Heat-resistant water-based ink

Abstract

To provide an expanded color gamut water-based printing (preferably, flexographic printing) ink set which enables printing of a printed matter having a low migration property even after exposure to temperatures in excess of 150°C.SOLUTION: There is provided a method for providing a packaged food, which comprises: printing on a substrate with a water-based printing ink composition; providing a printed substrate by drying the ink composition; and packaging a food with the printed substrate, wherein the method does not include printing or coating any layer on the dried ink composition and the ink composition comprises water and a polyester resin. Further, there is provided a use of a water-based printing ink for printing on a substrate, wherein the printed substrate has less than 50 ppb of migration species when heated to a temperature in excess of 150°C and a water-based ink composition comprises water and a polyester resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for providing a printed article comprising applying an aqueous printing ink to a substrate, the printed article being suitable for use in sensitive applications such as food packaging, and to the printed article obtained thereby. Advantageously, the method is suitable for providing heat-resistant printed articles, such as oven-safe food packaging, and is also suitable for printing images with an extended color gamut. [Background technology]

[0002] Four-color process printing, which includes a combination of cyan, magenta, yellow, and black inks (i.e., a four-color CMYK set), typically covers only about 55% of the Pantone spot color gamut. If a print design requires a color outside the gamut of the four-color CMYK set, such as skin tones, this can be achieved by using spot colors specially formulated to match the desired color. However, this approach can be limiting for print designs that require a number of colors outside the gamut achievable with a four-color CMYK set. To extend the color gamut of a process set, colors can be added to the process set to create a process set of five, six, seven, or more colors. A seven-color process set can typically cover more than 90% of the Pantone spot color gamut.

[0003] U.S. Patent No. 7,032,517 (Heidelberg) mentions how extended color gamut printing can be achieved through a CMYK ink set that can be expanded with at least one additional colorant selected from red, blue, and green pigments.

[0004] Multicolor process printing is now widely adopted in inkjet printing, where the use of specific additional spot colors is not possible due to the need for dedicated printhead arrays. Six- and seven-color process sets are now commonly used in inkjet printing. U.S. Patent No. 5,734,800 (Pantone) refers to a six-color printing process system. Similarly, Esko (U.S. Patent No. 7,164,498) refers to digital printing processes including six-color (CMYKOG) and seven-color (CMYKRGB) color process sets.

[0005] The present invention is directed to a seven-color process set that preferably includes orange, red, and violet inks in addition to CMYK, and optionally includes a white ink.

[0006] U.S. Patent No. 9,649,868 (Sun Chemical) describes a method for extending the color gamut of a four-color process set by simply adding one process color. In particular, it mentions flexographic printing, in which the extended color gamut is achieved by an ink set consisting of primary color inks formulated with Pigment Blue 79, Pigment Red 122, Pigment Yellow 74, Pigment Black 7, and Pigment Orange 34. It does not disclose a method for achieving heat-resistant printing suitable for low-migration printing, particularly for ovenable food packaging.

[0007] U.S. Patent No. 4,595,611 (International Paper Company) relates to a sulfopolyester dispersion containing ink that can be used for printing ovenable food containers. However, the print is coated with an overprint varnish and an additional plastic layer. Furthermore, the ink according to U.S. Patent No. 4,595,611 requires a crosslinking agent, such as a melamine / formaldehyde resin. Furthermore, no wide color gamut process ink set is disclosed.

[0008] U.S. Patent No. 4,912,157 (Eastman Kodak Company) relates to aqueous inks containing sulfopolyester dispersions, but the use of these dispersions in ovenable, low-migration, wide color gamut printing ink sets was not discussed.

[0009] U.S. Pat. No. 5,369,210 (Eastman Kodak Company) relates to sulfopolyester dispersions with enhanced high-temperature resistance properties. This is achieved through sulfopolyesters with glass transition temperatures greater than 89°C, increased melt viscosity, and improved heat resistance and printing properties such as blocking resistance. In fact, no mention is made of the use of these sulfopolyester dispersions in wide-gamut, ovenable ink sets. Furthermore, sulfopolyester dispersions preferably used in this invention have glass transition temperatures significantly lower than those required in U.S. Pat. No. 5,369,210. Examples include Eastek 1200 (65°C), Eastek 1100 (55°C), Eastek 1300 (36°C), and Eastek 1400 (29°C) (all from Eastman). Therefore, a further aspect of this invention is the use of sulfopolyester dispersions with glass transition temperatures less than 80°C.

[0010] US Patent No. 6,046,253 (Eastman Kodak Company) relates to aqueous ink jet compositions containing sulfopolyester dispersions. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] U.S. Patent No. 7,032,517 [Patent Document 2] U.S. Patent No. 9,649,868 [Patent Document 3] U.S. Patent No. 4,595,611 [Patent Document 4] U.S. Patent No. 4,912,157 [Patent Document 5] U.S. Patent No. 5,369,210 [Patent Document 6] U.S. Patent No. 6,046,253 Summary of the Invention [Problem to be solved by the invention]

[0012] An advantage of the present invention is that it provides an extended color gamut water-based printing (preferably flexographic) ink set that allows for printing of prints with low migration even after the prints have been exposed to temperatures above 150° C. This is achieved without applying a heat-resistant overprint varnish or additional coating (e.g., a heat seal layer) over the printed inks.

[0013] Compared to the aforementioned references, the present invention provides a solution for aqueous printing (preferably flexographic) inks, particularly inks for extended color gamut multicolor process sets, reducing the risk associated with the evolution of low molecular weight compounds (e.g., compounds with a molecular weight of less than 1,000 daltons) from printed articles at high temperatures, e.g., 150°C or higher, which could cause undesirable contamination of food contained in any packaging printed with the inks of the present invention. The present invention is particularly suitable for printing food packaging, including paper-based food packaging, where the packaging and its contents may be reheated or cooked at temperatures above 150°C and above 200°C for 5 minutes or more. Inks and printed articles prepared according to the present invention exhibit significantly less evolution of low molecular weight substances from printed articles at high temperatures compared to inks using polyurethane dispersions or styrene acrylic dispersions. Polyurethane dispersions and styrene acrylic dispersions are the primary resin binder chemistries currently used in state-of-the-art aqueous flexographic inks, and the inventors' knowledge has revealed that they are not suitable for use in ovenable inks for food packaging, a problem that the present invention solves. DETAILED DESCRIPTION OF THE INVENTION

[0014] Citation or identification of any reference herein shall not be construed as an admission that the reference constitutes prior art to the present application. The present invention describes an aqueous printing ink set comprising cyan, magenta, yellow, and black inks, and optionally at least one additional further ink, for example selected from green, orange, violet, and blue. Preferably, the present invention describes an aqueous flexographic printing ink set comprising cyan, magenta, yellow, and black inks, and optionally at least one additional further ink, for example selected from green, orange, violet, and blue. Preferably, the ink set further comprises a white ink. Preferably, the present invention describes an aqueous flexographic printing ink set comprising cyan, magenta, yellow, black, and white inks, and optionally at least one additional further ink, for example selected from green, orange, violet, and blue.

