Primer for digital printing

Abstract

An aqueous primer composition comprising: (i) a polymeric dispersion selected from an acrylic dispersion, a polyester urethane dispersion, or a blend thereof; and (ii) an aminated polymer, wherein the aminated polymer is a poly(ethylene imine), and wherein the poly(ethylene imine) is present in an amount of 0.5-25% (w / w).

Description

Technical Field

[0001] This invention provides an aqueous primer composition suitable for digital printing on plastic substrates. The aqueous primer composition of this invention is particularly suitable for printing on the plastic cores of payment cards and debit cards, followed by heat lamination of the printed surface with an additional plastic layer. Advantageously, the resulting plastic laminated articles have reduced dye leaching.

[0002] The present invention also provides a process for preparing digitally printed laminated articles and a laminated article prepared by said process. Background Technology

[0003] US 11,066,781 (Eastern Tech) relates to a fabric pretreatment solution for inkjet printing comprising greater than 40% (w / w) of a polyvalent salt, up to 5% (w / w) of a capped isocyanate, and up to 40% (%w / w) of an aqueous binder, said aqueous binder being a polyurethane dispersion (“PUD”). Such a high concentration of metal salts makes these primers unsuitable for the lamination process of this invention; furthermore, printing via digital electrophotographic printing (such as HP Indigo) is not disclosed.

[0004] US 6,761,940 (Hueck Folien) relates, without providing any illustrative examples, to a primer comprising a thermoplastic polymer, which may also contain a crosslinking agent. The thermoplastic polymer of the primer is preferably a copolymer of ethylene and acrylate monomers. It relates to printing via the HP Indigo electrophotographic digital process. US 6,761,940 does not relate to the use of the polymer dispersion according to the invention together with an amination polymer crosslinking agent.

[0005] The HP Indigo process uses so-called "electronic inks," which are essentially pigment dispersions in a carrier comprising a paraffin solvent and an ethylene copolymer (wherein the comonomers are selected from methacrylic acid and acrylic acid). These tend to have poor adhesion to plastic substrates and poor heat resistance. The thermoplasticity of the ethylene copolymer adhesive can cause deformation of the printed matter, thereby reducing print quality. This invention helps overcome these problems—namely, poor adhesion and poor lamination bond strength—while maintaining print quality during the high-temperature processing of such printed matter, including the hot lamination process covered by this invention. This invention also overcomes the problem of dye leaching.

[0006] The inks used in the HP Indigo process (commonly referred to in the art as liquid toner inks) contain thermoplastic polymers, such as copolymers of ethylene with methacrylic acid or acrylic acid. Numerous primers containing such copolymers have been addressed in the prior art for subsequent printing via liquid toners for electrophotographic printing. US 7,470,736 (Michelman) and WO 2020 / 190723 (Sun Chemical) relate to aqueous primer compositions containing copolymers of ethylene and acrylic acid (or methacrylic acid) and a polyurethane dispersion. While suitable as print-acceptable primers for digital printing, they would not be able to maintain print quality and achieve good lamination bond strength during hot lamination without the additional crosslinking agent present in the primers of this invention.

[0007] US 9,639,011 (HP) relates to a solvent-based base coat for electrophotographic digital printing, comprising a copolymer of ethylene and methacrylic acid or acrylic acid. This base coat is applied via electrophotographic printing prior to printing with a colored liquid toner (“HP Electrink”). Issues regarding adhesion, retention of print quality during heat lamination, and provision of good thermal bond strength are not discussed.

[0008] US10,564,562(HP) further considered this concept by applying a similar first-down water-based primer, “Digiprime 050” (e.g., Michael Menthol), prior to the application of the primer as disclosed in the route figures disclosed in US 9,639,011.

[0009] US10,851,262 (Sun Chemical Company) relates to a similar application primer for digital printing, particularly liquid electrophotographic digital printing ('LEP'). This primer comprises a mixture of a polyurethane dispersion and a self-crosslinking acrylic dispersion, which improves the adhesion and anti-blocking properties of the printed parts to a range of substrates.

[0010] US10,301,478 (Ashland Corporation) relates to a primer coating, specifically for LEP printing, comprising a cationic polyurethane dispersion and a poly(k-azoline) or N-vinylpyrrolidone copolymer. The use of any crosslinking agent is not disclosed.

[0011] WO 2021 / 011606 (Michael Men, Inc.) relates to a water-based primer coating comprising a polyvalent metal salt and an amine-containing polymer, suitable for digital printing via electrophotographic and inkjet processes. No thermal lamination process according to the invention is disclosed.

[0012] In recent years, the use of digital printing technologies such as powder and liquid electrophotographic printing and inkjet printing has grown significantly. Digital printing is now penetrating many markets traditionally served by analog printing processes (flexographic printing, gravure printing, offset printing, screen printing, etc.). These markets include, for example, graphics, packaging, corrugated paper, textiles, ceramics, and commercial printing. Some of the benefits associated with digital printing include on-demand printing, personalization, variable data printing, and reduced print inventory.

[0013] HP's "HP Indigo" liquid electrophotographic printing process has been successfully commercially implemented in a wide range of printing applications, including label and narrow-web packaging printing. In this process, a liquid toner image is formed on a photosensitive drum and electrostatically transferred to a heated intermediate blanket before being printed onto a web or sheet substrate. This technology is described in US 4,794,651 and US 5,407,771. Prints produced by such liquid toners often exhibit particularly poor adhesion to plastic substrates and may lack physical strength, thus requiring the use of protective overprinting varnishes in some applications. Furthermore, the problem addressed by this invention is that prints produced by such liquid electrophotographic printing may not produce laminates with sufficient bonding strength to meet technical requirements. Laminated prints produced by liquid electrophotographic printing (such as the "HP Indigo" printing process) are also prone to dye leaching. The primer according to the invention solves the problem of dye leaching by fixing the dye to the substrate. The problem of dye leaching has not been addressed in the prior art.

[0014] References to or identification of any documents in this application are not intended to acknowledge that such documents represent prior art of the present invention. Summary of the Invention

[0015] This invention enables the production of plastic laminates that have been printed using a liquid electrophotographic toner and subsequently heat-laminated onto a second or additional plastic layer, without dye leaching. Preferably, this invention relates to printing on the plastic core of payment cards and debit cards, followed by heat lamination of the printed surface to another plastic layer. Most specifically, this invention relates to printing on homopolymers and copolymers of vinyl chloride or vinylidene chloride containing a bank card core, followed by heat lamination of another plastic layer, which may also contain homopolymers and copolymers of vinyl chloride or vinylidene chloride.

