the water-miscible solvent are present in the ink in an amount of 15wt% to 40wt%; and - a latex, wherein the latex is present in an amount between 25wt% and 40wt%; wherein the resin particles in the latex increase 0 to 15% in particle size in the presence of a 25wt% aqueous solution of ethanol, wherein the particle size increase is the increase in the size of the resin particles of a latex material upon exposure to a 25wt% aqueous solution of ethanol at a temperature of 25°C for 10 minutes, as determined in a Horiba particle size analyzer by dynamic light scattering at 25°C; and wherein the flexographic printing is performed on a flexographic press at ≥600 meters / minute.

2. A method of gravure printing a water-based ink, wherein the water-based ink comprises: - a water miscible solvent having a boiling point of 56°C to 98°C; wherein the water miscible solvent comprises ethanol; - water; wherein in combination, the water and the water-miscible solvent are present in the ink in an amount of 15wt% to 40wt%; and - a latex, wherein the latex is present in an amount between 25wt% and 40wt%; wherein the resin particles in the latex increase 0 to 15% in particle size in the presence of a 25wt% aqueous solution of ethanol, wherein the particle size increase is the increase in the size of the resin particles of a latex material upon exposure to a 25wt% aqueous solution of ethanol at a temperature of 25°C for 10 minutes, as determined in a Horiba particle size analyzer by dynamic light scattering at 25°C; and wherein the gravure printing is performed on a gravure press at ≥200 meters / minute.

3. The method of any preceding claim, wherein the water miscible solvent is ethanol.

4. The method of any preceding claim, wherein resin particles in the latex increase 0% to 10% in particle size, preferably 0% to 5.0% in particle size, more preferably 0% to 3.0% in particle size, and even more preferably 0% to 1.0% in particle size, in the presence of alcohol.

5. The method of any preceding claim, wherein the latex comprises acrylic resin particles; and / or wherein the latex comprises resin particles of acrylic homo- and / or copolymers.

6. The method of any preceding claim, wherein the water-miscible solvent is present in the ink in an amount of 10wt% to 20wt%.

7. The method of any preceding claim, wherein the ink further comprises an additional resin component; and / or wherein the ink further comprises a surfactant; and / or wherein the ink further comprises a defoamer; and / or wherein the ink further comprises a dispersant.

8. The method of any preceding claim, wherein the dynamic surface tension of the ink is 0.025 N / m to 0.035 N / m (25 dynes / cm to 35 dynes / cm); and / or wherein the ink has a flash point that is ≥40°C, preferably ≥60°C, and more preferably ≥80°C.

9. The method of any preceding claim, wherein the ink further comprises a colorant.