[0015] The inks according to the present invention comprise a polyester resin (e.g., a polyester dispersion or solution) as the primary resin binder, and the inks are preferably suitable for printing packaging and other articles requiring low migration when the printed matter is heat-treated at high temperatures (e.g., 150°C or higher). The multicolor process ink set of the present invention preferably enables printing in 80% or more, more preferably 90% or more of the colors covered by the Pantone Matching System.

[0016] In one aspect, the present invention provides a method of providing a packaged food product, the method comprising printing a substrate with an aqueous printing ink composition, drying the ink composition to provide a printed substrate, and packaging the food product with the printed substrate, the method does not include printing or applying any layer over the dried ink composition, and the ink composition comprises water and a polyester resin. Preferably, the substrate is paper or corrugated board.

[0017] The present invention also provides a packaged food product, preferably an ovenable packaged food product, which does not include any additional ink layer, varnish layer, or plastic layer over the printed ink.

[0018] In another aspect, the present invention provides the use of an aqueous printing ink for printing on a substrate, wherein the printed substrate has less than 50 ppb of migrating species when heated to a temperature above 150°C, the aqueous ink composition comprising water and a polyester resin.

[0019] The inventors have found that aqueous polyester dispersions or solutions produce inks with superior heat resistance compared to styrene-acrylic, acrylic, and polyurethane dispersions or solutions typically used in preparing aqueous flexographic (i.e., flexographic) printing inks. Accordingly, the aqueous printing inks of the present invention are suitable for printing ovenable food packaging, i.e., food packaging in which the food inside can be reheated or cooked in an oven at temperatures up to 250°C or even 300°C. The inventors have found that the use of polyester resins, along with the appropriate selection of pigments, produces inks that do not generate high levels (e.g., 100 ppb or more) of low molecular weight compounds (e.g., compounds with a molecular weight of less than 1,000 daltons) when the printed matter bearing the ink is heated to temperatures that could result in undesirable and potentially dangerous contamination of the packaged food as a result of migration of low molecular weight compounds from the ink into the food. Advantageously, this is achieved without the need to apply a heat-resistant overprint varnish or seal a plastic layer over the ink.

[0020] The ink used in the present invention may contain an aqueous sulfopolyester dispersion as the polyester resin. The inventors have found that inks containing sulfopolyester dispersions have superior heat resistance compared to inks containing either polyurethane dispersions or styrene-acrylic dispersions. Therefore, the printing ink used in the present invention is suitable for printing food packaging that is heated to temperatures above 150°C without generating high levels (e.g., 100 ppb or more) of undesirable low-molecular-weight components (e.g., compounds with a molecular weight of less than 1,000 daltons) that could migrate from the printed material and contaminate the food inside the package. Advantageously, this is achieved without applying a heat-resistant overprint varnish or sealing a plastic layer over the ink. Therefore, it is possible to prepare printed food packaging that can withstand temperatures experienced during food reheating or cooking, while reducing the risk of contaminating the food with undesirable low-molecular-weight compounds that could migrate from the printed material, without the need for a heat-resistant overprint varnish or a sealing plastic layer surrounding the printed material.

[0021] A further advantage of the present invention is that through the selection of 5, 6 or 7 color process printing ink sets, an extended color gamut can be achieved, potentially printing designs that cover 70% or more of the Pantone spot color range.

[0022] The present invention also provides a method for providing a printed article, the method comprising applying one or more of the ink compositions disclosed herein onto a substrate and drying the substrate, wherein the ink is not overprinted with an overprint varnish. Furthermore, the method of the present invention does not require the application of an additional plastic layer on the printed ink. The present invention also provides a printed article obtained from the method of the present invention. Preferably, the printed article is a food package. The absence of an overprint varnish or additional plastic layer on the ink reduces the number of layers required for the food package, improving the sustainability and recyclability of the food package.

[0023] The present invention makes it possible to print ovenable food packaging with aqueous printing inks (preferably aqueous flexographic printing inks) while reducing the risk of causing undesired contamination of the food packaging. This is particularly important when the inks are used to print corrugated cardboard food packaging, which may not have a sufficient plastic barrier layer between the printed matter and the packaged food. This allows for the printing of food packaging derived from renewable resources (e.g., paper). Thus, the printing inks of the present invention are suitable for printing paper-based food packaging. Other potential end-use applications include packaging, electronics, and automotive parts, which typically involve high temperatures.

[0024] The present invention discloses an aqueous flexographic ink set capable of printing images with an extended color gamut on food packaging or other sensitive articles, and exhibits excellent heat resistance. The ink's good heat resistance is achieved by combining the use of an aqueous polyester resin solution or dispersion that does not generate significant amounts of low-molecular-weight compounds at temperatures above 150°C with pigment selection for a five-, six-, seven-, or more-process-color print set. Thus, an aqueous flexographic ink set is disclosed that includes cyan, magenta, yellow, and black pigments, as well as orange, green, violet, blue, and red pigments, suitable for printing packaging (preferably food packaging) that reduces the risk associated with migration of potentially harmful compounds with molecular weights less than 1,000 after the print is exposed to temperatures above 150°C. This is a well-recognized risk in the food packaging, printing, and converting industries, and is subject to several national regulations, such as EU Regulation (EC) No. 1935 / 2004. The European Printing Ink Association ("EUPIA") has established guidance for printing inks and established restrictions for printing inks used in printing food packaging. In particular, the EUPIA Food Packaging Guidelines recommend compliance with Article 3 of EU Regulation (EC) No. 1935 / 2004 when producing printed articles for food packaging. Article 3 of EU Regulation (EC) No. 1935 / 2004 stipulates that food contact materials must be produced in accordance with Good Manufacturing Practice (GMP). The inks of the present invention meet these requirements.

[0025] The printing ink composition according to the invention is suitable for food contact applications, for example food packaging or other articles intended to come into contact with food. The printing ink composition according to the invention is suitable for use on the outside of the food packaging (i.e. the surface that does not come into contact with food) or on the inside of the food packaging (i.e. the surface that comes into contact with food).

[0026] In addition to being safe for contact with food, the inks of the present invention can be formed into ink sets that have the ability to print images with an extended color gamut, thus enabling the printing of images on food packaging with an extended color gamut.

[0027] One aspect of the present invention is the use of sulfopolyester dispersions in the manufacture of inks. The inventors have found that inks containing sulfopolyester dispersions produce significantly less low molecular weight components (e.g., compounds having a molecular weight of less than 1000 Daltons) when printed copies of the ink are heated to temperatures above 150°C compared to conventional inks containing either polyurethane or styrene-acrylic dispersions. In fact, when printed copies of ink prepared according to the present invention are processed at 220°C for 2 hours, they produce levels of low molecular weight migrating species that can cause contamination, equivalent to less than 50 ppb in a food simulant. In comparison, aqueous flexographic inks containing styrene-acrylic dispersions produce levels of low molecular weight migrating species far exceeding the level equivalent to 100 ppb contamination in a food simulant.

