Digital printing primer

Abstract

1. An aqueous primer composition comprising: (i) a polymer dispersion selected from an acrylic dispersion, a polyester urethane dispersion, and blends thereof; and (ii) an aminated polymer, wherein the aminated polymer is poly(ethyleneimine), and the poly(ethyleneimine) is present at 0.5 to 25% (w / w).

Description

[Technical Field]

[0001] The present invention provides an aqueous primer composition suitable for use in digital printing of plastic substrates. The aqueous primer composition of the present invention is particularly suitable for printing the plastic core of payment and financial cards, followed by thermal lamination of the printed surface with an additional plastic layer. Advantageously, the resulting plastic laminate exhibits reduced dye leaching.

[0002] The present invention also provides a process for preparing a digitally printed laminate, and a laminate prepared by the process. [Background technology]

[0003] U.S. Patent No. 11,066,781 (Eastern Tech) refers to textile pretreatments for inkjet printing that contain more than 40% (w / w) of a multivalent salt in combination with up to 5% (w / w) of a blocked isocyanate and up to 40% (w / w) of an aqueous binder, which may be a polyurethane dispersion ("PUD"). Such high concentrations of metal salts make these primers unsuitable for the lamination process of the present invention, and furthermore, they are not intended for printing by digital electrophotographic printing, such as that of HP Indigo.

[0004] U.S. Patent No. 6,761,940 (Hueck Folien) mentions a primer containing a thermoplastic polymer, which may further contain a crosslinking agent, without providing any illustrative examples. The thermoplastic polymer of the primer is preferably a copolymer of ethylene and an acrylate monomer. It mentions printing by the HP Indigo electrophotographic digital process. U.S. Patent No. 6,761,940 does not mention the use of a polymer dispersion with an aminated polymer crosslinking agent according to the present invention.

[0005] The HP Indigo process uses what it calls "electroink," which is essentially a pigment dispersion in a carrier comprising a paraffinic solvent and an ethylene copolymer (with a comonomer selected from methacrylic acid and acrylic acid). They tend to have poor adhesion to plastic substrates and low heat resistance. The thermoplastic nature of the ethylene copolymer binder can result in print distortion, which impairs print quality. The present invention helps overcome these problems, i.e., poor adhesion and poor lamination bond strength, while maintaining print quality during high-temperature processing of such prints, including the thermal lamination process encompassed by the present invention. The present 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) incorporate thermoplastic polymers such as copolymers of ethylene and methacrylic acid or acrylic acid. Several primers containing such copolymers for subsequent electrophotographic printing with liquid toner have been mentioned in the prior art. U.S. Pat. No. 7,470,736 (Michelman) and WO 2020 / 190723 (Sun Chemical) refer to aqueous primer compositions containing a copolymer of ethylene and acrylic acid (or methacrylic acid) together with a polyurethane dispersion. While suitable as print-receptive primers for digital printing, due to the lack of the additional crosslinking agent present in the primers of the present invention, they do not maintain print quality and do not provide good lamination bond strength during thermal lamination.

[0007] U.S. Patent No. 9,639,011 (HP) mentions a solvent-based primer for electrophotographic digital printing, which contains a copolymer of ethylene and methacrylic acid or acrylic acid. This primer was applied by electrophotographic printing and then printed with a pigmented liquid toner ("HP Electrink"). The issues of adhesion, maintaining print quality during thermal lamination, and providing good thermal bond strength are not discussed.

[0008] U.S. Pat. No. 10,564,562 (HP) takes this concept further by analogically applying a first, underlying water-based primer, "Digiprime 050" from Michelman, followed by a digital primer application along the lines disclosed in U.S. Pat. No. 9,639,011.

[0009] U.S. Patent No. 10,851,262 (Sun Chemical) refers to an analog-applied primer for digital printing, particularly liquid electrophotographic digital printing ("LEP"), which contains a blend of a polyurethane dispersion with a self-crosslinking acrylic dispersion to improve adhesion and block resistance of the print on a range of substrates.

[0010] U.S. Patent No. 10,301,478 (Ashland) refers to a primer coating, particularly for LEP printing, that includes a cationic polyurethane dispersion with either a polyoxazoline or an N-vinylpyrrolidone copolymer. The use of any crosslinking agent is not disclosed.

[0011] WO 2021 / 011606 (Michelman) refers to an aqueous primer coating containing a polyvalent metal salt and an amine-containing polymer suitable for digital printing by electrophotography and inkjet processes. The thermal lamination process according to the present invention is not disclosed.

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

[0013] Hewlett-Packard Company's "HP Indigo" liquid electrophotographic printing process has been successfully implemented commercially in a wide range of printing applications, including label printing and narrow-web packaging. In this process, a liquid toner image is formed on a photosensitive drum, electrostatically transferred to a heated intermediate blanket, and then printed onto a web or sheet substrate. A description of this technology is provided in U.S. Pat. Nos. 4,794,651 and 5,407,771. Such liquid toners often produce prints with poor adhesion, especially to plastic substrates, and can also lack physical robustness, thus necessitating the use of protective overprint lacquers in some applications. Furthermore, prints produced by such liquid electrophotographic printing may not produce laminates with sufficient bond strength to meet technical requirements, a problem addressed by the present invention. Laminate prints produced by liquid electrophotographic printing (such as the "HP Indigo" printing process) are also prone to dye leaching. The primer of the present invention addresses this issue by fixing the dye to the substrate. The problem of dye leaching has not been identified in the prior art.

