FIELD OF THE INVENTION

[0001] The present invention relates to moisture vapor barrier coating compositions for paper and paperboard. In particular, the invention includes coating compositions, methods and articles for improving moisture barrier properties for paper or paperboard with in-line manufacturing process.

BACKGROUND OF THE INVENTION

[0002] Barrier to moisture vapor is commonly required for packaging goods in paper, paperboard or other substrate material. The current technology offers various solutions to barrier technology; however, there are limitations to the current technology, including high cost, insufficient barrier performance, and potentially detrimental environmental effects.

[0003] For many packages, plastic films such as polyethylene and polypropylene films encase the entire package to provide moisture vapor barrier protection. While such design provides good moisture vapor barrier properties, plastic films on packages limit recyclability because special equipment is required to separate the paperboards from the barrier film layers. In addition, the plastic films are not decomposable.

[0004] In some instances, solid resins, such as low density polyethylene (LDPE, LLDPE), are extruded directly onto paper and paperboard by extrusion to impart barrier properties. Because extrusion coating is an off-line process, there is a higher environmental impact such as increased waste and transportation. Also, a relatively higher coating weight of solid resins is required to achieve satisfactory barrier property. Wax coatings are also widely laminated onto paper and paperboard substrates to impart barrier properties; however high heat and energy is required to form a continuous wax coating on the substrates.

[0005] Coatings without any films and extruded resins are also known; however, barrier performances are inferior to films and extruded resins.

[0006] Chlorinated compounds and polyvinylidene chloride copolymers (PVdC) are also widely used to coat packages to impart moisture vapor barrier properties. However, chlorinated compounds and P VdC have several drawbacks since they typically require heavy coating weights, cause corrosion to the application equipments, and are known ozone depleting chemicals.

[0007] To increase the barrier performance for paper and paperboard, fillers and desiccant are added to the coating; however, fillers and desiccants typically render the coating optically opaque. Optically opaque coatings are not desirable for printed packages. Also, packages with multilayer coatings improve moisture vapor barrier properties; however, they are not robust enough for packages containing moisture vapor sensitive contents, e.g., detergent, food, feed and the like.

[0008] There remains a need for an environmentally sound moisture vapor barrier coating system for paper and paperboard that can be applied in-line along with the printing inks to produce finished and printed articles for filling with moisture vapor sensitive contents.

BRIEF SUMMARY OF THE INVENTION

[0009] The present invention relates to a radiation curable coating composition and method of using the coating composition, which provides a high moisture vapor barrier while maintaining optical clarity of the coating. The present invention balances the barrier and optical properties desired for packages while allowing the coating to be applied in in-line manufacturing of paper and paperboards packages. Also, the present invention provides an environmentally sound radiation curable coating composition that readily separates from a recyclable substrate upon exposure to an alkaline solution.

[0010] In one embodiment, there is provided a radiation curable coating composition with improved moisture vapor barrier properties; such composition comprising an acrylate monomer, an acrylate oligomer, a micronized wax, and optionally a photoinitiator.

[0011] Another embodiment provides a method of preparing a package having improved moisture vapor barrier properties, including the steps of: (1) providing a substrate having a first side and second side, (2) preparing a radiation curable coating composition having an improved barrier properties by combining together an acrylate monomer, an acrylate oligomer, a micronized wax, and optionally a photoinitiator; (3) applying the radiation curable coating composition onto the first side of the paper or paperboard; and (4) curing the radiation curable coating composition.

[0012] Still another embodiment provides an article comprising the radiation curable coating composition with improved moisture vapor barrier properties, the composition comprising an acrylate monomer, an acrylate oligomer, a micronized wax, and optionally a photoinitiator. Examples of such articles include paper or paperboards for packaging moisture sensitive contents. [0013] Yet another embodiment provides an article comprising a multilayer coating compositions, including at least one water-based moisture vapor barrier emulsion layer and a radiation curable composition with improved moisture vapor barrier properties comprising an acrylate monomer, an acrylate oligomer, a micronized wax, and optionally a photoinitiator.

[0014] A further embodiment provides an article comprising a multilayer coating compositions, including at least one water-based moisture vapor barrier emulsion layer, a decorative ink layer, and a radiation curable coating composition with improved moisture vapor barrier properties comprising an acrylate monomer, an acrylate oligomer, a micronized wax, and optionally a photoinitiator.