[0028] When sulfopolyester dispersions are used, they are preferably aqueous sulfopolyester dispersions having a solids content of from about 10% to about 40%, more preferably from about 15% to 35%.

[0029] As used herein, the term "sulfopolyester" refers to a polyester comprising the residue of a sulfomonomer. Sulfopolyesters are typically prepared using sulfonated dicarboxylic acid(s) as at least one of the monomers in the polyester. For example, sulfopolyester dispersions can be prepared by the reaction of sodiosulfoisophthalic acid with any blend of diols. The resulting polymer is dispersible in water due to the hydrophilic sodiosulfo groups attached along the polymer chain. Preferably, sulfopolyesters can be dispersed in water without the use of surfactants or amines. Thus, the aqueous sulfopolyester dispersions used in the present invention are preferably surfactant- and amine-free.

[0030] The sulfopolyester dispersion suitable for use in the present invention may optionally contain one or more water-soluble organic solvents. Suitable water-soluble organic solvents include, but are not limited to, alcohols (e.g., methanol, ethanol, propanol, isopropyl alcohol, butanol, polyols, ethylene glycol, propylene glycol, dipropylene glycol, glycerin, and PEG), ketones and ketone alcohols (e.g., acetone and diacetone alcohol), ethers (e.g., tetrahydrofuran, dioxane, alkyl ethers), and ethers of polyhydric alcohols (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, di(ethylene glycol) monomethyl ether, and the like). If used, the optional water-soluble organic solvent is preferably an alcohol selected from methanol, ethanol, n-propanol, isopropyl alcohol, and butanol, and more preferably n-propanol. If used, the optional water-soluble organic solvent is preferably present in an amount of 10% or less of the aqueous dispersion, preferably 5% or less of the aqueous dispersion.

[0031] Alternatively, sulfopolyester dispersions suitable for use in the present invention are co-solvent-free, that is, the sulfopolyester dispersions contain 1% or less of a co-solvent, such as a water-soluble organic co-solvent.

[0032] Preferably, the polyester resin used in the present invention has a glass transition temperature of 80° C. or less, more preferably 60° C. or less. Preferably, the polyester resin used in the present invention is a sulfopolyester having a glass transition temperature of 80° C. or less, more preferably 60° C. or less.

[0033] Various types of aqueous polyester solution and dispersion resins are suitable for preparing the aqueous inks of the present invention, for example, Eastman sulfopolyester dispersions such as Eastek 1100 (Tg 55°C), Eastek 1200 (Tg 65°C), Eastek 1300 (Tg 36°C), and Eastek 1400 (Tg 29°C) can be used.

[0034] Preferably, the polyester resin may be a rosin-derived polyester. Rosin esters, such as Lawter's Hydrorez series and Robert Kraemer's Erkamer series, are also suitable for preparing aqueous inks according to the present invention. In the case of inks prepared using rosin-derived polyesters, rosin (also known as colophony), a raw material derived from natural resources (primarily pine trees), is converted to polyester by subsequent reactions, such as with maleic anhydride and a polyol (which itself may be naturally occurring), improving the sustainability profile of the ink. Thus, the present invention further enhances the sustainability of aqueous printing inks for printing items requiring resistant thermal printing, which do not generate significant amounts of low-molecular-weight compounds during exposure to high temperatures of 150°C or higher.

[0035] Preferably, the polyester resin has an acid value of 50 mgKOH / g or more, preferably 100 mgKOH / g or more. Preferably, the polyester resin has an acid value of 250 mgKOH / g or less, more preferably 200 mgKOH / g or less. Preferably, the polyester resin has an acid value of about 50 to about 250 mgKOH / g, more preferably about 100 to about 200 mgKOH / g.

[0036] Preferably, the polyester resin has a hydroxyl value of 50 mgKOH / g or more, preferably 100 mgKOH / g or more. Preferably, the polyester resin has a hydroxyl value of 250 mgKOH / g or less, more preferably 200 mgKOH / g or less. Preferably, the polyester resin has a hydroxyl value of about 50 to about 250 mgKOH / g, more preferably about 100 to about 200 mgKOH / g.

[0037] Preferably, the polyester resin has a softening point of about 80 to about 180°C, more preferably about 110 to about 150°C.

[0038] Preferably, the polyester resin has a viscosity of 20 to 30 seconds, Ford Cup 4, at 22°C, when measured as a 50% by weight solution in ethanol.

[0039] As understood in the art, polyester resins are prepared from carboxylic acids or carboxylic acid derivatives and diols. Preferably, polyester resins suitable for use in the present invention are not prepared from sulfomonomers (i.e., the polyester does not contain any residues of sulfomonomers). In the most preferred embodiment of the present invention, the polyester resin is not prepared from isophthalic acid or sulfosuccinic acid esters and is therefore isophthalic acid ester and sulfosuccinic acid ester free.

[0040] Preferably, the ink composition used in the present invention contains at least 12% by weight of polyester resin, more preferably at least 20% by weight of polyester resin, and even more preferably at least 30% by weight of polyester resin. Preferably, the ink composition used in the present invention contains 50% by weight or less of polyester resin. Preferably, the ink composition used in the present invention contains about 12 to about 50% by weight of polyester resin, preferably about 20 to about 50% by weight of polyester resin, and more preferably about 30 to about 50% by weight of polyester resin.

[0041] Preferably, the ink composition used in the present invention includes one or more neutralizing agents. Suitable neutralizing agents include ammonia and amines having a boiling point below 100°C, such as triethylamine and dimethylamine. In the most preferred embodiment of the present invention, the ink composition includes ammonia. Preferably, the ammonia is in the form of an aqueous solution.

[0042] When used, the neutralizing agent is present in an amount of about 0.1% to about 5% by weight of the ink composition, preferably about 0.5% to 3% by weight of the ink composition. When used, the neutralizing agent is preferably ammonia, and the ammonia is preferably present in an amount of about 0.1% to about 5% by weight of the ink composition, preferably about 0.5% to 3% by weight of the ink composition.

[0043] In addition to the aforementioned polyester resin, the ink composition of the present invention may optionally contain one or more additional resin types, so long as the printed and dried article containing the ink composition complies with EUPIA food contact guidelines, especially at elevated temperatures (e.g., 150°C or higher). Examples of such resins include, but are not limited to, polyamides, ketones, aldehydes, alkyds, phenol-formaldehyde, rosin resins, hydrocarbons, phenols, nitrocellulose, vinyls, rosin esters, epoxies, and the like.

[0044] The present invention is most advantageous for flexographic and inkjet printing inks, with flexographic printing being most preferred. The present invention is preferably directed to water-based flexographic inks, but also encompasses inks (preferably pigmented inks) that can be applied by any other method, including inkjet printing, gravure printing, offset printing, and screen printing.