[0014] Citation or identification of any document in this application is not an admission that it represents prior art to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention allows for the production of plastic laminates that do not exhibit dye leaching when printed using liquid electrophotographic toner and subsequently heat-laminated to a second or additional plastic ply. The present invention is preferably directed to printing plastic cores of payment and financial cards, followed by heat-laminating the printed surface with an additional plastic layer. Most particularly, the present invention is directed to printing bank card cores containing vinyl chloride or vinylidene dichloride homopolymers and copolymers, followed by heat-laminating an additional plastic ply that may also contain vinyl chloride or vinylidene dichloride homopolymers and copolymers.

[0016] Thermal lamination is a process in which a second plastic film is contacted with the printed surface of the card core and then subjected to high temperatures (typically above 100°C, more usually above 120°C) and pressure (typically above 50 bar, up to 200 bar) to form a bonded laminate. Without the primer of the present invention, card cores printed with liquid electrophotographic fluids not only lack the necessary laminate bond strength, but also suffer from print quality degradation and dye leaching during thermal lamination. This print quality degradation is due to ink "migration" during thermal lamination. Similarly, dye leaching is due to internal dye migration during thermal lamination. The inventors do not wish to be bound by any theory behind the print quality degradation or dye leaching, but hypothesize that it is due, in part, to the thermoplastic properties of the toner's polymer binder, which softens and deforms during lamination.

[0017] The primer of the present invention helps overcome deficiencies in adhesion and lamination bond strength while maintaining print quality. The primer of the present invention also prevents dye leaching. This is achieved by using an appropriate polymer dispersion and aminated polymer crosslinker. Again, the inventors do not wish to be bound by any theory, but they hypothesize that after printing, some of the crosslinker migrates from the primer into the ink, and when the print is laminated, both the primer and the ink are crosslinked, maintaining print quality. Furthermore, the inventors hypothesize that after printing, some of the crosslinker migrates from the primer into the ink, fixing the dye to the substrate and preventing leaching.

[0018] The prior art does not disclose the use of print receptive primers according to the present invention in the manufacture of payment and financial cards, particularly for electrophotographic (toner) printing. Some examples in the background literature describe primers for electrophotographic printing that contain polymer dispersions, but do not contain the essential crosslinker (poly(ethyleneimine)) that is important for the process of the present invention.

[0019] There is no disclosure of a print receptive primer for digital printing, particularly by electrophotographic printing, that has a crosslinking agent that is activated during thermal lamination. Without the crosslinking agent, there is a loss of print quality during thermal lamination to form finished payment and financial cards, and the incorporation of the crosslinking agent results in significantly stronger lamination bond strength than would be achieved without its use.

[0020] The advantages of printing on a thermoplastic primer to ensure good print receptivity, followed by a curing reaction activated by the elevated temperatures of thermal lamination to maintain print quality during lamination and ensure good lamination bond strength, were not anticipated by the prior art. Furthermore, the use of a primer composition according to the present invention to prevent dye leaching after thermal lamination has not been disclosed in the prior art.

[0021] The present invention relates to an aqueous primer composition comprising (i) a polymer dispersion selected from an acrylic dispersion, a polyester urethane dispersion, or a blend thereof, and (ii) an aminated polymer, wherein the aminated polymer is poly(ethyleneimine), and the poly(ethyleneimine) is present in an amount of 0.5 to 25% (w / w). Preferably, the aqueous primer composition (also called a print-receptive primer) is applied to a substrate by flexographic printing, gravure printing, or screen printing. The primer can then be overprinted with one or more digital inks. Preferably, the overprinting is by digital electrophotographic (toner) printing.

[0022] Although primarily directed to aqueous print receptive primers for overprinting by digital electrophotographic (toner) printing, the primers of the present invention are also suitable for overprinting by inkjet printing, particularly aqueous inkjet printing inks (i.e., overprinting by inkjet printing with aqueous inkjet printing inks).

[0023] Aqueous print-receptive primers according to the present invention comprising poly(ethyleneimine) as crosslinker are described as being suitable for curing at temperatures above 80° C. after overprinting by electrophotographic (toner) or inkjet digital printing processes. Preferably, the primers are applied by flexographic, gravure or screen printing methods.

[0024] In a preferred application, the primers of the present invention are used in the manufacture of payment and financial cards (such as credit cards and bank cards) in which the primer is applied to a card core, digitally printed thereon, and then heat-laminated to a second, optionally additional, plastic ply. For the manufacture of payment and financial cards, the primers of the present invention ensure that print quality is maintained during the heat-lamination process and also ensure that the bond strength between the primed, digitally printed core and the subsequent plastic layer of the final card is preferably greater than 7 N after aging for two weeks at 55°C and 93% relative humidity. Bond strength can be measured using a JJ Lloyd bond strength tester, and preferably the minimum bond strength is 7 N / cm or greater, more preferably 10 N / cm or greater, even more preferably 15 N / cm or greater, even more preferably 17 N / cm or greater, or most preferably 20 N / cm or greater. The primers of the present invention also prevent dye leaching.