[0015] Another embodiment provides a method of preparing a package having improved moisture vapor barrier properties including the steps of: applying a water-based moisture vapor barrier emulsion layer, applying a decorative ink layer, and applying a radiation curable coating layer comprising an acrylate monomer, an acrylate oligomer, a micronized wax, and optionally a photoinitiator, wherein all layers are applied in in-line manufacturing process onto a paper or paperboard.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 shows a radiation curable coating applied on a clay-coated side of a substrate over a water-based layer and spot-coated ink layer.

[0017] Figure 2 is similar to Figure 1 and further includes a second water-based layer applied on the non-clay-coated side of the substrate.

[0018] Figure 3 shows a substrate of a clay coated paper or paperboard, where two water-based layers, a spot-coated ink layer the water-based primer, and a radiation curable coating are all applied on the clay-coated side the substrate.

[0019] Figure 4 shows a pre-coated embedded water-based layer in the substrate. The substrate is further spot-coated with an ink layer and covered with a radiation curable coating on the clay coated side of the substrate.

DETAILED DESCRIPTION OF THE INVENTION

[0020] All references cited are incorporated herein.

[0021] A monomer is defined herein as a single molecule that can bind chemically to other molecules to form an oligomer or a polymer.

[0022] An oligomer is defined herein as a molecule of intermediate relative molecular mass, the structure of which essentially comprises a small plurality of units derived from molecules of lower relative molecular mass (IUPAC 1996). Oligomer is a substance that is composed of molecules containing either a single intermediate molecular weight or a small number - typically two to about ten - of constitutional units in repetitive covalent linkage.

[0023] A polymer is not an oligomer. A polymer is defined as a molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetitions (IUPAC

1996).

[0024] The curable coating compositions comprise an acrylate monomer, an acrylate oligomer, a micronized wax, and optionally a photoinitiator. The curable coating composition is curable by electron beam, UV light or UV/LED light. Depending upon the curing source, the curable coating composition further comprises a photoinitiator.

[0025] Acrylate monomers useful for the moisture vapor barrier coatings include mono- functional, di-functional, tri-functional and multi-functional acrylate monomers. Exemplary mono-functional acrylate monomers include, but not limited to, octyl acrylate, decyl acrylate, tridecyl acrylate, 2-phenoxyethyl acrylate, isobornyl acrylate, 2(2-ethoxyethoxy)ethyl acrylate, nonylphenol acrylate, ethoxylated nonylphenol acrylate, stearyl acrylate, tetrahydrofurfuryl acrylate, aliphatic acrylate (Ebecryl 113, Cytec Industries Inc.), caprolactone acrylate, lauryl acrylate, cyclic trimethylolpropane formal acrylate, and the like. Exemplary di-functional acrylate monomers include, but not limited to, tricyclodecane dimethanol diacrylate,

tripropylene glycol diacrylate, dipropylene glycol diacrylate; 1,6 hexanediol diacrylate;

ethoxylated hexanediol diacrylate; 1,3-biutanedial diacrylate; 1, 4-butanediol diacrylate;

neopentyl glycol diacrylate; propoxylated neopentyl glycol diacrylate; diethylene glycol diacrylate; triethylene glycol diacrylate; tetraethylene glycol diacrylate; polyethylene glycol-200- diacrylate; 3-ethoxylated bisphenol-A diacrylate; and the like. Exemplary tri-functional acrylate monomers include, but not limited to, trimethyol propane triacrylate, ethoxylated trimethyol propane triacrylate, 6-ethoxylated trimethyol propane triacrylate, propoxylated trimethylol triacrylate, propoxylated glyceryl triacrylate, pentaerythritol triacrylate, and the like. Exemplary multi-functional acrylate monomers include, but not limited to, pentaerythritol tetraacrylate, di- trimethylol propane tetraacrylate, di- pentaerythritol pentaacrylate, and the like.

[0026] Preferred acrylate monomers for the coating compositions include 2-phenoxyethyl acrylate, isobornyl acrylate, stearyl acrylate, tetrahydrofurfuryl acrylate, cyclic trimethylolpropane formal acrylate, tricyclodecane dimethanol diacrylate; tripropylene glycol diacrylate; dipropylene glycol diacrylate; 1,6 hexanediol diacrylate, ethoxylated hexanediol diacrylate; 1 , 4-butanediol diacrylate; neopentyl glycol diacrylate; propoxyiated neopentyl glycol diacrylate; 4-ethoxylated bisphenol A diacrylate; trimethyol propane triacrylate; ethoxylated trimethyol propane triacrylate; propoxyiated glyceryl triacrylate; pentaerythritol tetraacrylate; di-trimethylol propane tetraacrylate; and di- pentaerythritol pentaacrylate.