[0045] Preferably, the inks of the present invention have a viscosity of 18 to 35 seconds (Zahn 2 cup) when measured using deionized water at 23°C.

[0046] The printing ink of the present invention may optionally contain any water-soluble organic co-solvent. Volatile solvents such as ethanol, propanol, and isopropanol can also be used, but if the ink is intended for inkjet printing, it is preferable to use one that is not highly flammable or volatile, typically of the polyol, alkylene glycol, alkylene glycol ether, or ether acetate type, non-limiting examples of which include: 4-hydroxy-4-methyl-2-pentanone, diethylene glycol, diethylene glycol butyl ether, diethylene glycol ethyl ether, diethylene glycol methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether, dipropylene glycol, dipropylene glycol ethyl ether, dipropylene glycol methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether, dipropylene glycol, dipropylene glycol ethyl ether, dipropylene glycol methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether, dipropylene glycol, dipropylene glycol ethyl ether, dipropylene glycol methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether, dipropylene glycol ethyl ether, dipropylene glycol methyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether, dipropylene glycol ethyl ether, dipropylene glycol methyl ether, dipropylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether, dipropylene glycol ethyl ether, dipropylene glycol monopropyl ... Examples of suitable cosolvents include propylene glycol methyl ether, ethylene glycol butyl ether, ethylene glycol ethyl ether, ethylene glycol isopropyl ether, ethylene glycol methyl ether, ethylene glycol propyl ether, glycerin carbonate, N-methyl-2-pyrrolidone, glycerol, propylene glycol, propylene glycol ethyl ether, propylene glycol ethyl ether acetate, propylene glycol methyl ether, propylene glycol n-propyl ether, triethylene glycol, triethylene glycol butyl ether, triethylene glycol methyl ether, tripropylene glycol, tripropylene glycol methyl ether, N-methylpyrrolidone, and urea. When such cosolvents are used, they should preferably comprise less than 35% (w / w), more preferably less than 30.0% (w / w), and even more preferably 25% (w / w) or less of the ink composition. Furthermore, the concentration of solvents having a boiling point above 250°C is preferably less than 10.0% (w / w), more preferably less than 5.0% (w / w) of the ink composition.

[0047] Preferably, the ink composition used in the present invention does not contain a crosslinker. Preferably, the ink composition does not contain a melamine-formaldehyde resin, zinc oxide, carbodiimide, copper oxide, magnesium oxide, calcium oxide, glutaraldehyde, glyoxal, borate, potassium persulfate, aluminum chloride, titanium tetrahydrochloride, zinc chloride, or any combination thereof. Most preferably, the ink composition used in the present invention does not contain a melamine-formaldehyde resin, zinc oxide, or a combination thereof.

[0048] Preferably, the ink composition used in the present invention does not contain a self-crosslinking acrylic resin. As understood in the art, a self-crosslinking acrylic resin contains self-reactive functional groups and therefore does not require a separate co-reactant. Self-crosslinking polymers are usually in the form of aqueous dispersions or emulsions and are typically the product of at least two monomers reacting with each other. For example, such polymers may contain both carbonyl and amine functional groups. There are several mechanisms by which polymers can self-crosslink. One mechanism is through the use of phase-separated polymers, such as core-shell polymers. The shell polymer is hydrophilic, while the core polymer is hydrophobic. The hydrophilic shell maintains the dispersion, while the hydrophobic core provides reactive sites for crosslinking. Alternatively or additionally, a self-crosslinking polymer emulsion may contain crosslinking functional groups attached to the polymer backbone in addition to a crosslinker (i.e., a multifunctional species that reacts with the crosslinking functional groups). Typically, in self-crosslinking acrylic polymer chemistry, a polymer containing ketone groups crosslinks at room temperature when combined with a di- or multifunctional compound that is reactive toward carbonyls.

[0049] Preferably, the ink composition used in the present invention does not contain a self-crosslinking acrylic polymer formed from methyl acrylate (MAA), methyl methacrylate (MMA), butyl acrylate, butyl methacrylate, styrene, and methylstyrene. Most preferably, the ink composition used in the present invention does not contain a self-crosslinking polymer that is a styrene / acrylic ester copolymer.

[0050] The inks used in the present invention are aqueous. Unless otherwise specified, aqueous inks comprise 20% or more, 25% or more, or 30% or more by weight. Preferably, the amount of water is 95% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, or 60% or less by weight. Thus, the amount of water in the composition is 20 to 95% by weight, for example, 20 to 80% by weight, or 20 to 70% by weight. Preferably, the range of water in the composition is typically 30 to 75% by weight, more preferably 30 to 60% by weight.

[0051] Because the products of the present invention are primarily aqueous in nature, it is also desirable to optionally include a biocide or fungicide. Suitable examples include, but are not limited to, products based on biocide structural types such as benzisothiazolinone, bromonitropropanediol, isothiazolinone, ethylenedioxydimethanol, or iodopropynyl butylcarbamate. Some commercially available grades include those sold under the trade names Intercide (Akcros Chemicals) or Nipacide (Clariant). Other types of biocides of interest include sodium dehydroacetate (Lonza's Geogard 111S), sodium benzoate (RTVANDERBILT's Vancide 51), sodium pyridinethiol-1-oxide (Arch Chemicals' Sodium Omadine), the sodium salt of o-phenylphenol (Dowicide A, Dow Chemical), and ethyl p-hydroxybenzoate (Aako's Nipastat Sodium). These are preferably used in an amount of 0.01 to 1.00% by mass in the ink composition.

[0052] Optionally, an antifoaming agent can be included in the formulation to prevent foam formation during ink production and jetting. Antifoaming agents are particularly important in recirculating printheads. Examples of suitable antifoaming agents include, but are not limited to, Evonik's 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 BYK are BYK-066N, 088, 055, 057, 1790, 020, BYK-A 530, 067A, and BYK 354. Additives DC62, DC65, DC68, 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. Surfynol 104PA, AD01, DF-110, DF-58, DF-62, DF-66, DF-695, DF-70, and MD-20 are available from Air Products.

[0053] Surface control additives are often optionally used to control the surface tension of the ink, which is necessary to tailor wetting on the printhead faceplate and also to achieve the desired drop spreading on the substrate, or wet-on-dry drop spreading in the case of multi-pass inkjet printing. Surface control additives can also be used to control the level of slip and scratch resistance of the coating. 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, 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. Sartomer's aliphatic silicone acrylate CN9800 can 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 DuPont.

[0054] The ink formulation can optionally include suitable degassing agents to prevent air entrapment and pinhole formation in the cured coating. They also reduce rectified diffusion, which can cause printhead reliability issues. Non-limiting examples include the following products available from Evonik: TEGO AIREX 900, 910, 916, 920, 931, 936, 940, 944, 945, 950, 962, 980, and 986.