[0025] The dye leaching problem is solved by using an aqueous primer coating composition containing a polymer dispersion with polyethyleneimine as an aminated polymer crosslinker. Specifically, the dye leaching problem is solved by using an aqueous primer coating composition containing a polymer dispersion selected from acrylic dispersions, polyester urethane dispersions, and blends thereof, along with 0.5 to 25% (w / w) poly(ethyleneimine). After printing, the primer is crosslinked during thermal lamination to form the finished card. It is believed that some of the crosslinker in the primer migrates into the ink, crosslinking both during lamination. Without the crosslinker, print quality may be reduced, and lamination bond strength may be weaker than achieved with its inclusion. Furthermore, without the crosslinker, dyes may leach from the ink.

[0026] The primers of the present invention enable the production of digitally printed payment and financial cards (as well as identity cards). This is highly beneficial, allowing the benefits associated with digital printing, such as variable data, personalization, on-demand printing, and even printing of individual security features, to be realized. The inventors have shown that the use of a primer according to the present invention is key to ensuring that print quality is maintained and good lamination bond strength is achieved when the primed and printed card core is heat laminated to additional plastic plies at temperatures exceeding 100°C. The use of a primer according to the present invention is also important to prevent dye leaching.

[0027] These significant advantages provided by the present invention enable digital print manufacturing of payment and financial cards, which is not currently possible.

[0028] Furthermore, the present invention enables the market desired shift from analog to digital printing of such cards.

[0029] A primer according to the present invention is first applied to a plastic card core, allowed to dry, and then digitally printed to produce the desired image and information, after which the printed core is heat laminated to a further plastic layer and subjected to any other manufacturing processes such as the inclusion of a hologram or the like.

[0030] After a substrate (e.g., card core) is coated with the primer of the present invention, it may be subsequently overprinted by any digital process, including liquid electrophotographic (toner) printing, dry electrophotographic (toner) printing, and inkjet printing. In the case of inkjet printing, the present invention is particularly suitable for printing with aqueous inkjet printing inks, but also allows for printing with UV and energy curable inkjet printing inks, as well as solvent-based inkjet printing inks. However, the present invention is particularly suitable for liquid electrophotographic (toner) printing, such as Hewlett Packard's "HP Indigo" process.

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

[0032] The primer according to the present invention also includes an aminated polymeric cross-linking reagent, which is poly(ethyleneimine). The poly(ethyleneimine) may have a linear or branched structure, but preferably has a branched structure. As will be appreciated, the poly(ethyleneimine) has amine functional groups on the polymer backbone. When the poly(ethyleneimine) is branched, the poly(ethyleneimine) may have amine functional groups on pendant side chains in addition to the polymer backbone. Preferably, the poly(ethyleneimine) is branched and has amine functional groups on the polymer backbone and pendant side chains.

[0033] The primers of the present invention may also optionally contain additional aminated polymers such as poly(vinylamine), copolymers of vinylamine, aminated starch, amine-functional poly(ethylene glycol), amine-functional poly(propylene glycol), and blends thereof.

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

[0035] The poly(ethyleneimine) may have an average molecular weight of 10,000 g / mol or more, for example, from about 10,000 g / mol to about 50,000 g / mol. Preferably, the poly(ethyleneimine) may have an average molecular weight of 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 primers of the present invention may also optionally contain additional crosslinking reagents such as heat-activated blocked isocyanates, polycarbodiimides (e.g., Carbodilite, manufactured by Nisshinbo), oxazoline-functional polymer crosslinkers (e.g., Epocros, manufactured by Nippon Shokubai), melamine-formaldehyde (e.g., Maprenal, manufactured by Ineos Melamines), zinc ammonium carbonate solution, zinc oxide nanoparticles (e.g., Oxylink, manufactured by Buhler).

[0037] The primers of the present invention may optionally further comprise a thermally blocking isocyanate. If used, the thermally blocking isocyanate is preferably present in an amount of 0.5 to 5 weight percent of the primer composition.

[0038] As understood in the art, blocked isocyanates are a class of crosslinkers in which the reactive isocyanate groups of the crosslinker have been reacted with a suitable blocking agent. Thus, a heat-activated blocked isocyanate crosslinker is a blocked isocyanate that can be unblocked (i.e., activated) upon heating, for example, above 80°C. Typically, heat-activated blocked isocyanate crosslinkers are unblocked (i.e., activated) at temperatures between 90 and 200°C, preferably between 100 and 180°C. Examples of blocking agents and their typical unblocking temperatures are diethyl malonate ("DEM," 100-120°C), 3,5-dimethylpyrazole ("DMP," 110-120°C), methyl ethyl ketoxime ("MEKO," 140-160°C), and caprolactam (160-180°C). Such blocked isocyanates, which may be difunctional, trifunctional, tetrafunctional, or higher in terms of 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 blocked isocyanate crosslinkers used in the preparation of the primers of the present invention are advantageously water-based. Trixene BI220 (e.g., Lanxess) was used in the preparation of the examples. The blocking group used in the preparation of Trixene BI220 is DMP, thus allowing for unblocking at temperatures typical of those used in the thermal lamination manufacturing of payment and financial cards, e.g., 120-160°C. Blocked 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 present invention, the primer composition preferably does not include additional crosslinking reagents such as heat-activated blocked isocyanates, polycarbodiimides, oxazoline-functional polymer crosslinkers, melamine-formaldehyde, zinc ammonium carbonate solution, zinc oxide nanoparticles, etc. For example, in an alternative preferred embodiment, the primer does not include heat-activated blocked isocyanates.