[0027] The barrier coating compositions further comprise an acrylate oligomer that contains terminal or pendant acrylate functional groups with epoxy, polyester, urethane, aliphatic or acrylic backbones. Preferably, this acrylate oligomer component is an acrylate terminated oligomer with film-forming properties and does not contain hydrophilic carboxylic acid functional group or high level of hydroxyl functional group. For example, and without limitation, the oligomer of this embodiment can be an acrylate oligomer such as an acrylate oligomer with a plurality of acrylate functional group per oligomer molecule. In some embodiments, the acrylate oligomer can have two to six acrylate sequences per oligomer molecule.

[0028] Examples of epoxy acrylate oligomers include, but are not limited to, bisphenol- A epoxy diacrylate (Ebecryl 3700, Ebecryl 3720 from Cytec Industries Inc.; CN120, CN104 from

Sartomer), modified bisphenol-A epoxy diacrylate (Ebecryl 3701 from Cytec Industries Inc.), epoxy acrylate (CN121, CNUVE151 from Sartomer), and the like. Typically, epoxy acrylate oligomers are available in a mixture with an acrylate monomer, wherein the oligomer is the major (typically greater than 50 weight percent) component of the mixture. Examples of urethane acrylate oligomers include, but are not limited to, aromatic urethane acrylate (Ebecryl 4827, Ebecryl 4849 from Cytec Industries Inc.), aromatic urethane hexα-acrylate (Ebecryl 220), aliphatic urethane diacrylate (Ebecryl 230, Ebecryl 270, Ebecryl 284, Ebecryl 4883, Ebecryl 8210, Ebecryl 8301 from Cytec Industries Inc.; CN301, CN9009, CN9014, CN9024, CN966, from Sartomer. Examples of polyester acrylate oligomers include, but are not limited to, CN292, CN293, CN704, CN710, CN2200, CN2203, CN2270, CN2262, CN2283, CN2298, and

NTX7418 from Sartomer; and Ebecryl 40, Ebecryl 810 Ebecryl 885, Ebecryl 888 from Cytec Industries Inc.; and the like. Examples of polybutadiene acrylate oligomers include CN307, CN301 (methacrylate), and CN303 (methacrylate) from Sartomer. Examples of aliphatic acrylate oligomers include CN308 and CN309 from Sartomer. Examples of acrylic acrylate oligomers include, but not limited to, CN549, CN711, CN821, CN822 and CN2285 from Sartomer; Ebecryl 745 from Cytec Industries. Inc.

[0029] Preferred acrylate oligomer components include bisphenol-A epoxy diacrylate, and various monomer dilutions thereof.

[0030] Also preferred are polyester acrylate oligomers including CN2203, CN2262, CN2283, CN2298, Ebecryl 40, Ebecryl 810; aromatic urethane acrylate Ebecryl 4849, Ebecryl 220;

aliphatic urethane diacrylate, CN301, CN9014 Ebecryl 8210, and various monomer dilutions thereof; polybutadiene acrylate oligomer including CN307; aliphatic acrylate oligomers includes CN308 and CN309.

[0031] The combined acrylate monomers and oligomers in the curable composition ranges from about 85 to about 99.4 wt%, based on the total weight of the composition. In one embodiment, the oligomer ranges from about 10 to about 70 wt%, based on the combined acrylate monomers and oligomers weights.

[0032] The barrier coating composition further comprises micronized waxes. Useful micronized waxes have an average particle size of about 0.001 micron to about 15 microns, preferably less than about 13 micron, preferably less than about 10 micron, more preferably less than about 8 micron, and most preferably less than 5 micron. The size of the waxes allows the coatings to remain optically clear and glossy. Micronized waxes are included in ranges of about 0.5 to about 10 wt%, preferably 1 to about 5 wt%, based on the total weight of the curable coating

composition. Micronized waxes are typically available as neat waxes or as pre-dispersed pastes in monomer or oligomer.

[0033] While micronized waxes are known for slip, anti-blocking and abrasion-resistance, only certain micronized waxes enhance the moisture vapor barrier properties in a curable coating system. Micronized waxes useful for the moisture vapor barrier coatings include carnauba, paraffin, paraffin alloy, montan, oxidized polyethylene, modified polypropylene,

polytetrafluoro ethylene (PTFE), ethylene-bis-stearamide (EBS), EBS alloy, synthetic

hydrocarbon waxes (Fischer Tropsch) and PTFE/synthetic hydrocarbon alloy. Without being bound to any particular theory, it is believed that these wax particles are pushed onto the surface of the coating due to incompatibility with the polymer developed during the crosslinking of the coating, and therefore forms a high concentration of a wax layer at the surface of the coating, which creates a longer path length for moisture vapor. While carnauba alloy and polyethylene waxes are also known for slip, anti-blocking and abrasion-resistance, they fail to enhance the moisture vapor barrier properties in the same curable coating system.