[0055] The printing ink of the present invention typically contains one or more colorants. Colorants may contribute to the overall migration of the printed structure. Therefore, it is important to select a colorant that does not exhibit excessive migration and is suitable for providing a printed structure that meets the EUPIA regulations for direct food content, especially at high temperatures. The method for selecting a low-migration colorant suitable for food contact applications is described in detail in WO2021007422, the entire text of which is incorporated herein by reference.

[0056] Examples of such low-migration colorants include Paliotol Yellow D1818, Paliotol Yellow D0960, Irgazin Orange D2905, Irgazin Rubine L4025, Heliogen Blue D6840, Cromophtal Violet D5700, Fastogen Super Magenta RY, XPB-509, Suncroma C47-2222, isoindoline yellow, diketopyrrolo-pyrrole orange, diketopyrrolo-pyrrole red, quinacridone red, phthalocyanine blue, dioxazine violet, carbon black, titanium dioxide, and mixtures thereof.

[0057] The ink composition of the present invention may optionally contain one or more additional colorants that may exhibit higher migration properties than those listed in the previous paragraph. Preferably, these highly migratory colorants would be used in small enough amounts so that the final printed structure still falls within the EUPIA food migration regulations. It should be understood that it is the final printed structure, not the individual materials themselves, that must pass the EUPIA regulations. This list of additional colorants includes pigments and / or dyes. Examples of suitable organic or inorganic pigments include carbon black, zinc oxide, titanium dioxide, phthalocyanines, anthraquinones, perylenes, carbazoles, monoazo and disazobenzimidazoles, rhodamines, indigoids, quinacridones, diazopyranthrones, dinitroanilines, pyrazoles, diazopyranthrones, pyrazoles, dianisidines, pyranthrones, tetrachloroisoindolines, dioxazines, monoazoacrylates, and anthrapyrimidines. Dyes include, but are not limited to, azo dyes, anthraquinone dyes, xanthene dyes, azine dyes, combinations thereof, and the like.

[0058] Commercially available organic pigments classified according to the Color Index International can be used, including, but not limited to, those with the following trademark designations: blue pigments PB1, PB15, PB15:1, PB15:2, PB15:3, PB15:4, PB15:6, PB16, PB60; brown pigments PB5, PB23, and PB265; green pigments PG1, PG7, PG10, and PG36; and yellow pigments. PY3, PY14, PY16, PY17, PY24, PY65, PY73, PY74, PY83, PY95, PY97, PY108, PY109, PY110, PY113, PY128, PY129, PY138, PY139, PY150, PY151, PY154, PY156, PY175, PY180, and PY213; orange pigments PO5, PO15, PO16, PO31, PO34, PO36, PO43, PO48, PO51, PO60, PO61, and PO71; red pigments PR4, PR5, PR7, PR9, PR22, PR23, PR48, PR48:2, PR49, RP112, PR122, PR123, PR149, PR166, PR168, PR170, PR177, PR179, PR190, PR202, PR206, PR207, PR224, PR254, and PR264: violet pigments PV19, PV23, PV32, PV37, and PV42; black pigments PBk1, PBk6, PBk7, PBk8, PBk9, PBk10, PBk11, PBk12, PBk13, PBk14, PBk17, PBk18, PBk19, PBk22, PBk23, PBk24, PBk25, PBk26, PBk27, PBk28, PBk29, PBk30, PBk31, PBk32, PBk33, PBk34, PBk35, NBk1, NBk2, NBk3, NBk4, NBk6; combinations thereof, etc. The present invention relates to a multicolor process printing ink set comprising a four-color process set that can include cyan, magenta, yellow, and black inks, to which an additional process color is added, comprising either an orange ink, a violet ink, or a red ink. A further aspect of the present invention is the inclusion of a white ink, optionally comprising titanium dioxide.

[0059] The pigment is typically ground to less than 1 micrometer, and the preferred particle size distribution after grinding is 10 to 500 nm, more preferably 10 to 350 nm, to achieve better transparency and a wider color gamut. Preferably, the pigment is ground in a bead mill filled with 0.7 to 0.9 μm ceramic beads. A suitable bead mill can be used to grind the pigment.

[0060] Pigments are produced as pigment concentrates in water and are shelf stable. This is typically achieved by dispersing the pigment in a water-soluble or water-dispersible resin using a water-soluble and / or water-dispersible surfactant that introduces hydrophilic functional groups onto the surface of the pigment particles. Examples of these dispersing resins are numerous and include polyvinyl alcohol, 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-α-methylstyrene-acrylic acid copolymers, styrene-α-methylstyrene-acrylic acid-acrylate copolymers, styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, vinylnaphthalene-acrylic acid copolymers, vinylnaphthalene-maleic acid copolymers, vinyl acetate-maleic acid copolymers, vinyl acetate-crotonic acid copolymers, and vinyl acetate-acrylic acid copolymers, as well as salts thereof. The copolymer can be used in any form of random copolymer, block copolymer, alternating copolymer, or graft copolymer. Examples of such resins include Joncryl 67, 678, 8500, 586, 611, 680, 682, 683, and 69 available from BASF. These resins are usually neutralized with ammonia to prepare polymer solutions. These resins can also be neutralized with any other organic amine or, of course, with an inorganic base.

[0061] Examples of surfactants that can be optionally used in the pigment dispersion include, but are not limited to, anionic surfactants such as alkanesulfonates, α-olefinsulfonates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, acylmethyltaurates, dialkylsulfosuccinates, alkyl sulfates, sulfurized olefins, polyoxyethylene alkyl ether phosphates, polycarboxylic acids, and monoglycerol phosphates; amphoteric surfactants such as alkylpyridinium salts; and nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamides, 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.

[0062] The printing ink of the present invention may further optionally contain a wax, emulsion, or wax dispersion. Numerous such products are available, including, but not limited to, carnauba wax, paraffin wax, low-density polyethylene wax, high-density polyethylene wax, polypropylene wax, polyamide wax, erucamide wax, and PTFE wax. In preferred embodiments where a wax is included, the wax should be a biopolymer-based wax, including micronized biopolymer-based wax. When present, the wax will be present in an amount of up to about 4% by weight of the ink composition. Preferably, the wax is present in an amount of about 0.1% to about 2% by weight of the ink composition.

[0063] The heat-resistant ink of the present invention can be printed on any substrate, including, but not limited to, polyester film, polyamide film, aluminum foil, paper, and corrugated board. If the substrate to be printed is to be used in oven-safe packaging, the substrate must be able to withstand temperatures of 150°C or higher without significant distortion or other loss of mechanical integrity. The present invention is advantageously directed to printing on paper and corrugated board packaging, such as folding corrugated board packaging. As the packaging industry seeks more sustainable technologies, the use of paper and corrugated board packaging, including coated derivatives, will undoubtedly become more important as an alternative to the use of plastic packaging, particularly polyester packaging, which dominates this sector. As understood in the art, coated derivatives are substrates that have been previously coated with a primer.