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

[0041] The crosslinker may form 0.5 to 25%, preferably 0.5 to 20%, more preferably 0.5 to 15% by dry weight of the primer composition.

[0042] Preferably, the polymer of the polymer dispersion forms 2.5 to 99.5% (w / w) of the primer composition, preferably 10.0 to 98%, more preferably 20.0 to 95%, by dry weight.

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

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

[0045] Alternatively, the primer according to the present invention preferably comprises an acrylic dispersion. Anionic, cationic and nonionic acrylic dispersions may be used, but nonionic acrylic dispersions are preferred. A suitable commercially available acrylic dispersion that can be used in the present invention is Alberdingk EP 124181 manufactured by Alberdingk-Boley.

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

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

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

[0049] Primers according to the present invention may optionally further comprise a polyurethane dispersion ("PUD") in which the polyurethane is prepared from a polyetherdiol, a polyacrylic diol, or a polycarbonate. For example, the primer composition may comprise a polyurethane prepared from a polyetherdiol (i.e., a polyetherurethane). A suitable polyetherurethane is Rheolate 278, available from Elementis. When used, the additional polyetherurethane is present at 0.01 to 5 weight percent of the primer composition. Typically, the additional polyetherurethane is used as a thickener to achieve the desired viscosity.

[0050] Anionic, cationic, and non-ionically stabilized PUDs are encompassed by the present invention, as are aromatic and aliphatic PUDs.

[0051] When the primer composition of the present invention further comprises a PUD prepared from a polyether diol, polyacrylic diol, or polycarbonate, anionic PUDs can be used, particularly those typically produced by incorporating carboxylic acids into the PUD's polymer structure, for example, by the urethane reaction of dimethylolpropionic acid ("DMPA"). When DMPA or other acid-containing species is incorporated into the PUD backbone, it can be neutralized with any organic or inorganic base to provide an anionic stabilization mechanism. These various resin types can be neutralized, where applicable, using organic bases including, but not limited to, ammonia, triethanolamine, triisopropanolamine, dimethylaminoethanol, N-methyldiethanolamine, or arginine. Alternatively, they may 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] There are a variety of commercially available PUDs that can be used in the present invention, including those sold under the trademarks Neorez (DSM), Bayhydrol (Covestro), Sancure (Lubrizol), Syntegra (Dow), Luplen (BASF), Beetafin (BIP), Daotan (Allnex), and those supplied by Albardingk-Boley under the "U" nomenclature.

[0053] Typically, the polymer dispersions used in the present invention have a solids content of 20 to 50%, preferably 25 to 45%.

[0054] The water-based primer of the present invention may also optionally further comprise any ionic or nonionic styrene-acrylic dispersion. Suitable styrene-(meth)acrylic resin dispersions are widely available commercially, including those sold under the trade names Joncryl (BASF), Revacryl (Synthomer), Hycar (Lubrizol), Neocryl (DSM), Neboplast (Necarbo), and Picassian AC range (Picassian Polymers). It should be understood that this is not a limiting list, and those skilled in the art will recognize that any other styrene-(meth)acrylic resin dispersion can be used.

[0055] The water-based primer of the present invention may also optionally further comprise any solution polymer (also referred to as an alkali-soluble polymer), including alkali-soluble acrylic polymers and styrene-acrylic polymers. As will be understood, alkali-soluble polymers typically refer to polymers that typically contain acid moieties as part of the monomer blend and can be neutralized with a suitable base, including but not limited to ammonia, an amine (e.g., triethylamine or triethanolamine), or an inorganic base (e.g., NaOH, KOH), to form a polymer that can be dissolved in water to form an aqueous solution. When alkali-soluble acrylic or styrene-acrylic polymers are used, they include those containing acrylic acid, methacrylic acid, maleic anhydride, or itaconic acid, along with any blend of ethylenic, acrylic, or methacrylic monomers, including, but not limited to, styrene, methyl methacrylate, butyl acrylate, butyl methacrylate, ethyl acrylate, ethyl methacrylate, ethylhexyl acrylate, and ethylhexyl methacrylate. Aqueous solutions of these acrylic polymers are formed by dissolving the polymer in water while neutralizing the carboxylic acid groups of the polymer with any base, including but not limited to ammonia, trimethylamine, triethanolamine, sodium hydroxide, and potassium hydroxide.

[0056] The primer according to the present invention may optionally further contain a polyvalent metal salt. When present, the polyvalent metal salt 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 cation salts such as calcium nitrate (and its hydrates), calcium ammonium nitrate, calcium acetate, and calcium chloride. Preferably, the primer according to the present invention contains less than 20% (w / w) of calcium nitrate (and its hydrates), calcium ammonium nitrate, calcium acetate, or calcium chloride, more preferably less than 10% (w / w) of calcium nitrate (and its hydrates), calcium ammonium nitrate, calcium acetate, or calcium chloride, and even more preferably less than 5% (w / w) of calcium nitrate (and its hydrates), calcium ammonium nitrate, calcium acetate, or calcium chloride.

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

[0058] The primer composition according to the present invention contains water. Advantageously, the water does not contain 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 present invention, including that supplied as part of the raw materials used, is 20 to 80% by mass, preferably 30 to 70% by mass, based on the total composition.

[0059] The primer may also optionally contain any co-solvent, including, but not limited to, ethanol, propanol, butanol, acetone, propylene glycol, glycerol, glycol ethers.

[0060] The primer may also optionally include any number of additives, including, but not limited to, surfactants, wetting aids, defoamers, degassing agents, biocides, etc. While suitable additives are described herein, it should be understood that the invention is not limited to those additives.

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

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

[0063] The primer may be suitable for application by any suitable printing or coating method, including but not limited to, flexography, gravure printing, screen printing, roller coating, spray coating, hi one embodiment, flexography and screen printing are deposition methods.

[0064] Because the primer of the present invention is primarily aqueous in nature, it may also contain a biocide or antifungal agent. Suitable examples include products based on the following biocide structural types: benzo-isothiazolinone, bromo-nitro-propane-diol, isothiazolinone, ethylenedioxydimethanol, or iodo-propynyl butylcarbamate, which are commercially available under the trade names Intercide (Akcros Chemicals) or Nipacide (Clariant). Other types of biocides that may be considered include sodium dehydroacetate (Geogard 111S from Lonza), sodium benzoate (Vancide 51 from RTVANDERBILT), sodium pyridinethiol-1-oxide (Sodium Omadine from Arch Chemicals), sodium salt of o-phenylphenol (Dowicide A from DOW Chemical), and ethyl p-hydroxybenzoate (Nipastat Sodium from Aako). These are typically used in primer compositions in amounts of 0.01 to 1.00% by weight.

[0065] Antifoaming agents can also be optionally included in the formulation to prevent foam formation during primer production and printing. Antifoaming agents are particularly important for recirculating printheads. Examples of suitable antifoaming agents 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. Additives DC62, DC65, DC 68, DC71, and DC74 are available from Dow Corning. Agitan 120, 150, 160, 271, 290, 298, 299, 350, 351, 731, 760, 761, and 777 are available from Munzing. 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 provide the desired spreading and wetting on the substrate. They can also be used to control the level of slip and scratch resistance of the coating. Examples of suitable surface control additives include, but are not limited to, TEGO FLOW 300, 370 and 425, TEGO GLIDE 100, 110, 130, 406, 410, 411, 415, 420, 432, 435, 440, 482, A115 and B1484, TEGO GLIDE ZG 400, TEGO RAD 2010, 2011, 2100, 2200N, 2250, 2300, 2500, 2600, 2650 and 2700, TEGO TWIN 4000 and 4100, TEGO WET 240, 250, 260, 265, 270, 280, 500, 505 and 510, and TEGO WET KL245, all of which are available from Evonik. 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 are available from BYK. EBECRYL 350 and 1360, MODAFLOW 9200, and EBECRYL 341 are available from Cytec. Aliphatic silicone acrylate CN9800 may be used from Sartomer. Surfynol 104, 420, 440, 465, 485, 61, 82, and 2502 are available from Air Products. Multiwet BD, EF, SU, SO, and VE are available from Croda. Capstone FS-30, 31, 34, 35, 50, 51, 60, 61, 63, 64, 65 and 3100 are available from DuPont. The non-ionic Hydropalat range from BASF is also suitable for use.

[0067] The primer may optionally contain a suitable degassing agent to prevent air entrapment and pinhole formation in the dried coating, which can affect the performance of the primer. 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 aqueous primer of the present invention is colorless. Alternatively, the aqueous 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 disazobenzimidazoles, rhodamine, indigoid, quinacridone, diazopyranthrone, dinitroaniline, pyrazole, dianisidine, pyranthrone, tetrachloroisoindoline, dioxazine, monoazoacrylate, and anthrapyrimidine. Dyes include, but are not limited to, azo dyes, anthraquinone dyes, xanthene dyes, azine dyes, combinations thereof, and the like.

[0069] The following trade names are used: 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, P Commercially available organic pigments classified according to the Color Index International may be used, including, but not limited to, R224 and PR254: blue-violet pigments PV19, PV23, PV32, PV37, and PV42; black pigments PBk1, PBk6, PBk7, PBk8, PBk9, PBk10, PBk11, PBk12, PBk13, PBk14, PBk17, PBk18, PBk19, PBk22, PBk23, PBk24, PBk25, PBk26, PBk27, PBk28, PBk29, PBk30, PBk31, PBk32, PBk33, PBk34, PBk35, NBk1, NBk2, NBk3, NBk4, NBk6; combinations thereof, and the like.

[0070] The pigment is milled to less than 1 micrometer after milling, and has a particle size distribution of 10-500 nm or 10-350 nm, so as to have better transparency and a wide color gamut.