[0034] The cured barrier coating composition with useful micronized waxes has a moisture vapor transmission rate and a gloss level comparable to standard oriented polypropylene films with a thickness of about 0.75mil. In a preferred embodiment, the cured barrier coating composition has a moisture vapor transmission rate less than 80 grams per square meter per day (gsm/day), more preferably less than 70 gsm/day, and most preferably less than 60 gsm/day, measured in accordance with ASTM E96-E96M-10 with a dry cup Desiccant Method at 80°F (26.7°C) and 80% relative humidity; and a gloss level greater than 60 GU, more preferably great than 70 GU, and most preferably greater than 80 GU, measured in accordance with ASTM D523, ASTM D2457, DIN 67530 or JIS Z8741.

[0035] The barrier coating composition optionally comprises additives that include antioxidants, stabilizers, anti-misting agents, optical brighteners, slip agent, defoamers, flow agents and leveling agents. One or more additives may be added up to 0.1 to about 5 wt%, based on the total weight of the composition.

[0036] Curing the barrier coating composition may be initiated with electron beam (EB) or with ultraviolet (UV) radiation.

[0037] For EB curing, processing is typically performed with a low to medium energy (90-200 Kilovolt) accelerators. A typical direct-current accelerator consists of a voltage generator, an electron gun, an accelerator tube, a scan horn, and a control system. The accelerator creates a beam of electrons and energizes it to near light speed. The target materials are passed through the electron curtain using conveyors, carts, reel-to-reel equipment, or other specialized handling means. These highly energetic electrons generated are known to effectively initiate the crosslinking polymerization of the acrylated functional group. The amount of electron beam radiation absorbed by the target is referred to as the dose, which is typically defined in terms of kiloGrays (where 1 kGy=1000 J/kg) or MegaRads (where 1 MRad=l ,000,000 erg/g). Typical dose for coating ranges from about 1 MRrad to 6 Mrads dosage with a 100 kilo volt or higher EB curing device.

[0038] For UV curing, standard and doped medium pressure mercury UV lamps and/or UV LED lamps are typically utilized to initiate curing. Typically, the curing dosage for UV curing radiation ranges from about 50 mJ/cm ² to 500 mJ/cm ² (measured by ETI UVICURE Plus II Radiometer).

[0039] For UV curing, the radiation curable coating compositions further comprise a

photoinitiator. One or mixtures of photoinitiators may be used in the barrier coating

compositions to produce fully cured compositions. Examples of photoinitiator include, but not limited to, benzophenone, 4-methyl benzophenone, liquid benzophenone (eutectic mixture of berrzophenone and methyl benzophenone), 4-phenylbenzyophenone, methyl-2-benzoylbenzoate, 2 -hydroxy-2 -methyl- 1 -phenyl- 1-propanone, 1-hydroxy-cyclohexyl-phenyl-ketone, a mixture benzophenone and 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 500 from Ciba); 2,2- dimethoxy-2phenyl acetophenone/benzyldimethyl ketal; methylbenzoylformate; 2-hydroxy-l [4- (2-hydroxyethoxy)phenyl]-2-methyl-l-propanone; dimethylhydroxy acetophenone; l-[4-(l,l- dimethylethyl)phenyl]-2-hydroxy-2-methylpropan-l-one (Chivacure 2173 from Chitec.

Technology); 2,4,6-trimethylbenzoyl phosphine oxide; ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate; phenyl bis(2,4,6-trimethyl benzoyl) phosphine oxide; a mixture of 2,4,6- trimethylbenzoyl phosphine oxide and 2-hydroxy-2 -methyl- 1 -phenyl- 1-propanone (Daracur 4265 from Ciba); a 25/75 blend of bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 2 -hydroxy-2-methyl-l -phenyl- 1-propanone; a 20/80 blend of phenyl bis(2,4,6- trimethyl benzoyl) phosphine oxide and proprietary phosphine derivative; a mixture of oxy- phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid 2- [2-hydroxy-ethoxy]-ethyl ester; oligo(2-hydroxy-2-methyl-l-(4-(l -methyl vinyl)phenyl) propanone) (Esacure one from Lamberti); oligo [2-hydroxy-2-methyl-l-[ 4-(l-methylvinyl) phenyl] propanone] (Esacure KIP 150 from Lamberti); 1 -propanone, 1- [4- [(4- benzoylphenyl)thio]phenyl]-2-methyl-2-[(4-methylphenyl)sulfo nyl] (Esacure 1001 from