[0064] As used herein, ovenable foods are reheated or cooked in an oven at a temperature of about 150° C. to about 300° C., preferably about 150° C. to about 250° C. Typically, ovenable foods are reheated or cooked in an oven for at least 5 minutes.

[0065] In addition to printing food packaging, the present invention is also suitable for other applications where the printed matter is exposed to temperatures of 150° C. or higher and where the generation of large amounts of low molecular weight substances, typically less than 1000 daltons, particularly less than 500 daltons, can be problematic. Thus, the printing ink of the present invention can also be used in a variety of applications, such as dielectric inks and coatings for electronic devices and printing inks for automotive parts.

[0066] In addition to the aqueous printing inks described above, the present invention also includes the optional application of a primer. A primer coating may be applied to the substrate before printing with the aqueous ink of the present invention. The primer coating can be used to improve the adhesion and print quality of the ink of the present invention.

[0067] After being printed with the inks of the present invention, the substrate may be further processed to allow for the formation of final packaging by processes including applying adhesives, laminating to other plastic, aluminum foil, and paper-based substrates, folding, creasing, etc. It should be understood that such processes are not an essential feature of the present invention, and that those skilled in the art will simply recognize that printed articles using the water-based inks of the present invention can be further manipulated to produce final products.

[0068] Glass transition temperature (Tg): Unless otherwise specified, glass transition temperature is measured by differential scanning calorimetry (DSC). Preferably, measurements were performed according to the following standard test method, based on the method described in ASTM E1356-98. The sample was maintained under a dry nitrogen atmosphere for the duration of the scan. A flow rate of 20 ml / min and Al pans were used. The sample (5 mg) was heated from 20°C to 350°C at 20°C / min. As described in ASTM E1356-98, the value of Tg was determined as the extrapolated onset temperature of the glass transition observed in the DSC scan (heat flow rate (W / g) versus temperature (°C)).

[0069] Softening Point: Unless otherwise specified, softening point is measured using a ring and ball apparatus according to ASTM E28-18.

[0070] Viscosity: Unless otherwise stated, ink viscosity was measured in deionized water at 23°C using a Zahn 2 cup (i.e., Zahn cup #2).

[0071] Particle size / mean particle size: In the context of the present invention, the term "particle size", or "mean particle size", refers to the volume distribution median particle diameter (the equivalent spherical diameter corresponding to 50% of the volume of all particles, as read on a cumulative distribution curve relating volume % to particle diameter; often referred to as the "D(v,0.5)" value). Particle size can be measured by electron microscopy, Coulter counter, sedimentation analysis, static or dynamic light scattering. Techniques based on the diffraction of laser light are preferred.

[0072] Acid Number (AV): Acid value (or acid number) is defined as the mass (in milligrams) of potassium hydroxide (KOH) required to neutralize one gram of a chemical. Acid number is preferably measured according to ISO 2114:2000(E) (Method B) standard.

[0073] Hydroxyl Number (OHV): The hydroxyl number (or hydroxyl value) is defined as the number of milligrams of potassium hydroxide required to neutralize the acetic acid absorbed during the acetylation of one gram of a chemical containing a free hydroxyl group. The hydroxyl number is suitably measured according to standard ISO 4629-1:2016(E).

[0074] Although the present invention has been described in detail, including preferred embodiments thereof, it will be appreciated that those skilled in the art, upon consideration of this disclosure, may make modifications and / or improvements thereto within the scope and spirit of the present invention.

[0075] The invention is further described by the following numbered paragraphs.

[0076] 1. An aqueous printing ink composition comprising water, a polyester resin, and optionally one or more colorants, wherein the printed composition meets EUPIA food contact guidelines when exposed to elevated temperatures of 100°C or greater.

[0077] 2. The composition of paragraph 1, wherein the printed composition meets EUPIA food contact guidelines when exposed to elevated temperatures of 150°C or greater.

[0078] 3. The composition of paragraph 1, wherein the printed composition meets EUPIA food contact guidelines when exposed to temperatures above 200° C.

[0079] 4. The composition of paragraph 1, wherein the printed composition meets EUPIA food contact guidelines when exposed to temperatures above 220° C.

[0080] 5. The composition of any of the preceding paragraphs, further comprising one or more waxes.

[0081] 6. The composition of paragraph 5, wherein the wax is derived from a bio-based wax.

[0082] 7. The composition of any of the preceding paragraphs, wherein the composition is suitable for inkjet printing, gravure printing, offset and screen printing, flexographic printing, and inkjet printing.

[0083] 8. The composition of any of the preceding paragraphs, wherein the composition is suitable for flexographic printing or inkjet printing.

[0084] 9. The composition of any of the preceding paragraphs, wherein the polyester resin is selected from the group consisting of an aqueous polyester dispersion, a solution of a sulfopolyester, a rosin-derived polyester, or a mixture thereof.

[0085] 10. The composition of any of the preceding paragraphs, wherein the polyester is a renewable polyester.

[0086] 11. The composition of any of the preceding paragraphs, wherein the polyester resin has a glass transition temperature of 80°C or less.

[0087] 12. The composition of any of the preceding paragraphs, wherein the colorant is selected from the group consisting of Paliotol Yellow D1818, Irgazin Orange D2905, Irgazin Rubine L4025, Heliogen Blue D6840, Cromophtal Violet D5700, Suncroma C47-2222, Isoindoline yellow, Diketopyrrolo-pyrrole Orange, Diketopyrrolo-pyrrole Red, Quinacridone Red, Phthalocyanine Blue, Dioxazine Violet, carbon black, titanium dioxide, and mixtures thereof.

[0088] 13. The composition of any of the preceding paragraphs, wherein the colorant used to prepare the ink is selected from the group consisting of Pigment Yellow 138, Pigment Orange 71, Pigment Red 264, Pigment Blue 15:0, Pigment Violet 37, Pigment Red 122, or mixtures thereof.

[0089] 14. The composition of any of the preceding paragraphs, further comprising a crosslinking agent.

[0090] 15. The composition of paragraph 14, wherein the crosslinking agent is a carbodiimide.

[0091] 16. A printing ink set comprising, in addition to the cyan, magenta, yellow, and black inks, at least one further ink selected from orange, green, or violet, and optionally a white ink, said inks being based on the composition of any one or more of paragraphs 1 to 15.

[0092] 17. A method of providing a printed article, the method comprising applying an ink of any one or more of paragraphs 1 to 16 onto a substrate and allowing the ink to dry.

[0093] 18. The method of paragraph 17, wherein the ink is not overprinted with an overprint varnish.

[0094] 19. The method of paragraph 17 or 18, wherein the printed article is a food packaging article.

[0095] 20. The method of any one or more of paragraphs 17 to 19, wherein the printed article is paper-based.