[0016] Thermal lamination is a process in which a second plastic film is brought into contact with the printed surface of a card core, and then subjected to high temperatures (typically exceeding 100°C, more commonly exceeding 120°C) and high pressures (typically exceeding 50 bar, and up to 200 bar) to form a bonded laminate. Without the primer of this invention, not only do card cores printed with liquid electrophotographic fluid lack the necessary lamination bond strength, but print quality is also reduced during thermal lamination and dye leaching. This reduction in print quality is due to ink “movement” during thermal lamination. Similarly, dye leaching is caused by internal dye movement during thermal lamination. The inventors do not wish to be bound by any theory behind this reduction in print quality or dye leaching, but rather hypothesize that it is partly due to the thermoplasticity of the polymer binder of the toner, which softens and deforms during lamination.

[0017] The primer according to the invention helps overcome defects related to adhesion and lamination bond strength while maintaining print quality. The primer according to the invention also prevents dye leaching. This is achieved by using a suitable polymer dispersion and an amination polymer crosslinking agent. Similarly, the inventors do not wish to be bound by any theory, but rather assume that after printing, a portion of the crosslinking agent migrates from the primer to the ink, such that when the print is laminated, both the primer and the ink crosslink to maintain print quality. Furthermore, the inventors assume that after printing, a portion of the crosslinking agent migrates from the primer to the ink and fixes the dye to the substrate, thereby preventing leaching.

[0018] The prior art does not disclose the use of the printable primer according to the present invention in the manufacture of payment cards and financial cards, particularly for electrophotographic (toner) printing. Many examples in the background art references describe primers for electrophotographic printing that contain polymer dispersions but do not contain the necessary crosslinking agent (poly(ethyleneimine)) that is critical to the process of the present invention.

[0019] An acceptable primer for printing, particularly for electrophotographic printing, containing a crosslinking agent activated during thermal lamination, has not yet been disclosed. Without the crosslinking agent, print quality deteriorates during thermal lamination used to form finished payment and debit cards, and the inclusion of a crosslinking agent results in significantly stronger lamination bond strength compared to the absence of a crosslinking agent.

[0020] The benefits of printing onto a thermoplastic primer to ensure good printability, followed by high-temperature activation of the curing reaction during hot lamination to ensure print quality and good lamination bond strength, have not been anticipated in the prior art. Furthermore, the use of the primer composition according to the invention to prevent dye leaching after hot lamination is not disclosed in the prior art.

[0021] This invention relates to a water-based primer composition comprising: (i) a polymer dispersion selected from acrylic dispersions, polyester urethane dispersions, or blends thereof; and (ii) an amination polymer, wherein the amination polymer is poly(ethyleneimine), and wherein the poly(ethyleneimine) is present in an amount of 0.5-25% (w / w). Preferably, the water-based primer composition (also referred to as a printable primer) is applied to a substrate via flexographic printing, gravure printing, or screen printing. The primer can then be overprinted with one or more digital inks. Preferably, overprinting is performed via digital electrophotographic (toner) printing.

[0022] Although primarily intended for water-based printing acceptable for overprinting via digital electrophotographic (toner) printing, the primer of the present invention is also applicable to overprinting via inkjet printing, and particularly applicable to water-based inkjet printing inks (i.e., overprinting via inkjet printing using water-based inkjet printing inks).

[0023] The invention describes an aqueous, printable primer containing poly(ethyleneimine) as a crosslinking agent, suitable for curing at temperatures above 80°C after overprinting via electrophotographic (toner) or inkjet digital printing processes. Preferably, the primer is applied by flexographic printing, gravure printing, or screen printing.

[0024] In a preferred application, the primer of the present invention is used in the manufacture of payment cards and debit cards (such as credit cards, bank cards, etc.), wherein the primer is applied to the card core, digital printing is performed on it, and then it is thermally laminated onto a second layer and possibly additional plastic layers. For the manufacture of payment cards and debit cards, the primer of the present invention ensures that print quality is maintained during the thermal lamination process and also ensures that, after aging for 2 weeks at 55°C and 93% relative humidity, the bond strength between the primer-coated and digitally printed core and the subsequent plastic layers of the final card preferably exceeds 7 N. The bond strength can be measured using a JJ Lloyd bond strength tester, and preferably, the minimum bond strength is ≥7 N / cm, more preferably ≥10 N / cm, even more preferably ≥15 N / cm, even more preferably ≥17 N / cm, or most preferably ≥20 N / cm. The primer of the present invention also prevents dye leaching.

[0025] The problem of dye leaching is solved by using an aqueous primer coating composition comprising a polymer dispersion and poly(ethyleneimine) as a crosslinking agent for the amination polymer. Specifically, the problem of dye leaching is solved by using an aqueous primer coating composition comprising a polymer dispersion selected from acrylic dispersions, polyester urethane dispersions, and blends thereof, and 0.5-25% (w / w) of poly(ethyleneimine). After printing, the primer crosslinks during hot lamination to form the finished card. It is conceivable that some of the crosslinking agent in the primer will migrate into the ink, thus both will crosslink during lamination. Without the crosslinking agent, print quality may decrease, and the lamination bond strength may be weaker than when the crosslinking agent is included. Furthermore, without the crosslinking agent, dye will leach from the ink.

[0026] The primer of this invention allows for the manufacture of digitally printed payment cards and debit cards (as well as ID cards). This is highly advantageous, enabling the realization of advantages associated with digital printing, such as variable data, personalization, on-demand printing, and even printing personal security features. The inventors have demonstrated that using the primer according to the invention is crucial for ensuring consistent print quality and achieving excellent lamination bond strength when the primer-coated and printed core of the card is heat-laminated to another plastic layer at temperatures exceeding 100°C. Using the primer of this invention is also key to preventing dye leaching.

[0027] These significant advantages provided by the present invention enable the digital printing production of payment cards and financial cards, which is currently impossible.

[0028] Furthermore, this invention realizes the market's expectation of a shift from analog printing to digital printing for this type of card.

[0029] First, the primer according to the invention is applied to the plastic card core, dried, and then digitally printed to produce the desired image and information. The printed core is then thermally laminated onto another plastic layer and any other production processes are performed, such as including holograms.

[0030] After the substrate (e.g., a card core) is coated with the primer of this invention, it can then be overprinted using any digital process, including liquid electrophotographic (toner) printing, dry electrophotographic (toner) printing, and inkjet printing. For inkjet printing, this invention is particularly suitable for printing with water-based inkjet inks, but also allows printing with UV-curable, energy-curable, and solvent-based inkjet inks. However, this invention is particularly suitable for liquid electrophotographic (toner) printing, such as HP's "HP Indigo" process.