Lamberti); poly{l-[4-(phenylcarbonyl)-4'-(methyldiphenylsulphide)]ethyl ene} (Speedcure 7003 from Lambson); a mixture of:-l,3-di({ -2-(phenylcarbonyl)benzoylpoly[oxy(l- methylethylene)] }oxy)-2,2-bis ({α-2-phenylcarbonyl)-benzoylpoly[oxy(l - methylethylene)] }oxymethyl) propane and{α-2-(phenylcarbonyl)benzoylpoly(oxyethylene)- poly[oxy(l-methyl-ethylene)]-poly(oxyethylene)} 2-(phenylcarbonyl)benzoate (Speedcure 7005 from Lambson); poly { 1 -[4-(phenylcarbonyl)phenyl] ethylene} (Speedcure 7006 from Lambson); poly{l-[4-(phenylcarbonyl)-4'-(chlorophenyl)]ethylene} (Speedcure 7020 from Lambson); polymeric benzophenonic derivative (Genopol BP-1); and mixtures thereof.

[0040] Preferred initiators includes benzophenone; 2-hydroxy-2-methyl-l -phenyl- 1-propanone; 1 -hydroxy-cyclohexyl-phenyl-ketone; 2,2-dimethoxy-2-phenyl

acetonephenenone/benzyldimethyl ketal; 2,4,6-trimethylbenzoyl phosphine oxide; ethyl (2,4,6- trimethylbenzoyl) phenylphosphinate; phenyl bis(2,4,6-trimethyl benzoyl) phosphine oxide; a 20/80 blend of phenyl bis(2,4,6-trimefhyl benzoyl) phosphine oxide and various phosphine oxide derivatives; a mixture of oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester.

[0041] In conjunction with the above mentioned initiators, cure synergist like tertiary amine and benzoate may be added to the composition in order to cure at higher speed in ambient air environment. Typical amine synergists includes methyldiethanol amine (MDEA), trietbanol amine (TEOA), and amine acrylates (such as Ebecryl P104, Ebecryl P105, Ebecryl 7100 from Cytec Industries Inc. Genomer 5142, 5161, 5275 from Rahn Corporation, AgiSyn 002, 003, 006, 007, 008 from DSM-AGI or their equivalent and polymeric analog); and benzoates includes ethyl 4-(dimetliylamino) benzoate, 2-ethylhexyl-4-(dimethylamino) benzoate, ethyl 2- (dirnethylarnino) benzoate, n-butoxyethyl 4-(dimethylamino) benzoate; poly[oxy(methyl-l,2- thanediyl)], α-[4-(dimethylamino)benzyl-ω-butoxy (Speedcure PDA from Lambson);

poly(ethyleneglycol) bis(p-dimethylamino benzoate) (Omipol ASA from IGM Resin); a mixture of l,3-di({ α-4 -(dimethylamino)benzoylpoly [oxy ( 1 -methylethylene)] } oxy)-2,2 -bis ({ α-4- (dimethylamino)-benzoylpoly [oxy(l -mefhylethylene)] } oxymethyl) propane and {α-4- (dimethylamino)b enzoylpoly (oxyethylene)-poly [oxy( 1 -methylethylene)] -poly(oxy ethylene) } 4- dimethyl-amino)benzoate (Speedcure 7040 from Lambson); polymeric aminobenzoate derivative (Genopol AB-1 from Rhan USA); and mixtures thereof.

[0042] Preferred cure synergists include methyldiethanol amine (MDEA), amine acrylates (such as Ebecryl P104, Ebecryl P105, Ebecryl 7100 from Cytec Industries Inc. or their equivalent and polymeric analog; ethyl 4- (dimethyl amino) benzoate, 2-ethylhexyl-4-(dimethylamino) benzoate, ethyl 2-(dimethylamino) benzoate, poly(ethyleneglycol) bis(p-dimethylamino benzoate) (Omipol ASA from IGM Resin), polymeric aminobenzoate derivative (Genopol AB-1 from Rhan USA); and mixtures thereof.

