Energy-curable inkjet ink for container decoration

Abstract

Disclosed herein are ink compositions that can be ink jetted onto a substrate with improved performance, low odor, and low transfer properties. Exemplary ink compositions include monofunctional monomers, including hydrophilic monofunctional monomers, difunctional monomers, optional colorants, and optional photoinitiators. Also disclosed are substrates decorated with the cured ink compositions, and methods of decorating substrates with the ink compositions.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 309,931, filed February 14, 2022, which is incorporated by reference in its entirety.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to energy curable inkjet ink compositions and their use in container decoration. Inkjet compositions having useful adhesive properties and low odor can be beneficial in the decoration of beverage containers. [Background technology]

[0003] Beverages such as beer and soft drinks are primarily sold in aluminum cans, glass bottles, or plastic bottles. The beverage industry often uses aluminum cans known as two-piece cans. Two-piece cans are packaging containers made from a single sheet of metal by deep drawing to form the bottom end and body, and then the second end is sewn closed to form a complete container for sale. The entire can is made up of two pieces.

[0004] The body of a two-piece can can be partially or completely decorated (printed) through several conventional printing processes (e.g., dry offset) that impart important image information to the can surface, making the aluminum can more attractive to consumers. However, conventional printing processes require that the image carrier (e.g., printing plate / blanket) be prepared in advance for each color and for each job. This is undesirable for beverage can manufacturers, because the plate costs can only be recovered by running so-called "long print runs." Similar problems can occur when printing on paper-based cartons, plastic bottles, labels, etc.

[0005] However, short-run printing is becoming more popular in the packaging industry because it offers manufacturers and consumers more freedom and flexibility in image design and brand logo upgrades. Inkjet printing, especially energy-curable inkjet printing, is considered suitable for short-run printing. First, this printing method does not require an image carrier for the job to be printed. This reduces the cost of plate, plate-making materials, and plate-making time consumption. Second, short-run printing reduces the time to apply a new design to a substrate. The color (image information) can be changed on demand, and the job can be computer-to-print. This allows for one-off printing or short-run printing for various brands and consumers. Third, inkjet printing allows for any shade or hue by applying the ink wet-on-dry or wet-on-wet overlays. As a result, the image becomes clearer, and photorealistic designs can be printed. In addition, the use of energy-curable inkjet printing for containers provides additional benefits such as fast curing, high gloss, low VOC, good water resistance, good solvent resistance, and good chemical resistance.

[0006] However, several challenges exist when applying energy curable inkjet inks (e.g., UV curable inks or LED curable inks) to beverage containers such as two-piece aluminum beverage cans, because according to common practice in the beverage can industry, decoration of two-piece cans typically involves three steps. Print the ink onto the outside of the can and then allow the ink to harden. · A protective layer of water-based overprint varnish is immediately applied to the surface of the cured ink, and the can is baked at a relatively high temperature (e.g., 350°F to 400°F for several minutes) to fully thermally cure both the overprint varnish and any barrier coats (e.g., epoxy coats) within the can. After the beverage is filled and the can is sealed, the can is pasteurized.

[0007] In the above step 1, when the energy curable inkjet ink is applied to the surface of the can body, it is preferable to fully LED or UV cure it to make the surface tack-free. This allows the cured can to be conveniently packaged and transferred to an operating unit used in step 2, where an overprint varnish can be applied immediately to the surface of the cured ink. The inkjet ink in the above step 1 should be able to wet the can body well and adhere strongly to the can surface after curing.

[0008] In the beverage can industry, two-piece cans are often coated with a thin base coat (a water-based coating) before printing ink on the can. These cans are also called "precoated cans". This base coat is said to help protect the can's surface and improve its visual quality. However, because the base coat contains acrylic / melamine resins and other additives, this type of can has a relatively low surface energy itself, which often leads to adhesion problems when applying ink to the can body. To obtain the desired print quality and acceptable adhesion between the ink layer and the base coat layer of the precoated can, it is desirable for the applied inkjet ink to have a low surface tension. However, this conflicts with the ink properties required in step 2 above. In step 2, it is desirable for the inkjet ink to have a moderately high surface tension so that the overprint varnish can wet the cured ink layer well and form a strong cohesive bond.

[0009] Even if the cured ink can impart desirable adhesion properties to the base coat and overprint varnish applied to the beverage can, poor adhesion of the ink to the metal surface and / or poor cohesion of the ink to the overprint varnish is often encountered during the pasteurization process mentioned in step 3 above. In this regard, imparting desirable water resistance, chemical resistance (such as MEK rub resistance), and desirable mechanical properties (such as pencil hardness) to the decorative ink are also challenges that the beverage can industry must overcome.

[0010] Finally, there is an increasing demand in the beverage can industry for the use of inks and coatings with low odor and low extractables. Conventional energy-curable inkjet inks are not suitable for direct printing on food packaging materials because the main components used in these types of inks are monofunctional monomers, which require low viscosity. UV-curable monofunctional monomers are generally highly volatile and often have a strong odor. The odors from these monomers are unpleasant for printing operators. These odors persist after the ink film has cured and can also be detected by end users of the printed product. For example, they can be detected through the lips and mouth when the end user drinks from the beverage container. Summary of the Invention [Problem to be solved by the invention]

[0011] From a safety and environmental standpoint, odorless (or low odor) energy curable inks / coatings would be useful in the beverage can industry. To date, the beverage can industry has not offered such energy curable inkjet ink / coating products. Thus, there remains a need to provide inkjet inks that have low odor both at the printing stage and when used by the end user. [Means for solving the problem]

[0012] In one embodiment, an ink composition is disclosed that includes a monofunctional monomer, including a hydrophilic monofunctional monomer, a difunctional monomer, an optional colorant, and an optional photopolymerization initiator, wherein the ratio of the weight of the difunctional monomer to the weight of the monofunctional monomer in the ink composition is greater than 0.1.

[0013] In another embodiment, an ink composition is disclosed that includes, in weight percent based on the total weight of the ink composition, about 5% to about 35% of a hydrophilic monofunctional monomer, about 30% to about 70% of a bifunctional monomer, about 0% to about 4% of a colorant, and an optional photopolymerization initiator, and has an average double bond density of the polymerizable components that exceeds 1.5.

[0014] In another aspect, a method of printing decoration onto a substrate is disclosed, the method comprising applying to a surface of the substrate an ink composition comprising a monofunctional monomer comprising a hydrophilic monofunctional monomer, a difunctional monomer, an optional colorant, and an optional photoinitiator, wherein the ratio of the weight of the difunctional monomer to the weight of the monofunctional monomer in the ink composition is greater than 0.1. The method further comprises irradiating the ink composition with ultraviolet light, light emitting diode radiation, or electron beam radiation to cure the ink composition on the surface of the substrate and provide a decorated substrate.

[0015] In another aspect, a decorated substrate is disclosed that includes a substrate and a cured ink composition derived from the ink composition disclosed herein on a surface of the substrate.

[0016] In another aspect, an energy curable inkjet ink composition is disclosed that comprises a monofunctional monomer, a multifunctional monomer, a colorant, and one or more functional materials to adjust the wetting / flow / cure properties of the monomer(s) and colorant(s), which is fully cured after application to a substrate following exposure to LED light, UV light, or EB radiation.

[0017] The energy curable inkjet ink composition may have at least one monomer that is a hydrophilic monofunctional monomer that contains at least one hydrophilic group such as a hydroxyl group, an amide group, a carboxyl group, or an amino group in its molecular structure. Examples of the hydrophilic monofunctional monomer include 4-hydroxybutyl acrylate (4HBA), diacetone acrylamide (DAAM), 2-[[(butylamino)carbonyl]oxy]ethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-carboxyethyl acrylate, hydroxyethyl caprolactone acrylate, vinylmethyloxazolidone (VMOX), or mixtures thereof, at a level of about 3% to about 46% by weight of the total ink composition. The hydrophilic monofunctional monomer, together with other monofunctional monomer(s), may comprise about 3% to about 80% by weight of the total ink composition.

[0018] At least one of the multifunctional monomers can be a difunctional monomer at a level of about 10% to about 80% by weight of the total ink composition. The difunctional monomers can include 3-methyl-1,5-pentanediyl diacrylate, propoxylated neopentyl glycol diacrylate, 1,10-decanediol diacrylate, 2-hydroxy 3-methacrylpropyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, 1,6-hexanediol (2EO) diacrylate, propoxylated hexanediol diacrylate, and 2-(2-vinyloxyethoxy)ethyl acrylate, or mixtures thereof. The multifunctional monomers can further include a trifunctional monomer at a level of up to about 20% by weight of the total ink composition. The trifunctional monomer may include ethoxylated trimethylolpropane triacrylate (EOTMPTA), propoxylated trimethylolpropane triacrylate (POTMPTA), 2-tris(2-hydroxyethyl)isocyanurate triacrylate, or mixtures thereof. The multifunctional monomer may further include tetra-, penta-, or hexa-functional monomers at a level of up to about 15% by weight of the total ink composition. The tetra-, penta-, or hexa-functional monomers may include pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, or mixtures thereof. The weight / weight ratio of difunctional monomer to monofunctional monomer may be greater than 0.1. The average double bond density of the polymerizable components may be greater than 1. The average double bond density of the polymerizable components can belong to when difunctional monomers, trifunctional monomers, multifunctional monomers, or combinations thereof are used in the disclosed ink compositions.

[0019] At least one of the colorants can be a pigment or dye that is compatible with the monomers and dispersants used in the ink composition and capable of forming a stable pre-dispersion under appropriate shear conditions. The individual colorants of each process color can comprise up to about 4% by weight of the total ink composition.

[0020] At least one of the functional materials for curing the monomer can be an acylphosphine oxide-based initiator or a polymeric initiator, at a level of up to about 15% by weight of the total ink composition when the curing involves the use of LED or UV light. The acylphosphine oxide-based initiator can include phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Bapo), and the polymeric initiator can include polymeric thioxanthone derivatives (Omnipol™ TX) or / and polymeric aminoalkylphenones (Omnipol 910). The functional materials can further include synergists, stabilizers or polymerization inhibitors, wetting / flow agents, defoamers / defoamers, inactive resins, oligomers, and the inactive resins or oligomers can include at least one hydrophilic group in their molecular structure, such as hydroxyl, amide, carboxyl, or amino groups.

[0021] The ink compositions can have a viscosity of about 40 cPs or less at about 25° C. and about 15 cps or less at about 45° C., and a surface tension of about 20 mN / m or more and about 27 mN / m or less at room temperature, respectively.

[0022] In another aspect, a method of substrate decoration is disclosed that includes the steps of: (a) jetting the disclosed energy curable inkjet ink composition onto an optionally precoated substrate (e.g., a white base can or a clear coat can); (b) LED-curing, UV-curing or EB-curing the inkjet ink on the substrate surface; (c) laminating the cured inkjet ink by imprinting a water-based overprint varnish through a roll-coating process; and, optionally, (d) baking the imprinted substrate at high temperature (about 350°F to about 400°F) to impart useful properties to the finished product (e.g., a metal beverage can), such as low transfer, chemical resistance and pasteurization resistance.

[0023] In another aspect, an inkjet ink composition is disclosed that can be applied to a beverage can through a printhead to provide good adhesion to the can surface once the ink is cured by a radiation source including LED light, UV light, or electron beam.

[0024] In another aspect, an inkjet ink composition is disclosed that can be overprinted with a water-based clear coat. The inkjet ink can be used in combination with the water-based overprint clear coat to provide a finished can with desirable adhesion properties, gloss level, hardness, chemical resistance, and / or pasteurization resistance.

[0025] In another aspect, an energy curable inkjet ink composition is disclosed that includes at least a monofunctional monomer, a difunctional monomer, and a colorant. [Brief description of the drawings]

[0026] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] FIG. 1 is an explanatory view showing an example of a substrate.

[0027] [Diagram 2] FIG. 2 is an illustration showing a cross-section of an example of a finished substrate printed with the disclosed ink composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] (Detailed Description) Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. In case of conflict, the present specification, including definitions, will control. Exemplary methods and materials are described below, but methods and materials similar or equivalent to those described herein can be used to practice or test the disclosed invention. All publications, patent applications, patents, and other documents mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and are not intended to be limiting.

[0029] As used herein, the terms "comprise(s)", "include(s)", "having", "has", "can", "contain(s)", and variations thereof are intended to be open-ended conjunction phrases, terms, or words that do not exclude the possibility of additional acts or structures. The singular forms "a", "and", and "the" include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments that "comprising", "consisting of", and "consisting essentially of" the embodiments or elements presented herein, whether or not expressly stated.

[0030] For the recitation of numerical ranges herein, each intervening numerical value with the same degree of precision is expressly contemplated. For example, for the range of 6-9, 7 and 8 are expressly contemplated in addition to 6 and 9, for the range of 6.0-7.0, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0 are expressly contemplated, and for the range of 1.5-2, 1.5, 1.6, 1.7, 1.8, 1.9, 2 are expressly contemplated.

[0031] The modifier "about" used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes at least the degree of error associated with measurement of the particular quantity). The modifier "about" should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. For example, the phrase "about 2 to about 4" also discloses the range "2 to 4". The term "about" may refer to plus or minus 10% of the indicated numerical value. For example, "about 10%" may indicate a range of 9% to 11%, and "about 1" may mean 0.9 to 1.1. Other meanings of "about" may be apparent from the context, such as rounding, so for example, "about 1" may also mean 0.5 to 1.4.

[0032] As used herein, the term "acrylate" refers to an α,β-unsaturated ester or acid functionality (e.g., H2C=CHC(O)-O- and H2C=CRC(O)-O-, where R is an alkyl group).