[0096] 21. The method of any one or more of paragraphs 17 to 19, wherein the printed article complies with EUPIA food packaging regulations when exposed to temperatures of 100°C or higher.

[0097] 22. The method of any one or more of paragraphs 17 to 19, wherein the printed article complies with EUPIA food packaging regulations when exposed to temperatures of 150°C or higher.

[0098] 23. The method of any one or more of paragraphs 17 to 19, wherein the printed article complies with EUPIA food packaging regulations when exposed to temperatures of 200°C or higher.

[0099] 24. The method of any one or more of paragraphs 17 to 19, wherein the printed article complies with EUPIA food packaging regulations when exposed to temperatures of 220°C or higher.

[0100] 25. A printed article obtained by the method of any one or more of paragraphs 17 to 23.

[0101] 26. An article according to paragraph 25 which is a paper-based food packaging article.

[0102] Although the present invention has been described in detail, including preferred embodiments thereof, it will be appreciated that those skilled in the art, upon consideration of this disclosure, may make modifications and / or improvements thereto within the scope and spirit of the present invention. [Example]

[0103] The present invention is further described by the following non-limiting examples which further illustrate the present invention and are not intended to, and should not be construed as, limiting the scope of the invention.

[0104] For the preparation of water-based flexographic ink examples according to the present invention, the following varnishes were prepared so that both pigment dispersions and ink examples could be prepared:

[0105] [Table 1]

[0106] [Table 2]

[0107] [Table 3]

[0108] The pigment concentrate formulations are shown in Table 4 and the final ink compositions are shown in Table 5.

[0109] [Table 4]

[0110] The pigment concentrate was prepared by first premixing the pigment into the ovenable varnish using a Dispermat high shear mixer, then passing the premix through a bead mill filled with 0.7-0.9 μm ceramic beads to completely disperse it.

[0111] Ink examples of the present invention were prepared by mixing pigment concentrate with more ovenable varnish and bio-based wax using a Dispermat high shear mixer.

[0112] [Table 5]

[0113] As a further example, an ovenable overlacquer (Example 8) was prepared by mixing 98% ovenable technical varnish with 2% bio-based wax.

[0114] All inks were reduced to a viscosity of 25 seconds using deionized water.

[0115] For comparison, a commercially available water-based flexographic ink containing a blend of acrylic emulsions and an ink set based on PY13, PO34, PR266, PV37, PB15:0, and Pigment Black 7 was also tested.

[0116] Ink is 9.5cc / m 2 Anilox was used to print onto MGBK (Machine Glazed Bleached Kraft) paper or polyester film, a typical paperboard used in a variety of food packaging applications.

[0117] The resulting prints were tested for brightness, dip properties, bleed, and rub resistance. The results are shown in the table below. The inks of the present invention were compared to Aquaprop ink (a commercially available acrylic food packaging ink available from Sun Chemical). It should be noted that the inks of the present invention provide similar or better properties compared to the comparative inks, which typically require an overprint varnish.

[0118] To demonstrate suitability for use, the inks of the present invention were subjected to immersion, smear, and rub tests and compared to a comparative Aquaprop ink.

[0119] The prints were immersed in the liquid reagent, removed after 1 hour, and patted dry to assess whether the print had been removed. The results are shown in Table 6.

[0120] [Table 6]

[0121] Table 6 shows that the immersion resistance properties of the inks of the present invention are as good as Aquaprop's commercial inks.

[0122] Table 7 - Bleeding test The prints were placed on a piece of filter paper placed on a square glass plate and immersed in various liquid reagents. Another piece of filter paper was placed on top, and a square of glass was placed to hold the sandwich together, with a 1 kg weight added to apply pressure. After 18 hours, the structure was disassembled and the prints were tapped dry. Ink removal was recorded using the same rating scale as above. [Table 7]

[0123] Table 7 shows that the inks of the present invention exhibited similar bleed resistance as the comparative inks.

[0124] Table 8 - Friction test The rub resistance of the prints was evaluated using a SATRA circular rub tester equipped with a fabric pad. Dry rub resistance was measured after 100 revolutions at a load of 2 psi. Wet rub resistance was evaluated using a PIRA tester after the fabric pad was immersed in water and rotated 10 times without applying pressure. As a further test, the prints were immersed in water for 1 hour and rubbed with a finger 10 times to evaluate print removal. The rating scale was the same as above. [Table 8]

[0125] In Table 8, the inks of the present invention performed similarly to the Aquaprop inks.

[0126] Migration Test The prints (on PET film) were placed in a migration cell and contacted with Tenax simulant for 2 hours at 220°C. Tenax is a polymer (poly(2,6-diphenylphenylene oxide)) used as a dry food simulant in migration tests, and its use is well known to those skilled in the art. The use of Tenax in these tests allowed for evaluation of component migration from the prints at elevated temperatures. To ensure that contaminants were not introduced during cell construction or sample testing, a Tenax-based cell "blank" was used, contacting unused aluminum foil. After 2 hours, the cell was emptied and the Tenax extracted into 40 ml of acetonitrile. The acetonitrile was then evaporated to 1 ml using an autoevaporator, and the resulting concentrate was analyzed by GC-MS. Although the migration tests were performed at 220°C, it is well known that inks that perform well at 220°C also perform well at lower temperatures, such as 220°C or less, 210°C or less, 200°C or less, 190°C or less, 180°C or less, 170°C or less, 160°C or less, 150°C or less, 140°C or less, 130°C or less, 120°C or less, 110°C or less, 100°C or less, or other temperatures below 220°C, including room temperature.

[0127] The table below shows that the inks of the present invention have significantly lower levels of migratory species compared to a commercial ink (Aquaprop), due to the ink's improved heat resistance as the commercial ink, which produces low levels of migratory materials under ambient conditions without heat treatment as in typical packaging applications.

[0128] This result shows that 1kg of food has 6dm 2 The amount of migratory species contaminating a food product according to standard EU model packaging is reported as the amount of migratory species contained within a package of food, assuming the entire package is printed with the ink of the present invention and the comparative ink.

[0129] Migration Data

[0130] [Table 9]

[0131] [Table 10]

[0132] The results in Tables 9 and 10 show that inks of the present invention containing aqueous polyester resins produce a significant reduction in migratory species when prints are heated at 220° C. for 2 hours and then subjected to the migration test described above. This is clearly due to the careful selection of the binder resin (and pigment) used to prepare the inks of the present invention.

Claims

1. 1. A method of providing a packaged food product, comprising: printing a substrate with an aqueous printing ink composition; drying the aqueous printing ink composition to provide a printed substrate; packaging a food product with the printed substrate; Including, the method does not include printing or applying any layer onto the dried ink composition; The method wherein the aqueous printing ink composition comprises water and a polyester resin.

2. The method of claim 1 , wherein the substrate is paper or corrugated cardboard.

3. 1. A method of providing a printed article, comprising: applying an aqueous ink composition onto a substrate; drying the water-based ink; Including, the aqueous ink composition comprises water and a polyester resin; The method wherein said water-based ink is not overprinted with an overprint varnish.