[0043] The moisture vapor barrier coating compositions may be formed by combining the solid and liquid components together. Heat and/or shear can be adjusted to form a uniform mixture. The viscosities of the compositions can be adjusted with solvent to suit a particular application method and to obtain a desired application viscosity and thickness. Typically, the desirable viscosity is in the range of about 10 centipoise (cps) to about 3000 cps at 25 to 40°C.

[0044] In another embodiment, a package article is formed by the steps of (1) applying the barrier coating composition on one surface of the substrate and (2) curing the barrier coating composition. Substrates include paper, plastics, wood, composite wood and metals. The substrate may be substantially smooth two-dimensional surface or have plurality of surfaces, including rounded edges. Preferably, the substrate is a virgin or recycled paper or paperboard with clay- coating on at least one side.

[0045] The package article comprising the radiation curable coating composition may further comprise one or more waterborne barrier coatings.

[0046] Waterborne barrier coatings are generally known in the art. Various waterborne barrier primers and sealers are described in US 4,265,976; US 4,201,642; US 5,929,155; US 5,897,411; US 6,441,080; US 5,837,383; US 5,935,664; US 6,548,120 Bl; US 5,985,772; US 5,989,724; US 6,013,128; US 5,929,155; US 2005/0112387; US 2006/0289138; US 2011/0262745; US 2008/0017069; US 2007/0232743; US 2010/0136355; WO2009/012292 W096/22329 and WO 2005/061608. Typically, the waterborne barrier coatings comprise an emulsion resin, optionally hydrophobic fillers and additives.

[0047] Emulsion resins known in the art include carboxylated butadiene copolymer dispersion, polyvinyl acetate dispersion, polyvinyl alcohol polyvinyl acetate-ethylene dispersion, polyvinyl acrylic dispersion, ethylene acrylic acid polymer polydispersion, acrylic (polyethylacrylate) emulsion, acrylic polymers, acrylic copolymer , styrene-butadiene rubber copolymer, acrylic/wax, tackifier resin dispersion, copolymer of vinyl acetate, C1-C4 ester of (meth)acrylic acid, copolymer of styrene and C1-C4 ester of (meth)acrylic acid, cyclodextrin or substituted cyclodextrin compound, Neoprene rubber, nitrile rubber, EPDM, polyisobutylene,

polyvinylidene chloride dispersion (PVDC), and polyvinyl chloride. However, chlorine containing emulsion resins should be avoided to due to environmental concerns.

[0048] Suitable hydrophobic fillers and desiccants include mica, talc, silica, clay, kaolin, calcium carbonate, silicate, aluminum oxynitride, silicon oxynitride, metal poly silicate, exfoliated nano- particle filler, dolomites, alumina trihydrite, magnesium hydroxides, and talcum, and combination thereof. Waterbome coatings that include hydrophobic fillers typically decrease optical clarity of the coating, and are often referred to as waterborne sealers. Highly filled waterborne sealers are useful for applying on surfaces where optical clarity is not required. Often, waterborne sealers are applied on the backside (non-clay coated surface) of the substrates to gain the benefits of the moisture impermeability without adversely affecting the transparency of the front side of the substrate. In another embodiment, waterborne coatings with desiccants and hydroscopic fillers are embedded within the substrate.

[0049] Waterborne primers, on the other hand, are formulated to be optically transparent.

Waterborne primers are typically applied over inks to enhance its decorative appeal and/or holdout (forms a protective coatings thereby prevents other coatings from going into the cellulosic substrate) properties.

[0050] Additives to the waterborne coatings generally include gloss agents, biocides, defoamers, wetting agents, slip additive, wax, plasticizer and the like.

[0051] Various combinations of the waterborne coatings and radiation curable coating compositions are applied onto the substrates to form package articles.

[0052] The package article comprises, as demonstrated in Figure 1, a substrate (100) that is spot- coated with an ink layer (110) on the surface of the first surface (10) of the substrate, and a water-based primer coating (120) covers substantially the entire first surface of the substrate. The radiation curable barrier coating (130) covers the water-based primer coating. Preferably, the first surface (10) is pre-treated with a clay coating. In this embodiment, the water-based layer (primer) is optically clear.

[0053] In another embodiment, and as demonstrated in Figure 2, a water-based layer (sealer) (140) is applied onto the second surface (20) of the substrate. Opaque and/or dark colored hydrophobic fillers are included in the water-based sealer to provide a greater moisture barrier because the fillers seal the open pores of the untreated (non-clay coated) side of the substrate. Again, the ink layer (110), water-based primer coating layer (120) and radiation curable barrier coating (130) are applied on the first surface (10) of the substrate. Preferably, the first surface (10) is pre-treated with a clay coating.