[0031] The waterborne primer according to the present invention comprises a polymer dispersion selected from acrylic dispersions, polyester urethane dispersions (e.g., nonionic polyester urethane dispersions) and blends thereof.

[0032] The primer according to the invention further comprises an amination polymer crosslinking agent, which is poly(ethyleneimine). Poly(ethyleneimine) may have a linear or branched structure, but a branched structure is preferred. It should be understood that poly(ethyleneimine) has amine functional groups on the polymer backbone. In the case where the poly(ethyleneimine) is branched, in addition to having amine functional groups on the polymer backbone, it may also have amine functional groups on its side chains. Preferably, the poly(ethyleneimine) is branched and has amine functional groups on both the polymer backbone and its side chains.

[0033] The primer of the present invention may optionally contain additional amination polymers, such as poly(ethyleneamine), copolymers of ethyleneamine, amination starch, amine-functionalized poly(ethylene glycol), amine-functionalized poly(propylene glycol), and blends thereof.

[0034] A suitable commercially available poly(ethyleneimine) that can be used in this invention is Loxanol MI 6735 (BASF).

[0035] The average molecular weight of the poly(ethyleneimine) can be ≥10,000 g / mol, for example, from about 10,000 g / mol to about 50,000 g / mol. Preferably, the average molecular weight of the poly(ethyleneimine) can be from about 20,000 g / mol to about 40,000 g / mol, more preferably from about 20,000 g / mol to about 30,000 g / mol.

[0036] The primer of the present invention may optionally contain additional crosslinking agents, such as thermally activated end-capped isocyanates, polycarbodiimides (e.g., Carbodilite, e.g., Nisshinbo); □-azoline functional polymer crosslinking agents (e.g., Epocros, e.g., Nippon Shokubai); melamine-formaldehyde (e.g., Maprenal, e.g., Ineos Melamines); zinc carbonate ammonium solution; zinc oxide nanoparticles (e.g., Oxylink, e.g., Buhler).

[0037] The primer of the present invention may optionally contain a heat-sealed isocyanate. When used, the heat-sealed isocyanate is preferably present in an amount of 0.5-5% by weight of the primer composition.

[0038] As understood in the art, capped isocyanates are a class of crosslinking agents in which the reactive isocyanate groups of the crosslinking agent have reacted with a suitable capping agent. Therefore, a thermally activated capped isocyanate crosslinking agent is a capped isocyanate that can be decapped (i.e., activated) upon heating (e.g., at temperatures above 80°C). Typically, thermally activated capped isocyanate crosslinking agents are decapped (i.e. activated) at 90-200°C, preferably 100-180°C. Examples of capping agents and their typical decapping temperatures are as follows: diethyl malonate (“DEM”; 100-120°C), 3,5-dimethylpyrazole (“DMP”; 110-120°C), methyl ethyl ketone oxime (“MEKO”; 140-160°C), and caprolactam (160-180°C). Such end-capped isocyanates, which can be bifunctional, trifunctional, tetrafunctional, or more functional relative to the number of isocyanate groups per molecule, allow for the preparation of stable, one-component, crosslinkable compositions and are used in many applications, including automotive coatings and textile inks. The end-capped isocyanate crosslinking agent used to prepare the primer of the present invention is advantageously water-based. Trixene BI220 (e.g., Lanxess) was used in the preparation of the examples. The end-capping group used in the preparation of Trixene BI220 is DMP, thus allowing the end-capping to be decapsulated at typical temperatures (such as 120-160°C) used in the production of payment cards and debit cards thermal lamination. End-capped isocyanates are available from several suppliers, including Lanxess (“Trixene”), Covestro (“Imprafix”), Aquaspersions (“Aqualink”), Rudolf GmbH (“Rucopud”), and Evonik (“Vestanat”).

[0039] In an alternative embodiment of the invention, the primer composition preferably does not contain additional crosslinking agents, such as thermally activated end-capped isocyanates, polycarbodiimides, □-azoline functional polymer crosslinking agents, melamine-formaldehyde, zinc ammonium carbonate solution, or zinc oxide nanoparticles. For example, in an alternative embodiment, the primer does not contain thermally activated end-capped isocyanates.

[0040] The primer composition contains 0.5-25% (w / w), preferably 0.5-20% (w / w), more preferably 0.5-15% (w / w) of poly(ethyleneimine).

[0041] On a dry weight basis, the crosslinking agent may account for 0.5-25% of the primer composition, preferably 0.5-20%, more preferably 0.5-15%.

[0042] Preferably, the polymer dispersion comprises 2.5-99.5% (w / w) of the primer composition on a dry weight basis; more preferably 10.0-98%; more preferably 20.0-95%.

[0043] Preferably, the primer according to the invention comprises a polyester urethane dispersion. Anionic, cationic, and nonionic polyester urethane dispersions can be used, but nonionic polyester urethanes are preferred. A suitable commercially available polyester urethane dispersion for use in this invention is NeoRez R-9340 from Cavestro. The polyester urethane can be aromatic or aliphatic.

[0044] Preferably, the primer composition according to the invention comprises a polyester urethane dispersion and 0.5% to 25% (w / w) of poly(ethyleneimine), preferably 0.5% to 15% (w / w) of poly(ethyleneimine), more preferably 0.5% to 8% (w / w) of poly(ethyleneimine).

[0045] Alternatively, the primer according to the invention preferably comprises an acrylic dispersion. Anionic, cationic, and nonionic acrylic dispersions can be used, but nonionic acrylic dispersions are preferred. A suitable commercially available acrylic dispersion for use in this invention is Albertdingk EP 124181 from Albertdingk-Boley.

[0046] Preferably, the acrylic dispersion is an acrylic homopolymer dispersion. As will be understood in the art, the homopolymer comprises at least 95 mol% of a single monomer unit, preferably at least 98 mol% of a single monomer unit, more preferably at least 99.5 mol% of a single monomer unit. For example, acrylic homopolymers typically comprise at least 95 mol% of acrylic monomer, preferably at least 98 mol% of acrylic monomer, more preferably at least 99.5 mol% of acrylic monomer. As used herein, unless otherwise stated, the acrylic monomer constituting the acrylic homopolymer may be acrylic acid or methacrylic acid. For example, acrylic homopolymers may comprise polymers comprising at least 95 mol% of monomer units derived from acrylic acid and / or methacrylic acid, but homopolymers comprising 95 mol% of monomer units derived from acrylic acid are preferred. As will be understood in the art, ethylene-acrylic acid copolymers comprising less than 95 mol% of acrylic monomer are not acrylic homopolymers. Preferably, the primer composition according to the invention does not contain any ethylene-acrylic acid copolymer (i.e., ethylene-acrylic acid copolymers comprising less than 95 mol% of acrylic monomer).

[0047] Preferably, the primer composition according to the invention comprises an acrylic dispersion and 0.5% to 25% (w / w) of poly(ethyleneimine), preferably 1% to 20% (w / w) of poly(ethyleneimine), more preferably 3% to 15% (w / w) of poly(ethyleneimine).

[0048] Alternatively, the primer composition according to the invention preferably comprises an acrylic dispersion and a polyester urethane dispersion.

[0049] The primer according to the invention may optionally further comprise a polyurethane dispersion (“PUD”), wherein the polyurethane is prepared from polyether glycol, polyacrylate glycol, or polycarbonate. For example, the primer composition may comprise a polyurethane prepared from polyether glycol (i.e., a polyether urethane). A suitable polyether urethane is Rheolate 278, available from Elementis. In use, additional polyether urethane is present at 0.01-5% by weight of the primer composition. Typically, the additional polyether urethane acts as a thickener to achieve the desired viscosity.

[0050] Anionic, cationic, and nonionic stable PUDs, as well as aromatic and aliphatic PUDs, are all covered by this invention.

[0051] In cases where the primer composition of the present invention further comprises a PUD prepared from polyether glycol, polyacrylate glycol, or polycarbonate, anionic PUDs can be used, particularly those typically produced by incorporating a carboxylic acid into the polymeric structure of the PUD (e.g., via a urethane reaction of dimethylolpropionic acid (“DVA”). When DMPA or other acidic substances are incorporated into the PUD backbone, neutralization can be performed with any organic or inorganic base to provide an anionic stabilization mechanism. Where applicable, these various resin types can be neutralized with organic bases, including (but not limited to) ammonia, triethanolamine, triisopropanolamine, dimethylaminoethanol, N-methyldiethanolamine, or arginine. Alternatively, they can be neutralized with inorganic bases, including (but not limited to) alkali metal oxides, alkali metal hydroxides or alkali metal carbonates, sodium hydroxide, and potassium hydroxide.

[0052] A variety of commercially available PUDs are available for use in this invention, including those sold under the trademarks Neorez (DSM), Bayhydrol (Covestro), Sancure (Lubrizol), Syntegra (Dow), Luplen (BASF), Beetafin (BIP), and Daotan (Allnex), as well as those supplied under the "U" naming convention of Opaldi.

[0053] Typically, the solids content of the polymer dispersion used in this invention is 20-50%, preferably 25-45%.

[0054] The waterborne primer of the present invention may optionally further comprise any ionic or nonionic styrene-acrylic dispersion. Suitable styrene-(meth)acrylic resin dispersions are widely available commercially and include those marketed under trade names such as Joncryl (BASF), Revacryl (Synthomer), Hycar (Lubrizol), Neocrryl (DSM), Neboplast (Necarbo), and the Picassian AC series (Picassian Polymers). It should be understood that this is not a limiting enumeration, and those skilled in the art will understand that any other styrene-(meth)acrylic resin dispersion may be used.

[0055] The waterborne primer of the present invention may optionally also further comprise any solution polymer (also known as an alkali-soluble polymer), including alkali-soluble acrylic and styrene-acrylic polymers. It should be understood that an alkali-soluble polymer generally refers to a polymer that typically contains an acid moiety as part of a monomer blend, which can be neutralized with a suitable alkali (including but not limited to ammonia, amines (e.g., triethylamine or triethanolamine), or inorganic alkalis (e.g., NaOH, KOH)) to form a polymer that is soluble in water to form an aqueous solution. In the case of using alkali-soluble acrylic or styrene-acrylic polymers, they include any blend containing acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and vinyl, acrylic, or methacrylic acid monomers (including (but not limited to) styrene, methyl methacrylate, butyl acrylate, butyl methacrylate, ethyl acrylate, ethyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate). The aqueous solution of these acrylic polymers is formed by neutralizing the carboxylic acid groups of the polymer with any alkali (including (but not limited to) ammonia, trimethylamine, triethanolamine, sodium hydroxide, potassium hydroxide) while dissolving the polymer in water.

[0056] The primer according to the invention may optionally also contain a polyvalent metal salt. If a polyvalent metal salt is present, it is preferably present in an amount of less than 20% (w / w), more preferably less than 10% (w / w), and even more preferably less than 5% (w / w). Suitable polyvalent metal salts include (but are not limited to) polyvalent cationic salts, such as calcium nitrate (and its hydrate), calcium ammonium nitrate, calcium acetate, and calcium chloride. Preferably, the primer according to the invention contains less than 20% (w / w) of calcium nitrate (and its hydrate), calcium ammonium nitrate, calcium acetate, or calcium chloride, more preferably less than 10% (w / w) of calcium nitrate (and its hydrate), calcium ammonium nitrate, calcium acetate, or calcium chloride, and even more preferably less than 5% (w / w) of calcium nitrate (and its hydrate), calcium ammonium nitrate, calcium acetate, or calcium chloride.

[0057] Alternatively, the primer according to the invention is substantially free of polyvalent metal salts, i.e., the primer contains less than 1% (w / w) of polyvalent metal salts. Therefore, in an alternative preferred aspect of the invention, the primer contains less than 1% (w / w) of calcium nitrate (and its hydrate), calcium ammonium nitrate, calcium acetate, or calcium chloride. In a more preferred alternative aspect of the invention, the primer is free of any (i.e., does not contain) calcium nitrate, calcium ammonium nitrate, calcium acetate, or calcium chloride. Preferably, the primer is free of any (i.e., does not contain) polyvalent metal salts.

[0058] The primer composition according to the invention comprises water. Advantageously, the water is free of ionic impurities. In one embodiment, the water is ion-exchanged water or distilled water. In one embodiment, the amount of water used according to the invention comprises water supplied as part of the raw materials used, which will account for 20-80% by mass of the total composition, preferably 30-70% by mass.

[0059] The primer may also optionally contain any co-solvent, including but not limited to: ethanol, propanol, butanol, acetone, propylene glycol, glycerin, and ethylene glycol ether.

[0060] The primer may also optionally contain any number of additives, including but not limited to surfactants, wetting agents, antifoaming agents, degassing agents, and biocides. Suitable additives are described herein, but it should be understood that the invention is not limited to these additives.

[0061] The primer may also optionally contain any dispersion of inorganic materials, including but not limited to silica, alumina, and clay.

[0062] Preferably, the total solids content of the primer composition is 5.0-60.0% (w / w), more preferably 5.0-40.0% (w / w).

[0063] The primer can be applied by any suitable printing or coating method, including but not limited to flexographic printing, gravure printing, screen printing, roll coating, and spraying. In one embodiment, flexographic printing and screen printing will be deposition methods.

[0064] Since the primers of this invention are primarily water-based, they may also contain biocides or antifungals. Suitable examples include products based on the following biocidal structure types, sold under the trade names Intercide (Akcros Chemicals) or Nipacide (Clariant): benzisothiazolinone, bromonitrobenzyl glycol, isothiazolinone, ethylene glycol dihydroxymethyl ether, or iodopropynyl butylcarbamate. Other types of biocides that may be considered include sodium dehydroacetate (Geogard 111S from Lonza), sodium benzoate (Vancide 51 from RTVANDERBILT), sodium mercaptopyridine-1-oxide (Sodium Omadine from Arch Chemicals), sodium salts of o-phenylphenol (Dowicide A from Dow Chemicals), and ethyl p-hydroxybenzoate (Nipastat sodium from Aako). These are typically used in amounts of 0.01-1.00% by mass of the primer composition.

[0065] Defoamers may optionally be included in the formulation; these defoamers prevent foam formation during primer manufacturing and printing. Defoamers are particularly important for recycle printheads. Examples of suitable defoamers include TEGO FOAMEX N, FOAMEX 1488, 1495, 3062, 7447, 800, 8030, 805, 8050, 810, 815N, 822, 825, 830, 831, 835, 840, 842, 843, 845, 855, 860 and 883, TEGO FOAMEX K3, TEGO FOAMEX K7 / K8, and TEGO TWIN 4000, all available from Evonik. BYK-066N, 088, 055, 057, 1790, 020, BYK-A 530, 067A, and BYK 354 are available from BYK Chemical Company. Additives DC62, DC65, DC68, DC71, and DC74 are available from Dow Corning. Agitan 120, 150, 160, 271, 290, 298, 299, 350, 351, 731, 760, 761, and 777 are available from Munzing. Surfynol 104PA, AD01, DF-110, DF-58, DF-62, DF-66, DF-695, DF-70, and MD-20 are available from Air Products.

[0066] Surface control additives can optionally be used to control the surface tension of the primer to achieve the desired spreading and wetting on the substrate. They can also be used to control the anti-slip and scratch resistance levels of the coating. Examples of suitable surface control additives include, but are not limited to, TEGO FLOW 300, 370 and 425, TEGO GLIDE 100, 110, 130, 406, 410, 411, 415, 420, 432, 435, 440, 482, A115 and B1484, TEGO GLIDE ZG 400, TEGO RAD 2010, 2011, 2100, 2200N, 2250, 2300, 2500, 2600, 2650 and 2700, TEGO TWIN 4000 and 4100, TEGO WET 240, 250, 260, 265, 270, 280, 500, 505 and 510, and TEGO WET KL245, all of which are available from Evonik. Available from BYK Chemicals are BYK 333 and 337, BYK UV 3500, BYK 378, 347 and 361, BYK UV 3530 and 3570, CERAFLOUR 998 and 996, NANOBYK 3601, 3610 and 3650, and CERMAT 258. Available from Cytec are EBECRYL 350 and 1360, MODAFLOW 9200, and EBECRYL 341. Aliphatic silicone acrylates CN9800 from Sartomer can be used. Surfynol 104, 420, 440, 465, 485, 61, 82 and 2502 are available from Air Products. Multiwet BD, EF, SU, SO and VE are available from Croda. DuPont offers Capstone FS-30, 31, 34, 35, 50, 51, 60, 61, 63, 64, 65, and 3100. BASF's non-ionic Hydropalat series is also suitable for use.

[0067] Optionally, a suitable degassing agent may be included in the primer to prevent the formation of air inclusions and pinholes in the dried coating that could affect the primer's performance. Examples include the following products available from Evonik: TEGO AIREX 900, 910, 916, 920, 931, 936, 940, 944, 945, 950, 962, 980, and 986.

[0068] Preferably, the water-based primer of the present invention is colorless. Alternatively, the water-based primer may also contain one or more colorants, including pigments and / or dyes. Examples of suitable organic or inorganic pigments include carbon black, zinc oxide, titanium dioxide, phthalocyanine, anthraquinone, perylene, carbazole, monoazo and diazobenzimidazole, rhodamine, indigo, quinacridone, diazopinanthrone, dinitroaniline, pyrazole, diazopinanthrone, pyrazole, bianisidine, pinanthrone, tetrachloroisoindoline, diazine, monoazoacrylide, and anthrapyrimidine. Dyes include, but are not limited to, azo dyes, anthraquinone dyes, xanthine dyes, azine dyes, and combinations thereof.

[0069] Commercial organic pigments classified according to the International Dye Index may be used, including but not limited to those named according to the following trade names: blue pigments PB1, PB15, PB15:1, PB15:2, PB15:3, PB15:4, PB15:6, PB16, PB60; brown pigments PB5, PB23 and PB265; green pigments PG1, PG7, PG10 and PG36; yellow pigments PY3, PY14, PY16, PY17, PY24, PY65, PY73, PY74. PY83, PY95, PY97, PY108, PY109, PY110, PY113, PY128, PY129, PY138, PY139, PY150, PY151, PY154, PY156, PY175, PY180 and PY213; orange pigments PO5, PO15, PO16, PO31, PO34, PO36, PO43, PO48, PO51, PO60, PO61 and PO71; red pigments PR4, PR5, PR7, PR9, PR22, PR23, PR48, PR48:2, PR49, PR112, PR122, PR123, PR149, PR166, PR168, PR170, PR177. PR179, PR190, PR202, PR206, PR207, PR224 and PR254; purple pigments PV19, PV23, PV32, PV37 and PV42; black pigments PBk1, PBk6, PBk7, PBk8, PBk9, PBk10, PBk11, PBk12, PBk13, PBk14, PBk17, PBk18, PBk19, PBk22, PBk23, PBk24, PBk25, PBk26, PBk27, PBk28, PBk29, PBk30, PBk31, PBk32, PBk33, PBk34, PBk35, NBk1, NBk2, NBk3, NBk4, NBk6, and combinations thereof.

[0070] After grinding with a particle size distribution of 10-500nm or 10-350nm, the pigment is ground to less than 1 micrometer to achieve better transparency and a wider color gamut.

[0071] To incorporate the above-described pigments into the compositions of the present invention, the pigments can be manufactured and stably stored in water as pigment concentrates. This is typically achieved by dispersing the pigments in a water-soluble or water-dispersible resin using water-soluble and / or water-dispersible surfactants that introduce hydrophilic functional groups onto the surface of the pigment particles. Examples of such dispersing resins are numerous and may include polyvinyl alcohol, polyacrylic acid, acrylic acid-acrylonitrile copolymers, vinyl acetate-acrylate copolymers, acrylic acid-acrylate copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-α-methylstyrene-acrylic acid copolymers, styrene-α-methylstyrene-acrylate-acrylate copolymers, styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, vinylnaphthalene-acrylic acid copolymers, vinylnaphthalene-maleic acid copolymers, vinyl acetate-maleic ester copolymers, vinyl acetate-crotonic acid copolymers, and vinyl acetate-acrylic acid copolymers, and their salts. The copolymers can be used in any form of random copolymers, block copolymers, alternating copolymers, and graft copolymers. Examples of such resins include Joncryl 67, 678, 8500, 586, 611, 680, 682, 683, and 69, available from BASF. Examples of salts include salts of sodium hydroxide, potassium hydroxide, and basic compounds such as ammonia, ethylamine, diethanolamine, triethanolamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, diethanolammonium, triethanolamine, triisopropanolamine, dimethylethanolamine, aminomethylpropanol, and morpholine. The amount of basic compound is not strictly limited, as long as the resin dispersant is equal to or greater than the neutralizing equivalent.

[0072] Examples of surfactants used in the preparation of pigment dispersions include anionic surfactants such as alkane sulfonates, α-olefin sulfonates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, acylmethyl taurate, dialkyl sulfosuccinates, alkyl sulfates, sulfurized olefins, polyoxyethylene alkyl ether phosphates, polycarboxylic acids, and monoglycerides; amphoteric surfactants such as alkylpyridinium salts; and nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamides, glyceryl alkyl esters, and sorbitol alkyl esters. Examples include BASF's EFKA 1000, 4000, 5000, and 6000 series, Dow's Tamol series, and Lubrizol's Solsperse 27,000, 40,000, 44,000, 46,000, and 47,000.

[0073] The primer of the present invention is suitable for application to plastic substrates (such as plastic cards). Suitable plastic substrates (e.g., plastic cards) include those made of any blend of polyvinyl chloride acetate, polyvinyl chloride, polyvinylidene chloride, or these polymers or copolymers thereof. The substrate is preferably polyvinyl chloride. Preferably, the substrate is a plastic card. Plastic cards are suitable for being made of any blend of polyvinyl chloride acetate, polyvinyl chloride, polyvinylidene chloride, or these polymers or copolymers thereof. Therefore, the substrate is preferably a plastic card made of any blend of polyvinyl chloride acetate, polyvinyl chloride, polyvinylidene chloride, or these polymers or copolymers thereof.

[0074] Preferably, the primer of the present invention is applied to the plastic core of the card (preferably a payment card). The primer of the present invention is applied to the plastic core of the card by any suitable printing or coating method, such as flexographic printing or screen printing. The core of a payment card is typically made of polyvinyl chloride acetate, polyvinyl chloride, polyvinylidene chloride, or any blend of these polymers or copolymers thereof. However, it should be understood that the primer is suitable for coating any plastic core used in the manufacture of payment cards and debit cards.

[0075] Once the substrate (e.g., the card core) has been coated with the primer of the present invention, it is then printed using any of the digital printing processes previously outlined. Preferably, the primer-coated core is printed using a liquid electrophotographic process (such as HP's "Indigo").

[0076] In one embodiment, the film weight (after drying) of the primer coating applied to the first substrate of the present invention is between 0.1 and 10.0 gm. -2 Preferably, 0.1-5.0 gm -2 More preferably 0.2-5.0gm -2 Within the range.

[0077] The printed, primer-coated core is then heat-laminated onto another plastic layer, which may be the same polymer type as the core or a different polymer. This is a process well known to those skilled in the art and typically involves bringing the laminated plastic layer into contact with the printed core and subjecting the plastic layer to a temperature typically 120-160°C under pressure, although lower or higher temperatures may be used. Pressures typically exceed 5 psi, and more often exceed 10 psi. Wherein, heat lamination typically takes from 0.1 seconds to 30 minutes.

[0078] Without the primer according to the invention, the inventors discovered that cards produced via Indigo printing have insufficient lamination bond strength and are prone to leaching. The primer provides lamination bond strength of ≥5 N / cm, ≥7 N / cm, ≥10 N / cm, 15 N / cm, or ≥17 N / cm for the final card structure. Detailed Implementation

[0079] definition

[0080] Molecular weight – “Molecular weight” or “average molecular weight” refers to weight-average molecular weight (Mw). Molecular weight is appropriately measured using techniques known in the art, such as gel permeation chromatography. Preferably, molecular weight is measured by comparison with polystyrene standards. For example, molecular weight measurements can be performed on a HP 1050 Series HPLC system equipped with two GPC Ultrastyragel columns (103 and...). (5μm mix, 300mm × 19mm, Waters Millipore Corporation, Milford, Massachusetts, USA) with THF as the mobile phase. Those skilled in the art should understand that this definition of molecular weight applies to polymer materials that typically have a molecular weight distribution.

[0081] Particle size / average particle size - The term "particle size" or "average particle size" refers to the median particle size of the volume distribution (equivalent to the diameter of an sphere representing 50% of the total volume of all particles, read on a cumulative distribution curve of volume % versus particle diameter - often referred to as the "D(v,0.5)" value). Particle size is preferably measured by laser diffraction.

[0082] Unless otherwise stated, the term nanoparticle refers to a one-dimensional particle smaller than 100 nm.

[0083] Unless otherwise specified, lamination bond strength is measured using a JJ Lloyd tensile meter at a separation speed of 300 mm / min via a T-peel test. Lamination bond strength is reported in N / cm, which is the force required to separate the top film from the primer-coated and printed core for a 1 cm wide strip; for example, a lamination bond strength reported as N / 25 cm is the force required to separate the top film from the primer-coated and printed core for a 25 cm wide strip. Ideally, minimum bond strengths are ≥5 N / cm, ≥7 N / cm, ≥10 N / cm, ≥15 N / cm, ≥17 N / cm, or ≥20 N / cm.

[0084] Unless otherwise specified, viscosity should be measured at 50 rpm and at 19.1°C using a Brookfield CAP200 viscometer equipped with a No. 4 spindle.

[0085] Leaching

[0086] Black inks are typically tinted with alkaline blue pigments. When alkaline blue is used to tint carbon black, this makes dark blacks more aesthetically pleasing. However, alkaline blue is primarily a dye, and under certain conditions, such as exposure to moisture / heat and / or high relative humidity (e.g., 50°C / 90% RH), as seen in credit card lamination, the blue dye can bleed out of the black ink, causing the black printed image (in the case of HP indigo) to appear significantly bluer, which is detrimental. The bleed-out effect is also noticeable in fine text, where blue shading can be seen outlining black letters, and when layered, the laminating adhesive can become blue due to migration over the alkaline blue. Embodiments 1 and 2 of the present invention address this bleed-out problem by providing dye fixative properties that prevent the blue dye from bleeding out throughout the printed image.

[0087] Example 1 of the present invention solved the leaching problem using 0.53% by weight of poly(ethyleneimine). In contrast, dye leaching was still observed in Reference Example 5, which contained only 0.30% by weight of poly(ethyleneimine). Therefore, those skilled in the art will understand that while waterborne primers containing less than 0.3% by weight of poly(ethyleneimine) provide good lamination bond strength, they do not solve the dye leaching problem.

[0088] The present invention, including its various embodiments, has been described in detail. However, it should be understood that those skilled in the art, upon considering this disclosure, can make modifications and / or improvements to the invention within its scope and spirit.

[0089] Example

[0090] The invention is further described by way of the following non-limiting embodiments, which further illustrate the invention and are not intended to, nor should be construed as, limiting the scope of the invention.

[0091] Preparation of flexographic and screen printing primers according to the present invention

[0092] Prepare the primer coating according to the formulations listed in Table 1. Add the components sequentially, starting with the polymer dispersion, and then blend using a Dispermat high-shear mixer.

[0093] Table 1: Examples of primer formulations

[0094]

[0095] 1 Anionic polyurethane dispersion (Opdi Corporation; 28% solids); 2Oil-in-water emulsion of ethylene-acrylic acid copolymer (Honeywell; 44.5% solids); 3 Nonionic polyester urethane dispersion (40% solids content; Covestro); 4 Multifunctional cationic poly(ethyleneimine) crosslinking agent (BASF); 5 Water-based polymer dispersion (Paramelt; 33% solids); 6 Defoamer (Evonik); 7a,7b biocides (Thor; 7a 35% solids 7b 50% solids); 8 Surfactants / wetting aids (Evonik); 9 Polyurethane thickener (Zhanxin Company; 37.5% solids); 10 Terminal isocyanate dispersion (Lanxess; 41% solids); 11 Carbodiimide crosslinking agent (Nisshinbo Corporation; 40% solids); 12 Anionic dispersions of PU polyols, such as those from Evonik (33% solids); 13 Polyurethane-based thickener (25% solids); 14 Non-anionic acrylic dispersion (40% solids content; Opaldi).

[0096] Viscosity (poise) was measured using a Brookfield CAP200 viscometer (spindle #4, 50 rpm, 19.1°C).

[0097] Example description:

[0098] Reference Example 1: Formulation of flexographic printing PUD primer containing end-capped isocyanate dispersion crosslinking agent.

[0099] Reference Example 2: A screen printing PUD primer formulation containing a capped isocyanate dispersion crosslinking agent.

[0100] Reference Example 3: A PUD primer formulation containing an oil-in-water emulsion of ethylene-acrylic acid copolymer, a capped isocyanate dispersion crosslinking agent, and a carbodiimide crosslinking agent.

[0101] Reference Example 4: A PUD primer formulation containing an oil-in-water emulsion of ethylene-acrylic acid copolymer, a capped isocyanate dispersion crosslinking agent, and an anionic dispersion of PU polyol.

[0102] Example 1 of the present invention: A screen-printed polyester urethane primer formulation containing 0.53% by weight of a multifunctional cationic polyethyleneimine crosslinking agent with improved leaching resistance.

[0103] Example 2 of the present invention: A screen printing acrylic primer formulation containing a polyfunctional cationic polyethyleneimine crosslinking agent with improved leaching resistance.

[0104] Reference Example 5: A screen-printed polyester polyurethane primer formulation containing 0.3% by weight of a multifunctional cationic polyethyleneimine crosslinking agent.

[0105] The primer composition was applied to a PVC-based payment card core at 12 gsm (wet) and then dried to achieve a dry film weight in the range of 2.5 to 3.5 gsm (dry). The primer-coated PVC core was then printed with liquid electrophotographic ink via an HP Indigo feeder. The primer-coated and printed core was then thermally laminated onto a second flexible PVC film under various conditions according to Table 2. The lamination bond strength was measured using a JJ Lloyd tensile meter at a separation speed of 300 mm / min via a T-type peel test; this is a test type familiar to those skilled in the art. The lamination bond strength is reported as N / cm; this is the force required to separate the top PVC film from the primer-coated and printed core for a 1 cm wide strip.

[0106] Adhesion was measured using 3M Scotch Magic Tape via a tape test. Following ASTM F2252 / 52252M-13 (2018), the tape was placed on the surface of a printed substrate and rolled five times with a 2 kg roller. Ink removal rate was then recorded as a percentage. All embodiments of the invention passed the tape test, demonstrating good adhesion.

[0107] It was observed that, without any primer, the transfer of ink to the vinyl card core was poor, and the adhesion, as assessed by the tape test, was also poor.

[0108] Table 2: Performance Characteristics of Primer

[0109]

[0110] The results in Table 2 show that the primer of the present invention improves lamination bond strength compared to the case without a primer. As shown in Table 3, Examples 1 and 2 of the present invention also prevent the leaching of basic blue dye from indigo black ink.

[0111] Table 3: Leaching Assessment

[0112]

[0113] Test methods for leaching assessment

[0114] HP indigo ink was diluted with basic blue dye in a 2:1 ratio with Isopar (2 parts black ink: 1 part Isopar) and printed using a 40-micron k-bar, which deposited a wet coating weight of approximately 40 gsm on a portion of the HP EPDM image transfer blanket.

[0115] Once coated, the rubber is transferred to a hot plate at 160°C until all solvent evaporates, leaving only the ink as a film. The rubber blanket is then placed ink-side down on a pre-primed PVC substrate and pressed multiple times onto the surface using a 2kg hand-operated ink roller. The print is then allowed to cool completely before further testing.

[0116] Lamination: The ink is printed onto a pre-primed substrate and allowed to cool completely. The areas printed with black ink are cut into strips and laminated onto a PVC overlay using a heat sealer (140°C / 40psi / 20 seconds). The strips are then cut into 25mm strips and divided into multiple portions. One portion is placed in a humidity-controlled oven (50°C / 90% RH / 7 days), while the remaining samples are left in a controlled dark environment. Visual and color measurements are performed on both the humidity-aged samples and those stored in the controlled environment.

[0117] X-Rite (obtaining LAB and ΔLAB results) method: This method uses an X-Rite spectrometer to measure the color change of a sample. The spectrometer measures the following parameters to provide numerical values ​​indicating the color change:

[0118] ΔE is a standard measurement method that uses a combination of dL*, da*, and db* to quantify the difference between two colors.

[0119] ΔE is measured in the range of 0 to 100, where values ​​≤1.0 are generally imperceptible to the human eye. Values ​​between 1.0 and 2.0 can be observed with careful observation. Values ​​between 2.0 and 10 are readily apparent. Values ​​in the range of 11 to 49 are clearly distinguished by different colors. Values ​​>49 are considered to be the opposite.

[0120] dL* represents the difference in brightness / darkness between two measurements.

[0121] Compared to the samples observed to leach, the samples exhibiting less leaching had lower ΔE(DEcmc) and ΔL values.

[0122] Visual color assessment: Samples aged in a humidity-controlled oven (as described above) are visually compared with unaged samples and evaluated. No color change is considered a pass; slight visual color change is a marginal pass; significant visual color change is considered a fail.

[0123] Table 3 shows the improvements of Examples 1 and 2 of the present invention in terms of lower measured color change values ​​and reduced visual color change. Therefore, Examples 1 and 2 are particularly suitable for applications where reduced leaching is desired.

Claims

1. A water-based primer composition comprising: (i) a nonionic acrylic dispersion and 1-20% (w / w) of poly(ethyleneimine); or (ii) Nonionic polyester urethane dispersion and 0.5-25% (w / w) of poly(ethyleneimine); The polymer in the dispersion comprises 2.5-99.5% of the primer composition by dry weight.

2. The primer composition according to claim 1, comprising a nonionic polyester urethane dispersion and 0.5-25% (w / w) of poly(ethyleneimine).

3. The primer composition according to claim 1, comprising a nonionic acrylic dispersion and 1-20% (w / w) of poly(ethyleneimine).

4. The primer composition according to any one of the preceding claims, wherein the nonionic acrylic dispersion or nonionic polyester urethane dispersion accounts for more than 40% (w / w) of the total composition.

5. The primer composition according to claim 1, 2 or 4, comprising a nonionic polyester urethane dispersion and 0.5-15% (w / w) of poly(ethyleneimine).

6. The primer composition according to claim 5, comprising 0.5-8% (w / w) of poly(ethyleneimine).

7. The primer composition according to claim 1, 3 or 4, comprising a nonionic acrylic dispersion and 3-15% (w / w) of poly(ethyleneimine).

8. The primer composition according to any one of the preceding claims, wherein the poly(ethyleneimine) has a molecular weight of about 10,000 g / mol to about 50,000 g / mol.

9. The primer composition according to any one of the preceding claims, wherein the nonionic polymer of the dispersion accounts for 10.0-98% of the primer composition on a dry weight basis.

10. The primer composition according to claim 9, wherein the nonionic polymer of the dispersion accounts for 20.0-95% of the primer composition on a dry weight basis.

11. The primer composition according to any one of the preceding claims, wherein the total solids content of the primer composition is 5.0-60.0% (w / w).

12. The primer composition according to claim 11, wherein the total solids content of the primer composition is 5.0-40.0% (w / w).

13. The primer composition according to any one of the preceding claims, wherein the composition is substantially free of polyvalent metal salts (i.e., the composition contains less than 1% w / w of polyvalent metal salts).

14. The primer composition according to any one of the preceding claims, wherein the composition comprises less than 1% (w / w) of calcium nitrate, calcium ammonium nitrate, calcium acetate, calcium chloride, or a blend thereof.

15. The primer composition of claim 14, wherein the composition comprises less than 0.5% (w / w) of calcium nitrate, calcium ammonium nitrate, calcium acetate, calcium chloride, or a blend thereof.

16. The primer composition according to any one of the preceding claims, wherein the composition is free from any calcium nitrate, calcium ammonium nitrate, calcium acetate, or calcium chloride.

17. The primer composition according to any one of the preceding claims, wherein the composition comprises 20-80% water by weight of the composition.

18. The primer composition of claim 17, wherein the composition comprises 30-70% water by weight of the composition.

19. A method of providing a primer-coated substrate, comprising applying a primer composition according to any one or more of claims 1-18 and drying the primer.

20. The method of claim 19, wherein the substrate is polyvinyl chloride (PVC).

21. The method of claim 19 or 20, wherein the primer is applied to the substrate by flexographic printing, gravure printing or screen printing.

22. A method of providing a primer-coated and printed substrate, comprising applying a primer composition according to any one or more of claims 1-18 and drying the primer, thereafter printing one or more inks on top of the primer and drying the subsequent one or more inks.

23. The method of claim 22, wherein the substrate is polyvinyl chloride (PVC).

24. The method of claim 22 or 23, wherein the primer is applied to the substrate by flexographic printing, gravure printing or screen printing.

25. The method of claim 22, 23 or 24, wherein the one or more inks are printed onto a primer-coated substrate by digital printing.

26. The method of claim 25, wherein the one or more inks are printed on a primer-coated substrate by liquid indigo printing, dry indigo printing, or inkjet printing.

27. The method according to any one or more of claims 19-26, wherein the primer-coated and printed substrate is heat-laminated with one or more additional plastic layers.

28. The method according to claim 27, wherein, The heat lamination of the additional plastic layer is carried out at ≥80°C.

29. The method according to claim 28, wherein, The heat lamination of the additional plastic layer is carried out at ≥100°C.

30. A method for preparing a laminated structure, comprising the following steps: a. Applying the primer composition according to any one of claims 1 to 18 to a first substrate; b. Dry the primer; c. Overprinting a primer-coated substrate using one or more digital inks; d. Dry the one or more digital inks; and e. Laminating a second substrate onto a first substrate coated with a primer and printed at ≥80°C to create a laminated structure.

31. The method of claim 30, wherein the lamination is performed at ≥100°C.

32. A laminated structure prepared according to the method of claim 30 or 31.

33. The laminated structure according to claim 32 is a plastic payment card.

34. Use of a water-based primer composition for reducing dye leaching in a laminated structure, wherein the water-based primer composition is defined according to any one of claims 1 to 18.

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