4. The method according to any one of claims 1 to 3, wherein the water-based printing ink is not overprinted with a heat-resistant overprint varnish.

5. The method of claim 3 or 4, wherein the printed article is a food packaging article.

6. The method according to any one of claims 3 to 5, wherein the printed article is a paper-based or corrugated paper-based food packaging article, preferably the printed article is a paper-based food packaging article.

7. The method according to any one of claims 1 to 6, wherein the water-based printing ink is not overprinted with a heat-resistant overprint varnish comprising a polyester resin.

8. The method according to any one of claims 1 to 7, wherein no additional plastic layer is applied over the printed ink.

9. 9. The method according to any one of claims 1 to 8, wherein the aqueous printing ink composition is applied by inkjet printing, gravure printing, offset printing, screen printing or flexographic printing, preferably by flexographic printing or inkjet printing, more preferably by flexographic printing.

10. 1. Use of an aqueous printing ink for printing on a substrate, comprising: the printed substrate has less than 50 ppb of migrating species when heated to temperatures above 150°C; The aqueous ink composition comprises water and a polyester resin.

11. 11. The use according to claim 10, wherein the printing is by inkjet printing, gravure printing, offset printing, screen printing or flexographic printing, preferably by flexographic printing or inkjet printing, more preferably by flexographic printing.

12. 12. Use according to any one of claims 10 or 11, wherein the migration species has a molecular weight of less than 1000 Daltons, preferably less than 500 Daltons.

13. Use according to any one of claims 10 to 12, wherein the aqueous printing ink is not overprinted with an overprint varnish or a heat-seal layer.

14. Use according to any one of claims 10 to 13, wherein no additional plastic layer is applied onto the printed ink.

15. The use according to any one of claims 10 to 14, wherein the substrate is a polyester film, a polyamide film, an aluminum foil, paper or a corrugated cardboard, preferably the substrate is paper or a corrugated cardboard, more preferably the substrate is paper.

16. The use according to any one of claims 10 to 15, wherein the printed substrate is a food packaging article, preferably a paper or cardboard based food packaging article.

17. 1. Use of an aqueous printing ink composition for printing on the surface of an ovenable food packaging, comprising: the aqueous printing ink composition comprises water and a polyester resin; Use where no additional ink layer, varnish layer, or plastic layer is present on the printed ink.

18. 18. The use according to claim 17, wherein the ovenable food packaging is a paper or cardboard food packaging.

19. 10. The method of any one of claims 1, 2, 4, and 7-9, wherein the food product is ovenable.

20. 20. The method or use of any one of claims 1 to 19, wherein the polyester resin has an acid number of from about 50 to about 250 mg KOH / g, more preferably from about 100 to about 200 mg KOH / g.

21. 21. The method or use according to any one of the preceding claims, wherein the aqueous printing ink composition comprises from about 12 to about 50% by weight of polyester resin, preferably from about 20 to about 50% by weight of polyester resin, more preferably from about 30 to about 50% by weight of polyester resin.

22. The method or use according to any one of the preceding claims, wherein the aqueous printing ink composition is free of crosslinkers.

23. A method or use according to any preceding claim, wherein the aqueous printing ink composition comprises one or more colorants.

24. 24. A method or use according to any one of the preceding claims, wherein the aqueous printing ink composition further comprises one or more waxes, preferably wherein the aqueous printing ink composition comprises up to 4% by weight of a wax.

25. 25. The method or use of claim 24, wherein the wax is derived from a bio-based wax.

26. 26. The method or use of any one of claims 1 to 25, wherein the polyester resin is selected from the group consisting of aqueous polyester dispersions, aqueous sulfopolyester dispersions, polyester solutions, sulfopolyester solutions, rosin-derived polyesters, and mixtures thereof.

27. 27. The method or use of claim 26, wherein the polyester is a rosin-derived polyester.

28. The method or use of any preceding claim, wherein the polyester is a renewable polyester.

29. 29. The method or use of any one of claims 1 to 28, wherein the polyester resin has a glass transition temperature of 80°C or less.

30. 30. The method or use according to any one of the preceding claims, wherein the polyester resin is a sulfopolyester resin, preferably a sulfopolyester having a glass transition temperature of 80°C or less.

31. 31. The method or use of any one of claims 23 to 30, wherein the colorant is selected from the group consisting of Paliotol Yellow D1818, Irgazin Orange D2905, Irgazin Rubine L4025, Heliogen Blue D6840, Cromophtal Violet D5700, Suncroma C47-2222, Isoindoline yellow, diketopyrrolo-pyrrole orange, diketopyrrolo-pyrrole red, quinacridone red, phthalocyanine blue, dioxazine violet, carbon black, titanium dioxide, and mixtures thereof.

32. 31. The method or use of any one of claims 23 to 30, wherein the colorant is selected from the group consisting of Pigment Yellow 138, Pigment Orange 71, Pigment Red 264, Pigment Blue 15:0, Pigment Violet 37, Pigment Red 122, or mixtures thereof.

33. 33. The method or use of any one of claims 1 to 32, wherein the printed article or substrate complies with EUPIA food packaging guidelines when exposed to temperatures as high as 100°C or higher.

34. 34. The method or use of any one of claims 1 to 33, wherein the printed article or substrate complies with EUPIA food packaging guidelines when exposed to temperatures as high as 150°C or higher.

35. 35. The method or use of any one of claims 1 to 34, wherein the printed article or substrate complies with EUPIA food packaging guidelines when exposed to temperatures as high as 200°C or higher.

36. 36. The method or use of any one of claims 1 to 35, wherein the printed article or substrate complies with EUPIA food packaging guidelines when exposed to temperatures as high as 220°C or higher.

37. A printed article obtainable by the method according to any one of claims 3 to 9 and 20 to 36.

38. 38. The article of claim 37, wherein the article is a cardboard-based or paper-based food packaging article.

39. A packaged food product obtained by the method according to any one of claims 1, 2, 4, 7 to 9 and 20 to 36.

40. 40. The packaged food of claim 39, or the printed article of any one of claims 37 or 38, wherein the packaged food or printed article does not include an additional ink layer, varnish layer, or plastic layer over the printed ink.

41. A packaged food product comprising a food product and a printed substrate, the printed substrate comprises an ink layer derived from an aqueous printing ink composition comprising water and a polyester resin; A packaged food product, wherein the packaged food product does not include an additional ink layer, varnish layer, or plastic layer over the printed ink.

42. 42. The packaged food product of any one of claims 39 to 41, wherein the food product is ovenable.

43. The printed article of any one of claims 37, 38 and 40, or the packaged food of any one of claims 39 to 42, wherein the printed article or packaged food is oven safe.

44. The packaged food product of any one of claims 39 to 43, wherein the printed substrate is printed paper or cardboard.

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