[0054] Yet in another embodiment, and as demonstrated in Figure 3, all coatings are applied on the first surface (10) of the substrate. A transparent water-based sealer (160) is applied directly on the first surface, ink layer (110) is spot applied on the water-based sealer, water-based primer (120) is applied to cover the ink and water-based sealer layers, and the top coating is the radiation curable barrier coating (130). The transparent water-based sealer employs optically clear, white, or off -while fillers without any wax in order not to affect the color of the substrate and the over-printability of subsequence layers.

[0055] In another embodiment, and as demonstrated in Figure 4, the substrate (100) contains an embedded water-based sealer (150) within the substrate. An ink layer (110) is spot applied on the first surface (10) of the substrate, and the radiation curable barrier coating (130) is applied on the first surface, covering the ink layer.

[0056] The above articles with various coating layer combinations give an improved barrier properties by at least greater than the additive barrier property of each separate coating layers. In one embodiment, the inventive barrier coating has a MVTR value less than 80 gsm/day, preferably less than 70 gsm/day, more preferably 60 gsm/day, measured in accordance with ASTM E96/E96M-10 at 80°F (26.7°C) and 80% relative humidity; and a gloss level greater than 60 GU measured in accordance with ASTM D523, ASTM D2457, DIN 67530 or JIS Z8741.

[0057] All of the coating compositions, waterborne and radiation curable barrier coating compositions are applied by various means on the substrate. Applicators for water-based barrier coatings include all conventional application means such as gravure printing, digital ink jet printing, flexographic printing, roller coater, spraying, and the like, can be utilized by adjusting the viscosity and rheology of the coating composition. Applicators for the radiation barrier coatings include all conventional application means such as gravure printing, digital ink jet printing, flexographic printing, silk-screen printing, roller coater, spraying, air brushing, and the like can be utilized by adjusting the viscosity and rheology of the coating composition. Heat, alone or with air flow, can be used to evaporate the water in the waterborne components. EB or UV curing is the preferred method of curing the radiation curable barrier coatings.

[0058] The coatings may be applied in one in-line manufacturing process. In one embodiment, the article is formed by first applying a waterborne coating on one surface of the substrate and drying/curing the waterborne coating prior to applying the radiation curable barrier coating composition. The waterborne coating composition may be applied on either or both surfaces of the substrate. Additionally, in-line processing can be configured to apply the waterborne coatings successively or conjunctively. Optionally, an ink layer, including designs, is applied on portions of the surface of the substrate prior to applying any coatings. In one preferred embodiment, the ink layer is spot-applied on the first surface of the substrate and cured, the water-based coating is applied on the entire first surface of the substrate and dried/cured, and the radiation barrier coating is applied as the top most coating on the first surface of the substrate. In a preferred embodiment, all three layers are applied on a substrate surface that has been pre- treated with a clay coating. Optionally, a second water-based coating is applied and dried/cured on the second surface of the substrate. The water-based coatings are typically dried/cured with microwave radiation, infrared radiation, and/or heat. The in-line processing can be configured to coatings successively or apply multiple coatings at the same time onto a virgin or recycled paper or paperboard and dry/cure the coatings to form a ready-to -be-filled package article.

[0059] The curable coating composition and the entire package are recyclable. The radiation curable coating composition readily separates from the substrate upon exposure to an alkaline solution. The waterborne coatings dissolve in the same alkaline solution and the substrate can be recycled.

Examples

[0060] MVTR - Moisture vapor transmission rate was measured in accordance with ASTM

E96/E96M-10 using a dry cup Desiccant Method at test condition of 80°F (26.7°C) and 80% relative humidity (RH). Permeability cup was Model# 13-338Q from Fisher Scientific and the desiccant was 2-5 mm particle size silica gel with from Desisccare, Inc.

[0061] Gloss - Gloss was measured at 60 degrees with a BYK micro-Tri- gloss Gloss Meter in accordance with ASTM D523, ASTM D2457, DIN 67530 or JIS Z8741.

[0062] Viscosity - Viscosity was measured with a Brookfield Viscometer model LV with appropriate spindle and rpm at 25°C per manufacturer instructions.

[0063] The weight percent (wt%) of the coating was based on the total weight of the barrier coatings.

[0064] The substrates were 20 point, one-side pre-treated with clay-coated, recycle board.