[0033] As used herein, "monomer" refers to a material that has a viscosity less than that of an oligomer and a relatively low molecular weight (e.g., less than about 1000 g / mol) and contains one or more unsaturated groups (e.g., acrylate groups or C=C double bonds) that can be polymerized to form an oligomer or polymer. Monomers generally have a viscosity of 500 cPs or less at 25°C.

[0034] As used herein, the term "monofunctional acrylate monomer" refers to a monomer that contains one functional acrylate group.

[0035] As used herein, the term "difunctional acrylate monomer" refers to a monomer that contains two functional acrylate groups.

[0036] As used herein, the term "trifunctional acrylate monomer" refers to a monomer that contains three functional acrylate groups.

[0037] As used herein, the term "multifunctional acrylate monomer" refers to an acrylate monomer that contains three or more functional acrylate groups or three C=C double bonds.

[0038] As used herein, the terms "(meth)acrylate" and "(meth)acrylic acid" include both acrylate and methacrylate compounds.

[0039] As used herein, the term "ethoxylated" refers to compounds that have been chain extended through the use of ethylene oxide.

[0040] As used herein, the term "propoxylated" refers to compounds that are chain extended with the use of propylene oxide.

[0041] As used herein, the term "alkoxylated" refers to compounds that are chain extended with either or both of ethylene oxide and propylene oxide.

[0042] As used herein, "oligomer" refers to a material having a viscosity greater than that of a monomer, a relatively intermediate molecular weight (e.g., 5,000 g / mol to 200,000 g / mol), and one or more unsaturated groups that can be polymerized to form a higher molecular weight polymer.

[0043] As used herein, the term "molecular weight" means number average molecular weight, unless otherwise specified. Molecular weight can be measured by techniques used in the art, such as size exclusion chromatography, gel permeation chromatography, mass spectrometry, rheometry, etc.

[0044] As used herein, "polymer" refers to a macromolecule having a molecular structure made up of many smaller units joined together, the smaller units generally being derived from monomers or oligomers.

[0045] As used herein, the term "inactive resin" refers to a resin that does not contain double C=C bonds or other reactive groups that allow it to be incorporated into, for example, a polymer, and does not react with monomers / oligomers in the ink composition, with or without exposure to energy radiation (e.g., UV, LED, EB).

[0046] As used herein, "energy curable" refers to curing in response to exposure to a suitable energy source, such as light radiation (e.g., ultraviolet (UV) radiation and light emitting diode (LED) radiation) and electron beam radiation.

[0047] As used herein, "cure" or "curing" refers to a process that results in polymerization, hardening, and / or crosslinking of monomeric and / or oligomeric units to form a polymer. Curing can occur via any polymerization mechanism initiated by UV, LED, EB, or other suitable energy source.

[0048] As used herein, the term "room temperature" refers to an ambient temperature of about 23°C to about 25°C.

[0049] As used herein, the term "coat weight" refers to the amount of ink or coating applied to a given side or surface of a substrate, which is usually expressed in grams of composition per square meter ("gsm") of substrate.

[0050] The term "low extractables" as used herein refers to a contamination level of a given manufactured packaging product that is less than 50 parts per billion (ppb) of a particular uncured monomer that may leach from the ink or coating after it has cured on a substrate. "Low extractables" also refers to contamination with photoinitiator residues and decomposition products, which must also be less than 50 ppb, or below the specific transition limit (SML) present for the particular photoinitiator.

[0051] The term "low odor" as used herein means that there is little lasting emotional impact when an olfactory test is performed under a particular atmosphere. Odors themselves are volatilized chemical compounds that are detected by the sense of smell by humans and other animals, usually at very low concentrations. Odors can be measured as described in the Examples.

[0052] Provided herein is a low odor, energy curable inkjet ink composition that can be laminated to a substrate (e.g., metal cans, paper-based cartons, plastic bottles, etc.) and cured to the extent that a layer of water-based overprint varnish can be printed when exposed to LED light, UV light, or EB radiation to the extent that the surface can be tack-free, and the ink composition can impart useful adhesion properties, hardness properties, low transfer properties, and chemical and pasteurization resistance to the finished substrate. The ink composition can be applied to the substrate by inkjet, and therefore can be referred to herein as an inkjet ink composition. Thus, the ink composition has a suitable viscosity to be inkjetted.

[0053] The ink composition can include at least one monofunctional monomer (the monofunctional monomer can include at least one hydrophilic monofunctional monomer), a difunctional monomer, an optional colorant, and an optional photoinitiator. The ink composition can further include a trifunctional monomer, a multifunctional monomer, or a combination thereof. The ink composition can also include at least one functional material that can adjust the wetting / flow / cure properties of the monomer(s) and / or colorant(s).

[0054] The amounts of the components of the disclosed ink compositions described below are in weight percent (wt%) unless otherwise specified. For example, an embodiment containing more than 3 wt% of a monofunctional monomer of the total ink composition refers to an ink composition containing more than 3 wt% of a monofunctional monomer based on the weight of the total ink composition.

[0055] (Monofunctional monomer) Monofunctional monomers have one functional acrylate group. In other words, monofunctional monomers have one C=C double bond. Monofunctional monomers may also be referred to as monofunctional acrylate monomers. Examples of monofunctional monomers provided herein include aliphatic mono(meth)acrylates, aromatic mono(meth)acrylates, alkoxylated (meth)acrylates, tetrahydrofurfuryl (meth)acrylates, and alkoxylated tetrahydrofurfuryl (meth)acrylates. Monofunctional monomers are available from suppliers such as Sartomer, Allnex, BASF, and Rhan.

[0056] Monofunctional monomers can contain one or more hydrophobic groups in their molecular structure. The hydrophobic group(s) can impart flexibility and water resistance to the cured ink film. This type of monofunctional monomer is called "hydrophobic monofunctional monomer". Hydrophobic monofunctional monomers also refer to monomers that have low water solubility, usually less than 0.01 g / L. Examples of hydrophobic monofunctional monomers include octyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, and o-phenylphenoxyethyl acrylate. Lauryl acrylate (SR-335, Mt. 240, Tg -30°C, viscosity 6 cPs, surface tension 30.3 mN / m from Sartomer), isooctyl acrylate (SR-440, Mt. 184, Tg -54°C, viscosity 5 cps, surface tension 28 mN / m from Sartomer), tricyclodecane ethanol acrylate (SR-789, Mt. 220, Tg 35°C, viscosity 15 cPs from Sartomer), cyclic trimethylolpropane formal acrylate (SR-531, Mt. 200, Tg 10°C, viscosity 15 cPs, surface tension 33 mN / m from Sartomer), phenol [4 EO] acrylate (Photomer 4039, Mt. 280, Tg 12°C, viscosity 30 cPs, surface tension 40.7 mN / m IGM), tripropylene glycol monomethyl ether acrylate (TPGMEMA, Photomer 8061, Mt. 260, viscosity 7 cPs, surface tension 31 mN / m, IGM), and o-phenylphenoxyethyl acrylate (EM2105, Mt. 268, Tg 107° C., viscosity 135 cPs, Eternal) are examples of illustrative hydrophobic monofunctional monomers.

[0057] The monofunctional monomer may include one or more hydrophilic groups in its molecular structure. It has been found that the monofunctional monomer in the disclosed ink composition, which includes at least one hydrophilic monofunctional monomer, can adjust the wettability of the energy curable digital ink to a substrate surface and can adjust the imprintability of the energy curable digital ink to an aqueous overprint clear coating. "Hydrophilic monofunctional monomer" refers to a monofunctional monomer that has a relatively high "water solubility", where the solubility is generally imparted by a hydroxyl group, an amide group, a carboxyl group, an amino group, or another polar group in its molecular structure. Thus, in some embodiments, the hydrophilic monofunctional monomer includes at least one polar group. In some embodiments, the hydrophilic monofunctional monomer includes at least one hydroxyl group, an amide group, a carboxyl group, or an amino group, or a combination thereof. In some embodiments, the hydrophilic monofunctional monomer includes at least one hydroxyl group, an amide group, a carboxyl group, or an amino group.

[0058] This type of "water solubility" (sometimes also referred to as "water wettability" or "hydrophilic") may be derived from polar groups attached to the di-, tri-, tetra-, penta-, or hexa-functional monomers, inactive resins, and oligomers in the ink composition. However, the hydrophilic components of the present disclosure are preferably those having relatively low molecular weights and relatively low viscosities. In some embodiments, the hydrophilic components of the ink composition are derived from monofunctional monomers. In some embodiments, the hydrophilic components of the ink composition are derived only from monofunctional monomers. In some embodiments, the hydrophilic components of the ink composition are not derived from di-, tri-, tetra-, penta-, or hexa-functional monomers, inactive resins, and / or oligomers.

[0059] Examples of hydrophilic monofunctional monomers include hydroxyl (meth)acrylates such as 4-hydroxybutyl acrylate (4HBA, Mt. 144, Tg -40°C, viscosity 11 cPs, surface tension 35.0 mN / m, manufactured by BASF) and 2-hydroxy-3-phenoxypropyl acrylate (CN-131B, Mt. 222, Tg 13°C, viscosity 250 cPs, manufactured by Sartomer), (meth)acrylamides such as diacetone acrylamide (DAAM, Mt. 229, Tg 77°C, viscosity 18 cPs, surface tension 30.6 mN / m, manufactured by KH Neochem), (meth)acrylics such as acrylic acid (AA, Mt. 72, viscosity 1.3 cPs, Tg 374°C, surface tension 28.1 mN / m, manufactured by BASF), and N-vinylpyrrolidone (NVP, M Vinyl compounds such as N-vinylcaprolactam (NVC, Mt. 111, viscosity 2.5 cPs, Tg 150°C, surface tension 32.5 mN / m, manufactured by Ashland), N-vinylcaprolactam (NVC, Mt. 139, viscosity 5 cPs, Tg 147°C, surface tension 43.9 mN / m, manufactured by Ashland), and vinylmethyloxazolidone (VMOX, Mt. 127, viscosity 4 cPs, manufactured by BASF); acryloylmorpholine compositions such as 4-acryloylmorpholine (ACMO, Mt. 141, viscosity 12 cPs, Tg 145°C, surface tension 45 mN / m, manufactured by BASF); caprolactone acrylate (SR-495, Mt. 186, viscosity 80 cPs, Tg -53°C, surface tension 42.95 mN / m, manufactured by Sartomer); 4034, Mt. 334, viscosity 80 cPs, manufactured by IGM).

[0060] The ink composition can include a combination of hydrophobic monofunctional monomers and hydrophilic monofunctional monomers. The type and ratio of hydrophobic and hydrophilic components can play a role in imparting the final properties of the amphipathic copolymer formed by the energy curing reaction. The properties of the amphipathic copolymer can adjust the wetting of the ink to the substrate surface and also the recoatability of the cured ink with an aqueous overprint clear.

[0061] The hydrophobic monomer(s) and hydrophilic monomer(s) can be used in any ratio as long as they are compatible with each other and can form a homogeneous solution in the inkjet ink system. Based on the chemical category of the hydrophilic monomer used, the hydrophilic monomer(s) can comprise a minimum of about 3% by weight of the total inkjet ink composition, or a maximum of about 46% by weight of the total inkjet ink composition. Thus, in some embodiments, the ink composition comprises from about 3% to about 46% by weight of the total weight of the ink composition, for example, from about 3% to about 42% by weight, from about 5% to about 40% by weight, from about 10% to about 35% by weight, from about 10% to about 40% by weight, from about 15% to about 35% by weight, from about 5% to about 30% by weight, from about 10% to about 25% by weight, from about 3% to about 12% by weight, from about 5% to about 15% by weight, from about 15% to about 46% by weight, from about 20% to about 45% by weight, or from about 18% to about 32% by weight of the hydrophilic monofunctional monomer. In some embodiments, the ink composition comprises 3% by weight or more, 5% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight or more of the hydrophilic monofunctional monomer of the total weight of the ink composition. In some embodiments, the ink composition comprises less than 46%, less than 40%, less than 35%, less than 30%, or less than 25% by weight of the hydrophilic monofunctional monomers of the total ink composition.

[0062] The hydrophilic monofunctional monomer can comprise various amounts of the total monofunctional monomer present in the ink composition. For example, the monofunctional monomer can comprise about 50% to about 100% by weight of the monofunctional monomer, such as about 55% to about 100% by weight, about 60% to about 100% by weight, about 50% to about 95% by weight, about 75% to about 100% by weight, about 80% to about 100% by weight, or about 90% to about 100% by weight of the monofunctional monomer. In some embodiments, the monofunctional monomer comprises more than 50% by weight, more than 60% by weight, more than 70% by weight, more than 80% by weight, more than 85% by weight, more than 90% by weight, or more than 95% by weight of the monofunctional monomer. In some embodiments, the hydrophilic monofunctional monomer comprises about 100% by weight of the monofunctional monomer.

[0063] The ink composition contains a hydrophobic monofunctional monomer in an amount of about 0% to about 77% by weight of the entire ink composition, for example, about 1% to about 77%, about 1% to about 70%, about 10% to about 60%, about 15% to about 55%, about 25% to about 77%, about 50% to about 77%, about 1% to about 50%, about 5% to about 75%, about 40% to about 75%, about 20% to about 65%, about 1% to about 25%, about 0.5% to about 20%, about 1% to about 10%, about 0.5% to about 15%, about 0.1% to about 12%, about 2% to about 15%, or about 5% to about 12%. In some embodiments, the ink composition comprises more than 0%, more than 0.1%, more than 0.5%, more than 1%, more than 2%, more than 3%, more than 4%, more than 5%, more than 10%, more than 20%, more than 30%, more than 40%, more than 50%, more than 60%, or more than 70% of the hydrophobic monofunctional monomer based on the weight of the entire ink composition. In some embodiments, the ink composition comprises less than 77% by weight, less than 70% by weight, less than 60% by weight, less than 50% by weight, less than 40% by weight, less than 30% by weight, less than 25% by weight, less than 20% by weight, less than 15% by weight, less than 12% by weight, or less than 10% by weight of the hydrophobic monofunctional monomer based on the weight of the entire ink composition. In some embodiments, the hydrophobic monofunctional monomer is present in the ink composition at a lower weight than the hydrophilic monofunctional monomer. In some embodiments, the ink composition does not comprise a hydrophobic monofunctional monomer.