[0071] To incorporate the pigments into the compositions of the present invention, they can be prepared and stored stably as pigment concentrates in water. This is typically achieved by dispersing the pigment in a water-soluble or water-dispersible resin using a water-soluble and / or water-dispersible surfactant that introduces hydrophilic functional groups onto the surface of the pigment particles. Examples of these dispersing resins are numerous and include polyvinyl alcohol, polyacrylic acid, acrylic acid-acrylonitrile copolymers, vinyl acetate-acrylate copolymers, acrylic acid-acrylate copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylate copolymers, styrene-α-methylstyrene-acrylic acid copolymers, styrene-α-methylstyrene-acrylic acid-acrylate copolymers, styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, vinyl naphthalene-acrylic acid copolymers, vinyl naphthalene-maleic acid copolymers, vinyl acetate-maleate copolymers, vinyl acetate-crotonic acid copolymers, and vinyl acetate-acrylic acid copolymers, as well as salts thereof. The copolymer can be used in any form, including 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 sodium hydroxide, potassium hydroxide, and salts of basic compounds such as ammonia, ethylamine, diethanolamine, triethanolamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, diethanolamine, triethanolamine, triisopropanolamine, dimethylethanolamine, aminomethylpropanol, and morpholine. The amount of basic compound is not strictly limited, as long as the resin dispersant is at least the neutralization equivalent.

[0072] Examples of surfactants used in the preparation of pigment dispersions include anionic surfactants such as alkanesulfonates, α-olefinsulfonates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, acylmethyltaurates, dialkylsulfosuccinates, alkyl sulfates, sulfurized olefins, polyoxyethylene alkyl ether phosphates, polycarboxylic acids, and monoglycerol phosphates; amphoteric surfactants such as alkylpyridinium salts; and nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamides, glycerol alkyl esters, and sorbitan alkyl esters. Examples include EFKA 1000, 4000, 5000, and 6000 series products from BASF, Tamol series products from Dow, and Solsperse 27,000, 40,000, 44,000, 46,000, and 47,000 from Lubrizol.

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

[0074] The primer of the present invention is preferably applied to the plastic core of a 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 from polyvinyl chloride acetate, polyvinyl chloride, polyvinylidene dichloride, or any blend of these polymers or copolymers. However, it should be understood that the primer is suitable for coating any plastic core used in the manufacture of payment cards and financial cards.

[0075] After the substrate (e.g., card core) is coated with the primer of the present invention, it is then printed by any digital printing process as previously outlined. Preferably, the primed core is printed by a liquid electrophotographic process such as Hewlett Packard's "Indigo."

[0076] In one embodiment, the dried film weight 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 to 5.0 gm -2 , more preferably 0.2 to 5.0 gm -2 The range is.

[0077] The printed and primed core is then heat-laminated to an additional plastic layer, which can 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 contacting the plastic layer to be laminated with the printed core and subjecting the plastic layer to temperatures typically between 120 and 160°C under pressure, although lower and higher temperatures can also be used. Pressures greater than 5 psi are typically used, more typically greater than 10 psi. Heat lamination typically takes anywhere from 0.1 seconds up to 30 minutes.

[0078] The inventors have found that without the primer of the present invention, cards produced by Indigo printing lack lamination bond strength and are prone to leaching. The primer provides a lamination bond strength of at least 5 N / cm, at least 7 N / cm, at least 10 N / cm, at least 15 N / cm, or at least 17 N / cm to the final card structure.

[0079] definition Molecular weight - "molecular weight" or "average molecular weight" refers to weight average molecular weight (Mw). Molecular weight is suitably measured by techniques known in the art, such as gel permeation chromatography. Preferably, molecular weight is measured by comparison with polystyrene standards. For example, molecular weight determination can be carried out on a Hewlett-Packard 1050 series HPLC system equipped with two GPC Ultrastyragel columns (5 μm mixed, 300 mm × 19 mm, Waters Millipore Corporation, Milford, Massachusetts, USA) of 103 Å and 104 Å, using THF as the mobile phase. Those skilled in the art will understand that this definition of molecular weight typically applies to polymeric materials with a molecular weight distribution.

[0080] Particle size / average particle size - The term "particle size" or "average particle size" refers to the volume distribution median particle size (the equivalent spherical diameter corresponding to the volume of 50% of the total particles, as read on a cumulative distribution curve relating volume % to particle diameter, often referred to as the "D(v,0.5)" value). Particle size is preferably measured by laser light diffraction.

[0081] Unless otherwise specified, the term nanoparticle refers to a particle having one dimension less than 100 nm.

[0082] Unless otherwise specified, lamination bond strength was measured using a JJ Lloyd tensiometer by T-peel test at a separation speed of 300 mm / min. Lamination bond strength is reported as N / cm. This is the force required to separate the top film from the primed, 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 primed, printed core for a 25 cm wide strip. Ideally, the minimum adhesive strength is 5 N / cm or greater, 7 N / cm or greater, 10 N / cm or greater, 15 N / cm or greater, 17 N / cm or greater, or 20 N / cm or greater.

[0083] Unless otherwise stated, viscosity was measured using a Brookfield CAP200 viscometer equipped with spindle No. 4 at 50 rpm and a temperature of 19.1°C.

[0084] leaching Black inks are very often toned with reflective (alkali) blue pigments. Toning carbon black with alkali blue can make deep black tones more aesthetically tame. However, alkali blue is primarily a dye, and under certain conditions, such as when exposed to moisture / heat and / or high relative humidity (e.g., 50°C / 90% RH), the blue dye can leach from the black ink, causing the black printed image (in this case, HP Indigo) to appear significantly bluer, which is undesirable, as in the case of credit card laminates. The leaching effect is also evident in fine text, where a blue shadow can be seen surrounding the outline of black letters, and when peeled, the laminate adhesive appears blue due to the migration of alkali blue. This leaching issue is addressed by invention examples 1 and 2, which provide dye-fixing properties, thus stopping the leaching of blue dye throughout the printed image.

