Ink & coatings with oxygen barrier properties

Abstract

Printing ink and coating compositions having good gas barrier properties such as water vapor barrier properties and oxygen barrier properties.

Description

[0001] INK & COATINGS WITH OXYGEN BARRIER PROPERTIES

[0002] The invention relates to an ink with oxygen barrier properties.

[0003] BACKGROUND OF THE INVENTION

[0004] Background Documents:

[0005] JP6075623B2:

[0006] Refers to the use of a gas-barrier polyester polyol made from ethylene glycol, glycerol and phthalic anhydride cured with a polyisocyanate to produce a film with high oxygen and vapor barrier properties. Such film is claimed to have high adhesive strength, resulting in a gas barrier film laminate. The application does not describe how to formulate a pigmented or clear coating with oxygen barrier properties. Additionally, glycerol is not present in the polyester resin of the present invention.

[0007] JP6405874B2:

[0008] Refers to a resin composition containing at least one dicarboxylic acid selected from the group consisting of isophthalic acid, orthophthalic acid, and phthalic anhydride, an aliphatic dicarboxylic acid having 3 to 5 carbon atoms, an aliphatic diol having 2 to 4 carbon atoms and an aminoalcohol having a number of 2 to 4 carbon atoms used to produce a gas-barrier adhesive when combined with an aromatic polyisocyanate. No description is provided on how to use such combination to formulate a pigmented or clear coating with oxygen barrier properties. Additionally, no amide functionality is contained in the polyester resin of the present invention.

[0009] Applicants acknowledge the following references attributed to Dainippon Ink & Chemicals (applicants’ parent company):

[0010] JP 2016 079285; JP 2013 116961; WO 2022 / 172760; WO 2020 / 045027:

[0011] All of these references are drawn to adhesive compositions while the present application is drawn to printing inks. Applicants show that an adhesive is not suitable for use as a printing ink.

[0012] EP 3395570;; JP 2018 001539:

[0013] These references are drawn to laminate structures and adhesives and do not mention the ink compositions of the present application.

[0014] JP 2016 006140; JP 2013 129735:

[0015] These references are compositional in nature but do not mention the ink compositions of the present application.

[0016] Packaging materials typically used in the food & beverage sector require strength, resistance to cracking, retort resistance, and heat resistance to protect the contents from various stresses, which can be mechanical, thermal etc.

[0017] To seal the package, a non-stretched polyolefin film with good heat processability is required, but such polyolefin film has many functions when used as a packaging material. One particularly desirable property is to serve as a gas-barrier for the purpose of maintaining the quality and extending the shelf-life of the package contents.

[0018] When imparting a barrier function to a multilayer film, it is difficult to impart the barrier function to the unstretched polyolefin film used for the inner layer (sealant side) by coating or vapor deposition. Therefore, various films such as polyethylene terephthalate (PET) and other polyester resins, polyamide resins, and oriented polyolefin resins used for the outer layer are often provided with a barrier function.

[0019] To impart gas barrier properties, there are means such as laminating metal foil (e.g. aluminum); coating or laminating other resins having high gas barrier properties; and vapordepositing aluminum or silicum. However, there are problems associated with these processes, such as loss of transparency, the need for a complicated and non-environmentally friendly manufacturing process, and loss of mechanical performance.

[0020] Moreover, these multi-layer packaging materials are more difficult to recycle as they are made with aluminum foil and plastic films differing in chemical nature. This has steered the technology towards gas barrier solutions based on mono-material laminates.

[0021] Conventionally, polymers that contain a high-density of hydrogen bonding groups with high hydrophilicity in their molecules, for example polyvinyl alcohol (PVOH) and ethylene vinyl alcohol (EVOH), are used as gas barrier polymers.

[0022] EVOH and PVOH are known to be humidity-sensitive and due to their high crystallinity, may impair film stretchability and have poor thermal stability. Due to their hydrophilic nature, both EVOH and PVOH tend to absorb water in the form of water vapor from the atmosphere and such water molecules can disrupt the hydrogen bond lattice and thus disrupt the barrier properties of the material.

[0023] The present application is directed to gas barrier inks and coatings, comprising phthalic anhydride-based polyester resins. In the present case, barrier performance stems from high- density aromatic ring regions. Such regions are not hydrophilic, so water is unable to penetrate this type of lattice, providing enhanced barrier properties.

[0024] To the inventors’ knowledge, this is the first instance where the specific compositions of the present application and their use as inks and coatings is described, especially in white inks for use as a mono-component ink or cured with an aromatic polyisocyanate. This type of chemistry would typically be used in adhesives, but until now, has not been described for use in inks and coatings.

[0025] In the present application the terms “gas barrier” and “oxygen barrier” are both used. Though the main focus of the present application is to provide inks and coatings with oxygen barrier properties, it is understood that such inks and coatings would also have barrier properties for other gasses (e.g. CO2, and N2), as well as water vapor, odors, pollutants, etc.

[0026] In addition to oxygen-barrier properties, the printing ink serves the secondary role of being decorative on packaging structures. White ink is of particular importance on packaging structures as it often used as a backing ink providing a continuous layer on the printed material. In the packaging industry, a full-coverage white ink layer is often used to protect colours and graphics from damage along the converting chain, especially when laminated into a multi-layer material, since the interaction with laminating adhesive may affect the visual outcome of the print. This means white ink can serve the dual role of a backing white with barrier properties.

[0027] Using a gas-barrier white ink removes the extra conversion step required by the need for a separate barrier coating, applied either as a primer (before applying inks), or as a topcoat (over the top of inks) typically applied in offline processes.

[0028] Citation or identification of any document in this application is not an admission that such represents prior art to the present invention.

[0029] DETAILED DESCRIPTION

[0030] The chemistry described in the present application would be typically used for laminating adhesive applications. It would not be apparent to one skilled in the art to use the technology to formulate printing inks or coatings. Printing inks are significantly different from laminating adhesives, as the inks must not retain any significant tackiness after drying, while adhesive performance is dependent on residual tackiness1.

[0031] ’All of the inventive inks and coatings in the Examples section below dried to a tack-free finish. Inventive Examples 11, 12 & 14 were tested for blocking and were shown to be resistant to blocking - see Table 2. Conversely, laminating adhesives are, by nature, tacky after drying in order to impart adhesive properties. To demonstrate this, a blocking test was performed on a standard commercial laminating adhesive using the testing protocol described in the test methods section of this application. As expected, the adhesive was tacky after drying and exhibited severe blocking as this is the role of a laminating adhesive.

[0032] Further, the employed resins must be able to properly disperse pigments and provide performance characteristics that are different from adhesives, such as:

[0033] (i) developing colour strength

[0034] (ii) stabilizing powder materials that are dispersed in the inks

[0035] (iii) providing scratch resistance or other resistance properties

[0036] (iv) providing adhesion to substrates The goal of the present invention is to provide a printing ink or coating composition using general-purpose solvents, for example acetates and alcohols, and having good gas barrier properties such as water vapor barrier properties and oxygen barrier properties.

[0037] The ink compositions in the present solution comprise a polyester resin containing a polyester polyol, wherein the polyester polyol is a poly condensate mainly composed of ethylene glycol, phthalic anhydride and adipic acid preferably with a MW between 400 - 2000 g / mol, more preferably between 400 and 600 g / mol.

[0038] The resultant inks or coatings would preferably be used as a 2-part (2K) printing ink or coating curable with polyisocyanates to provide a gas-barrier printing ink or coating appropriate for various printing processes, for example flexo and gravure inks for surface printing and reverse printing, especially on laminated structures. Preferable end-use substrates include, but are not limited to, polyolefin-based films, for example polypropylene (PP), polyethylene (PE) and medium density polyethylene (MDOPE).

[0039] One embodiment of the present invention would use orthophthalic acid or its anhydride as one of the dicarboxylic acid components.

[0040] An aromatic polyvalent carboxylic acid having a carboxylic acid substituted at the ortho-position or an anhydride thereof has a small free volume pore between molecules due to 7t-stacking of benzene rings, and easily imparts a gas barrier function. In addition, since the substitution position is the ortho-position, rotational movement of the molecular chain is suppressed, which also imparts a high barrier function. In addition, the asymmetric structure also ensures the solubility in general-purpose solvents.

[0041] Another embodiment of the present invention would use an aliphatic dicarboxylic with a chain from 4 to 6 carbon atom to impart the final resin with solubility in ester-type solvents.

[0042] Another embodiment of the present invention would use other carboxylic acid compounds in combination as long as the performance of the inks, particularly the gas barrier function, is not impaired. In one embodiment, a vegetable oil-based compound is used in combination to increase the biological component of the raw material. Specific examples include coconut oil, rapeseed oil, sesame oil, corn oil, olive oil, etc., and saturated fatty acids that constitute these, lauric acid, myristic acid, palmitic acid, stearic acid, and unsaturated fatty acids. Examples include linoleic acid, oleic acid, etc.

[0043] Another embodiment of the present invention would use ethylene glycol as a main component as the dihydric alcohol. Ethylene glycol has only 2 carbon atoms between hydroxyl groups, so compared to polyester polyols, which have a longer chain alkyl in the skeleton, the free volume pores between molecules are smaller, making it more difficult for molecules like water and oxygen to pass through.

[0044] Another embodiment of the present invention would use a dihydric alcohol component other than ethylene glycol as long as it does not impair the performance of the inks, particularly the gas barrier function. Alkylene diols having 3 to 6 carbon atoms are preferable since too long an alkyl chain may degrade barrier function. These compounds include diols such as propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-l,5-pentanediol, 1,6- hexanediol, methylpentanediol and dimethylbutanediol. In a preferred embodiment 10% by mass or less of the total dihydric alcohol component would be used.

[0045] To give a specific example of the production method, ethylene glycol, phthalic anhydride and adipic acid used as raw materials are charged into a mixing vessel, and the temperature is raised, for example to about 200-220°C while stirring to cause a dehydration condensation reaction. Water must be removed from the reaction mixture to shift the reaction equilibrium towards the products. Alternatively, each raw material may be reacted in multiple stages. Alternatively, a diol component such as ethylene glycol volatilized at the reaction temperature may be added to adjust the hydroxyl value to within ±5% of the target value.

[0046] Although the reaction can proceed without a catalyst, a catalyst may be used. Catalysts used for the reaction include tin catalysts such as monobutyl tin oxide and dibutyl tin oxide; titanium catalysts such as tetra-isopropyl-titanate and tetra-butyl-titanate; and acids such as zirconia catalysts, for example tetra-butyl-zirconate catalysts. It is preferable to use a combination of the above titanium-based catalyst such as tetra-isopropyl-titanate, tetra-butyl- titanate, etc., which have high activity for the ester reaction. The amount of the catalyst used is preferably 1-1000 ppm, more preferably 10-100 ppm, relative to the total mass of the reaction raw materials used. If it is less than 1 ppm, it is difficult to obtain the effect as a catalyst, and if it exceeds 1000 ppm, the reaction may become difficult to control.

[0047] The number average molecular weight of the polyester polyol is not particularly limited as long as it satisfies the properties as a gas barrier material. A preferred range is 400-3000, more preferably 400-2000. If the molecular weight is less than 400, the amount of the curing agent may be too large, which may cause loss of mechanical properties due to excessive rigidity. On the other hand, if the molecular weight exceeds 3000, the solubility in general -purpose solvents such as ethyl acetate may deteriorate, and it may become difficult to use.

[0048] MW may be calculated considering the OH number expressed in mgKOH / g, using the following equations: (eqgiycoi - eqacid * 56,l(# / eq) * 1000 (mgKOH / g)

[0049] O l number (mgKOH / g) = reaction mass (g)

[0050] 56,l(g / eq) * 1000 (mgKOH / g)

[0051] Eqw g / eq) = OH number (mgKOH / g)

[0052] MW (g / mol) = Eqw g / eq) * f(eq / moV)

[0053] Where:

[0054] MW = molecular weight

[0055] Eqw = equivalent weight

[0056] 56.1 g / eq is the equivalent weight of KOH f= polymer functionality

[0057] In one embodiment, the printing ink would be a white ink with a dry component content of about 20-80%, preferably about 40-60%.

[0058] In the present invention, a co-resin could be used in order to improve, for example, the rheology of the ink. Preferred co-resins include polyurethanes, polyamides, ketonic, maleic, polyvinylderivatives (such as polyvinyl butyral and / or polyvinyl chloride) and / or cellulose derivatives such as nitrocellulose (NC), ethyl cellulose but more preferably cellulose acetate butyrate (CAB) or cellulose acetate propionate (CAP). In some applications it would be advantageous to minimize or eliminate the use of NC to prevent the formation of nitrosamines as well as provide better heat treatment (for example sterilization) and recycling properties. In applications where heat treatment is not required, NC may be suitable.

[0059] Though the present application is mainly directed to white inks and clear coatings, it is understood that the technology would also be suitable for use in inks with other colorants.

[0060] Suitable colorants include but are not limited to: organic or inorganic pigments and dyes. The dyes include but are not limited to fluorescent dyes, azo dyes, anthraquinone dyes, xanthene dyes, azine dyes, combinations thereof and the like. Organic pigments may be one pigment or a combination of pigments, such as for instance Pigment Yellow Numbers 12, 13, 14, 17, 74, 83, 114, 126, 127, 174, 188; Pigment Red Numbers 2, 22, 23, 48: 1, 48:2, 52, 52: 1, 53, 57: 1, 112, 122, 166, 170, 176, 184, 202, 210, 266, 269; Pigment Orange Numbers 5, 16, 34, 36; Pigment Blue Numbers 15, 15:3, 15:4; Pigment Violet Numbers 3, 23, 27, 32; and / or Pigment Green Number 7. Inorganic pigments may be one of the following non-limiting pigments: iron oxides, titanium dioxides, chromium oxides, ferric ammonium ferrocyanides, ferric oxide blacks, Pigment Black Number 7 and / or Pigment White Numbers 6 and 7. Other organic and inorganic pigments and dyes can also be employed, as well as combinations that achieve the colors desired.

[0061] In a further embodiment, the compositions of the present application could be formulated without colorants and employed as an overprint or clear coating.

[0062] In a preferred embodiment, the inks of the present invention would be used in conjunction with a suitable curing agent to provide a 2K (2-pack) system.

[0063] The curing agent used in the present invention is not particularly limited as long as it can react with the hydroxyl groups of polyols. In one embodiment, known curing agents such as polyisocyanate and epoxy compounds can be used.

[0064] In another embodiment an aromatic polyisocyanate would be chosen to impart gasbarrier enhancement.

[0065] Suitable polyisocyanate compounds include, for example, aromatic and aliphatic diisocyanates and polyisocyanates having a valence of 3 or more and may be either low- molecular-weight compounds or high-molecular-weight compounds. Examples include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate or trimers of these isocyanate compounds, and excess of these isocyanate compounds with amounts such as ethylene glycol, propylene glycol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4- bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, and adducts obtained by reacting with low-molecular- weight active hydrogen compounds such as diethanolamine, triethanolamine, meta- xylylenediamine and their alkylene oxide adducts, various polyester resins, polyether polyols, high-molecular active hydrogen compounds such as polyamides, etc.

[0066] The isocyanate compound may be a blocked isocyanate. Examples of isocyanate blocking agents include phenols such as phenol, thiophenol, methylthiophenol, ethylthiophenol, cresol, xylenol, resorcinol, nitrophenol and chlorophenol; oximes thereof such as acetoxime, methylethylketoxime and cyclohexanone oxime. Alcohols such as ethanol, propanol, and butanol; halogen- substituted alcohols such as ethylene chlorohydrin and l,3-dichloro-2- propanol; tertiary alcohols such as t-butanol and t-pentanol; examples include lactams such as caprolactam, 5-valerolactam, y-butyrolactam, and P-propyrolactam, and active methylene compounds such as aromatic amines, imides, acetyl acetone, acetoacetate, and ethyl malonate, mercaptans, imines, ureas, diaryl compounds, sodium bisulfite, and the like. The blocked isocyanate can be obtained by addition reaction of the above isocyanate compound and an isocyanate blocking agent by a conventionally known methods. Moreover, when the polyester resin is synthetized in excess of acid equivalents, an epoxy compound can be used as a curing agent. Epoxy compounds include diglycidyl ether of bisphenol A and its oligomers; diglycidyl ether of hydrogenated bisphenol A and its oligomers, diglycidyl orthophthalate, diglycidyl isophthalate, diglycidyl terephthalate, p-oxybenzoic acid di glycidyl ester, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, diglycidyl succinate, diglycidyl adipate, diglycidyl sebacate, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1 ,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether and polyalkylene glycol diglycidyl ethers, trimellitic acid triglycidyl ester, triglycidyl isocyanurate, 1,4-di glycidyl oxybenzene. Diglycidyl examples include propylene urea, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, triglycidyl ether of glycerol alkylene oxide adducts, and the like.

[0067] When an epoxy compound is used as a curing agent, a commonly known epoxy curing accelerator may be appropriately added for the purpose of accelerating curing as long as the gas barrier property, which is the object of the present invention, is not impaired.

[0068] Among them, the curing agent is preferably the above-mentioned polyisocyanate, and if it is a polyisocyanate containing the above-mentioned aromatic skeleton, gas barrier properties can be improved not only by hydrogen bonding of urethane groups but also by 7t-7t stacking between aromatic rings. Examples include polyisocyanates containing a toluene, a diphenylmethane and a m-xylilene skeleton.

[0069] The ink and the curing agent are preferably blended so that the hydroxyl groups and the reactive components of the curing agent are 1.0 / 0.6 to 1.0 / 2.0 (equivalence ratio), more preferably 1.0 / 0.8 to 1 / 1.1. If the curing agent component exceeds this range, the resulting cured ink may be too rigid and lose adhesion. If the curing agent is below this range the resulting cured ink may remain too soft and cause blocking issues.

[0070] In a 2K ink system, the base and the curing agent are blended in the desired ratio preferably immediately before use in the printing process. In the present system, once the base and curing agent are blended, the ink typically remains usable for up to about 6 hours, after which a significant increase in viscosity may be observed.

[0071] The curing agent may be used in combination with a known adhesion promoter or accelerator selected according to its nature. Examples of adhesion promoters include silane coupling agents such as hydrolyzable alkoxysilane compounds, titanate-based coupling agents, aluminum-based coupling agents, and epoxy resins. Silane coupling agents and titanate-based coupling agents are also preferable in terms of improving adhesiveness to various film materials. Various additives may be added to the ink or clear coating composition of the present invention as long as the gas barrier properties are not impaired in order to optimize properties such as blocking tendency. Examples of additives include inorganic fillers such as silica, alumina, mica, talc, aluminum flakes and glass flakes, layered inorganic compounds for improving the gas barrier function, stabilizers (antioxidants, heat stabilizers, ultraviolet absorption agents, etc.), plasticizers, antistatic agents, lubricants, antiblocking agents, coloring agents, fillers, crystal nucleating agents, waxes. Examples of layered inorganic compounds for improving the gas barrier function include hydrous silicates (phyllosilicate minerals, etc.); kaolinite group clay minerals (halloysite, kaolinite, endellite, dickite, nacrite, etc.); and antigorite; group clay minerals (antigorite, chrysotile, etc.); smectite group clay minerals (montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, stevensite, etc.); vermiculite group clay minerals (vermiculite, etc.), mica or mica group clay minerals (mica such as muscovite and phlogopite, margarite, tetrasilylic mica, teniolite, etc.). These minerals may be natural clay minerals or synthetic clay minerals.

[0072] The solvent is used as a reaction medium during the preparation of the polyester resin and curing agent, and as a diluent during ink / coating formulation and printing. Suitable solvents include, for example, esters such as ethyl acetate, butyl acetate; ketones such as acetone, methyl ethyl ketone (MEK), isobutyl ketone and cyclohexanone; ethers such as tetrahydrofuran and dioxane; and aromatics such as toluene and xylene.

[0073] In a preferred embodiment, the polyester resin composition and the polyisocyanate resin composition of the present invention uses ethyl acetate, which is commonly used in rotogravure printing process.

[0074] Care should be taken when using alcohol solvents, since they can react with the NCO- groups of the curing agent and can impair barrier effect. Hindered / longer chain alcohols like isopropanol, methoxypropanol, ethoxypropanol etc. are preferred to limit their reactivity.

[0075] In one embodiment, the inks of the present invention would be adjusted by diluting with a proper solvent to a print viscosity of, for example, 5-25 seconds or 10-15 seconds, measured using DIN Cup #4 at 25°C, to obtain a flexographic or gravure gas barrier ink for film printing and lamination.

[0076] The filmic substrate for printing and lamination the inks and coatings of the present application is not particularly limited.

[0077] In one embodiment, a thermoplastic resin film would be selected according to the desired application. For example, for food packaging, PET film, polystyrene film, polyamide film, polyacrylonitrile film; polyethylene films such as LLDPE (low density polyethylene film), MDOPE (medium density-oriented polyethylene film), HDPE (high density polyethylene film); polypropylene films such as CPP (unstretched polypropylene film), OPP; polyolefin films such as biaxially stretched polypropylene films; polyvinyl alcohol films, ethylene-vinyl alcohol copolymer films, and the like. These may be oriented in one or two directions, since orientation of films allows for property improvements otherwise not attainable in blown or cast films such as stiffness, toughness, and heat resistance.

[0078] In one embodiment, substrate surface treatment, such as flame treatment, corona treatment may be applied to the film surface, if necessary, in order to provide improved adhesion of the applied ink / coating / adhesive layer to the substrates.

[0079] In another embodiment, the gas barrier printed film provided by the inks and coatings of the present application would be allowed to age after application. When polyisocyanate is used as a curing agent, the aging conditions would preferably be in the range of 15-100°C for 24 to 170 hours, during which time the polyester resin reacts with the curing agent to generate the barrier layer properties.

[0080] In another embodiment, the resultant printed film is suitable for lamination and external printing and can be combined with oxygen barrier adhesives and coatings to further enhance the overall barrier effect.

[0081] In another embodiment, the inks and coatings of the present invention would be nitrocellulose-free to prevent the formation of nitrosamines and provide easier recycling and better suitability for thermal treatments (such as sterilization). Thermal treatments such as pasteurization and retort processes are particularly important for some specific food contact applications, in which the food / beverage may be processed at >100°C when already packed. It is fundamental that the packaging used is safe under these specific processing conditions, meaning that no potentially harmful species are able to migrate from the packaging to the foodstuff under such conditions. Among those potentially harmful species is nitrosamines, which can be generated by nitrocellulose in the presence of heat and secondary amines coming from multiple sources including pigments and foodstuff itself.

[0082] The present invention will be specifically described with reference to examples and comparative examples. “Parts” and “%” are based on weight % unless otherwise specified. In addition, the abbreviations of adipic acid (AA), phthalate (oPA), and ethylene glycol (EG) are used.

[0083] The numbers after each abbreviation indicate the molar ratio. Therefore, for example, the polyester polyol molar ratio of “AAloPA3EG5” means adipic acid:phthalic anhydride:ethylene glycol = 1 :3:5. White inks are identified by the polyester resin they contain and by a progressive number related to their formula (e.g. AAloPA3EG5_whitel).

[0084] Such white inks are meant to be reacted with a suitable curing agent, so the final combination is identified by the polyester resin used, a progressive number related to the ink formulation and a pair of numbers that indicate the mix ratio by weight between the ink and the curing agent.

[0085] For example: AAloPA3EG5_whitel_100_38 refers to a white ink formulation 1 containing polyester resin AAloPA3EG5 and such ink is mixed 100:38 by weight with the selected curing agent.

[0086] Clear coatings are identified by the polyester resin they contain and by a progressive number related to their formula (e.g. AAloPA3EG5_clearl).

[0087] Such clear coatings are meant to be reacted with a suitable curing agent, so the final combination is identified by the polyester resin used, a progressive number related to the coating formulation and a pair of numbers that indicate the mix ratio by weight between the coating formulation and the curing agent.

[0088] For example: AAloPA3EG5_clearl_100_150 refers to a clear coating formulation 1 containing polyester resin AAloPA3EG5 and such coating is mixed 100: 150 by weight with the selected curing agent.

[0089] The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as "The method of any one of embodiments 1 to 5", every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to " The method of any one of embodiments 1, 2, 3, 4 and 5". Further, it is explicitly noted that the following set of embodiments is not the set of claims determining the extent of protection, but represents a suitably structured part of the description directed to general and specific aspects of the present invention.

[0090] 1. A 2-part printing ink or coating composition, comprising: a first part comprising a polyester derived from one or more aromatic dicarboxylic acids selected from the group consisting of isophthalic acid, orthophthalic acid, and phthalic anhydride; an aliphatic dicarboxylic acid having 3 to 6 carbon atoms; an aliphatic diol having 2 to 4 carbon atoms; one or more organic solvents; and a second part comprising a polyisocyanate catalyst.

[0091] 2. The ink or coating composition of paragraph 1, wherein the polyisocyanate is based on a TDI-trimer.

[0092] 3. The ink or coating composition of paragraph 1 or 2, wherein the aromatic dicarboxylic is a phthalic anhydride.

[0093] 4. The ink or coating composition of paragraph 3, wherein the polyisocyanate is based on monomers selected from the group consisting of methylene diisocyanate (MDI), toluene diisocyanate (TDI), and m-Xylylene diisocyanate.

[0094] 5. The ink or coating composition of paragraph 4, wherein the equivalent NCO / OH ratio between the polyester resin and the polyisocyanate is from 0.6 to 1.10.

[0095] 6. The ink or coating composition of paragraph 5, wherein the equivalent NCO / OH ratio between the polyester resin and the polyisocyanate is 0.90.

[0096] 7. The ink or coating composition of paragraph 6, wherein the polyisocyanate is blended such that the hydroxyl groups and the reactive components of the curing agent are 1.0 / 0.6 to 1.0 / 2.0 (equivalence ratio), more preferably 1.0 / 0.8 to 1 / 1.1.

[0097] 8. The ink or coating composition of paragraph 7, wherein the aliphatic dicarboxylic acid having 3 to 6 carbon atoms is adipic acid.

[0098] 9. The ink or coating composition of paragraph 8, wherein the molecular weight is 400-2000 g / mol, more preferably 400-600 g / mol.

[0099] 10. The ink or coating composition of paragraph 9, further comprising one or more co-resins selected from the group consisting of polyurethanes, polyamides, ketonic, maleic, polyvinylderivatives (such as polyvinyl butyral and / or polyvinyl chloride); cellulose derivatives such as nitrocellulose, ethyl cellulose, cellulose acetate butyrate (CAB), cellulose acetate propionate (CAP) and combinations thereof.

[0100] 11. The ink or coating composition of paragraph 10, wherein the co-resin is a modified cellulose comprising ester and / or ether functional groups.

[0101] 12. The ink or coating composition of any one or more of paragraphs 1-11, comprising a ratio of ink:curing agent of 100:50 to 100:200, and wherein the ink or coating is free of colorants.

[0102] 13. The ink or coating composition of any one or more if paragraphs 1-11, further comprising one or more colorants.

[0103] 14. The ink or coating composition of paragraph 13, wherein the one or more colorants comprises titanium dioxide. 15. The ink or coating composition of paragraph 14, comprising a ratio of ink:curing agent of 100:5 to 100:50.

[0104] 16. The ink or coating composition of any preceding paragraph, wherein at least one of the solvents is an ester.

[0105] 17. The ink or coating composition of paragraph 16, wherein at least one of the ester solvents is ethyl acetate.

[0106] 18. A printed structure comprising the ink or coating composition of any one or more of paragraphs 1-17.

[0107] 19. The structure of paragraph 18, wherein the structure is a laminate structure.

[0108] 20. The laminate structure of paragraph 19, wherein the structure is a packaging structure.

[0109] 21. A method of providing a printed structure, comprising applying the composition of any one or more of paragraphs 1-17 onto a substrate and curing.

[0110] 22. The method of paragraph 21, wherein the printed structure comprises a laminate structure.

[0111] The present invention has been described in detail, including various embodiments thereof. However, it will be appreciated that those skilled in the art, upon consideration of the present disclosure, may make modifications and / or improvements on this invention that fall within the scope and spirit of the invention.

[0112] EXAMPLES

[0113] The invention is further described by the following non-limiting examples which further illustrate the invention, and are not intended, nor should they be interpreted to, limit the scope of the invention.

[0114] Test Methods

[0115] Resin Viscosity is measured using a Brookfield DV1 viscometer equipped with a small sample adapter at 23°C, using S21 spindle at 12 rpm.

[0116] OH number, expressed as mgKOH / g, is measured using a T5 titrator from Mettler- Toledo according to the procedures described in ASTM El 899.

[0117] Ink viscosity expressed in seconds as measured using a DIN 4 cup at 25°C.

[0118] Ink application to the substrate was performed using the following protocol:

[0119] Ink is blended with the polyisocyanate curing agent at the desired ratio in mass

[0120] Ink is diluted to a printing viscosity between 10-15 seconds using a #4 DIN cup at 25°C. Inks can be adjusted with a suitable solvent.

[0121] Ink is applied to the substrate using a K hand-coater with a k bar (type 1 or 2) or a hand-proofer (preferably 78, 70 or 55 lines / cm). To counteract any potential issues related to pot life, the test prints are preferably made within 6 hours of the blending of the ink and curing agent; more preferably within 3 hours; and most preferably within 1 hour.

[0122] Ink adhesion to the films is evaluated using a TESA TAPE 4104. The tape must be applied on the drawdown and peeled off. Tape and drawdown are visually inspected to check if the ink layer remains on the substrate or if it is peeled off together with the tape. The results are expressed with a number from 0 to 5, where:

[0123] 0 = 100% loss of adhesion

[0124] 1 = 60-99% loss of adhesion

[0125] 2 = 41-59% loss of adhesion

[0126] 3 = 26-40% loss of adhesion

[0127] 4 = 1-25% loss of adhesion

[0128] 5 = 0% loss of adhesion

[0129] Oxygen transmission rate (OTR) of unprinted and printed films can be measured at 23°C, 50% relative humidity (RH) for both the upper and inner part of the chamber using an OXYGEN PERMEATION ANALYZER manufactured by Permetech (ASTM F1927, rH 50% or 85%). In a preferred embodiment, the OTR would be < 1000 cm3 / m'2 / 24 h'1; more preferably < 600; and most preferably < 300.

[0130] Bond strength testing of the laminated structures can be measured using a ZwickiLine Zwick Roell dynamometer using the following test conditions:

[0131] Loading cell: 100 N

[0132] Delamination speed: 100 mm / min

[0133] Peel extension: 100 mm max

[0134] Specimen: 15 mm width stripes

[0135] Delamination mode: peel at 180° - T shape

[0136] Note: a bond strength rating of “not peelable” (sometimes referred to as “destruct bond”) is preferred. This refers to the cohesive forces between the primary substrate, the ink, the adhesive and the secondary substrate being higher than the cohesive forces of the materials themselves, causing the substrate to fail (destruct) before the printing ink / coating films. In such cases, the bond strength is recorded as “not peelable” since an actual numerical value cannot be obtained.

[0137] Blocking can be measured using an automatic press (ATLAS Autotouch 8T) equipped with a temperature controller (West 6100+). The ink is applied on the primary substrate using the above described method and then coupled with a secondary film. The resulting double-layer structure (filml / ink / film2) is placed in the press at 40°C for Ih at a pressure of 5 ton / 10cm2. The two layers are then manually separated and a visual inspection is made to check the integrity of the printed layer. The results are expressed with a number from 0 to 5, where:

[0138] 0 = extreme blocking, i.e. it is very difficult to separate the two substrates and the printed layer transfers from the primary to the secondary substrate

[0139] 1 = high blocking, i.e. it is rather difficult to separate the two substrates and the printed layer transfers from the primary to the secondary substrate

[0140] 2 = moderate / high blocking, i.e. it is rather difficult to separate the two substrates, however no ink transfer from primary to secondary film

[0141] 3 = moderate blocking, i.e. it is easy to separate the two substrates, no ink transfer from primary to secondary film

[0142] 4 = minimal blocking, i.e. it is very easy to separate the two substrates, no ink transfer from primary to secondary film

[0143] 5 = no blocking, i.e. the two layers are already separated, no ink transfer from primary to secondary film

[0144] Rub resistance of the printed ink is measured using a Sutherland 2000 rub tester following the GIS 18 test method or similar methods. The number of cycles has been set to 100. The printed ink is visually inspected after 100 cycles and the results are expressed with a number from 0 to 5, where:

[0145] 0 = 100% ink transfer on the neutral film

[0146] 1 = 60-99% ink transfer on the neutral film

[0147] 2 = 41-59% ink transfer on the neutral film

[0148] 3 = 26-40% ink transfer on the neutral film

[0149] 4 = 1-25% ink transfer on the neutral film

[0150] 5 = 0% ink transfer on the neutral film

[0151] Note: in the present application the terms “surface printing” and “internal printing” are used. Surface printing refers to the outer or top surface of the substrate (i.e. the exposed surface); while internal printing refers to subsurface printing of a multi-layer or laminate structure. A preferred rub rating is >3, more preferably >4, and most preferably 5. The inks of the present application are suitable for both surface and internal printing, but those with a higher rub resistance value (preferably 5) would be preferred for surface printing applications to convey mechanical resistance.

[0152] Thermal resistance of the printed ink can be measured using a heat sealer (HSG-C B rugger), using the following set of conditions: Sealing time: 0.8 s.

[0153] Pressure: 450 N.

[0154] Sealing temperature: 100°C up to ink or substrate failure.

[0155] The printed layer is sealed against an aluminum foil. The results are expressed as the maximum temperature in °C the sealing bars can reach before a defect in the printed layer (i.e., ink is partially transferred to the ALU foil) and / or melting of the plastic substrate are observed.

[0156] Example 1 : Polyester Synthesis

[0157] Production method of polyester polyol “AAloPA2EG4” consisting of adipic acid, orthophthalic acid and ethylene glycol.

[0158] 100.4 parts of adipic acid, 237.4 parts of phthalic anhydride, 162.2 parts of ethylene glycol, and 0.015 part of titanium tetraisopropoxide are charged in a polyester reaction vessel equipped with a stirrer, nitrogen gas inlet tube, a rectifying column, and condenser. The internal temperature was maintained at 220°C by heating gradually so that the temperature on top of the column did not exceed 100°C. When the acid value became less than 2 mgKOH / g, the esterification reaction was terminated to obtain a polyester resin “AAloPA2EG4”. The product was diluted adding 111.6 parts of ethyl acetate.

[0159] Polyester polyol “AAloPA2EG4” is characterized by a viscosity between 700 and 2000 mPa*s, %NV (non-volatile content) between 78 and 82, a residual acid value below 2 mgKOH / g and a OH number between 54 and 60 mgKOH / g. MW (molecular weight) is roughly 2000 g / mol.

[0160] Example 2: Polyester synthesis

[0161] Production method of polyester polyol “AAloPA3EG5” consisting of adipic acid, orthophthalic acid and ethylene glycol

[0162] 91.40 parts of adipic acid, 217.6 parts of phthalic anhydride, 191.0 parts of ethylene glycol, and 0.015 part of titanium tetraisopropoxide are charged in a polyester reaction vessel equipped with a stirrer, nitrogen gas inlet tube, a rectifying column, and condenser. The internal temperature was maintained at 220°C by heating gradually so that the temperature on top of the column did not exceed 100°C. When the acid value became less than 2 mgKOH / g, the esterification reaction was terminated. The product was diluted adding 50.42 parts of ethyl acetate.

[0163] Polyester polyol “AAloPA3EG5” is characterized by a viscosity between 2000 and 5000 mPa*s, %NV (non-volatile content) between 88.00 and 92.00 and a residual acid value below 2 mgKOH / g and a OH number between 200 and 220 mgKOH / g. MW (molecular weight) is roughly 500 g / mol. Comparative Example 3: Standard saturated polyester resin not containing phthalic anhydride.

[0164] Megapel MM 150 / 100 supplied by Megara Resins (NV% 100, n°OH=156 mgKOH / g) has been used as standard polyester resin.

[0165] The above disclosed polyester resins were used to formulate printing inks.

[0166] Example 4: Inventive White Ink formulation

[0167] Formulation of white ink containing AAloPA2EG4 - AAloPA2EG4_whitel

[0168] 64.0 parts of AAloPA2EG4 polyester resin were charged in a vessel equipped with a cowles-type stirrer and mixed with 14.0 parts of ethyl acetate and 22.7 parts of titanium dioxide were added under stirring at room temperature for a time between 30 and 90 minutes at 1000 rpm until the complete and homogeneous dispersion of titanium dioxide pigment.

[0169] Example 5 : Inventive White Ink formulation

[0170] Formulation of white ink containing AAloPA2EG4 - AAloPA2EG4_white2

[0171] 16.5 parts of AAloPA2EG4 polyester resin were charged in a vessel equipped with a cowles-type stirrer and mixed with 41.2 parts of ethyl acetate and 42.3 parts of titanium dioxide were added under stirring at room temperature for a time between 30 and 90 minutes at 1000 rpm until the complete and homogeneous dispersion of titanium dioxide pigment.

[0172] Example 6: Inventive White Ink formulation

[0173] Formulation of white ink containing AAloPA3EG5 - AAloPA3EG5_white3

[0174] 14.7 parts of AAloPA3EG5 polyester resin were charged in a vessel equipped with a cowles-type stirrer and mixed with 43.0 parts of ethyl acetate and 42.3 parts of titanium dioxide were added under stirring at room temperature for a time between 30 and 90 minutes at 1000 rpm until the complete and homogeneous dispersion of titanium dioxide pigment.

[0175] Example 7 : Inventive White Ink formulation

[0176] Formulation of white ink containing AAloPA3EG5 - AAloPA3EG5_white4

[0177] 20.0 parts of AAloPA3EG5 polyester resin were charged in a vessel equipped with a cowles-type stirrer and mixed with 34.7 parts of ethyl acetate, 3.0 part of CAB and 42.3 parts of titanium dioxide were added in sequence under stirring at room temperature for a time between 30 and 90 minutes at 1000 rpm until the complete and homogeneous dispersion of titanium dioxide pigment.

[0178] Example 8: Comparative White Ink formulation

[0179] Formulation of white ink containing Megapel MM150 / 100 - MegapolMM150_white5 not based on phthalic anhydride.

[0180] 11.0 parts of Megapel MM150 / 100 polyester resin were charged in a vessel equipped with a cowles-type stirrer and mixed with 52.0 parts of ethyl acetate and 37.0 parts of titanium dioxide were added under stirring at room temperature for a time between 30 and 90 minutes at 1000 rpm until the complete and homogeneous dispersion of titanium dioxide pigment.

[0181] Example 9: Comparative White Ink formulation commercial product Sun Chemical SolvaresTM_2K white (based on a saturated polyester resin which does not contain phthalic anhydride).

[0182] The above described white formulations were blended with the following curing agent catalysts using the below listed ratio in mass.

[0183] SAPICI (SunChemical) “Polurgreen IR 51 01 K” (%NCO=8.0, %NV=51.0) was used as “inventive” curing agent as it is a polyisocyanate based on TDI-trimer.

[0184] SAPICI (Sun Chemical) “Polurgreen FP 75 01 K” (%NCO=13.0, %NV=75.0) was used as “comparative / standard” curing agent as it is based on TDI but does not contain trimeric structures.

[0185] SAPICI (Sun Chemical) “Polurgreen OK 01 K” (%NCO=10.0, %NV=60.0) was used as “comparative / standard” curing agent as it is a mixed aliphatic / aromatic trimer.

[0186] Example 10: Inventive White Ink formulation

[0187] AAloPA2EG4_whitel was cured with Polurgreen IR 51 01 K in a ratio of 100:32, resulting in AAloPA2EG4_whitel_2K_100_32.

[0188] Example 11 : Inventive White Ink formulation

[0189] AAloPA2EG4_white2 was cured with Polurgreen IR 51 01 K in a ratio of 100:8.5, resulting in AAloPA2EG4_white2_2K_100_8.5.

[0190] Example 12: Inventive White Ink formulation

[0191] AAloPA3EG5_white3 was cured with Polurgreen IR 51 01 K in a ratio of 100:20, resulting in AAloPA3EG5_white3_2K_100_20.

[0192] Example 13: Inventive White Ink formulation

[0193] AAloPA3EG5_white4 was cured with Polurgreen IR 51 01 K in a ratio of 100:27, resulting in AAloPA3EG5_white4_2K_100_27.

[0194] Example 14: Inventive White Ink formulation

[0195] AAloPA3EG5_white4 was cured with Polurgreen IR 51 01 K in a ratio of 100:38, resulting in AAloPA3EG5_white4_2K_100_38.

[0196] Example 15: Comparative White Ink formulation

[0197] MegapolMM150_white5 was cured with Polurgreen FP 75 01, which is a polyisocyanate that does not contain trimeric structures in a ratio of 100: 15, resulting in MegapolMM 150_white5_2K_l 00_l 5. Example 16: Comparative White Ink formulation

[0198] AAloPA3EG5_white4 was cured with Polurgreen FP 75 01 K in a ratio of 100:23, resulting in AAloPA3EG5_white4_2K_100_23.

[0199] Example 17: Comparative White Ink formulation

[0200] SolvaresTM white has been cured with Polurgreen IR 51 01 K in a ratio of 100: 15, resulting in SolvaresTM_white_2Kexp_100_15.

[0201] Example 18: Comparative White Ink formulation

[0202] SolvaresTM_white has been cured with SUN HARDENER 11 75 in a ratio of 100: 15. It is based on a polyisocyanate that does not contain trimeric structures, resulting in SolvaresTM_white_2K _100 15.

[0203] Example 19: Inventive Clear coating formulation

[0204] Formulation of clear coating containing AAloPA3EG5 - AAloPA3EG5_clearl AAloPA3EG5 was used as such in AAloPA3EG5_clearl.

[0205] Example 20: Inventive Clear coating formulation

[0206] Formulation of clear coating containing AAloPA3EG5 - AAloPA3EG5_clear2

[0207] 95.0 parts of AAloPA3EG5 polyester resin were charged in a vessel equipped with a cowles- type stirrer and 5.0 parts of micronized silica were added under stirring at room temperature for a time between 30 and 90 minutes at 1000 rpm until the complete and homogeneous dispersion of silica particles.

[0208] Example 21 : Inventive Clear coating formulation

[0209] Formulation of clear coating containing AAloPA3EG5 - AAloPA3EG5_clear3

[0210] 47.5 parts of AAloPA3EG5 polyester resin were charged in a vessel equipped with a cowles- type stirrer. 7.5 parts of a thixotropic agent, followed by 20.0 parts of Ethyl acetate, 2.5 parts of mica powder and 22.5 parts of Ethyl acetate to adjust %NV were added under stirring at room temperature for a time between 30 and 90 minutes at 1000 rpm until the complete and homogeneous dispersion of mica particles.

[0211] Example 22: Inventive Clear coating formulation

[0212] Formulation of clear coating containing Paslim MB 520 B - MB520B_clear4 520B was used as such in 520B_clear4.

[0213] Example 23 : Comparative Clear coating formulation

[0214] Formulation of clear coating containing Rexin 1939 K - 1939K_clear5

[0215] Rexin 1939K was used as such in 1939K_clear5. Rexin 1939 K is a commercially available alkyd resin meant for clear coating with a chemical composition that does not meet the above- mentioned structural requirements. The above-described clear coating formulations were blended with the following curing agent catalysts using the below listed ratio in mass.

[0216] Example 24: Inventive Clear coating formulation

[0217] AAloPA3EG5_clearl was cured with Polurgreen IR 51 01 K in a ratio of 100: 150, resulting in AAloPA3EG5_clearl_2K_100_150.

[0218] Example 25: Inventive Clear coating formulation

[0219] AAloPA3EG5_clear2 was cured with Polurgreen IR 51 01 K in a ratio of 100: 143 resulting in AAloPA3EG5_clear2_2K_100_143.

[0220] Example 26: Inventive Clear coating formulation

[0221] AAloPA3EG5_clear3 was cured with Polurgreen IR 51 01 K in a ratio of 100:71 resulting in AAloPA3EG5_clear3_2K_100_71.

[0222] Example 27: Comparative Clear coating formulation

[0223] 1939K_clear5 was cured with Polurgreen OK 01 01 K in a ratio of 100:84 resulting in 1939K_clear5_2K_l 00_84.

[0224] Method for applying 2K white ink films

[0225] The 2K white inks were diluted with Ethyl Acetate to reach the printing viscosity of 13s DIN 4 25°C and then printed on the designated substrate using a Pamarco hand proofer 180 Q 90. The drawdown was dried at 50°C for 10 minutes and then cured for 1 week at room temperature.

[0226] Method for applying 2K clear coatings (OPV)

[0227] The 2K clear coatings were diluted with Ethyl Acetate to reach the printing viscosity of 13s DIN 425°C and then printed on the designated substrate using a Pamarco hand proofer 180 Q 90. The drawdown was dried at 50°C for 10 minutes and then cured for 1 week at room temperature.

[0228] Table 1 : OTR Values - 2K white ink on MDOPE substrate

[0229] OTR values have been obtained on the above-described drawdown after curing. The measurements were performed on an 11 x 11 cm print swatch. The relative humidity (RH) was set to 50%, the temperature at 23°C.

[0230] As shown in Table 1, the combination of the inventive polyester resins and the inventive curing agent provides a significant reduction in OTR values versus comparative 2K systems. Both parts of the inventive system contribute to the overall barrier performance as evident when comparing Example 14 in which the inventive polyester resin based on phthalic anhydride is combined with the inventive curing agent based on TDI-trimer, with Example 16, in which the very same inventive polyester resin based on phthalic anhydride is combined with the comparative curing agent based on TDI-adduct. Note that the white ink formulation in Example 14 is the same as Example 16, the only difference being the curing agent.

[0231] The same pattern is evident when comparing Example 17 and Example 18, but in this case the OTR values are significantly higher since no inventive resin has been used to formulate the white ink.

[0232] Comparing Example 13 with Example 14, both based on inventive resin and inventive curing agent, shows how OTR values also depend on the NCO / OH equivalent ratio, which is preferably close to 0.90 to obtain the best results in terms of barrier effect. Table 2: Ink Properties

[0233] The best performing inks in terms of OTR values have been further characterized.

[0234] Adhesion to various poly olefinic films was evaluated with TESA TAPE 4104 using the above disclosed method. Polyolefins were selected with the aim of producing a monomaterial, easy-to-recycle structure.

[0235] Inventive Examples 11 & 12 exhibit comparable performance to Example 18 (nonbarrier, commercially available SolvaresTM 2K white ink) for adhesion and blocking resistance with improved OTR properties. Examples 11 & 12 exhibit inferior rub resistance and thus would be better suited to internal printing for applications where mechanical resistance is less critical. Example 11 & 12 inks could also be used for surface printing. The excellent rub resistance of Example 14 makes it ideally suited for surface printing as well as internal printing. Rub resistance indicates the ability of a printed layer to withstand mechanical stress (scratch, abrasion, etc.), which can be important for surface printing applications.

[0236] For inks that will be used for surface printing, thermal resistance may be a desired performance property, e.g. for applications where the printed layer comes in contact or close proximity to heat-sealing bars used in producing packaging structures. Preferably the thermal resistance of the ink / coating would be observed as “material melting”, meaning that the thermal resistance of the printed ink / coating film is greater than that of the substrate (i.e. melting of the plastic substrate is seen before any defect in the printed layer). This allows the packaging structure to be heat-sealed without damaging the printed graphics. As shown in Table 2, in all cases the thermal resistance is reported as “material melting”.

[0237] Lamination results

[0238] The following solvent-free adhesive systems from Sun Chemical were used:

[0239] 1) NS 4158 / HA328 - standard solvent-free adhesive system

[0240] 2) ZA-1000 / ZB-301 - Ultra low monomer solvent-free adhesive system

[0241] 3) Paslim NS 602A / Paslim HA 601B - gas barrier solvent-free adhesive system

[0242] Drawdowns were prepared as previously described using Inventive Example 14 AAloPA3EG5_white4_2K_100_38 combined with the above listed solvent-free adhesives to obtain a monomaterial double-layer structure. They have been used both for internal and for surface printing.

[0243] Lamination trials were performed using a Labo Combi Matrix 400 lamination machine equipped with a Solvent-free adhesive unit. The obtained laminated structures were cured for 7 days at room temp., then characterized using the above-described methods in terms of OTR values and bond strength.

[0244] Table 3: Laminated double-layer structures

[0245] OTR values were measured at 23°C 85% RH, using the aforementioned method.

[0246] Table 4: OTR values on laminated double-layer structures

[0247] Table 4 shows that the use of Inventive Ex. 14 AAloPA3EG5_white4_2K_100_38 significantly lowers OTR values for both internal or surface printing and also when non-barrier solventless adhesive systems are employed.

[0248] Bond strength of the double-layer laminated structures were measured once the structures were cured (7 days at room temp.) using the method described above.

[0249] Table 5: Bond strength values (BSV) on laminated double-layer structures Bond strengths of the laminated double-layer structures shown in Table 5 were measured using a Zwick-Roell dynamometer with the method disclosed above. In all cases the result is “not peelable”, which is the best result that can be obtained when checking for bond strength in laminated structures.

[0250] Commonly, 2K inks are meant for surface printing applications thanks to their excellent mechanical, thermal and anti -blocking properties, but the use of the inks of the present application as laminating inks for internal printing is also disclosed.

[0251] Bond strength is not impaired using Inventive Example AAloPA3EG5_white4_2K_100_38 for internal printing, meaning Inventive Example 14 AAloPA3EG5_white4_2K_100_38 is very versatile and a preferred embodiment, as it can be employed both for surface and internal printing providing very good general performances as a full-coverage white ink together with unexpected gas barrier property.

[0252] Table 6: OTR values on laminated double-layer structures on MDOPE / PE laminated structures: effect of clear coating (OPV)

[0253] Table 6 shows the improved OTR values for print samples using the combination of inventive OPV clears in conjunction with inventive white inks.

Claims

CLAIMS1. A 2-part printing ink or coating composition, comprising: a first part comprising a polyester derived from one or more aromatic dicarboxylic acids selected from the group consisting of isophthalic acid, orthophthalic acid, and phthalic anhydride; an aliphatic dicarboxylic acid having 3 to 6 carbon atoms; an aliphatic diol having 2 to 4 carbon atoms; one or more organic solvents; and a second part comprising a polyisocyanate catalyst.

2. The ink or coating composition of claim 1, wherein the polyisocyanate is based on a TDI-trimer.

3. The ink or coating composition of claim 1 or 2, wherein the aromatic dicarboxylic is a phthalic anhydride.

4. The ink or coating composition of claim 3, wherein the polyisocyanate is based on monomers selected from the group consisting of methylene diisocyanate (MDI), toluene diisocyanate (TDI), and m-Xylylene diisocyanate.

5. The ink or coating composition of claim 4, wherein the equivalent NCO / OH ratio between the polyester resin and the polyisocyanate is from 0.6 to 1.10.

6. The ink or coating composition of claim 5, wherein the equivalent NCO / OH ratio between the polyester resin and the polyisocyanate is 0.90.

7. The ink or coating composition of claim 6, wherein the polyisocyanate is blended such that the hydroxyl groups and the reactive components of the curing agent are 1.0 / 0.6 to 1.0 / 2.0 (equivalence ratio), more preferably 1.0 / 0.8 to 1 / 1.1.

8. The ink or coating composition of claim 7, wherein the aliphatic dicarboxylic acid having 3 to 6 carbon atoms is adipic acid.

9. The ink or coating composition of claim 8, wherein the molecular weight is 400-2000 g / mol, more preferably 400-600 g / mol.

10. The ink or coating composition of claim 9, further comprising one or more co-resins selected from the group consisting of polyurethanes, polyamides, ketonic, maleic, polyvinylderivatives (such as polyvinyl butyral and / or polyvinyl chloride); cellulose derivatives such as nitrocellulose, ethyl cellulose, cellulose acetate butyrate (CAB), cellulose acetate propionate (CAP) and combinations thereof.

11. The ink or coating composition of claim 10, wherein the co-resin is a modifiedcellulose comprising ester and / or ether functional groups.

12. The ink or coating composition of any one or more of claims 1-11, comprising a ratio of ink: curing agent of 100:50 to 100:200, and wherein the ink or coating is free of colorants.

13. The ink or coating composition of any one or more if claims 1-11, further comprising one or more colorants.

14. The ink or coating composition of claim 13, wherein the one or more colorants comprises titanium dioxide.

15. The ink or coating composition of claim 14, comprising a ratio of ink: curing agent of 100:5 to 100:50.

16. The ink or coating composition of any preceding claim, wherein at least one of the solvents is an ester.

17. The ink or coating composition of claim 16, wherein at least one of the ester solvents is ethyl acetate.

18. A printed structure comprising the ink or coating composition of any one or more of claims 1-17.

19. The structure of claim 18, wherein the structure is a laminate structure.

20. The laminate structure of claim 19, wherein the structure is a packaging structure.

21. A method of providing a printed structure, comprising applying the composition of any one or more of claims 1-17 onto a substrate and curing.

22. The method of paragraph 21, wherein the printed structure comprises a laminate structure.

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