[0064] Some monofunctional monomers are known to have a high unpleasant odor. Such monofunctional monomers are limited or eliminated in the disclosed ink composition. Examples of monofunctional monomers having unpleasant odors include benzyl acrylate, 2-propylheptyl acrylate, 2-methoxyethyl acrylate, tetrahydrofurfuryl acrylate, dicyclopentyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentanyl acrylate, and dihydrocyclopentadienyl acrylate. In some embodiments, the ink composition does not include the aforementioned monofunctional monomers (individually or in any combination thereof) that have an associated unpleasant odor.

[0065] Other monofunctional monomers known to have a negative impact on odor or associated with adverse product claims are also limited or eliminated in the disclosed ink composition. Examples of these types of monofunctional monomers include 2-phenoxyethyl acrylate, isobornyl acrylate, t-butylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 2-hydroxyethyl acrylate (HEA), 2-ethoxyethoxyethyl acrylate (EOEOE), N-vinyl caprolactam (NVC), and N-vinyl pyrrolidone (NVP). In some embodiments, the ink composition does not include the aforementioned monofunctional monomers (individually or in any combination thereof) that have an associated negative impact on odor or are not associated with adverse product claims.

[0066] The monofunctional monomer may be used alone (for example, one type of monofunctional monomer is used in the ink composition), or two or more types of monofunctional monomers may be used in combination. The total monofunctional monomer composition present in the inkjet ink composition can be about 3% by weight to about 80% by weight of the entire ink composition, for example, about 2% by weight to about 55% by weight, about 10% by weight to about 40% by weight, about 15% by weight to about 35% by weight, about 20% by weight to about 50% by weight, about 30% by weight to about 60% by weight, about 5% by weight to about 70% by weight, about 10% by weight to about 65% by weight, about 15% by weight to about 40% by weight, about 20% by weight to about 45% by weight, or about 15% by weight to about 45% by weight. In some embodiments, the total monofunctional monomer composition present in the inkjet ink composition is greater than 3 wt%, greater than 5 wt%, greater than 10 wt%, greater than 15 wt%, greater than 20 wt%, greater than 25 wt%, greater than 30 wt%, greater than 35 wt%, greater than 40 wt%, or greater than 45 wt% of the total ink composition. In some embodiments, the total monofunctional monomer composition present in the inkjet ink composition is less than 80 wt%, less than 75 wt%, less than 70 wt%, less than 65 wt%, less than 60 wt%, less than 55 wt%, less than 50 wt%, less than 45 wt%, less than 40 wt%, less than 35 wt%, or less than 30 wt% of the total ink composition.

[0067] (Bifunctional Monomer) Difunctional monomers have two functional acrylate groups. In other words, they have two C=C double bonds. Difunctional monomers are sometimes called difunctional acrylate monomers. They generally have lower odor and faster cure than monofunctional monomers. Examples of difunctional monomers include aliphatic di(meth)acrylates, aromatic di(meth)acrylates, alkoxylated aliphatic di(meth)acrylates, alkoxylated aromatic di(meth)acrylates, glycol di(meth)acrylates, cyclohexane dimethanol di(meth)acrylate, etc. Difunctional monomers are available from suppliers such as Sartomer, Allnex, BASF, and Rhan.

[0068] Exemplary bifunctional monomers include 3-methyl-1,5-pentanediol diacrylate (MPDDA, SR341 Mt. 226, Tg 50° C., viscosity 8.5 cPs, surface tension 33 mN / m from Sartomer), 1,10-decanediol diacrylate (CD-595, Mt. 282, viscosity 15 cPs, Tg 91° C., surface tension 33.4 mN / m from Sartomer), propoxylated neopentyl glycol diacrylate (SR9003B, Mt. 212, Tg 32° C., viscosity 15 cPs, surface tension 32 mN / m from Sartomer), 1,6-hexanediol (2EO) diacrylate (Photomer 4361, EOHDDA, Mt. 314, viscosity 15 cPs, surface tension 37.5 mN / m from Sartomer), IGM), propoxylated hexanediol diacrylate (Photomer 4362, Mt. 342, viscosity 10-20 cPs, surface tension 34.4 mN / m IGM), 2-hydroxy 3-methacrylpropyl acrylate (NK ESTETR 701A, Mt. 214, viscosity 44 cPs Shin-Nakamura Chemical Co., Ltd.), dipropylene glycol diacrylate (DPGDA, SR508, Mt. 242, viscosity 10 cPs, Tg 104 °C, surface tension 33 MN / m Sartomer), tripropylene glycol diacrylate (TRPGDA, SR306, Mt. 300, viscosity 15 cPs, Tg 62 °C, surface tension 33 mN / m Sartomer), 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA, Mt. 186, viscosity 3.6 cPs (Manufactured by Nippon Shokubai).

[0069] The difunctional monomer may be used alone or in combination of two or more. The total difunctional monomer composition present in the entire inkjet ink composition may be about 10% to about 80%, for example, about 20% to about 70%, about 40% to about 60%, about 15% to about 75%, about 20% to about 60%, about 25% to about 65%, about 25% to about 60%, about 30% to about 65%, or about 35% to about 55% based on the weight of the entire ink composition. In some embodiments, the total difunctional monomer composition present in the entire inkjet ink composition is greater than 10%, greater than 15%, greater than 20%, greater than 25%, greater than 30%, greater than 35%, greater than 40%, or greater than 50% based on the weight of the entire ink composition. In some embodiments, the total difunctional monomer composition present in the total ink-jet ink composition is less than 80%, less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, or less than 50% by weight of the total ink composition.

[0070] The relationship between the difunctional monomer and the monofunctional monomer can be used to provide useful benefits to the ink composition and the cured ink composition thereof. For example, it has been found that the ratio of the difunctional monomer to the monofunctional monomer can be used to provide beneficial ink performance properties (e.g., cross-hatch adhesion, MEK resistance, pencil hardness, and pasteurization). The ratio of the weight of the difunctional monomer to the weight of the monofunctional monomer is greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.4, greater than 0.5, greater than 0.6, greater than 0.7, greater than 0.8, greater than 0.9, greater than 1, greater than 1.1, greater than 1.2, greater than 1.3, greater than 1.4, greater than 1.5, greater than 1.6, greater than 1.7, greater than 1.8, greater than 1.9, or greater than 2. In some embodiments, the ratio of difunctional monomers to monofunctional monomers (wt / wt) is less than 3, less than 2.8, less than 2.7, less than 2.6, less than 2.5, less than 2.4, less than 2.3, less than 2.2, less than 2.1, or less than 2. In some embodiments, the ratio (weight / weight) of difunctional monomer to monofunctional monomer is from about 0.1 to about 3, e.g., from about 0.1 to about 2.5, from about 0.4 to about 2.6, from about 0.5 to about 2.5, from about 1 to about 2.5, from about 1.5 to about 2.5, from about 0.1 to about 2, from about 0.7 to about 2.7, from about 0.8 to about 2.6, from about 1 to about 2.4, from about 1.5 to about 2.2, from about 1.7 to about 2.5, from about 1.8 to about 2.1, from about 1.2 to about 2.4, from about 0.6 to about 1.6, from about 0.7 to about 1.5, from about 0.8 to about 1.4, or from about 0.9 to about 1.2.

[0071] It has also been found that the average double bond density of the ink composition can be used to provide beneficial ink performance properties, such as cross-hatch adhesion, MEK resistance, pencil hardness, and pasteurization. The average double bond density (or average functionality) of the polymerizable component = (1 x moles of monofunctional component + 2 x moles of difunctional component + 3 x moles of trifunctional component + ...) / total moles of polymerizable component (or total moles of unsaturated component). Further explanation of the average double bond density used herein is provided in the examples.

[0072] The average double bond density of the polymerizable components can be greater than 1, greater than 1.1, greater than 1.2, greater than 1.3, greater than 1.4, greater than 1.5, greater than 1.6, greater than 1.7, greater than 1.8, or greater than 1.9. In some embodiments, the average double bond density of the polymerizable components is less than 2. In some embodiments, the average double bond density of the polymerizable components is less than 2, less than 1.9, less than 1.8, less than 1.7, less than 1.6, less than 1.5, less than 1.4, less than 1.3, less than 1.2, or less than 1.1. In some embodiments, the average double bond density of the polymerizable component is from about 1 to about 2, e.g., from about 1 to about 1.9, from about 1.1 to about 2, from about 1.2 to about 2, from about 1 to about 1.8, from about 1.2 to about 1.8, from about 1.3 to about 1.7, from about 1.4 to about 1.6, from about 1.1 to about 1.9, or from about 1.3 to about 2. The average double bond density of the polymerizable component can be assigned when difunctional monomers, trifunctional monomers, multifunctional monomers, or combinations thereof are used in the disclosed ink compositions.

[0073] (Trifunctional Monomer) A trifunctional monomer has three functional acrylate groups. In other words, a trifunctional monomer has three C=C double bonds. A trifunctional monomer may also be called a trifunctional acrylate monomer. A trifunctional monomer generally has lower odor and cures faster than a difunctional monomer. Examples of trifunctional monomers include trimethylolpropane tri(meth)acrylate and alkoxylated trimethylolpropane tri(meth)acrylate. For low ink viscosity, fast cure, low odor, and low extraction purposes, the trifunctional monomer can be alkoxylated and have a viscosity of less than 200 cPs, for example less than 100 cPs, at about 25°C.

[0074] Ethoxylated (3) trimethylolpropane triacrylate (EO3TMPTA, SR454, Mt. 429, Tg 103° C., viscosity 110 cPs, surface tension 40 mN / m, from Sartomer), propoxylated trimethylolpropane triacrylate (POTMPTA, SR492, Mt. 470, Tg −15° C., viscosity 90 cPs, surface tension 34 mN / m, from Sartomer), and 2-tris(2-hydroxyethyl)isocyanural triacrylate (SR368D, Mt. 375, Tg 61° C., viscosity 33 cps, surface tension 37 mN / m, from Sartomer) are examples of exemplary trifunctional monomers.

[0075] The trifunctional monomer may be used alone or in combination of two or more trifunctional monomers. The total trifunctional monomer composition present in the inkjet ink composition may be about 0% to about 20% based on the weight of the entire ink composition, for example, about 1% to about 20%, about 1% to about 15%, about 1% to about 10%, about 2% to about 18%, about 4% to about 16%, about 3% to about 15%, about 5% to about 10%, about 1% to about 5%, about 2% to about 8%, about 10% to about 20%, about 15% to about 20%, or about 8% to about 12% based on the weight of the entire ink composition. In some embodiments, the total trifunctional monomer composition present in the inkjet ink composition is greater than 0%, greater than 1%, greater than 2%, greater than 3%, greater than 4%, greater than 5%, greater than 6%, greater than 7%, greater than 8%, greater than 9%, or greater than 10% based on the weight of the entire ink composition. In some embodiments, the total trifunctional monomer composition present in the ink-jet ink composition is less than 20%, less than 19%, less than 18%, less than 17%, less than 16%, less than 15%, less than 14%, less than 13%, less than 12%, less than 11%, or less than 10% by weight of the total ink composition.

[0076] (Multifunctional Monomer) Multifunctional acrylate monomer refers to an acrylate monomer that contains three or more functional acrylate groups. Examples of multifunctional monomers include pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and the like. The use of multifunctional monomers can achieve fast curing and increase the degree of crosslinking. For the purposes of low ink viscosity, fast curing, and flexibility, the multifunctional monomer can have a viscosity of less than about 7000 cPs at about 25° C., for example, less than about 500 cPs.

[0077] Examples of exemplary polyfunctional monomers include pentaerythritol tetraacrylate (SR295, Mt. 352, viscosity 342 cps), ethoxylated pentaerythritol tetraacrylate (SR494, Mt. 528, viscosity 150 cps), dipentaerythritol pentaacrylate (SR399LV, Mt. 524, viscosity 7000 cPs) from Sartomer, and dipentaerythritol hexaacrylate (DPHA, Miramer 600, Mt. 580, viscosity 4000) from Miwon.

[0078] The multifunctional monomers may be used alone or in combination of two or more. The total multifunctional monomer composition present in the inkjet ink composition may be about 0% to about 15%, for example, about 1% to about 15%, about 2% to about 14%, about 3% to about 12%, about 1% to about 5%, about 2% to about 7%, about 1% to about 10%, about 10% to about 15%, about 6% to about 12%, or about 5% to about 10%, based on the weight of the entire ink composition. In some embodiments, the total multifunctional monomer composition present in the inkjet ink composition is greater than 0%, greater than 1%, greater than 2%, greater than 3%, greater than 4%, greater than 5%, greater than 6%, or greater than 7%, based on the weight of the entire ink composition. In some embodiments, the total amount of multifunctional monomer composition present in the inkjet ink composition is less than 15%, less than 14%, less than 13%, less than 12%, less than 11%, less than 10%, or less than 9%, based on the weight of the entire ink composition.

[0079] (coloring agent) The energy curable inkjet ink composition can be a transparent UV curable, LED curable, or EB curable ink composition. However, for beverage and food container applications, the ink composition can also include at least one colorant. The colorant can be a dye or a pigment. In some embodiments, the colorant is a pigment.

[0080] The pigments may be cyan, magenta, yellow, black, white, red, orange, violet, blue, green, brown, or mixtures thereof. The example pigments can be grouped by their corresponding color index, i.e. Pigment Yellow 1, 3, 5, 12, 13, 14, 15, 17, 34, 35, 37, 41, 42, 43, 55, 74, 81, 83, 87, 93, 94, 95, 97, 108, 109, 110, 117, 119, 138, 139, 153, 154, 155, 157, 166, 167, 168, 174, 175, 180, 185, 193, 213, 214, 215, Pigment Red 3, 5, 19, 22, 23, 31, 38, 41, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 52, 52:1, 52:2, 53:1, 57:1, 57:2, 58:4, 63:1, 64:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 95, 104, 108, 112, 122, 123, 136, 144, 146, 149, 166, 168, 169, 170, 175, 177, 178, 179, 184, 185, 208, 216, 226, 254, 257, 279, Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17:1, 22, 24, 24:1, 27, 28, 29, 36, 60, 61, 62, 63, 75, Pigment Black 7, 9, 10, 28, 34, Pigment White 6, 11, 12, 18, 21, 22, Pigment Orange 4, 5, 13, 16, 20, 34, 36, 64, Pigment Violet 1, 2, 3, 19, 23, 25, 27, 29, 30, 37, 50, Pigment Green 7, 8, 10, 17, 26, 36, Pigment Brown 3, 5, 25, 26.

[0081] Among the above, exemplary pigments include Yellow 185, Red 122, Blue 15:4, Black 7, White 6, Green 7, Orange 64, Violet 23, and Brown 25. These pigments can satisfy the low viscosity, good dispersibility, good weather resistance, and color reproducibility of the disclosed ink composition.

[0082] The colorant loading can be from about 0% to about 4% by weight of the total ink composition, for example, from about 1% to about 3%, 0.5% to about 4%, from about 1% to about 4%, or from about 1.5% to about 3.5% by weight of the total ink composition. In some embodiments, the colorant is present in the ink composition at greater than 0%, greater than 0.5%, greater than 0.75%, greater than 1%, greater than 1.5%, greater than 1.75%, greater than 2%, or greater than 2.25% by weight of the total ink composition, in some embodiments, the colorant is present in the ink composition at less than 4%, less than 3.75%, less than 3.5%, less than 3.25%, less than 3%, less than 2.75%, less than 2.5%, or less than 2% by weight of the total ink composition.

[0083] Exemplary colorants include TCY18501L (pigment yellow PY185) from Trust Chem., Cinquasia® Magenta D 4545 J (pigment magenta PR122) from BASF, Heliogen® Blue D 7110 (pigment blue PB 15:4) from BASF, and Printex® 27 (black pigment PK-7) from Orion Engineered Carbons.

[0084] For convenience in ink preparation, the colorant can be pre-dispersed with a suitable monomer and a suitable dispersant to produce a stable colorant dispersion. The use of a dispersant, particularly a polymeric dispersant, can not only improve the dispersibility of the colorant, but also improve the stability of the final ink. Commercially available polymeric dispersants include ByK-168, Byk-162, Byk-163, Byk-9151, Byk-9152 from Byk, Solsperse 39000, Solsperse 35000, Solsperse 32000, Solsperse 36000 from Noveon, and EFKA PX 4701 and EFKA PX 4702 from BASF. In some embodiments, the colorant is dispersed in a polymeric dispersant.

[0085] The dispersant loading in the pigment dispersion can be from about 1% to about 25% based on the weight of the total dispersion (e.g., weight of colorant+weight of dispersant+weight of monomer), for example, from about 2% to about 22%, from about 4% to about 15%, from about 1% to about 10%, from about 10% to about 25%, or from about 5% to about 20% based on the weight of the dispersion. In some embodiments, the dispersant loading in the pigment dispersion is greater than 1%, greater than 5%, or greater than 10% based on the weight of the dispersion. In some embodiments, the dispersant loading in the pigment dispersion is less than 25%, less than 20%, or less than 15% based on the weight of the dispersion.

[0086] BYKJET 9152 from Byk and EFKA PX4701 from BASF are exemplary polymeric dispersants.

[0087] (Functional material) The ink composition can include a functional material. The functional material includes a photoinitiator, an inactive resin, an oligomer, a synergist, a stabilizer, a wetting / flow agent, and a defoamer. In some embodiments, the ink composition includes an inactive resin, an oligomer, a synergist, a stabilizer, a wetting / flow agent, a defoamer, or a combination thereof. In some embodiments, the ink composition includes a synergist, a stabilizer, a flow agent, or a combination thereof.

[0088] (Photopolymerization initiator) Photoinitiators used in LED curable inkjet ink compositions can absorb in the longer actinic wavebands (e.g., 395 nm, 365 nm) emitted by LED lamps.

[0089] Photoinitiators used in UV curable inkjet ink compositions are capable of absorbing a wide range of the actinic waveband (eg, 220 nm to 410 nm) generated by conventional mercury UV lamps.

[0090] In the case of EB-curable inkjet inks, there is no need to use a photopolymerization initiator.

[0091] Exemplary photoinitiators include phenyl(trimethylbenzoyl)phosphine oxide, difunctional oligomeric hydroxyl ketone types, etc. Commercially available products include Omnirad 380, Esacure KIP160, and Irgacure 127 from IGM.

[0092] The use of polymerizable photoinitiators such as polymerizable benzophenone derivatives, polymerizable aminobenzoates, polymerizable thioxanthone derivatives, and polymerizable a-hydroxyketones helps to impart low extractability to the energy curable inkjet ink composition. Commercially available products include polymeric benzophenone derivatives GENOPOL BP-1 from Rahn and Omnipol BP from IGM, polymeric aminobenzoates GENOPOL AB-1 from Rahn and Omnipol ASA from IGM, polymeric thioxanthone derivatives GENOPOL TX-1 from Rahn and Omnipol TX from IGM, polymeric a-hydroxyketones Chivacure 150 and Chivacure 70 from Chitec, JR1251 from JIURI, PRO22669 and Speedcure XKm from Sartomer, and Omnipol 910 from IGM, polymeric photoinitiators based on aminoalkylphenone compounds.

[0093] The amount of photoinitiator present in the ink composition is generally less than about 15% by weight of the entire ink composition. In some embodiments, the amount of photoinitiator present in the ink composition is less than 15%, less than 14%, less than 13%, less than 12%, less than 11%, less than 10%, less than 9%, or less than 8% by weight of the entire ink composition. In some embodiments, the amount of photoinitiator present in the ink composition is greater than 0.5%, greater than 1%, greater than 2%, greater than 3%, greater than 4%, greater than 5%, or greater than 6% by weight of the entire ink composition. In some embodiments, the amount of photoinitiator present in the ink composition is from about 0% to about 15% by weight of the entire ink composition, for example, from about 1% to about 10%, from about 2% to about 12%, from about 3% to about 9%, or from about 4% to about 10% by weight of the entire ink composition.

[0094] Omnirad 819, bis[2,4,6-trimethylbenzoyl]phenylphosphine oxide, Omnipol 910, and Omnipol TX from IGM are exemplary photoinitiators.

[0095] (inert resin) Inactive resins can be used to impart flexibility and can reduce shrinkage of the film during the energy curing process because they do not react with the monomers or oligomers (e.g., are not incorporated into the polymer chain). Acrylic resins, acrylate resins, methacrylate resins, aldehyde resins, vinyl resins, rosin ester resins, cellulose resins, and hydrocarbon resins can be used in the inkjet ink composition. Exemplary inactive resins include thermoplastic resins having a glass transition temperature (Tg) of about -20°C to about 250°C, for example, about 10°C to about 100°C or about 20°C to about 90°C, and a molecular weight of about 800 g / mol to about 200,000 g / mol, for example, about 7,000 g / mol to about 80,000 g / mol or about 10,000 g / mol to about 60,000 g / mol.

[0096] TEGO® VariPlus SK resin from Evonic (Tg 90° C., hydroxy value 325 mg KOH / g), Laropal A81 resin from BASF (Tg 57° C., hydroxy value 40 mg KOH / g), and Elvacite 4402 from Lucite (Mt 40,000, Tg 76° C.) are exemplary inactive resins in the ink composition.

[0097] The inactive resin may be used alone or in combination of two or more inactive resins. The total inactive resin composition present in the ink composition may be about 0% to about 15% based on the weight of the entire ink composition, for example, about 1% to about 15%, about 1% to about 10%, or about 2% to about 5% based on the weight of the entire ink composition. In some embodiments, the total inactive resin composition present in the ink composition is greater than 0%, greater than 1%, greater than 2%, greater than 3%, greater than 4%, or greater than 5% based on the weight of the entire ink composition. In some embodiments, the total inactive resin composition present in the ink composition is less than 15%, less than 12%, less than 10%, or less than 8% based on the weight of the entire ink composition.

[0098] (Oligomer) The oligomer can improve the curing rate and can play a role similar to that of the inactive resin. Examples of the oligomer include epoxy (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, polyurethane (meth)acrylate, and the like. Exemplary oligomers have low viscosity and a glass transition temperature (Tg) of about -95°C to about 175°C, for example, about -10°C to about 100°C, or about 10°C to about 80°C.

[0099] Exemplary oligomers include CN-2302 (Tg 74° C., viscosity 300 cPs), CN147 (Tg 18° C., viscosity 115 cPs) from Sartomer, Laromer PO8967 (viscosity 120 cPs) from BASF, Genomer 1122 (Mt. 215) from RAHN, Photomer 6210 (Tg 32° C.), Photomer 4704 (viscosity 150 cPs) from IGM, Miramer SC6640 (acid number 240-270 mg KOH / g, viscosity 200 cPs) from Miwon.

[0100] The oligomers may be used alone or in combination of two or more oligomers. The total oligomer composition present in the ink composition may be about 0% to about 15% based on the weight of the entire ink composition, for example, about 1% to about 15%, about 2% to about 12%, about 1% to about 10%, or about 2% to about 5% based on the weight of the entire ink composition. In some embodiments, the total oligomer composition present in the ink composition is greater than 0%, greater than 1%, greater than 2%, greater than 3%, greater than 4%, or greater than 5% based on the weight of the entire ink composition. In some embodiments, the total oligomer composition present in the ink composition is less than 20%, less than 15%, less than 12%, less than 10%, less than 9%, less than 8%, less than 7%, or less than 6% based on the weight of the entire ink composition.

[0101] (Synergist) The use of synergists in the energy curing process can reduce oxygen inhibition of photopolymerization and increase the cure rate.

[0102] Suitable synergists for use in low extraction, energy curable (UV curable, LED curable, or EB curable) inkjet ink compositions include acrylate amine synergists or polymeric amine synergists. Commercially available acrylate amine synergist products include Ebecryl 115 and Ebecryl p116 from Allnex, CN3715 from Sartomer, Laromer PO 94F from BASF, LED03 from Allnex, Genomer 5161 from Rahn, and Etercure 6328 from Eternal. Commercially available polymeric amine synergist products include Omnipol ASA, Omnipol SZ from IGM, GENOPOL AB-1 from Rahn, etc.

[0103] The synergists described above can be incorporated into the ink composition at about 0% to about 20% by weight of the total ink composition, for example, about 2% to about 15%, about 1% to about 20%, about 3% to about 15%, about 3% to about 10%, or about 4% to about 8% by weight of the total ink composition. In some embodiments, the synergists are incorporated into the ink composition at greater than 0%, greater than 1%, greater than 2%, or greater than 4% by weight of the total ink composition. In some embodiments, the synergists are incorporated into the ink composition at less than 20%, less than 15%, less than 12%, less than 10%, less than 9%, less than 8%, less than 7%, or less than 6% by weight of the total ink composition.

[0104] The monofunctional amine CN3175 from Sartomer and the difunctional amine Etercure 6328 from Eternal are exemplary synergists in the ink composition.

[0105] (Stabilizer / Polymerization Inhibitor) The energy curable ink composition may include one or more polymerization inhibitors or stabilizers that can prevent ink from flocculating and gelling or reduce / eliminate surface cracks in the cured film. Examples of inhibitors include phenolic materials (e.g., benzoquinone, hydroquinone, hydroquinone monomethyl ether, butylated hydroxytoluene), phenothiazines, nitrosophenylhydroxylamine aluminum salts, benzotriazole aluminum salt amine complexes, aromatic ammines, nitroxyl compounds, and the like. Commercially available stabilizers include Genorad-26 from Nahn, Florstab UV-1, UV-2, UV-5 from Kromachem LTD, Irgastab UV-10, Irgastab UV-22 from BASF, and the like.

[0106] The polymerization inhibitor or stabilizer may be used alone or in combination of two or more, in an amount of about 0.05% by weight to about 3% by weight, for example, about 0.1% by weight to about 2.75% by weight, about 0.5% by weight to about 3% by weight, about 1% by weight to about 3% by weight, about 0.5% by weight to about 2.5% by weight, or about 1.5% by weight to about 3% by weight, based on the weight of the total ink composition. In some embodiments, the polymerization inhibitor or stabilizer is present in the ink composition at greater than 0.05% by weight, greater than 0.1% by weight, or greater than 1% by weight based on the weight of the total ink composition. In some embodiments, the polymerization inhibitor or stabilizer is present in the ink composition at less than 3% by weight, less than 2.5% by weight, or less than 2% by weight of the total ink composition.

[0107] Genorad-26 from Rahn, UV-5 from Kromachem.LTD, UV22 from BASF are exemplary polymerization inhibitors in the ink composition.

[0108] (Wetting agent / flow agent) Wetting agents / flow agents can be included in inkjet ink compositions to modify surface tension and control flow / leveling properties. This ensures that the substrate is properly wetted and that the ink flows / levels well when applied to the substrate. Wetting agents / flow agents can be silicone-free (e.g., acrylate polymers) or silicone-containing (e.g., polyether-modified polydimethylsiloxanes). Commercially available materials include Tego 2200, Tego 2250, Tego glide 410 from Evonic, Byk-377, Byk-333, Byk-315N, Byk361N, UV3500, UV3510 from Byk, and Ebecryl 350, Ebecryl 1360 from Allnex.

[0109] The humectant / flow agent may be used alone or in combination in an amount of about 0.01% to about 1.5%, for example, about 0.05% to about 1.25%, about 0.75% to about 1%, about 0.05% to about 1%, about 0.01% to about 0.5%, or about 0.10% to about 0.50% based on the weight of the total ink composition. In some embodiments, the humectant / flow agent is present in the ink composition at greater than 0.01%, greater than 0.05%, or greater than 0.1% based on the weight of the total ink composition. In some embodiments, the humectant / flow agent is present in the ink composition at less than 1.5%, less than 1%, or less than 0.5% based on the weight of the total ink composition.

[0110] Byk333, Byk377 from BYK, and Ebecryl 1360 from Allnex are exemplary humectants / flow agents in the ink composition.

[0111] The humectants / flow agents can facilitate the ink-jet ink composition having desired adhesion properties to a substrate when cured by LED, UV, or EB radiation. For example, by adjusting the type and ratio of hydrophilic polymerizable component(s) to hydrophobic polymerizable component(s), the curing of the ink composition can be appropriately controlled to render the cured ink imprintable when a water-based overprint clear is applied to the ink layer deposited on a substrate (e.g., the surface of a metal can, the surface of a paper-based carton, the surface of a plastic bottle, etc.).

[0112] (Defoamer / Antifoaming Agent) Suitable foam mitigating or destructive materials can be included in the inkjet ink composition as defoamers and / or antifoamers. Examples of defoamers / antifoamers include polyacrylates, polyglycols, polyols, polysiloxanes, oxyalkyleneamines, silicone oils and fluids, and polyether modified methylalkyl polysiloxane copolymers, and combinations thereof.

[0113] Defoamers can prevent the formation of air entrapment and pinholes in the cured ink. Examples of defoamers include TEGO 920 available from Evonik and Byk-535 available from Byk.

[0114] Defoamers (also called antifoam agents) are chemical additives that can suppress and prevent foam formation in industrial process fluids. Defoamers can prevent foam from forming during the manufacture of inks. Examples of defoamers include TEGO Foamex from Evonik, and Byk-1790 and BYK-1791 from BYK.

[0115] In embodiments of the ink composition, the defoamer (e.g., BYK-535) or antifoamer (e.g., BYK-1791) may be included at a loading of about 0% to about 2% based on the weight of the total ink composition, such as about 0.1% to about 2%, about 0.5% to about 1.5%, about 0.1% to about 1%, or about 0.25% to about 0.5% based on the weight of the total ink composition. In some embodiments, the ink composition includes greater than 0%, greater than 0.1%, or greater than 0.5% of the defoamer or antifoamer based on the weight of the total ink composition. In some embodiments, the ink composition includes less than 2%, less than 1.5%, or less than 1% of the defoamer or antifoamer based on the weight of the total ink composition.

[0116] (Characteristics of the ink composition) The ink composition may have a surface tension that can be used as an energy curable inkjet ink. The surface tension of the ink composition may be about 20 mN / m to about 27 mN / m at room temperature, for example, about 21 mN / m to about 26 mN / m, about 22 mN / m to about 25 mN / m, about 20 mN / m to about 25 mN / m, or about 23 mN / m to about 27 mN / m at room temperature. In some embodiments, the ink composition has a surface tension of more than 20 mN / m, more than 21 mN / m, more than 22 mN / m, or more than 23 mN / m at room temperature. In some embodiments, the ink composition has a surface tension of less than 27 mN / m, less than 26 mN / m, less than 25 mN / m, or less than 24 mN / m at room temperature. The surface tension of the ink composition may be measured by techniques used in the art, for example, a force tensiometer.

[0117] The ink composition may also have a viscosity that can be used as an energy curable inkjet ink. The ink composition may have a viscosity of about 10 cPs to about 40 cPs at about 25°C, for example, about 12 cPs to about 35 cPs, about 12 cPs to about 30 cPs, about 10 cPs to about 25 cPs, about 10 cPs to about 20 cPs, about 20 cPs to about 40 cPs, about 15 cPs to about 35 cPs, or about 15 cPs to about 28 cPs. In some embodiments, the ink composition has a viscosity of more than 10 cPs, more than 15 cPs, or more than 20 cPs at about 25°C. In some embodiments, the ink composition has a viscosity of less than 40 cPs, less than 35 cPs, or less than 30 cPs at about 25°C. The viscosity of the ink composition can be measured by techniques used in the art, such as viscometers (e.g., capillary viscometers, vibrational viscometers, etc.) and rheometers (e.g., rotational, microfluidic, etc.).

[0118] The ink composition may also have a low odor profile, which may be measured by olfactory analysis, as described in the Examples below.

[0119] In some embodiments, the ink composition has one of the following: a viscosity of 40 cPs or less at about 25° C.; a surface tension of 20 mN / m or less at room temperature; a low odor profile as measured by olfactory analysis; or a combination thereof.

[0120] The ink-jet ink composition can have desirable good lay and pinhole-free properties.

[0121] (Examples of Ink Compositions of the Embodiments) In some embodiments, the ink composition comprises, by weight based on the total weight of the ink composition, about 10% to about 35% hydrophilic monofunctional monomer, about 30% to about 70% difunctional monomer, about 0% to about 4% colorant, and optionally a photopolymerization initiator.

[0122] In some embodiments, the ink composition comprises, in weight percent based on the total weight of the ink composition, about 5% to about 35% hydrophilic monofunctional monomer, about 0% to about 15% hydrophobic monofunctional monomer, about 30% to about 65% bifunctional monomer, about 0% to about 4% colorant, and about 0% to about 15% photopolymerization initiator.

[0123] In some embodiments, the ink composition comprises, in weight percent based on the total weight of the ink composition, about 10% to about 35% hydrophilic monofunctional monomer, about 3% to about 12% hydrophobic monofunctional monomer, about 30% to about 60% bifunctional monomer, about 1% to about 4% colorant, and about 0% to about 12% photopolymerization initiator.

[0124] In some embodiments, the ink composition comprises, in weight percent based on the total weight of the ink composition, about 5% to about 35% hydrophilic monofunctional monomer, about 0% to about 15% hydrophobic monofunctional monomer, about 30% to about 70% bifunctional monomer, about 0% to about 4% colorant, about 0% to about 15% photoinitiator, and a functional material selected from the group consisting of inactive resins, oligomers, synergists, stabilizers, wetting / flow agents, defoamers, and combinations thereof.

[0125] (base material) Also provided herein is a substrate having a cured ink composition disposed on a surface of the substrate, which can be referred to as a decorated substrate. For example, the decorated substrate can include a substrate and a cured ink composition derived from the disclosed ink composition on a surface of the substrate.

[0126] The substrate may be a container, such as a container used in the food or beverage industry. In some embodiments, the substrate is a beverage container. The substrate may be metal, paper, plastic, or a combination thereof. In some embodiments, the substrate is metal, paper, or plastic. The substrate may be a metal container (e.g., a metal can), a paper container (e.g., a paper-based carton), or a plastic container (e.g., a plastic bottle). In some embodiments, the substrate is a metal container. In some embodiments, the substrate is a metal container for beverages or food products.

[0127] An example of a substrate 10 is shown in Figure 1. Substrate 10 includes a two-piece can body 12 having a first portion 14 and a second portion 16. First portion 14 defines a bottom end and body 12 and is formed from a single sheet of metal by a deep drawing process. Second portion 16 defines a second end that is sewn to first portion 14 to close and form the complete body 12. Ink 18 is deposited on substrate 10 by four-color process printing. In the illustrated embodiment, the colors of ink 18 are referenced as YMCK, which refers to the colors yellow, magenta, cyan, and black.

[0128] The surface of the substrate 10 may include the substrate itself, a pre-coating disposed on the surface of the substrate, or a combination thereof. Thus, in some embodiments, the cured ink composition is disposed on the surface of the pre-coating, which is disposed on the surface of the substrate. In other words, the pre-coating may be disposed between the surface of the substrate and the cured ink composition. In some embodiments, the pre-coat is a white basecoat.

[0129] The substrate can further include a coating disposed on the surface of the cured ink composition. For example, the substrate can include a visually clear coating disposed on the surface of the cured ink composition.

[0130] An example of a coated substrate 100 is shown in Figure 2, which is an illustration of a cross-section of a finished substrate 100 that has been jet-printed with the disclosed ink composition 102. During the coating process, a substrate (such as the substrate 10 described above) is pre-coated with a base coat 104 by depositing the base coat 104 on the surface of the substrate 10. The ink composition 102 is jetted onto the surface of the base coat 104 (i.e., the pre-coated substrate 10) and then cured. Finally, a water-based overprint varnish 106 is imprinted onto the cured ink composition 102.

[0131] The precoat or basecoat has a coat weight of from about 2.5 gsm to about 10.5 gsm, for example, from about 2.5 gsm to about 10.3 gsm, from about 3 gsm to about 10.3 gsm, from about 3 gsm to about 9.3 gsm, from about 3.5 gsm to about 8.3 gsm, from about 4 gsm to about 7.3 gsm, from about 3.5 gsm to about 6.3 gsm, from about 3 gsm to about 5.3 gsm, from about 6.2 gsm to about 10.3 gsm, or from about 2.5 gsm to about 4 gsm. In some embodiments, the precoat has a coat weight of greater than 2.5 gsm, greater than 3 gsm, greater than 3.5 gsm, greater than 4 gsm, greater than 5 gsm, greater than 6 gsm, or greater than 7 gsm. In some embodiments, the pre-coating has a coat weight of less than 10.5 gsm, less than 10.3 gsm, less than 9 gsm, less than 8 gsm, less than 7 gsm, less than 6 gsm, less than 5 gsm, less than 4.5 gsm, or less than 4 gsm.

[0132] The cured ink composition deposited on the surface of the substrate or on the precoat surface may have a coat weight of from about 0.5 gsm to about 15 gsm, e.g., from about 0.5 gsm, to about 10 gsm, from about 1 gsm to about 10 gsm, from about 2 gsm to about 8 gsm, from about 1.5 gsm to about 9.5 gsm, from about 0.5 gsm to about 5 gsm, from about 1 gsm to about 6 gsm, from about 6.5 gsm to about 10 gsm, from about 7 gsm to about 9.5 gsm, from about 8 gsm to about 10 gsm, or from about 6 gsm to about 8 gsm. In some embodiments, the cured ink composition has a coat weight of greater than 0.5 gsm, greater than 1 gsm, greater than 2 gsm, greater than 3 gsm, greater than 4 gsm, greater than 5 gsm, greater than 6 gsm, greater than 6.5 gsm, or greater than 7 gsm. In some embodiments, the cured ink composition has a coat weight of less than 15 gsm, less than 12 gsm, less than 10 gsm, less than 9.5 gsm, less than 8 gsm, less than 7 gsm, less than 6 gsm, or less than 5 gsm.

[0133] The coating disposed on the surface of the cured ink composition can have a coat weight of about 1.5 gsm to about 5 gsm, e.g., about 2 gsm to about 4.5 gsm, about 2.5 gsm to about 4 gsm, about 3 gsm to about 4.5 gsm, about 1.5 gsm to about 3 gsm, about 1.5 gm to about 2.5 gsm, or about 1.5 gsm to about 4.1 gsm. In some embodiments, the coating has a coat weight greater than 1.5 gsm, greater than 2 gsm, greater than 2.5 gsm, greater than 3 gsm, or greater than 3.5 gsm. In some embodiments, the coating has a coat weight less than 5 gsm, less than 4.5 gsm, less than 4 gsm, less than 3 gsm, or less than 2.5 gsm.

[0134] The decorated substrate can also have an advantageously low level of contamination that may result from the curing of the ink composition.For example, the decorated substrate can have a contamination level of less than 50 ppb (parts per billion) from uncured monomer, photoinitiator, or combination thereof, such as less than 45 ppb, less than 40 ppb, less than 35 ppb, less than 30 ppb, less than 25 ppb, less than 20 ppb, less than 15 ppb, or less than 10 ppb, as measured by alcohol extraction test.An example of the alcohol extraction test is described in the examples.

[0135] (method) Also provided herein is a method for applying the ink composition to a surface of a substrate, for example to provide a decorated substrate. The descriptions of the different monomers, colorants, functional materials, and substrates also apply to the methods disclosed herein.

[0136] The method may include applying an ink composition as disclosed herein to a surface of a substrate, which may be metal, paper, plastic, or a combination thereof. In some embodiments, the method includes jetting the ink composition onto the surface of the substrate. In some embodiments, the ink composition is printed with a Mayer rod. In some embodiments, the substrate is metal, such as a metal can. In some embodiments, the metal can is precoated. For example, the ink composition can be jetted onto a white base can or onto a clear coated can.

[0137] The method may further include irradiating the ink composition to cure the ink composition on the substrate surface to provide a decorated substrate. The method may include LED-curing, UV-curing, or EB-curing the ink composition on the substrate surface. This may provide a cured ink composition on the substrate surface. The cured ink composition may be tack-free.

[0138] In some embodiments, the substrate is coated with a white basecoat prior to contacting the ink composition.

[0139] The method can also include laminating the cured ink composition by imprinting a water-based overprint varnish through a roll coating process to provide an imprinted substrate (eg, an imprinted metal can).

[0140] In some embodiments, the ink composition is printed with a Mayer rod.

[0141] Additionally, the method may include baking the decorated substrate to be imprinted at an elevated temperature. For example, the decorated substrate may be baked at about 350°F to about 400°F. Baking may be performed for about 10 seconds to about 10 minutes, such as about 30 seconds to about 5 minutes or about 1 minute to about 7 minutes. Baking may impart useful properties to the substrate, such as low odor, low extractables, chemical resistance, and pasteurization resistance, which may be useful in the metal beverage / food container industry, for example.

[0142] (Example) The following examples (including the experiments and results achieved) are provided for illustrative purposes only and are not to be construed as limiting the claimed subject matter. All amounts set forth in the following examples are by weight percent (wt%) unless otherwise specified.

[0143] (Example 1: YMCK pigment dispersion) (Preparation of YMCK pigment dispersion) Pigment dispersions were prepared using 0.3 mm zirconium oxide beads as the milling media. Appropriate amounts of dispersant, monomer, stabilizer, and pigment were added to a 2000 ml metal container. The ratios of the above components are shown in Table 1-1. Each mixture in Table 1-1 was homogenized for 30 minutes at 3000 rpm using a homogenizer. The corresponding suspension was transferred to an HCPN mill containing 0.3 mm zirconium oxide beads, and the mill was operated at 4000 rpm for 4 to 20 hours to obtain the corresponding YMCK pigment dispersions. TIFF2025506156000002.tif79164

[0144] (Characteristics of YMCK pigment dispersions) The viscosity of the pigment dispersion was measured using a Brookfield CAP 2000 plus unit at 25° C. with a #1 spindle operating at a shear rate of 225 rpm for 60 seconds.

[0145] The particle size analyzer used for the pigment dispersions is a Malvern Zeta Sizer Nano series, Zen 3600 unit (Goffin-Meyvis). The numerical mean particle size is measured by photon correlation spectroscopy using a 4mW He-Ne laser at a wavelength of 633nm on diluted samples of the pigment dispersions. The measured particle size is the average of three consecutive measurements of 20 seconds x 12 measurements.

[0146] The pigment dispersion (30 g) was filled into a 60 ml black bottle and sealed. The odor was evaluated within 10 seconds after opening the cap to seal the bottle. Here, "E" indicates a strong and unpleasant odor, and "A" indicates an insignificant odor emanating from the pigment dispersion. For pigment dispersions used in the preparation of metal decoration inkjet inks, scale A or B (more preferably scale A) is desirable.

[0147] As shown in Table 1-2, the obtained pigment dispersions were: Dispersion-1 (yellow dispersion of Example-1-1) had an average particle size of 99.7 nm and a viscosity of 169.2 cPs; Dispersion-2 (magenta dispersion of Example-1-2) had an average particle size of 106.4 nm and a viscosity of 199.2 cPs; Dispersion-3 (cyan dispersion of Example-1-3) had an average particle size of 140.4 nm and a viscosity of 75.8 cPs; and Dispersion-4 (black dispersion of Example-1-4) had an average particle size of 156.1 nm and a viscosity of 277.5 cPs. All of the YMCK pigment dispersions prepared from Example-1 were given a grade A in the odor evaluation.

[0148] The resulting pigment dispersions had different viscosity and particle size values, while still being able to give an odor rating of A. Pigment dispersions were prepared using other low odor bifunctional monomers.

[0149] Monomers such as isobornyl acylate (IBOA), 2-phenoxyethyl acrylate (2PEA), and 1,6-hexanediol diacrylate (HDDA) were not selected for preparing the YMCK pigment dispersions due to unpleasant odors, health hazard ratings, and / or potential toxicity. TIFF2025506156000003.tif52169

[0150] (Example 2: Black ink composition containing hydrophilic monofunctional monomer and / or hydrophobic monofunctional monomer.) (Ink Preparation) Black inks (Examples 2-1 to 2-6) were prepared by mixing the ingredients shown in Table 2-1 using a Caframo constant torque brushless mixer. Each blend was stirred at 500 rpm to 1500 rpm at 60°C for 35 minutes until a homogenous ink solution was formed. The homogenous inks were filtered through a 1 micron filter (provided by Pall Canada) to remove impurities and each was placed in a black bottle.

[0151] All the inks described were prepared using the same black pigment dispersion (i.e., Dispersion-4 prepared from Example-1 above), the same photoinitiator, the same inhibitor, the same flow agent, and the same difunctional monomer. The main difference is in the monofunctional monomer used.

[0152] In Example 2-1, the ink composition contains 26% of low odor hydrophilic monomer 2 and 3.5% of low odor hydrophobic monomer 1.

[0153] In Example 2-2, the ink composition contains 16% of low odor hydrophilic monomer-1.

[0154] In Example 2-3, the ink composition contains 16% of low odor hydrophobic monomer-1.

[0155] In Example 2-4, the ink composition contains 16% of high odor hydrophobic monomer 2.

[0156] In Example 2-5, the ink composition contains 16% of high odor hydrophobic monomer 3.

[0157] In Example 2-6, the ink composition contains 16% of low odor hydrophobic monomer 4. TIFF2025506156000004.tif110164

[0158] (Ink characteristics) The viscosities of the inks were measured using a Brookfield Viscometer DV2 unit with a water jacket at 25° C. and 45° C., respectively. The “00” type spindle is operated at a shear rate of 10 rpm (at 25° C.) to 30 rpm (at 45° C.). To be suitable for ink jetting, the disclosed ink compositions have a viscosity of less than 15 cPs at 45° C., for example less than 12 cPs at 45° C.

[0159] The static surface tension of the ink was measured at 25° C. using a KRUSS tensiometer K-11 unit manufactured by KRUSS GmbH, Germany. A surface tension in the range of about 20 to about 27 mN / m is desirable for applying the inkjet ink to decorate a metal can.

[0160] The ink (30 g) was filled into a 60 ml black bottle and sealed. The odor of the wet ink was evaluated within 10 seconds of opening the cap sealing the bottle. Each ink was given a rating of A to E, where "E" indicates a strong, unpleasant odor and "A" indicates a negligible odor emanating from the ink. For inkjet inks used in decorating metal cans, a rating of A or B (more preferably, rating A) is desirable. TIFF2025506156000005.tif65165

[0161] All of the above inks exhibit desirable viscosity and surface tension values ​​for inkjet applications. However, for the wet inks, only those prepared using low odor monomers (i.e., Examples 2-1, 2-2, 2-3, and 2-6) can provide desirable low odor characteristics (scale A) in odor evaluation.

[0162] (Ink performance) The above inks were printed with a #6 Mayer rod onto flat white base metal sheets (obtained from cutting and flattening 12 oz. white base cans). The white base cans were prepared by roll-coating a layer of the water-based coat onto the surface of the can and baking at 340-390°F for approximately 45 seconds. The white base cans were commercially available from Ball, USA or other can manufacturers. The printed inks were LED cured at a total UV-A2 dose of 400mj / cm2 through an AMS LED curing unit (provided by Air Motion Systems) equipped with 17w / cm LED lamps. The prints were then immediately (within 10 seconds of curing) evaluated for surface odor. Since odor tolerance differs from the wet ink evaluation and the pigment dispersion evaluation, a score of 1-5 was assigned to each print, where 5 indicates a relatively strong and unpleasant odor and 1 indicates a relatively minor odor emanating from the print. In general, a score of 1 is desirable for energy beam cured cans.

[0163] Next, a water-based overprint varnish (PPG3825803, commercially available from PPG) was applied onto the LED-cured ink layer of the metal can sheet through a #6 Mayer rod. The can sheet was then baked in an oven at 360°F to 400°F for 3 minutes. The finished prints were then evaluated in terms of their odor, print density, gloss, MEK rub resistance, pencil hardness, crosshatch adhesion, and pasteurization resistance. The corresponding results are shown in Table-2-3.

[0164] It should be noted that odor evaluation of the finished metal cans (ink / OPV) was performed within 10 seconds after the fired cans were removed from the oven and allowed to cool for 1 minute. The evaluation method was the same as that used for the cured inks, as described in the Ink Performance section above (ink only). Each can was assigned a score of L-1 to L-5, where L-5 indicates a relatively strong and unpleasant odor and L-1 indicates a relatively minor odor emanating from the can. Generally, a score of L-1 is desirable for beverage can applications.

[0165] Print densities on the printed cans were measured using a module RN 42 densitometer attached to an X-rite unit manufactured by Grand Rapids, Michigan, U.S.A. Print densities of 1.0 (or greater) for yellow, 1.5 (or greater) for magenta, 1.5 (or greater) for cyan, and 1.5 (or greater) for black are generally desired for beverage can decoration.

[0166] The gloss of the printed cans was measured according to ASTM D523-08. A measurement of 80 (or greater) at a 60 degree angle is generally desired for beverage can applications.

[0167] In the beverage can industry, the MEK rub test is used to simulate what cans will encounter in a facility, filling, or environment. During the test, a can sample is cut flat and taped to a tray. An MEK rub guide is applied to the can in the test area, isolating the longest stroke of the can. Cans used in the beverage industry should be rubbed 30 double rubs, preferably 50 double rubs (or more).

[0168] The pencil scale is a hardness test that indicates how hard a coating is. According to ASTM D 3363, a pencil of a given hardness is pressed firmly against a surface at a 45 degree angle. The highest rating on the pencil scale is the rating that leaves no permanent mark on the surface. In the beverage can industry, the pencil hardness of the final cured stage coating (finished can with cured ink and cured overprint varnish) ranges from 3B to 9H.

[0169] The adhesion of the crosshatch tape was evaluated according to ASTM D3359-09 Standard Test Method for Measuring Adhesion by Tape Test. This involves scratching a grid into the surface of the can body using a crosshatch tool. A strip of adhesive tape (such as 3M premium clear cellophane Scotch 610-1PK) is then placed on top of the grid and pressed firmly. The tape is then removed at 180 degrees with moderate pressure. The percentage of the ink / coat / paint that was removed by the adhesive against the grid was determined. Adhesion is classified into six levels (5B, 4B, 3B, 2B, 1B, 0B) based on the percentage of area removed by the tape. Of these, 5B represents the best adhesion, with perfectly smooth edges of the cut and not a single square of the grid removed (also known as 0% coat / ink / paint removal). 4B represents excellent adhesion, with small flakes observed at the intersections of the cuts, typically affecting less than 5% of the cross-cut area. In the beverage can industry, decorated and pasteurized cans are desired to have a 4B or 5B rating on the cross-hatch tape test.

[0170] In the pasteurization test, the beverage can is immersed in a 0.7% surfactant solution (such as Joy solution) at 80°C for 30 minutes, and then the crosshatch tape on the beverage can is evaluated for adhesion, whitening, and color fade. When performing crosshatch tape adhesion according to ASTM D3359-09, the tape is placed under a microscope to see if the inner square of the crosshatch is visible, and also to see if the overprint varnish is destroyed and loses adhesion. The brushing evaluation is performed to see if the coating absorbs moisture, causing the printed surface to turn white. The color fade evaluation is performed to see if the coating absorbs moisture, which can cause the ink to fade. Both the brushing evaluation and color fade evaluation were performed visually. TIFF2025506156000006.tif178163

[0171] From Table-2-3, it can be seen that the cured inks followed the same pattern as the wet inks in terms of odor characteristics. The low odor inks (i.e., the inks of Examples-2-1,-2-2,-2-3, and-2-6) had low odor generated after LED curing, with an odor scale of 1. When the corresponding low odor ink layers were coated with a water-based overprint varnish (OPV), the odor from the finished can was also low, remaining in the L-1 range. When the corresponding high odor inks (the inks of Examples-2-4 and-2-5) were coated with a water-based overprint varnish, the odor from the finished can was reduced, but the corresponding odor scale was still in the L-2 range.

[0172] All cans decorated with the above inks showed favorable print density, gloss, pencil hardness, and MEK rub resistance. However, cans decorated with the inks of Examples 2-3, 2-4, 2-5, and 2-6 failed the crosshatch tape adhesion test, with the corresponding scales of 0B, 0B, 3B, and 2B for both finished and pasteurized cans, respectively. Only inks containing hydrophilic components in the polymerizable composition (e.g., Examples 2-1 and 2-2) were able to impart the desired adhesive properties to the decorated cans (both finished and pasteurized cans) (i.e., passed the crosshatch tape adhesion test).

[0173] Example 3: Black ink compositions with different average functionalities of polymerizable components (or different average double bond densities of polymerizable components) (Ink Preparation) Black inks (Examples 3-1 to 3-6) were prepared by mixing the components shown in Table 3-1 using a Caframo constant torque brushless mixer. Each blend was stirred at 500 rpm to 1500 rpm at 60°C for 35 minutes until a homogenous ink solution was formed. The homogenous inks were filtered through a 1 micron filter (provided by Pall Canada) to remove impurities and each was placed in a black bottle.

[0174] All inks were prepared using the same black pigment dispersion (i.e., Dispersion-4 prepared from Example-1 above), the same photoinitiator, the same inhibitor, the same flow agent, the same hydrophilic monomer, the same hydrophobic monomer, and the same multifunctional monomer. The main difference is in the ratio of difunctional and monofunctional monomers.

[0175] In Example 3-1, the ink composition is highly loaded with difunctional monomer (52.10%). Taking into account the content of difunctional monomer (derived from the pigment dispersion), the total loading of difunctional monomer in the ink composition is 58.01% (i.e., 52.10% + 5.91% = 58.01%), and the ratio of difunctional monomer to monofunctional monomer in the ink composition is 2.23.

[0176] Based on the same principle, the ratios of the difunctional monomer to the monofunctional monomer in the ink compositions of Examples 3-2, 3-3, 3-4, 3-5, and 3-6 are 1.44, 0.86, 0.50, 0.26, and 0.08, respectively.

[0177] Since trifunctional monomers and other polyfunctional monomers may also be used in the ink composition, the present specification introduces the concept of "average functionality of polymerizable components" or "average double bond density of polymerizable components" in order to more easily understand the degree of polymerization of the ink composition. The average double bond density of the polymerizable components can be calculated by the following formula.

[0178] Average double bond density (or average functionality) of polymerizable components = (1 x moles of monofunctional components + 2 x moles of difunctional components + 3 x moles of trifunctional components + ...) / total moles of polymerizable components (or total moles of unsaturated components). For example, the average double bond density (or average functionality) of the polymerizable components of the ink of Example-3-1 is calculated as follows. (1 x moles of monofunctional monomer + 2 x moles of difunctional monomer) is divided by the total moles of monofunctional monomer and difunctional monomer.

[0179] The average double bond densities (average functionality) of the polymerizable components corresponding to the inks of Examples 3-1, 3-2, 3-3, 3-4, 3-5 and 3-6 are 1.69, 1.59, 1.45, 1.32, 1.20 and 1.07, respectively. TIFF2025506156000007.tif125165

[0180] (Ink characteristics) The viscosity, static surface tension, and odor of the ink of Example 3 were tested and evaluated in the same manner as described in Example 2. The results are summarized in Table 3-2. TIFF2025506156000008.tif53163

[0181] All inks exhibited desirable viscosity and surface tension values ​​for inkjet applications. However, for wet inks, only the ink prepared in Example 3-1 achieves the desirable low odor characteristics (scale A) in the odor evaluation. In Examples 3-2 to 3-6, as the use of high odor (also high evaporation rate) monomers increases, the odor problem becomes more severe, with the corresponding odor scales of B, C, D, E, and E, respectively.

[0182] (Ink performance) The performance of the ink prepared in Example 3 was evaluated in the same manner as described in Example 2 above.

[0183] From Table-3-3, it can be seen that the cured inks follow a similar pattern to the wet inks in terms of odor characteristics. The low odor ink (i.e., Example-3-1) produced low odor after LED curing, scoring a 1 on the odor scale. When the corresponding low odor ink layer was coated with a water-based overprint varnish, the odor from the finished can remained in the L-1 range. When the corresponding high odor ink layer was coated with a water-based overprint varnish (Examples-3-2 to -3-6), the odor from the finished can was L-2 to L-3.

[0184] Cans decorated with the above inks exhibited desirable print density and gloss levels. Ink compositions with higher average double bond density (1.69, 1.59, and 1.46 in Examples 3-1, 3-2, and 3-3) could provide desirable pencil hardness and MEK rub resistance. Among them, Example 3-1, which has a much higher average double bond density in the composition (i.e., 1.69), could provide improved cross-hatch adhesion properties (4B-5B), and the corresponding finished cans could withstand pasteurization treatment. This finding is surprising because it is contrary to conventional wisdom and it was believed that the desired adhesion properties could only be obtained from a low crosslinking ink film. Furthermore, conventional wisdom held that inks based on monofunctional monomers would lose extensive adhesion when incorporating difunctional monomers at levels above 10% (where the calculated average double bond density of the corresponding polymerizable component is about 1.10) or trifunctional monomers at levels above 5% (where the calculated average double bond density of the corresponding polymerizable component is also about 1.10). According to this, the ink of Example-3-6 (having an average double bond density of 1.07) would perform better in terms of crosshatch adhesion test than the ink of Example-3-1. However, this ink failed the tape adhesion test (score 0B) and, interestingly, the OPV layer also completely peeled off from the ink layer when the can was pasteurized. The ink of Example-3-5 (average double bond density of 1.20) also showed peeling problems when the OPV-ink layer was subjected to the crosshatch adhesion test.

[0185] Therefore, in order for an ink-jet ink composition to exhibit the performance required for metal can decoration, the ink composition must have the following properties. The ink composition must contain specific hydrophilic components imparted by monomer(s), oligomer(s) and / or inert resin(s) such that upon exposure to LED, UV or EB radiation the cured ink has the desired amphiphilic properties. For low odor applications, the average double bond density (or average functionality) of the polymerizable components of the ink composition can be adjusted depending on the type of hydrophilic component used. A relatively high average double bond density (for example, the average double bond density of the black ink in Example-3-1 is 1.69) can be beneficial. TIFF2025506156000009.tif215164

[0186] (Example 4: YMCK 4-color process inkjet ink) Four-color process inkjet inks (Examples 4-1 to 4-4) of yellow, magenta, cyan, and black were prepared by mixing the components shown in Table 4-1 using a Caframo constant torque brushless mixer. Each blend was stirred at 500 rpm to 1500 rpm at 60°C for 35 minutes. The inks were then filtered through a 1 micron filter device (provided by Pall Canada) and stored in black bottles. TIFF2025506156000010.tif128163

[0187] (Ink characteristics) The viscosity, static surface tension, and odor of the ink of Example 4 were tested and evaluated in the same manner as described in Example 2. The results are summarized in Table 4-2. All the inks above exhibited desirable viscosity and surface tension values ​​for inkjet applications. They also exhibited desirable low odor properties (odor scale A). TIFF2025506156000011.tif40164

[0188] (Ink performance) The performance of the ink prepared in Example 4 was evaluated in the same manner as described in Example 2 above.

[0189] From Table-4-3, it can be seen that the cured inks followed the same pattern as the wet inks in terms of odor characteristics. The low odor inks (i.e., Examples-4-1 to 4-4 with an odor scale rating of A) produced low odor prints after LED curing, with an odor scale rating of 1. When the corresponding low odor ink layers were coated with a water-based overprint varnish, the odor from the finished cans was also low, remaining in the L-1 range.

[0190] All cans decorated with the above inks showed favorable print density, gloss, pencil hardness, MEK rub resistance, and crosshatch adhesion (4B-5B). All cans decorated with the above inks were able to withstand pasteurization treatment. TIFF2025506156000012.tif110163

[0191] The average double bond density of the polymerizable components of the YMCK inks was about 1.55.

[0192] Testing will show that the desired properties (low odor, good adhesion, good MEK rub resistance, good pasteurization resistance) can be achieved by using or incorporating other monomers, oligomers, inactive resins, and additives within the teachings of the specification set forth herein. When adjustments are made to the composition, it will be found that the average double bond density of the polymerizable components can be as low as about 1 and as high as about 2.0, and the corresponding ink will perform well in metal can decoration.

[0193] (Example 5: Press test of white base can) The YMCK inks prepared in Example 4 were evaluated in a two-piece metal can SLED press (manufactured by Inx International). This specially designed SLED unit was equipped with a Xaar1003 printhead (3 mm distance from the substrate being printed) and a 16w / cm Phoseon LED lamp (10 mm distance from the substrate being coated). The SLED press can rotate the can body circumferentially around the can axis under the printhead while jetting the inkjet composition. The coat weight of the jetted ink can be adjusted by adapting several printing resolutions, for example, a low resolution of 360x360 can be accommodated to provide a drop size of 42pl for single pass printing. The image files for the press test included the company logo, various tones (25%, 50%, 75%, 100%), fine lines (0.75pt), and fine print (5pt).

[0194] The YMCK inks were sprayed in a single pass onto the outer periphery of cylindrical 16 oz. white base cans at 45°C (coat weight 8.4 grams per square meter) and the printed cans were exposed to LED light at a linear speed of approximately 40 fpm (fpm). The 16 oz. white base cans were provided by Ball, USA, and had a diameter of 66 mm and a printable height of 160 mm. A water-based acrylic / melamine overprint varnish (PPG3825803, commercially available from PPG) was applied onto the LED-cured ink layer of the white base cans via an InterCan coater (supplied by Intercan, UK). The applied overprint varnish coat weight was adjusted to 2.5-2.9 grams per square meter (dry) or 80-100 mg per can (dry). The cans were then baked in a 380°F oven for 3 minutes. The finished prints were then evaluated for odor, print quality, print density, gloss, MEK rub resistance, pencil hardness, crosshatch adhesion, and pasteurization resistance.

[0195] The results in Table 5-1 show that the ink meets the requirements for decorating white base cans. TIFF2025506156000013.tif109164

[0196] (Low Extraction Rating) The residual amounts of unreacted monomer, photopolymerization initiator, and other components in the finished cans obtained from the press test were measured by a total extraction test. In this test, (1) the entire can was immersed in 10% ethanol at 40°C for 2 hours, and the can was removed from the ethanol suspension. (2) Internal standards (deuterated benzophenone, deuterated anthracene, and p-terphenyl) were added to the ethanol suspension, which was then concentrated using a C18 SPE cartridge. (3) The concentrated suspension was recovered in methanol and analyzed by GC-MS.

[0197] Extractable levels (Table 5-2) were calculated from internal standards using area count ratios and the results are reported in ppb (parts per billion), which is the equivalent amount of monomer (or photoinitiator) that would be present in 1 kg of food if all the extractables in the print were to migrate and contaminate the food, according to the EU packaging model (which assumes that 6 dm2 of substrate is needed to package 1 kg of food). TIFF2025506156000014.tif26163

[0198] LM testing showed that in this example, the extractable levels of monomer residues, photoinitiator-2 residues, and photoinitiator-3 residues were undetectable (i.e., less than 1 ppb). The extractable levels of photoinitiator-1 residues were also sufficiently low (8 ppb total). 2,4,6-trimethylbenzaldehyde, 2,4,6-trimethylbenzoic acid, methyl ester, and 2,4,6-trimethylbenzoic acid are decomposition by-products from photoinitiator-1.

[0199] Example 6: Use of the disclosed inks on other substrates The above YMCK inks of Example 5 were printed on various substrates using a #6 Mayer rod (Table-6-1). These substrates are widely used in inkjet, flexographic, and offset printing. Many of them are also used in food packaging, cosmetic packaging, and pharmaceutical packaging. The printed inks were LED cured using an AMS LED curing unit (manufactured by Air Motion Systems) with a 17w / cm LED lamp at a total UV-A2 dose of 400mj / cm2. The prints were then immediately (within 10 seconds of curing) evaluated for surface odor. A score of 1 to 5 for surface odor was assigned to each print, where 5 indicates a relatively strong and unpleasant odor and 1 indicates a relatively mild odor emanating from the print. In general, a score of 1 is desirable for the corresponding application of energy cured prints.

[0200] Tape adhesion test of cured ink can refer to the method "Measurement of Ink / Coating Adhesion to Substrate Using Tape", which is similar to ASTM D3359 but does not use crosshatch. Generally, three steps are required: (1) Place a standard adhesive tape (610 or 810 tape from 3M) on the print and apply moderate pressure to ensure proper adhesion between the adhesive tape and the print. (2) Peel the tape off at an angle of 120° to 150° and a smooth speed of approximately 1 cm / sec. (3) Observe the results and "fail" if less than 100% of the cured ink remains on the substrate. 610-Tape Test and / or 810-Tape Test are the more commonly used methods for paper printing and plastic printing applications.

[0201] As shown in Table 6-1, the cured ink exhibited good low odor characteristics (score 1) and good tape adhesion on a variety of substrates, indicating potential in paper, paper board, plastic, and plastic lamination applications. TIFF2025506156000015.tif174165

[0202] (Migration level of cured print) The level of contamination from the cured surface of the prints was determined by a "set-off" extraction test. Cured prints prepared from GF Post Satin paper were selected for this test.

[0203] In this test, 100 micron Sterling Digital Sheets were subjected to a 25 lb weight for 24 hours, covering 200 cm2 of the printed / cured surface. Contaminated Sterling Digital Sheets (due to set-off) were cut to 1 dm2 and extracted in 30 ml of 10% ethanol at 40°C (e.g. in an oven) for 2 hours. BP-D10 and Anthracene D-10 were added to the above extraction solution as internal standards. The solution containing the internal standards was then concentrated to 1 ml before being analyzed by GC-MS. Extraction levels were calculated from the internal standards using area count ratios and results are reported in ppb (parts per billion).

[0204] LM testing results showed that extractable levels of monofunctional monomer residues and photoinitiator-3 residues (Table 6-2) were not detected. Extractable levels of photoinitiator-1 residues were also relatively low (total 19+2=21ppb). Extractable levels of photoinitiator-2 residues were approximately 14ppb. Extractable levels of bifunctional monomer residues were approximately 28ppb. Both were below 50ppb. If an overprint clear was applied to cover the cured ink, it is expected that the extractable levels (contamination levels) would be further reduced. TIFF2025506156000016.tif40163

[0205] For completeness, various aspects of the invention are presented in the following numbered paragraphs:

[0206] (Item 1) An ink composition comprising a monofunctional monomer including a hydrophilic monofunctional monomer, a difunctional monomer, an optional colorant, and an optional photopolymerization initiator, wherein the ratio of the weight of the difunctional monomer to the weight of the monofunctional monomer in the ink composition is greater than 0.1.

[0207] (Item 2) The ink composition according to item 1, wherein the ink composition contains about 3% by weight to about 80% by weight of the monofunctional monomer based on the total weight of the ink composition.

[0208] (Item 3) The ink composition according to item 1 or 2, wherein the ink composition contains about 3% by weight to about 46% by weight of a hydrophilic monofunctional monomer based on the total weight of the ink composition.

[0209] (Item 4) The ink composition according to any one of Items 1 to 3, wherein the hydrophilic monofunctional monomer comprises 4-hydroxybutyl acrylate (4HBA), diacetone acrylamide (DAAM), 2-[[(butylamino)carbonyl]oxy]ethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-carboxyethyl acrylate, hydroxyethyl caprolactone acrylate, vinylmethyloxazolidone (VMOX), or a mixture thereof.

[0210] (Item 5) The ink composition according to any one of Items 1 to 4, wherein the monofunctional monomer further comprises a hydrophobic monofunctional monomer.

[0211] (Item 6) The ink composition according to any one of Items 1 to 5, wherein the ink composition contains about 10% by weight to about 80% by weight of a bifunctional monomer based on the total weight of the ink composition.