[0085] Inventive Example 1 addresses the leaching problem with 0.53 wt% poly(ethyleneimine). In contrast, dye leaching is still observed in Reference Example 5, which contains only 0.30 wt% poly(ethyleneimine). Therefore, it will be understood by those skilled in the art that a water-based primer with less than 0.3 wt% poly(ethyleneimine) provides good lamination bond strength but does not solve the dye leaching problem.

[0086] Although the present invention has been described in detail, including various embodiments thereof, it will be appreciated that those skilled in the art, upon consideration of this disclosure, may make modifications and / or improvements to the invention which fall within the scope and spirit of the invention.

[0087] example The present invention is further illustrated by the following non-limiting examples which further illustrate the invention and are not intended, nor should they be construed, to limit the scope of the invention.

[0088] Preparation of flexo primers and screen primers according to the present invention Primer coatings were prepared according to the formulations shown in Table 1. The ingredients were added sequentially, with the polymer dispersion being used first, and blended in a Dispermat high shear mixer.

[0089] [Table 1]

[0090] Viscosity (poise) was measured using a Brookfield CAP200 viscometer, spindle No. 4, 50 rpm, and 19.1°C.

[0091] Example explanation Reference Example 1: Flexographic PUD primer formulation with blocked isocyanate dispersion crosslinker.

[0092] Reference Example 2: Screen print PUD primer formulation with blocked isocyanate dispersion crosslinker.

[0093] Reference Example 3: A PUD primer formulation comprising an oil-in-water emulsion of ethylene acrylic acid copolymer, a blocked isocyanate dispersion crosslinker, and a carbodiimide crosslinker.

[0094] Reference Example 4: A PUD primer formulation comprising an oil-in-water emulsion of ethylene acrylic acid copolymer, a blocked isocyanate dispersion crosslinker and an anionic dispersion of PU polyol.

[0095] Inventive Example 1: A screen printing polyester polyurethane primer formulation containing 0.53 wt% multifunctional cationic polyethyleneimine crosslinker with improved leaching resistance.

[0096] Inventive Example 2: Screen printing acrylic primer formulation containing a multifunctional cationic polyethyleneimine crosslinker with improved leaching resistance.

[0097] Reference Example 5: Screen printing polyester polyurethane primer formulation containing 0.3 wt% multifunctional cationic polyethyleneimine crosslinker.

[0098] 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 ranging from 2.5 to 3.5 gsm (dry). The primed PVC core was then printed with liquid electrophotographic inks using an HP Indigo sheet-fed press. The primed and printed core was then heat-laminated to a second flexible PVC film under various conditions according to Table 2. Lamination bond strength was measured using a JJ Lloyd tensiometer with a T-peel test at a separation speed of 300 mm / min, a type of test well understood by those skilled in the art. Lamination bond strength is reported as N / cm. This is the force required to separate the top PVC film from the primed and printed core for a 1 cm wide strip.

[0099] Adhesion was measured by tape testing using 3M Scotch Magic Tape®, which was placed on the surface of the print substrate and rolled five times with a 2 kg roller according to ASTM F2252 / 52252M-13(2018). Ink removal was then recorded as a%. All inventive examples passed the tape test, indicating good adhesion.

[0100] Without either primer, poor ink transfer to the vinyl card core was observed, as well as poor adhesion as assessed by tape test.

[0101] [Table 2]

[0102] The results in Table 2 show that the primers of the present invention provide improved lamination bond strength compared to the absence of primer. As shown in the results in Table 3, Inventive Examples 1 and 2 also prevent the leaching of alkaline blue dye from the indigo black ink.

[0103] [Table 3]

[0104] Test methods for assessing leachability HP Indigo ink with alkaline blue dye was diluted with Isopar in a 2:1 ratio (2 parts black ink: 1 part Isopar) and printed using a 40 micron k-bar depositing a wet coat weight of approximately 40 gsm onto a section of HP EPDM image transfer blanket.

[0105] Once coated, the rubber is transferred to a 160°C hotplate until all the solvent has evaporated, leaving only the ink as a film layer. The blanket is then placed ink-side down on a pre-primed PVC substrate, and a 2 kg hand roller is used several times to apply pressure to the surface. The print is then left to cool completely before further testing.

[0106] Lamination: The ink is printed onto a pre-primed substrate and allowed to cool completely. The black ink-printed area is cut into strips and laminated to a PVC overlay using a heat sealer (140°C / 40 psi / 20 seconds). The strips are then cut into 25 mm strips and divided into sections. One section is placed in a humidity-controlled oven at 50°C / 90% RH / 7 days, while the remaining sample is left in a controlled, dark environment. Visual and color measurements are taken on the humidity-aged samples and the samples stored in a controlled environment.

[0107] X-Rite (provides LAB and ΔLAB results) Method: Samples are measured for color change using an X-rite spectrometer, which measures the following parameters to provide a numerical value indicating color change:

[0108] Delta E is a standard measurement that quantifies the difference between two colors using a combination of dL*, da*, and db*.