[0065] The components to various coatings are listed in Tables 1, 2 and 3. EB coatings in Table 1 were prepared by adding all components at room temperature in a stainless steel container and mixed with Cowles blade mixer until homogeneous. For neat solid wax as those listed in Table 5, the neat wax was first pre-dispersed in TPGDA monomer in 25% loading and mixed with a Cowles blade mixer until the paste was homogeneous.

[0066] For water-based primer and sealing coatings, all of the components were combined at room temperature and mixed with a paddle blade or a Cowles blade mixer until a homogenous mixture was formed.

[0067] For all examples and controls, MVTR and gloss values were measured and recorded in Table 4. The backside coating was coated on the non-clay coated side of the 20 point recycle board using wire wound rod # 10 and dried in 120°C oven for 10 seconds. The coatings for the clay side was applied with a wire wound rod #4 and dried at 120°C for 5 seconds. The EB coating was applied on the clay side (or over the dried water-based primer/sealer) with a wire wound rod #3 and then cured with Advance Electron Beam (AEB) lab curing unit at 3 Mrad, under nitrogen with <200 ppm oxygen level.

[0068] Example 1: Sealer 1 was coated on the non-clay coated side of the substrate using a wire wound rod #10, from Paul N. Gardner Co., Inc. (all wire wound rods used herein were from Paul N. Gardner Co., Inc.) and dried in 120°C oven for 10 seconds. Primer 1 was applied on the clay coated side of the same paperboard using wire wound rod #4 and dried at 120°C for 5 seconds. EB 1 coating was applied on top on the dried Primer 1 with a wire wound rod #3 and then cured with a EB lab curing unit at 3 Mrad, under nitrogen with≤200 ppm oxygen level.

[0069] Example 2: The multilayer coatings with the following configurations were prepared in the same manner as Example 1. Primer 2 was coated on both sides of the substrate. EB 1 coating was applied on top of the dried Primer 2 on the clay coated side of the substrate.

[0070] Example 3 : The multilayer coatings with the following configurations were prepared in the same manner as above Examples. Sealer 1 was applied on the non-clay coated side of the substrate. Primer 2 was coated on the clay coated side of the board. EB 1 coating was applied on top of the dried Primer 2 on the clay coated side of the substrate.

[0071] Example 4: The multiplayer coatings with the following configurations were prepared in the same manner above examples. Sealer 2 coating was applied on the clay coated side of the substrate. Primer 3 coating was applied on top of the dried Sealer 2 coating. EB 1 coating was applied on top of the dried Primer 3 coating.

[0072] Samples 5-1 : Samples 5 to 13 were prepared in the same manner as above examples with the noted configurations in Table 4.

[0073] Control Samples: Commercially available oriented polypropylene (OPP) 0.75 mil film laminated onto a 26 point one-side clay coated (ClS) recycled paperboard was used as Control 1. The same substrate with partially printed with water-based ink was used as Control 2. Plain 20 point, 26 points, and 30 points CIS paperboards (without the OPP film) were used as Control 3, Control 4 and Control 5, respectively.

[0074] Table 4 demonstrates that OPP laminated paperboards Controls 1 and 2 have lower MVTR values than plain paperboards: Control 3, 4 and 5. Examples 1-4 have comparable MVTR values (less than 80gsm/day) as those of OPP laminated Controls 1 and 2. Examples 1-4 have MVTR values that are about 200 times lower than plain paperboard. Also, the gloss values of Examples 1-4 are comparable to Controls 1 and 2 (higher than 60GU).

[0075] Table 4 also demonstrates that the combined multilayer of the sealer, primer and topcoat had MVTR values lower than Examples 5 to 13. Moreover, samples without any EB topcoat had much lower gloss values than those with EB topcoat.

[0076] Table 5 lists various types of micronized waxes evaluated as moisture barrier EB coatings. The listed waxes were replaced in Topcoat 1 and the resultant MVTR and gloss measurements are recorded in Table 5.

[0077] Not all hydrophobic waxes impart moisture vapor impermeability properties. As demonstrated in Table 5, compositions with waxes that impart a MVTR level less than

80gsm/day and a gloss level greater than 60 GU were carnauba, Montan, paraffin alloy, oxidized polyethylene, modified polypropylene, polytetrafluoroethylene, and ethylene-bis-stearamide. Polyethylene and carnauba alloy, while hydrophobic, fail to improve moisture impermeability properties to MVTR level of less than 80gsm/day. Although a combination of PTFE and Fischer Tropsch waxes impart a MVTR level less than 80gsm/day, the gloss level was less than 60 GU.

[0078] Many modifications and variations of this invention can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. The specific embodiments described herein are offered by way of example only, and the invention is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled.