Inkjet ink and primer fluid set

Abstract

The present disclosure provides an ink fluid set comprising an aqueous primer coating fluid and an aqueous inkjet ink or inkjet ink set. The aqueous primer coating fluid comprises two parts that are mixed together prior to application to form a coating on a print substrate. The aqueous inkjet ink or inkjet ink set is then printed onto the primer coated substrate. This fluid set is particularly suitable for printing on non-porous plastic substrates.

Description

[Technical field]

[0001] The present disclosure relates to an ink fluid set comprising an aqueous primer coating fluid and an aqueous inkjet ink or inkjet ink set. The aqueous primer coating fluid comprises two parts that are mixed together prior to application to form a coating on a substrate. The aqueous inkjet ink or inkjet ink set is then printed onto the primer coated substrate. [Background technology]

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. § 119(e) from U.S. Provisional Application No. 63 / 289,347, filed December 14, 2021.

[0003] Inkjet printing is a non-impact digital printing process in which droplets of ink are deposited on a substrate, such as paper, to form a desired image. For full-color printing, an inkjet printer typically includes an ink set that includes cyan, magenta, and yellow inks (CMY). Typically, the ink set also includes a black ink (CMYK), which is the most common ink. For transparent substrates, such as clear plastic, a white ink is generally required to enhance the color image. In this case, the ink set typically includes CMYKW inks.

[0004] Inkjet printing is becoming increasingly important in markets outside of traditional desktop printing for small / home offices. Digital printing methods are gaining popularity in textile, commercial and packaging printing and offer several potential advantages over traditional printing methods such as screen printing, offset printing, flexography and gravure printing. Inkjet digital printing may remove the set-up costs associated with manufacturing screens and plates, allowing for cost-effective short run production runs. In addition, inkjet printing allows for visual effects such as tone gradations and infinite pattern repeat sizes that are practically unachievable with screen and other analog printing processes.

[0005] Water-based inkjet inks have seen rapid growth in packaging applications in recent years, as it is a digital technology with less environmental impact compared to UV and solvent digital inks. Non-porous plastics, including both soft plastic films and rigid plastics, are common media / substrates in packaging applications. The surfaces of these plastics are inherently non-liquid absorbing and hydrophobic, imposing many performance challenges on water-based pigment-based inks. Key among them is poor image quality due to slow curing of the ink droplets as a result of the non-ink absorbing nature of the printed surface and low temperature drying to avoid damaging the printed plastic substrate or film. Another major challenge is poor adhesion of the ink to non-porous plastic films, especially poor lamination strength when the printed plastic film is laminated to another film to form a multi-layer laminate structure for various packaging applications. Slow settling and drying of the ink droplets can result in blurred images or inter-color bleeding, and poor bond strength of the laminate structure can result in delamination of the packaging material.

[0006] A common approach to improve print image quality on hydrophobic substrates is to coat the hydrophobic surface with a primer or pretreatment fluid. US 2008 / 0092309 discloses a pretreatment solution for treating textiles. The pretreatment solution contains a non-ionic latex polymer and a multivalent cationic salt solution. US 2014 / 356555 discloses an inkjet print medium including a base substrate and a coating layer. The coating layer contains a source of multivalent ions and a latex binder that forms a coherent film in the presence of multivalent ions. The base substrate may include paper, cloth, nonwoven fabric, felt, and synthetic (non-cellulosic) paper. However, these disclosures do not address printing on non-porous plastic film substrates, which differ from other common substrates in that non-porous plastic films are completely non-liquid permeable and difficult to adhere to due to the weak interactions between the plastic polymer and the ink, as well as in that non-porous plastic films often require lower drying and curing temperatures to accommodate the film, which is less resistant to heat.

[0007] JP 2011-189527 A discloses a recording pretreatment liquid containing a water-soluble carbodiimide group-containing resin and an ink containing particles containing a carboxy-functional polymer. The carboxy-functional polymer in the ink reacts with the carbodiimide in the pretreatment liquid during printing. US Patent Application Publication No. 2019 / 0390078 A discloses an ink set for printing on a film. The ink set includes a pretreatment liquid having a flocculant, water, polyester, polyolefin, and polyurethane. The ink of the ink set includes a pigment and a compound having an oxazoline group. After printing on the ink recording medium, the components in the pretreatment agent and the ink chemically react. JP 2019-006855 A discloses a recording liquid set for printing on a non-absorbent base material that can obtain high lamination strength. This recording liquid set includes an aqueous undercoat liquid containing an amphoteric resin and a coagulant, and may further include a crosslinking agent such as an epoxy-type crosslinking agent, an isocyanate-type crosslinking agent, a carbodiimide-type crosslinking agent, etc. All of these documents disclose an approach in which a component in the pretreatment / undercoat liquid chemically reacts with a component in the ink. Summary of the Invention [Problem to be solved by the invention]

[0008] There is a need for an improved inkjet ink set and primer fluid combination that can produce higher quality printed images with stronger lamination strength and better adhesion on non-porous plastic film surfaces, especially for plastic films that are widely used as packaging materials. The present disclosure meets this need by providing a two-part primer fluid set including an inkjet ink and a primer. The two-part primer includes parts A and B, which are mixed prior to application to form a primer coating. This newly formed primer coating interacts with the inkjet ink to achieve higher quality printed images on non-porous plastic films with strong lamination strength. [Means for solving the problem]

[0009] One embodiment of the present disclosure is an inkjet printing fluid set comprising: a) a two-part water-based primer coating fluid comprising a part A and a part B, wherein part A comprises an ink coagulant, a water-insoluble polymeric binder selected from a polyurethane polymer, an acrylic polymer, a polyvinyl acetate copolymer, and mixtures thereof, and part B comprises a water-dispersible co-reactant selected from a polyisocyanate, an epoxy, an epoxy silane, a carbodiimide, and mixtures thereof, and parts A and B are mixed before the primer coating fluid is applied to a recording medium, and parts A and B are mixed in a ratio ranging from 100:1 to 100:20 based on the total weight of parts A and B; and b) an aqueous inkjet ink comprising an aqueous vehicle and a pigment, the pigment being stabilized by a polymeric dispersant selected from the group consisting of polyurethane polymers, acrylic polymers, hydrolyzed styrene maleic anhydride copolymers and mixtures thereof; In one embodiment, an inkjet printing fluid set is provided, comprising:

[0010] Another embodiment of the present disclosure provides that the water insoluble polymeric binder of Part A is a polyurethane polymer.

[0011] Another embodiment of the present disclosure provides that the water-dispersible co-reactant of Part B is a polyisocyanate.

[0012] Another embodiment of the present disclosure provides that the polymeric dispersant is a polyurethane polymer.

[0013] Another embodiment of the present disclosure provides that the polymeric dispersant is an acrylic polymer.

[0014] Another embodiment of the present disclosure provides that the water insoluble polymeric binder of Part A is an acrylic polymer.

[0015] Yet another embodiment of the present disclosure provides that the water insoluble polymeric binder of Part A is a polyvinyl acetate copolymer.

[0016] These and other features and advantages of the present embodiments will be more readily understood by those of ordinary skill in the art upon reading the following detailed description. Certain features of the disclosed embodiments that are, for clarity, described above and below as separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosed embodiments that are described in the context of a single embodiment may also be provided separately or in any subcombination. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Unless otherwise stated or defined, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0018] Unless otherwise stated, all percentages, parts, ratios, etc. are by weight.

[0019] When an amount, concentration, or other value or parameter is given as a range, preferred range, or list of upper preferred values ​​and lower preferred values, this should be understood to specifically disclose all ranges formed from any pairing of any upper range limit or preferred value with any lower range limit or preferred value, whether or not the ranges are separately disclosed. When a range of numerical values ​​is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range.

[0020] When the term "about" is used to describe a value or an end point of a range, the disclosure should be understood to include the specific value or end point referred to.

[0021] As used herein, the term "dispersion" means a two-phase system in which one phase consists of fine particles (often in the colloidal size range) distributed throughout a bulk material, the particles being the dispersed or internal phase and the bulk material being the continuous or external phase.

[0022] As used herein, the term "dispersant" refers to a surfactant added to a suspension medium to promote uniform and maximum separation of very fine solid particles, often of colloidal size. In the case of pigments, the dispersant is most often a polymeric dispersant, and the dispersant and pigment are usually combined using a dispersing device.

[0023] As used herein, the term "aqueous vehicle" refers to water or a mixture of water and at least one water-soluble or partially water-soluble (ie, methyl ethyl ketone) organic solvent (co-solvent).

[0024] As used herein, the term "substantially" means to a great extent, almost entirely.

[0025] As used herein, the term "dynes / cm" means dynes per centimeter, a surface tension unit.

[0026] As used herein, the term "cP" means centipoise, a unit of viscosity.

[0027] Except only as expressly stated, the materials, methods, and examples herein are illustrative only and not intended to be limiting.

[0028] Additionally, singular references may include plurals (e.g., "a" and "an" may refer to one or to more than one) unless the context clearly indicates otherwise.

[0029] Non-porous plastic substrate Non-porous plastic substrates or films are one of the primary substrates used in flexible packaging. Flexible packaging is a container made of a material that can quickly change shape when filled or closed. These containers may use paper, non-porous plastic film or foil materials in any combination. Non-porous plastic films are typically: High density polyethylene (HDPE), Medium density polyethylene (MDPE), Low density polyethylene (LDPE) (including linear low density polyethylene (LLDPE)), Polyethylene terephthalate (PET), metallized PET (Met-PET), glass-coated PET, acrylic-coated PET, Polypropylene (PP) (including cast PP (CPP), oriented PP (OPP), biaxially oriented PP (BOPP) and metallized OPP (MOPP)); polystyrene, nylon, Polyvinyl chloride (PVC, vinyl), Ethylene vinyl acetate polymer (EVA), and Ethylene vinyl alcohol copolymer (EVOH) It is manufactured from

[0030] Each film is equipped with various functions and properties suitable for a specific application. Alternatively, films can be combined to create multi-layer films with notable barrier properties for better protection or longer shelf life. The elements of custom design also extend to visual properties such as transparency, gloss and high-quality printed graphics in various colors and designs to stylishly encase the product and include important information right on the packaging. These substrate films can be non-oriented or oriented films. The thickness of the substrate film is not critical, but should usually be in the range of 1-500 μm. The printing surface of the substrate film is preferably treated with corona discharge. For example, silica or alumina can be deposited on the surface of the film.

[0031] Primer Composition In the present disclosure, a two-part primer coating fluid is used. Part A of the primer coating fluid includes an ink coagulant, a water-insoluble polymeric binder selected from polyurethane polymers, acrylic polymers, polyvinyl acetate copolymers, and mixtures thereof. Part B of the primer coating fluid includes a water-dispersible co-reactant selected from polyisocyanates, epoxies, epoxy silanes, carbodiimides, and mixtures thereof. The mixing ratio of parts A and B is typically in the range of 100:1 to 100:20, more typically in the range of 100:1 to 100:15, based on the total weight of parts A and B. The ink coagulant and water-insoluble polymeric binder of part A chemically react with the co-reactant of part B at a temperature below 85°C.

[0032] Primer A Liquid Primer Part A includes an ink coagulant and a water-insoluble polymeric binder selected from polyurethane, acrylic, and polyvinyl acetate copolymers. Part A should include sufficient ink coagulant to provide adequate fixation of the inkjet ink. Typically, Part A includes at least about 0.5% by weight of ink coagulant. The maximum amount of ink coagulant is limited by the solubility of the particular ink coagulant utilized. Preferably, Part A includes from about 1% to about 30% by weight of ink coagulant based on the total weight of the Part A fluid.

[0033] Ink flocculant Primer A contains an ink agglomerating agent that "precipitates" or "collides" with the colorant or other components in the ink. Preferred ink agglomerating agents include polyvalent metal salts and / or organic acids.

[0034] "Multivalent" refers to two or more oxidation states, typically Z for the element "Z". 2+ , Z 3+ , Z 4+ For simplicity, multivalent cations are referred to herein as Z xThe multivalent cations are substantially dissolved in the aqueous primer solution and preferably are present (in solution) in a substantially ionized state so that they are free and in a form capable of interacting with the inkjet ink.

[0035] Z x The polyvalent cations include, but are not limited to, the polyvalent cations of the following elements: Mg, Ca, Sr, Ba, Sc, Y, La, Ti, Zr, V, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Cu, Au, Zn, Al, Ga, In, Sb, Bi, Ge, Sn, Pb. In another embodiment, the polyvalent cations include at least one of Mg, Ca, Ba, Ru, Co, Zn, and Ga. In yet another embodiment, the polyvalent cations include at least one of Ca, Ba, Ru, Co, Zn, and Ga. Preferably, the polyvalent cations are Mg and Ca.

[0036] Z x can be incorporated into the primer solution by adding it in the form of a salt or in the form of an alkali, which can be used as a base in adjusting the pH of the primer solution.

[0037] The relevant anionic materials can be selected from any common anionic material, especially halides, nitrates and sulfates. The form of the anion is selected so that the multivalent cation is soluble in the aqueous primer solution. The multivalent cationic salts can be used in their hydrated form. One or more multivalent cationic salts can be used in the primer solution.

[0038] In the case of Ca, the preferred polyvalent cation salts are calcium chloride, calcium nitrate, calcium nitrate hydrate and mixtures thereof.

[0039] In the case of Mg, the preferred polyvalent cation salts are magnesium chloride, magnesium nitrate, magnesium nitrate hydrate and mixtures thereof.

[0040] The organic acid as the flocculating agent lowers the pH of the ink and solidifies the pigment dispersion and other ink components, thereby causing the ink droplets to precipitate. Specific examples of acids are polyacrylic acid, acetic acid, glycolic acid, malonic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, orthophosphoric acid, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid and derivatives of these compounds. Polyacrylic acid and acetic acid are particularly preferred.

[0041] Primer Polymer Binder Primer A contains a compatible polymer binder that does not "precipitate" or "clash" with the flocculant. The primer polymer binder and ink flocculant solution thus formed must be stable as a solution or as a stable emulsion to allow coating of the film substrate. If the primer polymer binder gels or its emulsion precipitates in the presence of the ink flocculant, e.g., a polyvalent cationic salt solution, it cannot be used as a primer additive. A screening test to determine if a primer polymer binder is stable in the presence of an ink flocculant is to mix 10% by weight of the polymer (on a dry basis) with 15% by weight of calcium nitrate tetrahydrate and observe if the solution / emulsion is stable. Stability is observed at 10 minute and 24 hour intervals at ambient temperature (approximately 25°C). The primer polymer binder must result in a stable polymer / polyvalent cationic solution / emulsion mixture.

[0042] Some suitable compatible polymeric binders include non-ionic water-insoluble polymers in colloidal particle form, including, for example, acrylic latexes, polyurethane dispersions, vinyl acetate copolymer latexes, polyester and polyamide dispersions. These polymers can be made by any known process, including, but not limited to, free radical, group transfer, ionic, RAFT, condensation and other types of polymerization.

[0043] The primer polymer binder can be formed by incorporating a non-ionic stabilizer chemically bonded or physically absorbed into the polymer. Examples of non-ionic reactive components include ethylene oxide derivatives, acrylamides, hydroxyethyl substituted monomers, vinylpyrrolidone, ethyleneimine, and the like. Incorporation can be during or after the polymerization step to prepare the latex polymer. In the case of the ethylene oxide non-ionic component, the substitution is sufficient (-CH2-CH2O-) to impart non-ionic stability. n The nonionic component can take the form of incorporating a glycol having units. For example, a polyurethane can have an alkyl polyethylene glycol incorporated into a nonionic polyurethane. The nonionic component can be the major component in the nonionic latex polymer, so long as its properties meet the stability tests described above.

[0044] The primer polymer binder may also have ionic components incorporated into the polymer. For polyurethanes, as an example, an ionic component such as an acid may be used in the polyurethane reaction, with a specific example of an acid being dimethylolpropionic acid. For acylamide and hydroxyethyl-substituted non-ionic latex polymers, the ion source may be from (meth)acrylic acid. There is a limit to the content of ionic components in the polymer, as they may form complexes with the ink flocculant, leading to instability of the polymer / multivalent cationic solution. A balance between the non-ionic and ionic components must result in a stable solution as described above.

[0045] The polymeric binder is combined with the ink coagulant to form the A Part fluid. The polymeric binder is advantageously used at a level of at least about 5%, typically at least about 10%, based on the total weight of the A Part fluid. The upper limit is determined by the viscosity of the primer or other physical limitations. In more typical embodiments, no more than about 50% polymeric binder is present in the A Part composition, and most typically no more than about 40% based on the total weight of the primer A Part fluid. The combined total weight of the polymeric binder and the ink coagulant can be up to about 45% by weight, based on the total weight of the A Part fluid.

[0046] The Part A composition may further include a surfactant to impart wetting properties to the film substrate. Some suitable surfactants include those that are miscible with the ink flocculant and polymer, i.e., those that do not form precipitates or aggregates upon mixing. Some useful surfactants include cationic, nonionic, and amphoteric surfactants. Some suitable cationic surfactants include, for example, quaternized ammonium or pyridinium surfactants, such as dodecyltrimethylammonium chloride, cetyltrimethylammonium bromide, cetyltrimethylpyridinium chloride, and the like. Some suitable nonionic surfactants include ethoxylated acetylenic diols (e.g., Evonik's Surfynol® series), ethoxylated primary alcohols (e.g., Shell's Neodol® series) and secondary alcohols (e.g., Dow Chemical's Tergitol® series), Pluronic® block copolymer surfactants, sulfosuccinates (e.g., Cytec's Aerosol® series), organosilicones (e.g., Evonik's Dynol™ series), and fluorosurfactants (e.g., Chemours' Zonyl® series). Amphoteric surfactants that are cationic within a certain pH range can also be used. In this case, the pH of the liquid composition must be adjusted below the isoelectric point of the surfactant. Some examples of useful zwitterionic surfactants include N,N-dimethyl-N-tetradecylamine oxide (NTAO), N,N-dimethyl-N-hexadecylamine oxide (NHAO), and related amine oxide compounds. Another example is N-dodecyl-N,N-dimethylglycine. Further examples include phosphates, phosphites, phosphonates, lecithin, and phosphonate esters such as phosphomyelin. Surfactants may be used in amounts typically from about 0.1 to about 10%, more typically from about 0.5 to about 5%, based on the total weight of the primer fluid.

[0047] Part A may further contain additional additives to modify viscosity, prevent film curl, or improve blocking resistance, including but not limited to colloidal silica dispersions and wax emulsions. Preferred colloidal silica dispersions are nano-sized silica particles stabilized by cationic charge or without charge as long as the silica dispersion is stable when mixed with the ink flocculant. Examples include the surface treated silicas SNOWTEX® ST-AK, ST-AK-ML, ST-AK-L, ST-AK-A, and ST-AK-XK (Nissan Chemical America, Houston TX) and the elongated shaped silicas SNOWTEX® ST-OUP and string-of-pearls SNOWTEX® ST-PS-SO and ST-PS-MO. Colloidal silica may typically be used in amounts of 1% to 50% based on the total weight of the Part A fluid. Examples of wax emulsions include, but are not limited to, olefin waxes such as LDPE, HDPE and PP, paraffin wax, carnauba wax, and amide waxes that are colloidally stabilized by non-ionic emulsification and therefore stable when mixed with the ink flocculant. Examples of preferred waxes are AQUACER 539, AQUACER 513, AQUACER 519 and AQUACER 497 (BYK-Chemie Wesel, Germany). Waxes may typically be used in amounts of 0.05% to 5% based on the total weight of the A-Part fluid.

[0048] Other components in the primer A fluid may further include, but are not limited to, humectants and biocides. Biocides prevent microbial decomposition, and the selection and use of biocides is generally well known in the art. Suitable humectants are the same as those suitable for use in the color inkjet inks described in more detail below.

[0049] Primer B Liquid Primer B part contains a water-soluble or dispersible co-reactant capable of chemically reacting with Primer A part at temperatures below 85°C. Suitable co-reactants include monomers, oligomers and polymers containing functional groups selected from polyisocyanates, epoxies, epoxy silanes, carbodiimides and mixtures thereof. Typically, the amount of co-reactant ranges from 70% to 100% based on the total weight of B part. Examples of suitable co-reactants include polyisocyanate crosslinkers such as Bayhydur® 304 and Bayhydur® 3100 from Covestro (Leverkusen, Germany); co-reactants containing epoxy groups such as Denacol® 321, 920, 512 and 614B from Nagase Chemical Corporation (Osaka, Japan); Carbodilite® V-02, V-02-L2, SV-L2, E-02 and E-03A from Nisshinbo Holdings Inc. (Tokyo, Japan) and co-reactants such as ethylenediaminetetraacetate (EDTA) from Stahl Polymers (Waalwijk, Germany). carbodiimide coreactants such as Picassian® XL-702 and XL-703 from Momentive (Netherlands); silane crosslinkers such as Silquest® A-187 from Momentive (Waterford, NY); and various Dynasylan® silane coupling agents from Evonik (Essen, Germany).

[0050] Primer application Prior to printing the inkjet ink, the film substrate is coated with the primer fluid of the present disclosure by various available coating methods, including flexographic, gravure, rod, spray, roll, curtain and knife coating methods. The preferred methods are flexographic, gravure and rod coating methods. The application of the primer can be in-line or off-line with the inkjet ink printing process, depending on the printer design and machine integration.

[0051] Primer A and B solutions undergo a chemical reaction below 85°C, so the two parts must be mixed together on the same day when coating the film / printing substrate. The mixed primer solution can be used as long as it has not gelled due to a chemical reaction. Typically, the coating process is carried out within 24 hours of mixing primer A and B parts.

[0052] Regardless of the coating method, the film / printing substrate coated with the primer needs to be thoroughly dried before printing the inkjet ink. The drying process can be various, such as hot air, infrared and near infrared, and is not limited to any method, as long as the drying temperature is not so high as to damage the integrity of the film. Typically, the drying temperature ranges from 40°C to 120°C, more typically from 50°C to 100°C. The thickness of the coating of the dried primer can vary from 0.3 to 10 μm, preferably from 0.5 to 8 μm, and more preferably from 0.6 to 5 μm. Those skilled in the art can adjust and optimize the print image quality of the ink or ink set by adjusting the thickness and tackiness, drying speed, haze, adhesion, etc. of the primer coating. The time interval between primer coating and inkjet printing is not limited and can range from a few seconds to several days. To obtain a superior quality print image using the two-component primer of the present disclosure, no chemical reaction between the coated primer and the inkjet ink is required.