[0212] (Item 7) The ink composition according to any one of Items 1 to 6, wherein the bifunctional monomer comprises 3-methyl-1,5-pentanediyl diacrylate, propoxylated neopentyl glycol diacrylate, 1,10-decanediol diacrylate, 2-hydroxy 3-propyl methacrylate acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, 1,6-hexanediol (2EO) diacrylate, propoxylated hexanediol diacrylate, and 2-(2-phenyloxyethoxy)ethyl acrylate, or a mixture thereof.

[0213] (Item 8) The ink composition according to any one of Items 1 to 7, wherein the ratio is from about 0.4 to about 2.6.

[0214] (Item 9) The ink composition according to any one of Items 1 to 8, wherein the ink composition has an average double bond density of the polymerizable components that is greater than 1.

[0215] (Item 10) The ink composition according to any one of Items 1 to 9, wherein the ink composition contains about 1% by weight to about 4% by weight of the colorant based on the total weight of the ink composition.

[0216] (Item 11) The ink composition according to any one of Items 1 to 10, wherein the colorant comprises a dye or a pigment.

[0217] (Item 12) The ink composition according to any one of Items 1 to 11, wherein the colorant comprises Yellow 185, Red 122, Blue 15:4, Black 7, White 6, Green 7, Orange 64, Violet 23, and Brown 25, or a combination thereof.

[0218] (Item 13) The ink composition according to any one of Items 1 to 12, wherein the colorant is dispersed in a dispersant.

[0219] (Item 14) The ink composition according to item 13, wherein the dispersant is a polymeric dispersant.

[0220] (Item 15) The ink composition according to item 13 or 14, wherein the dispersant is contained in an amount of about 1% by weight to about 25% by weight of the total dispersion liquid.

[0221] (Item 16) The ink composition according to any one of Items 1 to 15, wherein the ink composition contains 15% by weight or less of the photopolymerization initiator based on the total weight of the ink composition.

[0222] (Item 17) The ink composition according to any one of Items 1 to 16, further comprising a trifunctional monomer, a polyfunctional monomer, or a combination thereof.

[0223] (Item 18) The ink composition according to item 17, wherein the ink composition contains 20% by weight or less of the trifunctional monomer based on the total weight of the ink composition.

[0224] (Item 19) The ink composition according to any one of items 1 to 18, further comprising an inactive resin, an oligomer, a synergist, a stabilizer, a wetting / flow agent, a defoamer, or a combination thereof.

[0225] (Item 20) The ink composition according to any one of items 1 to 19, further comprising a synergist, a stabilizer, a flow agent, or a combination thereof.

[0226] (Item 21) The ink composition according to any one of items 1 to 20, wherein the ink composition has a viscosity of 40 cPs or less at about 25° C., a surface tension of 20 mN / m or less at room temperature, a low odor profile as measured by olfactory analysis, or a combination thereof.

[0227] (Item 22) An ink composition comprising, in weight percent based on the total weight of the ink composition, about 5% to about 35% of a hydrophilic monofunctional monomer, about 30% to about 70% of a bifunctional monomer, about 0% to about 4% of a colorant, and optionally a photopolymerization initiator, wherein the ink composition has an average double bond density of the polymerizable components that exceeds 1.5.

[0228] (Item 23) The ink composition according to item 22, wherein the hydrophilic monofunctional monomer comprises 4-hydroxybutyl acrylate (4HBA), diacetone acrylamide (DAAM), 2-[[(butylamino)carbonyl]oxy]ethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-carboxyethyl acrylate, hydroxyethyl caprolactone acrylate, vinylmethyloxazolidone (VMOX), or a mixture thereof.

[0229] (Item 24) The ink composition according to item 22 or 23, wherein the difunctional monomer comprises 3-methyl-1,5-pentanediyl diacrylate, propoxylated neopentyl glycol diacrylate, 1,10-decanediol diacrylate, 2-hydroxy 3-methacrylpropyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, 1,6-hexanediol (2EO) diacrylate, propoxylated hexanediol diacrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, or a mixture thereof.

[0230] (Item 25) The ink composition according to any one of Items 22 to 24, further comprising a trifunctional monomer, a polyfunctional monomer, or a combination thereof.

[0231] (Item 26) The ink composition according to any one of Items 22 to 25, further comprising a synergist, a stabilizer, a flow agent, or a combination thereof.

[0232] (Item 27) A decorated substrate comprising a substrate and a cured ink composition derived from the ink composition according to claim 1 on a surface of the substrate.

[0233] 28. The decorated substrate according to claim 27, wherein the substrate comprises metal, paper, plastic, or a combination thereof.

[0234] (Item 29) The decorated substrate according to item 27 or 28, wherein the substrate is a metal container.

[0235] (Item 30) The decorated substrate according to any one of Items 27 to 29, wherein the cured ink composition has a coat weight of about 0.5 gsm to about 15 gsm.

[0236] (Item 31) The decorated substrate according to any one of Items 27 to 30, further comprising a precoating disposed between the surface of the substrate and the cured ink composition.

[0237] (Item 32) The decorated substrate according to any one of Items 27 to 31, wherein the precoating is a white base coating and has a coat weight of about 2.5 gsm to about 10.5 gsm.

[0238] (Item 33) The decorated substrate according to any one of Items 27 to 32, further comprising a coating disposed on a surface of the cured ink composition.

[0239] (Item 34) The decorated substrate according to item 33, wherein the coating is visually transparent and has a coat weight of about 1.5 gsm to about 5 gsm.

[0240] (Item 35) The decorative substrate according to any one of Items 27 to 34, wherein the cured ink composition has a contamination level of uncured monomers, photopolymerization initiators, or a combination thereof of less than 50 parts per billion as measured by an alcohol extraction test.

[0241] (Item 36) A method for printing decoration on a substrate, the method comprising: (a) applying to a surface of the substrate an ink composition comprising a monofunctional monomer including a hydrophilic monofunctional monomer, a difunctional monomer, an optional colorant, and an optional photopolymerization initiator, wherein the ratio of the weight of the difunctional monomer to the weight of the monofunctional monomer in the ink composition is greater than 0.1; and (b) irradiating the ink composition with ultraviolet light, light emitting diode radiation, or electron beam radiation to cure the ink composition on the surface of the substrate and provide a decorated substrate.

[0242] 37. The method according to claim 36, wherein the step of applying the ink composition comprises ink-jet processing.

[0243] (Item 38) The method according to items 36 or 37, wherein the substrate comprises metal, paper, plastic, or a combination thereof.

[0244] (Item 39) The method according to any one of Items 36 to 38, wherein the substrate is a metal container.

[0245] (Item 40) The method according to any one of Items 36 to 39, wherein the substrate is coated with a white base coat prior to step (a).

[0246] (Item 41) The method of any one of Items 36 to 40, further comprising laminating the cured ink composition with a varnish coating.

[0247] (Item 42) The method according to any one of Items 36 to 41, further comprising baking the decorated substrate at about 350°F to about 400°F.

Claims

1. a monofunctional monomer including a hydrophilic monofunctional monomer; A bifunctional monomer, An optional colorant; and an optional photoinitiator. An ink composition, wherein a ratio by weight of the difunctional monomer to the monofunctional monomer in the ink composition is greater than 0.

1.

2. The ink composition of claim 1, wherein the ink composition comprises from about 3% to about 80% by weight of the monofunctional monomer of the total ink composition.

3. The ink composition of claim 1, wherein the ink composition comprises from about 3% to about 46% by weight of the total ink composition of the hydrophilic monofunctional monomer.

4. 2. The ink composition of claim 1, wherein the hydrophilic monofunctional monomer comprises 4-hydroxybutyl acrylate (4HBA), diacetone acrylamide (DAAM), 2-[[(butylamino)carbonyl]oxy]ethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-carboxyethyl acrylate, hydroxyethyl caprolactone acrylate, vinylmethyloxazolidone (VMOX), or a mixture thereof.

5. The ink composition of claim 1 , wherein the monofunctional monomer further comprises a hydrophobic monofunctional monomer.

6. The ink composition of claim 1, wherein the ink composition comprises from about 10% to about 80% by weight of the total ink composition of the difunctional monomer.

7. 2. The ink composition of claim 1, wherein the difunctional monomer comprises 3-methyl-1,5-pentanediyl diacrylate, propoxylated neopentyl glycol diacrylate, 1,10-decanediol diacrylate, 2-hydroxy 3-propyl methacrylate acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, 1,6-hexanediol (2EO) diacrylate, propoxylated hexanediol diacrylate, and 2-(2-phenyloxyethoxy)ethyl acrylate, or a mixture thereof.

8. The ink composition of claim 1, wherein the ratio is from about 0.4 to about 2.

6.

9. The ink composition of claim 1 , wherein the ink composition has an average double bond density of the polymerizable components greater than one.

10. The ink composition of claim 1, wherein the ink composition comprises from about 1% to about 4% by weight of the colorant of the total ink composition.

11. The ink composition according to claim 1 , wherein the colorant comprises a dye or a pigment.

12. 2. The ink composition of claim 1, wherein the colorants include Yellow 185, Red 122, Blue 15:4, Black 7, White 6, Green 7, Orange 64, Violet 23, and Brown 25, or combinations thereof.

13. The ink composition of claim 1 , wherein the colorant is dispersed in a dispersant.

14. The ink composition of claim 13, wherein the dispersant is a polymeric dispersant.

15. The ink composition of claim 13, wherein the dispersant comprises from about 1% to about 25% by weight of the total dispersion.

16. The ink composition according to claim 1 , wherein the ink composition contains the photopolymerization initiator in an amount of 15% by weight or less of the total ink composition.

17. The ink composition of claim 1 , further comprising a trifunctional monomer, a multifunctional monomer, or a combination thereof.

18. The ink composition according to claim 17, wherein the ink composition comprises 20% by weight or less of the trifunctional monomer of the total ink composition.

19. The ink composition of claim 1 further comprising an inactive resin, an oligomer, a synergist, a stabilizer, a wetting / flow agent, a defoamer, or a combination thereof.

20. The ink composition of claim 1 further comprising a synergist, a stabilizer, a flow agent, or a combination thereof.

21. The ink composition comprises a viscosity of 40 cPs or less at about 25° C.; A surface tension of 20 mN / m or less at room temperature; A low odor profile as determined by olfactory analysis, or The ink composition of claim 1 having one of these combinations.

22. An ink composition comprising, in weight percent based on the total weight of the ink composition: about 5% to about 35% of a hydrophilic monofunctional monomer; about 30% to about 70% of a difunctional monomer; from about 0% to about 4% colorant; and an optional photoinitiator. The ink composition has an average double bond density of the polymerizable components greater than 1.

5.

23. 23. The ink composition of claim 22, wherein the hydrophilic monofunctional monomer comprises 4-hydroxybutyl acrylate (4HBA), diacetone acrylamide (DAAM), 2-[[(butylamino)carbonyl]oxy]ethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-carboxyethyl acrylate, hydroxyethyl caprolactone acrylate, vinylmethyloxazolidone (VMOX), or a mixture thereof.

24. 23. The ink composition of claim 22, wherein the difunctional monomer comprises 3-methyl-1,5-pentanediyl diacrylate, propoxylated neopentyl glycol diacrylate, 1,10-decanediol diacrylate, 2-hydroxy 3-methacrylpropyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, 1,6-hexanediol (2EO) diacrylate, propoxylated hexanediol diacrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, or a mixture thereof.

25. The ink composition of claim 22, further comprising a trifunctional monomer, a multifunctional monomer, or a combination thereof.

26. The ink composition of claim 22, further comprising a synergist, a stabilizer, a flow agent, or a combination thereof.

27. A substrate; A decorated substrate comprising: a cured ink composition derived from the ink composition according to claim 1 on a surface of the substrate.

28. 28. The decorated substrate of claim 27, wherein the substrate comprises metal, paper, plastic, or a combination thereof.

29. The decorated substrate according to claim 27 , wherein the substrate is a metal container.

30. The decorated substrate of claim 27, wherein the cured ink composition has a coat weight of from about 0.5 gsm to about 15 gsm.

31. 28. The decorated substrate of claim 27, further comprising a precoating disposed between a surface of the substrate and the cured ink composition.

32. 32. The decorated substrate of claim 31, wherein the pre-coating is a white basecoat and has a coat weight of from about 2.5 gsm to about 10.5 gsm.

33. The decorated substrate of claim 27 , further comprising a coating disposed on a surface of the cured ink composition.

34. 34. The decorated substrate of claim 33, wherein the coating is optically clear and has a coat weight of from about 1.5 gsm to about 5 gsm.

35. 28. The decorated substrate of claim 27, wherein the cured ink composition has a contamination level of uncured monomer, photoinitiator, or a combination thereof of less than 50 parts per billion as measured by an alcohol extraction test.

36. 1. A method for printing decoration onto a substrate, the method comprising: (a) on a surface of a substrate, applying an ink composition comprising a monofunctional monomer, including a hydrophilic monofunctional monomer, a bifunctional monomer, an optional colorant, and an optional photopolymerization initiator, wherein a ratio of a weight of the bifunctional monomer to a weight of the monofunctional monomer in the ink composition is greater than 0.1; (b) exposing the ink composition to ultraviolet light, light emitting diode radiation, or electron beam radiation to cure the ink composition on the surface of the substrate to provide a decorated substrate.

37. The method of claim 36 , wherein the step of applying the ink composition comprises an ink-jet process.

38. 37. The method of claim 36, wherein the substrate comprises metal, paper, plastic, or a combination thereof.

39. The method of claim 36, wherein the substrate is a metal container.

40. 37. The method of claim 36, wherein prior to step (a), the substrate is coated with a white basecoat.

41. 37. The method of claim 36, further comprising laminating the cured ink composition with a varnish coating.

42. 37. The method of claim 36, further comprising firing the decorated substrate at about 350°F to about 400°F.

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