[0109] Delta E is measured on a scale of 0 to 100, with values ​​below 1.0 generally imperceptible to the human eye. Values ​​in the range of 1.0 to 2.0 are perceptible through close observation. Values ​​from 2.0 to 10 are perceptible at first glance. Values ​​in the range of 11 to 49 are significantly different colors. Values ​​above 49 are considered inconsistent.

[0110] dL* represents the difference in lightness / darkness between the two measurements.

[0111] Samples that exhibit less leaching have lower values ​​of ΔE(DEcmc) and ΔL than samples where leaching is observed.

[0112] Visual Color Assessment: Samples aged in a humidity controlled oven (described above) are visually compared and assessed against unaged samples. No color change is considered a pass, a slight visual color change is considered a marginal pass, and a significant visual color change is considered a fail.

[0113] Table 3 shows the improvement of Inventive Examples 1 and 2 in terms of reduced measured color change values ​​and reduced visual color change. Inventive Examples 1 and 2 are therefore particularly well suited for applications where reduced leaching is desirable.

Claims

1. 1. An aqueous primer composition comprising: (i) a polymer dispersion selected from an acrylic dispersion, a polyester urethane dispersion, or a blend thereof; and (ii) an aminated polymer, wherein the aminated polymer is poly(ethyleneimine), and the poly(ethyleneimine) is present at 0.5 to 25% (w / w).

2. The primer composition of claim 1 wherein the polymer dispersion is a polyester urethane dispersion and the aminated polymer is poly(ethyleneimine).

3. The primer composition of claim 1 wherein the polymer dispersion is an acrylic dispersion and the aminated polymer is poly(ethyleneimine).

4. The primer composition of claim 1 , wherein the polymer dispersion forms more than 40% (w / w) of the total composition.

5. 5. The primer composition according to claim 1, comprising 0.5 to 20% (w / w) of the aminated polymer, preferably 0.5 to 15% (w / w) of the aminated polymer.

6. The primer composition of any one of claims 1 to 5, wherein the poly(ethyleneimine) has a molecular weight of about 10,000 g / mol to about 50,000 g / mol.

7. 7. The primer composition of any one of claims 1 to 6, wherein the polymer of the dispersion forms, by dry weight, 2.5 to 99.5% of the primer composition, preferably 10.0 to 98% of the primer composition, more preferably 20.0 to 95% of the coating composition.

8. 8. The primer composition of any one of claims 1 to 7, having a total solids content of 5.0 to 60.0% (w / w), more preferably 5.0 to 40.0% (w / w).

9. 9. The primer composition of claim 1, which is substantially free of polyvalent metal salts (i.e., contains less than 1% w / w of polyvalent metal salts).

10. 10. The primer composition of any one of claims 1 to 9, comprising less than 1% (w / w) of calcium nitrate, calcium ammonium nitrate, calcium acetate, calcium chloride or blends thereof, preferably less than 0.5% (w / w) of calcium nitrate, calcium ammonium nitrate, calcium acetate, calcium chloride or blends thereof.

11. 11. The primer composition of claim 1, which does not contain any calcium nitrate, calcium ammonium nitrate, calcium acetate, or calcium chloride.

12. 12. The primer composition of any one of claims 1 to 11, comprising 20 to 80% water by weight of the composition, preferably 30 to 70% water by weight of the composition.

13. 13. A method of providing a primed substrate comprising applying the primer composition of any one of claims 1 to 12 and allowing the primer to dry.

14. The method of claim 13, wherein the substrate is polyvinyl chloride (PVC).

15. 15. The method of claim 13 or 14, wherein the primer is applied to the substrate by flexographic printing, gravure printing or screen printing.

16. 13. A method of providing a primed and printed substrate, comprising applying a primer composition according to any one of claims 1 to 12, allowing the primer to dry, thereafter printing one or more inks over the primer, and thereafter allowing the one or more inks to dry.

17. 17. The method of claim 16, wherein the substrate is polyvinyl chloride (PVC).

18. 18. The method of claim 16 or 17, wherein the primer is applied to the substrate by flexographic printing, gravure printing or screen printing.

19. 19. The method of claim 16, 17 or 18, wherein the one or more inks are printed onto the primed substrate by digital printing, preferably by liquid electrophotography (Indigo), dry electrophotography (toner) or inkjet printing.

20. 20. The method of any one of claims 13 to 19, wherein the primed and printed substrate is subjected to thermal lamination to one or more further plastic layers.

21. 21. The method according to claim 20, wherein said heat lamination of the further plastic layer is carried out at 80°C or higher, preferably 100°C or higher.

22. a. applying the primer composition of any one of claims 1 to 12 onto a first substrate; b. Allowing the primer to dry; c. overprinting the primed substrate with one or more digital inks; d. Allowing the one or more digital inks to dry; e. laminating a second substrate to the primed and printed first substrate at 80°C or above to produce a laminate structure; 1. A method for preparing a laminated structure, comprising:

23. 23. The method of claim 22, wherein the laminating is performed at 100°C or above.

24. 24. A laminate structure prepared by the method of claim 22 or 23.

25. 25. The laminate structure of claim 24, which is a plastic payment card.

26. 13. Use of an aqueous primer composition for reducing dye leaching in a laminate structure, wherein the aqueous primer composition is as defined in any one of claims 1 to 12.

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