[0053] Ink set The term "ink set" refers to all the individual inks or other fluids that an inkjet printer is equipped to jet. A white ink used to print an image after printing colored inks or a white ink used to print before printing colored inks is considered part of an ink set. This ink set, together with a primer fluid, forms an inkjet ink printing fluid set.

[0054] In one preferred embodiment, the ink set comprises at least two different color inkjet inks, at least one of which is a white pigment-based inkjet ink as described above.

[0055] In another preferred embodiment, the ink set comprises at least four different colour inkjet inks, at least one being a cyan inkjet ink, at least one being a magenta inkjet ink, at least one being a yellow inkjet ink and at least one being a white inkjet ink.

[0056] In addition to the color inkjet inks just described, it is also preferred to include a black inkjet ink in the ink set.

[0057] In addition to the CMYKW inks listed above, the ink set may contain additional inks of different colors as well as different strength versions of the CMYKW and other inks.

[0058] For example, an ink set of the present invention may include a full strength version and a "light" version of one or more of the inks in the ink set.

[0059] Further colors of the inkjet ink set may include, for example, orange, violet, green, red and / or blue.

[0060] The preferred inks of the ink set are pigment-based inks.

[0061] Pigments The colorants used to print color images can be dyes or pigments. Dyes include disperse dyes, reactive dyes, acid dyes, etc. As used herein, the term "pigment" means an insoluble colorant that requires being dispersed with a dispersant and processed under dispersing conditions in the presence of the dispersant. Pigment-based inks are preferred.

[0062] Suitable pigments for use are those generally well known in the art for aqueous inkjet inks. The selected pigment may be used in dry or wet form. For example, pigments are usually manufactured in aqueous media and the resulting pigment is obtained as a water-moistened presscake. In presscake form, the pigment does not agglomerate to the same extent that it does in dry form. Thus, pigments in the form of water-moistened presscake do not require as much mixing energy to be deagglomerated in the premixing process as pigments in dry form. Representative commercially available dry pigments are listed in U.S. Pat. No. 5,085,698.

[0063] Some examples of pigments having colorant properties useful in inkjet inks include, but are not limited to, the following: cyan pigments Pigment Blue 15:3 and Pigment Blue 15:4, magenta pigments Pigment Red 122 and Pigment Red 202, yellow pigments Pigment Yellow 14, Pigment Yellow 74, Pigment Yellow 95, Pigment Yellow 110, Pigment Yellow 114, Pigment Yellow 128 and Pigment Yellow 155, Pigment Orange 5, Pigment Orange 34, Pigment Orange 43, Pigment Orange 62, Pigment Red 17, Pigment Red 49:2, The red pigments are Pigment Red 112, Pigment Red 149, Pigment Red 177, Pigment Red 178, Pigment Red 188, Pigment Red 254, Pigment Red 184, Pigment Red 264, and Pigment Red PV 19, the green pigments are Pigment Green 1, Pigment Green 2, Pigment Green 7, and Pigment Green 36, the blue pigments are Pigment Blue 60, Pigment Violet 3, Pigment Violet 19, Pigment Violet 23, Pigment Violet 32, Pigment Violet 36, and Pigment Violet 38, and the black pigment Carbon Black. The pigment names and abbreviations used herein are the "CI" designation for pigments established by the Society of Dyers and Colourists, Bradford, Yorkshire, UK, and published in The Color Index, Third Edition, 1971.

[0064] Examples of white materials include, but are not limited to, white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, antimony oxide, and zirconium oxide. In addition to such white inorganic pigments, white organic pigments such as white hollow resin particles and polymer particles can also be used. A preferred pigment for aqueous pigment-based white inks is titanium dioxide. The titanium dioxide (TiO2) pigment used can be in rutile or anatase crystalline form. It is generally made by either the chloride process or the sulfate process. In the chloride process, TiCl4 is oxidized to TiO2 particles. In the sulfate process, sulfuric acid and titanium-containing ores are dissolved, and the resulting solution undergoes a series of steps to produce TiO2. Both the sulfate and chloride processes are described in more detail in "The Pigment Handbook", Vol. 1, 2nd Ed., John Wiley & Sons, NY (1988), the relevant disclosures of which are incorporated herein by reference for all purposes as if fully set forth.

[0065] The titanium dioxide particles can have a variety of average particle sizes up to about 1 micron depending on the desired end use of the ink. For applications requiring high hiding or decorative printing applications, the titanium dioxide particles preferably have an average size of less than about 1 micron (1000 nanometers). Preferably, the particles have an average size of about 50 to about 950 nanometers, more preferably about 75 to about 750 nanometers, and even more preferably about 100 to about 500 nanometers. These titanium dioxide particles are commonly referred to as pigmentary TiO2.

[0066] For applications requiring a white color with some degree of transparency, "nano" titanium dioxide is preferred as a pigment. "Nano" titanium dioxide particles typically have an average size ranging from about 10 to about 200 nanometers, preferably from about 20 to about 150 nanometers, and more preferably from about 35 to about 75 nanometers. Inks containing nano titanium dioxide can improve saturation and transparency while still maintaining good resistance to fading from light and suitable hue angles. A commercially available example of uncoated nano-grade titanium dioxide is P-25 available from Degussa, Parsippany NJ.

[0067] The titanium dioxide pigment may be substantially pure titanium dioxide or may include other metal oxides such as silica, alumina, and zirconia. The other metal oxides may be incorporated into the pigment particles, for example, by co-oxidizing or co-precipitating the titanium compound with other metal compounds. When co-oxidized or co-precipitated metals are present, they are preferably present in an amount of from about 0.1% to about 20% by weight, more preferably from about 0.5% to about 5% by weight, and even more preferably from about 0.5% to about 1.5% by weight, as metal oxides, based on the total weight of the titanium dioxide pigment.

[0068] Titanium dioxide pigments can also have one or more metal oxide surface coatings. These coatings can be applied using techniques known to those skilled in the art. Examples of metal oxide coatings include silica, alumina, alumina-silica, boria, and zirconia, among others. Such coatings can be optionally present in an amount of about 0.1% to about 10% by weight, preferably about 0.5% to about 3% by weight, based on the total weight of the titanium dioxide pigment. These coatings can provide improved properties, such as reducing the photoreactivity of titanium dioxide. Commercial examples of such coated titanium dioxide include R700 (alumina coated, available from Chemours, Wilmington Del.), RDI-S (alumina coated, available from Kemira Industrial Chemicals, Helsinki, Finland), R706 (available from Chemours, Wilmington Del.) and W-6042 (silica-alumina treated nano-grade titanium dioxide from Tayco Corporation, Osaka, Japan).

[0069] Titanium dioxide pigments may also have one or more organic surface coatings, such as, for example, carboxylic acids, silanes, siloxanes, and hydrocarbon waxes and their reaction products with the titanium dioxide surface. The amount of organic surface coating, if present, generally ranges from about 0.01% to about 6% by weight, preferably from about 0.1% to about 3% by weight, more preferably from about 0.5% to about 1.5% by weight, and even more preferably about 1% by weight, based on the total weight of the pigment.

[0070] Polymer Dispersants Traditionally, pigments are stabilized by dispersants, such as polymeric dispersants or surfactants, to produce a stable dispersion of the pigment in the vehicle. More recently, however, so-called "self-dispersing" or "self-dispersing" pigments (hereinafter "SDPs") have been developed. As the name suggests, SDPs are dispersible in water without dispersants.

[0071] Polymeric dispersants for non-self-dispersing pigments can be random or structured polymers. Typically, acrylic polymeric dispersants are copolymers of hydrophobic and hydrophilic monomers. Some examples of hydrophobic monomers used are methyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, benzyl methacrylate, 2-phenylethyl methacrylate and the corresponding acrylates. Examples of hydrophilic monomers are, for example, methacrylic acid, acrylic acid, dimethylaminoethyl (meth)acrylate and their salts. Quaternary salts of dimethylaminoethyl (meth)acrylate can also be used. "Random polymer" means a polymer in which the molecules of each monomer are randomly arranged in the polymer backbone. For references to suitable random polymeric dispersants, see U.S. Pat. No. 4,597,794. "Structured polymer" means a polymer with a block, branched, graft or star structure. Examples of structured polymers include AB or BAB block copolymers such as those disclosed in U.S. Pat. No. 5,085,698, ABC block copolymers such as those disclosed in EP 0556649, and graft polymers such as those disclosed in U.S. Pat. No. 5,231,131. Other polymeric dispersants that can be used are described, for example, in U.S. Pat. Nos. 6,117,921, 6,262,152, 6,306,994, and 6,433,117.

[0072] "Random polymer" also includes polyurethanes. Particularly useful are the polyurethane dispersants disclosed in US Patent Publication No. 2012 / 0214939, in which the polyurethane dispersant is crosslinked after dispersing the pigment to form the pigment dispersion.

[0073] Another type of suitable polymeric dispersant is a styrene maleic anhydride (SMA) copolymer. "Styrene maleic anhydride copolymer" or "SMA copolymer" means a polymer formed from styrene, maleic anhydride monomer, and optionally one or more additional comonomers. The copolymer can have a molar ratio of styrene / maleic anhydride repeat units of 0.2 to 5, preferably 0.5 to 2. The dispersant is usually in the form of a hydrolyzed solution of the SMA copolymer. The hydrolyzed solution preferably comprises the SMA copolymer dissolved in an aqueous alkaline solution. The aqueous alkaline solution is useful for hydrolyzing the SMA copolymer because the SMA copolymer is poorly soluble in water. The hydroxyl ions of the alkaline solution hydrolyze or react with the carbonyl carbon on the anhydride ring, cleaving the carbon-oxygen single bond. This reaction opens the ring and the hydroxyl ions react with the carbonyl carbon and the monoacid carboxylate group to form a monoacid group. The aqueous alkaline solution used to dissolve the SMA copolymer is preferably prepared from ammonium hydroxide, sodium hydroxide, potassium hydroxide or an organic amine. Hydrolyzed SMA copolymer solutions suitable for the present invention include those commercially available from Polyscope Polymers under the trade name XIRAN® SL.

[0074] Color pigment dispersion Colored pigment dispersions stabilized by added polymeric dispersants can be prepared by methods known in the art. It is generally desirable to have the stabilized pigment in a concentrated form. The stabilized pigment is prepared by first premixing the selected pigment with the polymeric dispersant in an aqueous carrier medium (such as water and optionally a water-miscible solvent) and then dispersing or deflocculating the pigment. The premixing step is generally carried out in an agitated mixing vessel, with high speed dispersers (HSDs) being particularly suitable for the mixing step. Cowels-type blades mounted on the HSDs, operating at 500 rpm to 4000 rpm, more typically 2000 rpm to 3500 rpm, provide optimal shear to achieve the desired mixing. Sufficient mixing is usually achieved after 15 to 120 minutes of mixing under the above conditions. The subsequent dispersion step can be accomplished in a two-roll mill, media mill, horizontal mini mill, ball mill, attritor, or by passing the mixture through multiple nozzles in a liquid jet interaction chamber at a liquid pressure of at least 5,000 psi to produce a uniform dispersion of pigment particles in an aqueous carrier medium (microlubricator). Alternatively, the concentrate can be prepared by dry grinding the polymeric dispersant and pigment under pressure. The media for the media mill is selected from commonly available media such as zirconia, YTZ, and nylon. These various dispersion processes are well known in the art in a general sense, as exemplified in U.S. Pat. Nos. 5,022,592, 5,026,427, 5,310,778, 5,891,231, 5,976,232, and U.S. Patent Publication No. 2003 / 0089277. The disclosures of each of these publications are incorporated herein by reference for all purposes as if fully set forth. Preferably, by a two roll mill, a media mill and forcing the mixture through multiple nozzles in a liquid jet interaction chamber at a liquid pressure of at least 5,000 psi.

[0075] After the milling process is complete, the color pigment concentrate can be "let down" into an aqueous system. "Let down" refers to the dilution of the concentrate by mixing or dispersion, the intensity of the mixing / dispersion is usually determined by trial and error using traditional methodologies and often depends on the combination of polymeric dispersant, solvent and pigment.

[0076] The useful particle size range after dispersion is typically about 0.005 micrometers to about 15 micrometers. Typically, the pigment particle size should be in the range of about 0.005 micrometers to about 5 micrometers, especially about 0.005 micrometers to about 1 micrometer. The average particle size as measured by dynamic light scattering is less than about 500 nm, typically less than about 300 nm.

[0077] White pigment dispersion One or more dispersants as described for the color pigments are also used to stabilize the titanium dioxide. It is generally desirable to make the stabilized TiO2 pigment in the form of a concentrated slurry. The TiO2 slurry is generally carried out in a mixing vessel that is stirred, with a high speed disperser (HSD) being particularly suitable for the mixing step. A Cowels type blade mounted on the HSD, operating at 500 rpm to 4000 rpm, more typically 2000 rpm to 3500 rpm, provides optimal shear to achieve the desired mixing. Sufficient mixing is usually achieved after 15 to 600 minutes of mixing under the above conditions. The amount of titanium dioxide present in the slurry composition is preferably about 35% to about 80% by weight based on the total weight of the slurry, more preferably about 50% to about 75% by weight based on the total weight of the slurry. The titanium dioxide preferably has a 50% average particle size (hereinafter referred to as "D50") in the range of 50 to 500 nm, more preferably in the range of 150 to 350 nm. Titanium dioxide having a D50 within these ranges enables the printed film to exhibit sufficient opacity of the image, which allows for the formation of high quality images.

[0078] In the case of colored pigments, the ink may contain up to about 30% by weight of pigment, preferably about 0.1 to about 25% by weight, and more preferably about 0.25 to about 10% by weight, based on the total weight of the ink. When an inorganic pigment such as a TiO2 pigment is selected, the ink will tend to contain a higher weight percentage of pigment than a comparable ink using a colored pigment, possibly as much as about 75%, since inorganic pigments generally have a higher specific gravity than organic pigments.

[0079] Post-modification of polymeric dispersants after formation of pigment dispersion The polymeric dispersant that disperses the pigment may be crosslinked after the pigment dispersion is prepared to form a crosslinked pigment dispersion before it is included in the inkjet ink. The crosslinkable polymeric dispersant is a polymer substituted with a crosslinkable moiety selected from the group consisting of acetoacetoxy, acid, amine, epoxy, hydroxyl, blocked isocyanate, and mixtures thereof. The crosslinker is selected from the group consisting of acetoacetoxy, acid, amine, anhydride, epoxy, hydroxyl, isocyanate, blocked isocyanate, and mixtures thereof. In the crosslinking step, the crosslinking is performed by adding a crosslinker to the pigment dispersion after dispersing the pigment and heating the mixture at an elevated temperature for several hours. After the crosslinking step, excess polymer can be removed by a purification process such as ultrafiltration. Specific examples of crosslinking moiety / crosslinker pairs are hydroxyl / isocyanate and acid / epoxy.

[0080] Ink Polymer Binder Ink binders for CMYKW inks are polymeric compounds or mixtures of polymeric compounds that are added to the ink formulation. Binders can impart properties to the printed material, such as, for example, imparting greater durability to the printed material. Typical polymers used as binders in inkjet inks include polyurethane dispersions and solutions, acrylics, styrene acrylics, styrene butadiene, styrene butadiene acrylonitrile, neoprene, ethylene acrylic acid, ethylene vinyl acetate emulsions, latexes, and the like. The binders can be in solution or stabilized as emulsions by having ionic substituents such as carboxylic acids, sulfur-containing acids, amine groups, and other similar ionic groups. Alternatively, the binders can be stabilized by external surfactants. Binders can be used alone or in combination with other binders. Typically, the binders are polyurethanes and acrylics. Binders are typically present in the ink in an amount of at least 0.2% by weight based on the total weight of the ink. Examples of ink binder polymers include polyurethane polymers such as Takelac® WS5100, Takelac® WS4022, Takelac® W5030, XW-Um601, and XW-Um602A from Mitsui Chemicals, Inc. (Tokyo, Japan); acrylic polymers such as Joncryl® FLX5000-A, Joncryl® FLX5220, and Joncryl® FLX5026A from BASF (Ludwigshafen, Germany).

[0081] Typically, the binder is non-reactive with the colorant, unlike the polymeric dispersants mentioned above. The binder is typically added to the ink during the final formulation stage, not during the preparation of the pigment dispersion. The binder is typically present in the ink in an amount of at least 0.2% by weight, based on the total weight of the ink. This amount can be from 1 to 15% by weight.

[0082] Ink Vehicle The pigment-based inks of the present disclosure include an ink vehicle, also known as an aqueous carrier medium, typically an aqueous ink vehicle, an aqueous dispersion, and optionally other ingredients.

[0083] An ink vehicle is a liquid carrier (or medium) for the aqueous dispersion and optional additives. The term "aqueous ink vehicle" refers to an ink vehicle consisting of water or a mixture of water and one or more organic water-soluble vehicle components, commonly referred to as co-solvents or humectants. Selection of an appropriate mixture depends on the requirements of a particular application, such as the desired surface tension and viscosity, the pigment selected, the drying time of the pigment-based inkjet ink, and the type of medium onto which the ink will be printed.

[0084] Examples of water-soluble organic solvents and humectants include alcohols, ketones, keto-alcohols, ethers and others, such as thiodiglycol, sulfolane, 2-pyrrolidine, 1,3-dimethyl-2-imidazolidinone and caprolactam, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, trimethylene glycol, butylene glycol and hexylene glycol, addition polymers of oxyethylene or oxypropylene such as polyethylene glycol, polypropylene glycol, triols such as glycerol and 1,2,6-hexanetriol, lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl, diethylene glycol monoethyl ether, lower dialkyl ethers of polyhydric alcohols such as diethylene glycol dimethyl or diethyl ether, urea and substituted ureas.

[0085] A mixture of water and a polyhydric alcohol such as diethylene glycol is typical for the aqueous ink vehicle. In the case of a mixture of water and diethylene glycol, the ink vehicle usually contains from 30% water and 70% diethylene glycol to 95% water and 5% diethylene glycol, more typically from 60% water and 40% diethylene glycol to 95% water and 5% diethylene glycol. The percentages are based on the total weight of the ink vehicle. A mixture of water and butyl carbitol is also an effective ink vehicle.

[0086] The amount of ink vehicle in the ink is typically in the range of about 70% to about 99.8% by weight, more typically about 80% to about 99.8% by weight, based on the total weight of the ink.

[0087] The ink vehicle can be made fast drying by including solvents such as glycol ethers and 1,2-alkanediols. Glycol ethers include ethylene glycol monobutyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-n-propyl ether and dipropylene glycol mono-isopropyl ether. Typical 1,2-alkanediols are C4-C6 alkanediols, with 1,2-hexanediol being the most typical. The amount of glycol ether and 1,2-alkanediol added is typically in the range of about 1% to about 15% by weight, more typically about 2% to about 10% by weight, based on the total weight of the ink.

[0088] Surfactants are typically added to the ink to adjust surface tension and wetting properties. Suitable surfactants include ethoxylated acetylenic diols (e.g., the Surfynol series available from Evonik), ethoxylated alkyl primary alcohols (e.g., the Neodol series available from Shell) and secondary alcohols (e.g., the Tergitol series available from Dow Chemical), sulfosuccinates (e.g., the Aerosol series available from Cytec), organosilicones (e.g., the DYNOL series available from Evonik), and fluorosurfactants (e.g., the CAPSTONE series available from Chemours). Typically, surfactants are used in amounts up to about 3% by weight, more typically up to 1% by weight, based on the total weight of the ink.

[0089] Other components, additives, may be incorporated into the ink-jet ink to the extent that such other components do not interfere with the stability and jettability of the ink-jet ink, which can be readily determined by one of ordinary skill in the art through routine experimentation.

[0090] The inclusion of a sealing (or chelating) agent such as ethylenediaminetetraacetic acid, iminodiacetic acid, ethylenediamine-di(o-hydroxyphenylacetic acid), nitrilotriacetic acid, dihydroxyethylglycine, trans-1,2-cyclohexanediaminetetraacetic acid, diethylenetriamine-N,N,N',N'',N''-pentaacetic acid and glycoletherdiamine-N,N,N',N'-tetraacetic acid and salts thereof can be beneficial, for example, to remove the deleterious effects of heavy metal impurities.

[0091] Biocides may be used to inhibit microbial growth.

[0092] Ink characteristics Jet velocity, separation length of droplets, droplet size and stream stability are highly influenced by the surface tension and viscosity of the ink. Typically, pigmented inkjet inks have a surface tension ranging from about 20 dynes / cm to about 45 dynes / cm at 25° C. Viscosity can be as high as 30 cP at 25° C., but is typically much lower, more typically less than 10 cP at 25° C. The ink has physical properties that are compatible with a wide range of ejection conditions, i.e., driving frequencies of piezo elements or ejection conditions of thermal heads in drop-on-demand or continuous devices, as well as nozzle shapes and sizes. The ink must have excellent storage stability over long periods of time so as not to clog to any significant extent in the inkjet device. Additionally, the ink must not corrode parts of the inkjet printing device with which it comes into contact, and must be essentially odorless and non-toxic. The preferred pH of the ink ranges from about 6.5 to about 8.5.

[0093] printing The method of the present invention relates to digitally printing a non-porous plastic film substrate. Typically, this involves the following steps: (a) providing an inkjet printer responsive to digital data signals; (b) providing a non-porous plastic substrate; (c) mixing an aqueous primer composition comprising Part A and Part B; (d) applying the aqueous primer composition onto a non-porous plastic substrate followed by drying to form a coating having a dry thickness of 0.4 to 5.0 microns; (e) loading an aqueous white inkjet ink and one or more aqueous non-white color inkjet inks into a printer, wherein the white inkjet ink comprises a titanium dioxide pigment dispersion and a polyurethane binder or an acrylic binder, the titanium dioxide pigment dispersion having a D50 particle size in the range of 200-350 nm, and at least one of the aqueous non-white color inkjet inks comprises a pigment dispersion and a second polyurethane binder or a second acrylic binder; and (f) printing onto the primer coated substrate of step (d) using the white inkjet ink and the non-white color inkjet inks in response to a digital signal. Includes.

[0094] The time interval between steps (d) and (f) is not particularly limited. It can range from a few seconds to several days. In step (f), the white ink can be printed first as a background image, and then the color inks can be printed. Alternatively, the non-white color inks can be printed first and then covered by the white ink in a reverse print setting. Drying between the non-white color inks or between the white and non-white color inks is optional.

[0095] Printing can be performed with any inkjet printer equipped to handle and print film substrates. Films printed with pigmented inks are dried at elevated temperatures after printing. Drying temperatures range depending on printer and dryer design and line speed, but should not be too high so as to damage the integrity of the printed film. Typically, drying temperatures are below 120°C, preferably below 100°C, and more preferably below 95°C.

[0096] Lamination Lamination is used throughout the flexible packaging industry to create packages with desired properties not available with one material alone. Typically, a film printed with ink is laminated to another film with the printed ink sandwiched between the two films. If a primer is utilized, a primer is also placed between the films. Multi-layer structures can be represented as film / adhesive / ink / primer / film, with each line representing a layer.

[0097] The most common lamination process involves bonding two or more films together with a packaging adhesive with the aid of heat energy and pressure. The adhesive can be solventless, water-based or solvent-based, depending on its chemistry. The energy required to laminate the two substrates is usually supplied as heat energy both in the laminating nip and in a hot chamber for curing at elevated temperatures. For room temperature curing, heat is supplied only to the laminating nip rolls. The adhesive can be applied to the ink-printed or unprinted film side. For solvent- and water-based adhesives, the water and solvent are allowed to dry before being laminated to the second web. Almost all types of adhesives are separated into two parts, one labeled as the adhesive and the other as the curing agent. When mixed, they react to form an intertwined cross-linked structure that provides bond strength, water resistance and heat resistance. The adhesive curing reaction typically takes 3-10 days at room temperature to reach the final cured bond. Bond strength is one of the important properties of a laminate structure. After the adhesive has fully cured, the bond strength can be measured on an Instron using an appropriate load cell. EXAMPLES

[0098] The invention is further illustrated, but not limited, by the following examples in which parts and percentages are by weight unless otherwise noted.

[0099] Ingredients and Abbreviations DBTL = dibutyltin dilaurate DMPA = Dimethylolpropionic acid EDA = ethylenediamine IPDI = Isophorone diisocyanate TEA = triethylamine MDEA = methyldiethanolamine DETA = diethylenetriamine MEK = methyl ethyl ketone TMP = Trimethylolpropane CHDM = 1,4-cyclohexanedimethanol

[0100] Unless otherwise stated, the above mentioned chemicals were obtained from Aldrich (Milwaukee, WI) or other similar research chemical suppliers. Terathane® T650 - a polyether polyol from Invista, Wilmington, Del. Tegomer® D3403 - Polyether polyol from Evonik, Essen, Germany Eternacoll® UC-200 and UH-50 - polycarbonate polyols from UBE Corporation (Tokyo, Japan) Vestamin® A95 - a 50% solids solution of sodium 2-[(2-aminoethyl)amino]ethanesulfonate in water from Evonik, Essen, Germany Surfynol® 440, 420 and 465 - non-ionic surfactants from Evonik, Essen, Germany TegoWet™ 280 - a silicone surfactant from Evonik, Essen, Germany SNOWTEX® ST-AK-ML - Nanosilica dispersion at 28% solids from Nissan Chemical America (Houston TX) Levasil CC151 - Aqueous dispersion of colloidal silica at 28% solids from Nouryon (Amsterdam, Netherlands) Levasil CC301 - Aqueous dispersion of colloidal silica at 15% solids from Nouryon (Amsterdam, Netherlands) Bayhydur® 3100 - a 100% solids water-dispersible polyisocyanate hardener from Covestro (Leverkusen, Germany) Carbodilite V-02-L2 - A VOC-free polycarbodiimide-based crosslinking aqueous solution with 40% solids from Nisshinbo Chemical Co., Ltd. (Tokyo, Japan) ROBOND™ CR 9-101 - 100% solids water-dispersible isocyanate coreactant from Dow Chemical Co. (Midland, MI) ROBOND™ L-2150 - Water-based polyurethane dispersion laminating adhesive from Dow Chemical Co. (Midland, MI) ADCOTE™ 555 - the isocyanate-terminated polyester urethane component of a two-part laminating adhesive system in ethyl acetate and ADCOTE™ 536B - the other part of a two-part laminating adhesive system in ethyl acetate, available from Dow Chemical Co., Midland, MI

[0101] Pigment Dispersion Cyan pigment dispersion-1 Cyan Dispersion-1 was prepared according to the procedures disclosed in U.S. Patent Application Publication No. 2012 / 0214939, the disclosure of which is incorporated by reference for all purposes as if fully set forth herein, using Cyan TRB2 pigment and crosslinking the dispersant after dispersing the pigment.

[0102] Cyan pigment dispersion-2 Cyan Pigment Dispersion-2 was prepared according to the procedure disclosed in US Patent Application Publication No. 2012 / 0214939, the disclosure of which is incorporated by reference for all purposes as if fully set forth herein, using cyan TRB2 pigment, the dispersant was neutralized with triethylamine, and no crosslinking was performed after dispersing the pigment.

[0103] Ink Polymer Binder Ink binder-1 To a dry, alkali- and acid-free flask equipped with an addition funnel, condenser, stirrer, and nitrogen gas line was added 15.8 g CHDM, 104.7 g Terathane T650, 4.0 g TMP, and 118 g acetone. The contents were heated to 40° C. and mixed thoroughly. 120 g IPDI was then added to the flask via the addition funnel over a period of 5 minutes at 40° C., and the remaining IPDI was rinsed into the flask from the addition funnel with 2 g acetone.

[0104] The temperature of the flask was increased to 50° C. After holding at 50° C. for 240 minutes, an additional 15.8 g of DMPA was added to the flask via the addition funnel, followed by 11 g of TEA, then rinsed with 2 g of acetone. The temperature of the flask was then increased again to 50° C. and held at 50° C. until the NCO% reached 2.0% or less.

[0105] At a temperature of 50° C., 570 g of deionized (DI) water was added over 10 minutes, followed by 38 g of EDA (as a 10% solution in water) added via addition funnel over 5 minutes. The mixture was held at 50° C. for 1 hour and then cooled to room temperature.

[0106] Acetone (about 122.0 g) was removed under vacuum leaving a final dispersion of polyurethane at about 30.0% solids by weight.

[0107] Ink Binder-2 To a dry, alkali- and acid-free flask equipped with an addition funnel, condenser, stirrer, and nitrogen gas line was added 21 g MDEA, 180 g Terathane T650, 7.0 g TMP, and 192 g acetone. The contents were heated to 40° C. and mixed thoroughly. 202 g IPDI was then added to the flask via the addition funnel over a period of 5 minutes at 40° C., and the remaining IPDI was rinsed from the addition funnel into the flask with 10 g acetone.

[0108] The temperature of the flask was increased to 50° C. After holding at 50° C. for 240 minutes, an additional 27 g of DMPA was added to the flask via the addition funnel, followed by 9 g of TEA, then rinsed with 10 g of acetone. The temperature of the flask was then increased again to 50° C. and held at 50° C. until the NCO% reached 2.2% or less.

[0109] At a temperature of 50° C., 890 g of deionized (DI) water was added over 10 minutes, followed by 128 g of EDA (as a 5% solution in water) added via addition funnel over 5 minutes. The mixture was held at 50° C. for 1 hour and then cooled to room temperature.

[0110] Acetone (about 212.0 g) was removed under vacuum leaving a final dispersion of polyurethane at about 30.0 wt. % solids.

[0111] Ink Binder-3 Ink Binder-3 is polyurethane PUD EX2, as described in US Pat. No. 9,255,207, which is incorporated by reference for all purposes as if fully set forth.

[0112] Ink preparation The inks used in the examples were made according to standard procedures in the inkjet art. Component amounts are weight % of the final ink. Polymer binders and colorants are listed on a solids basis. As an example of ink preparation, an ink vehicle was prepared and added to the aqueous ink binder with stirring. After stirring until a uniform mixture was obtained, the solution was added to the pigment dispersion and again mixed until uniform. The inks were prepared using the components listed in Table 1 below.

[0113] [Table 1]

[0114] Primer Binder P-1 A dry, alkali- and acid-free flask equipped with an addition funnel, condenser, stirrer, and nitrogen gas line was charged with 40 g CHDM, 160 g Eternacoll UT-200, 57 g Tegomer D3403, 8.3 g DMPA, 6.2 g TEA, and 200 g MEK. The contents were heated to 50°C and mixed thoroughly. 127 g IPDI was then added to the flask via the addition funnel over a period of 5 minutes at 40°C, and the remaining IPDI was rinsed from the addition funnel into the flask with 10 g MEK.

[0115] The temperature of the flask was increased to 65°C and held until the NCO% was 1.45% or less. The flask was then cooled to 55°C and 877g of deionized (DI) water was added over 10 minutes, followed by 93g of DETA (as a 5% aqueous solution) via addition funnel over 5 minutes. The mixture was held at 50°C for 1 hour and then cooled to room temperature.

[0116] The MEK (about 210 g) was removed under vacuum leaving a final dispersion of polyurethane having a solids content of about 30.0 wt %.

[0117] Following a procedure similar to that for preparing primer binder P-1, primer binders P2-P5 were prepared using the components listed in Table 2 below.

[0118] [Table 2]

[0119] Preparation of primers Primer Part A was prepared using the ingredients listed in Tables 3, 4 and 5 below by combining the listed ingredients with stirring until a uniform mixture was obtained. Primer Part B was used as listed in Table 6.

[0120] [Table 3]

[0121] [Table 4]

[0122] [Table 5]

[0123] [Table 6]

[0124] Preparation of primer coating The primer fluids were applied to Mylar MLBT, a transparent PET film from DuPont Teijing Film, using a Gardco film applicator rod with wire size 2.5 (Paul N. Gardner Inc., Florida, USA) to form coatings with dry thicknesses that varied from 0.5 to 2.0 μm depending on solids content and viscosity. For the comparative primer coatings, Part A was applied alone to the film. For the primer fluids of the invention, Parts A and B were mixed for 5 to 10 minutes to ensure uniform mixing before application to the film. In both cases, the coatings were dried in a convection oven at 65° C. for 3 minutes.

[0125] Printing with Ipsio Printer Ink-2 from Table 1 was printed onto primer-coated Mylar MLBT film using a Ricoh IPSiO GX e5500 printer. Approximately 7-10 g / m 2 A 3×9 inch solid block with an ink coverage of 1000 μm was printed with the printer set to 8 pass color mode. The printed film was then dried at 65° C. for 3 minutes.

[0126] Printing with Samba Printhead Rig Primer-coated Mylar MLBT from DuPont Teijin Film was printed with inks 1 and 3 from Table 1 using a lab printing system in which inks were jetted from a fixed-mount Fujifilm Corporation (Tokyo, Japan) Samba G3L printhead onto the film held on a rotating cylinder below. Approximately 10 g / m 2 A 1" x 4" solid block was printed having an ink coverage of 1000 x 1000 mm. The printed film was then dried at 65°C for 3 minutes.

[0127] Laminate preparation and laminate strength testing The ink-printed Mylar film was laminated to 30 μm thick medium density polyethylene film (MDPE) supplied by Bemis (Sheboygan Falls, WI) using a dry bonding process using a flexible laminating adhesive from Dow Chemical (Midland, MI) listed in Table 7.

[0128] [Table 7]

[0129] For the lamination process, the adhesive was applied onto the ink using a wire size 5 Gardco film applicator rod (Paul N. Gardner Inc., Florida, USA) and dried at 65 °C for 3 min to form a dried adhesive layer with a thickness that varied from 2.0 to 3.5 μm. Within 5 min after drying, an MDPE film was placed on top of the adhesive and pressed down while rolling back and forth 20 times with a hand roller to form a Mylar / primer / ink / adhesive / MDPE laminate structure. The formed laminate was stored at 21-23 °C and atmospheric humidity for 6 days to complete the curing process. The T-peel strength of the laminate was then measured using ASTM 1876 with an Instron at a T-peel speed of 10 inches / minute and a power value of Newtons / inch (N / inch). The laminate strength was reported according to the following evaluation scale: Rating 1, less than 1 N / inch Rating 2, 1N / inch to 2.5N / inch Rating 3, 2.5N / inch to 3.5N / inch Rating 4, over 3.5N / inch

[0130] [Table 8]

[0131] [Table 9]

[0132] [Table 10]

[0133] [Table 11]

[0134] [Table 12]

[0135] As shown in Tables 8 to 12, the two-component primer of the present invention having components A and B exhibited excellent laminate strength.

Claims

1. 1. An ink fluid set comprising: a) a two-component water-based primer coating fluid comprising Part A and Part B, wherein Part A comprises an ink coagulant, a water-insoluble polymeric binder selected from polyurethane polymers, acrylic polymers, polyvinyl acetate copolymers, and mixtures thereof, and Part B comprises a water-dispersible co-reactant selected from polyisocyanates, epoxies, epoxy silanes, carbodiimides, and mixtures thereof, Parts A and B being mixed before the primer coating fluid is applied to a recording medium, and Parts A and B being mixed in a ratio ranging from 100:1 to 100:20 based on the total weight of Parts A and B; and b) an aqueous inkjet ink comprising an aqueous vehicle and a pigment, wherein the pigment is stabilized by a polymeric dispersant selected from the group consisting of polyurethane polymers, acrylic polymers, hydrolyzed styrene maleic anhydride copolymers, and mixtures thereof. an ink fluid set comprising:

2. 10. The ink fluid set of claim 1, wherein the water-insoluble polymeric binder of Part A is a polyurethane polymer.

3. 3. The ink fluid set of claim 2, wherein the water-dispersible co-reactant of Part B is a polyisocyanate.

4. The ink fluid set of claim 3 , wherein the polymeric dispersant is a polyurethane polymer.

5. The ink fluid set of claim 3 , wherein the polymeric dispersant is an acrylic polymer.

6. The ink fluid set of claim 1 , wherein the water-insoluble polymeric binder of Part A is an acrylic polymer.

7. 7. The ink fluid set of claim 6, wherein the water-dispersible co-reactant of Part B is a polyisocyanate.

8. The ink fluid set of claim 7 , wherein the polymeric dispersant is a polyurethane polymer.

9. The ink fluid set of claim 7 , wherein the polymeric dispersant is an acrylic polymer.

10. 10. The ink fluid set of claim 1, wherein the water-dispersible co-reactant of Part B is a polyisocyanate.

11. The ink fluid set of claim 10, wherein the polymeric dispersant is a polyurethane polymer.