UV coating for monoweb films and labels

Abstract

The present invention provides a method for preparing a monoweb label, comprising: (a) providing a substrate; (b) depositing an energy-curable coating composition on the substrate; and (c) applying an energy-curable coating composition to the deposited coating at a rate of from about 30 to about 100 mJ / cm. 2 and curing the coating with ultraviolet radiation of about 50 wt % to about 99 wt % of one or more acrylates, wherein at least about 50 wt % of the total weight of the acrylates is selected from the group consisting of pentaerythritol (5EO) tetraacrylate, propoxylated glycerol triacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, tripropylene glycol diacrylate, and blends thereof; about 1 wt % to about 20 wt % of one or more photoinitiators, including a Norrish Type I photoinitiator and a Norrish Type II photoinitiator; and about 5 wt % to about 20 wt % of one or more amine synergists.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 385,652, filed December 1, 2022, which is incorporated herein in its entirety.

[0002] SUMMARY OF THE INVENTION The present invention relates to ultraviolet radiation curable coatings for monoweb films and labels. [Background technology]

[0003] In the packaging industry, high gloss multi-layer laminate labels and films provide durability and protection, add certain aesthetic properties to the underlying printing ink, provide informative and decorative graphics when sealed between layers of different combinations of polymeric, or paper-based, or metallized substrates, and result in a layered structure.

[0004] Radiation-curable laminated flexible packaging materials are known in the art, such as those disclosed in U.S. Patent No. 7,294,658 B2. However, such layered structures can be difficult to recycle because different polymer and material layers within the structure must be separated. Therefore, there is a need to provide labels that can be more easily recycled without separating the various layers present in the laminated structure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 7,294,658 Summary of the Invention [Problem to be solved by the invention]

[0006] This application addresses this need by describing energy-curable (EC) coatings and methods of their use on a mono-web film comprised of a readily recyclable polyolefin core to produce mono-web labels that do not require lamination and have the necessary end-use performance properties for durability, aesthetics, label conversion, label application, shipping, and storage. The replacement of multi-layer laminate structures with mono-web labels greatly facilitates recycling, as it eliminates the need to separate the various layers of the laminate structure before introducing the material into the recycling stream.

[0007] Another consideration when using printed labels on items such as food packaging is the migration of unwanted and / or toxic compounds into the product. For example, photoinitiators (PIs) can undergo photodegradation and produce unexpected by-products. Benzene is formed at trace levels as a photodegradation product of most UV-curable materials, likely originating from aromatic precursors in the PI or other ink, varnish, adhesive, or substrate components. Scarsella et al., “Identification and Migration Studies of Photolytic Decomposition Products of UV-Photoinitiators in Food Packaging,” Molecules 2019, 24(19), 3592; doi:10.3390 / molecules24193592. The concentration of benzene produced is directly proportional to the amount of UV light energy the material is exposed to during the UV-curing process. Ibid. This application also addresses the need to reduce migratory photoinitiator by-products during UV curing.

[0008] Citation or identification of any document in this application is not an admission that such document represents prior art to the present invention. [Means for solving the problem]

[0009] In one aspect of the invention, there is provided a method for preparing a mono-web label, comprising the steps of: (a) providing a substrate; (b) depositing an energy curable coating composition onto the substrate, the energy curable coating composition comprising: i. about 50% to about 99% by weight of one or more acrylates, based on the total weight of the composition, wherein at least about 50% by weight of the total weight of the acrylates is selected from the group consisting of pentaerythritol (5EO) tetraacrylate, propoxylated glycerol triacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, tripropylene glycol diacrylate, and blends thereof; ii. about 1 wt. % to about 20 wt. % of one or more photoinitiators, including Norrish Type I photoinitiators and Norrish Type II photoinitiators, based on the total weight of the composition; iii. depositing an energy curable coating composition comprising: from about 5 wt. % to about 20 wt. % of one or more amine synergists, based on the total weight of the composition; (c) treating the deposited coating with about 30 to about 100 mJ / cm 2 of ultraviolet-A, ultraviolet-B, and ultraviolet-C radiation; 2 and curing with ultraviolet radiation of (d) A method is provided that does not require multi-layer lamination processing to prepare the label.

[0010] In another aspect of the invention, there is provided a monoweb label prepared by the method of the invention.

[0011] In yet another aspect of the present invention, there is provided a method for providing an easily recycled label that does not require separation of layers or laminations, comprising preparing a mono-web label according to the method of the present invention.

[0012] In a further aspect of the invention, the coating is formulated to minimize the amount of extractable components, such as extractable benzene. DETAILED DESCRIPTION OF THE INVENTION

[0013] This application describes EC (energy curable) coatings and methods for their use to replace multi-layer laminate label or packaging film structures. Advantageously, the EC coatings have low residue and photolytic benzene production, low UV curing energy dose requirements, and will meet the end-use requirements of the applications in which they are used.

[0014] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of any subject matter claimed.

[0015] Headings are for organizational purposes only and are not intended to limit the invention in any way.

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. All patents, patent applications, published applications, and publications, websites, and other published materials mentioned throughout this disclosure are incorporated by reference in their entirety for any purpose unless otherwise noted. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, preferred methods are described.

[0017] definition As used herein, the use of the singular includes the plural unless specifically stated otherwise. As used herein, the singular forms "a," "an," and "the" are intended to include the plural as well, unless the context clearly indicates otherwise.

[0018] As used herein, the use of "or" means "and / or" unless stated otherwise. Also, where clear from the context in which it is used, "and" may be interpreted as "or," such as a list of alternatives that cannot all be true or present at once.

[0019] As used herein, the terms "comprises" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Furthermore, to the extent the terms "includes," "having," "has," "with," "composed," "comprised," or variations thereof are used in either the detailed description or the claims, such terms are intended to be encompassed in a similar manner as the term "comprising."

[0020] When the terms "consist of," "consists of," or "consisting of" are used in the body of a claim, the claim term offset with "consist of," "consists of," and / or "consisting of" is limited to the elements recited immediately following "consist of," "consists of," and / or "consisting of," and is closed to unrecited elements associated with that particular claim term. The term "combinations thereof," when included in the list of recited elements following "consist of," "consists of," and / or "consisting of," means combinations of only two or more of the recited elements.

[0021] As used herein, ranges and amounts may be expressed as "about" a particular value or range. "About" is intended to include the exact amount. Thus, "about 5 percent" means "about 5 percent," and also "5 percent." "About" means within typical experimental error for the intended use or purpose. As used herein, the term "about" means within 5%, more preferably within 1%, of a given value or range. For example, "about 3.7%" means 3.5-3.9%, preferably 3.66-3.74%. When the term "about" is used in conjunction with a range of values, such as "about X%-Y%, "about" is intended to modify both the lower (X) and upper (Y) limits of the recited range. For example, "about 20%-40%" corresponds to "about 20%-about 40%."

[0022] When a range of numerical values ​​is recited, it is understood that it includes the endpoints, all values ​​within that range, and all narrower ranges within that range, whether or not they are specifically recited.

[0023] Throughout this disclosure, all parts and percentages are by weight (wt % or mass % based on total weight) and all temperatures are in °C unless otherwise specified.

[0024] As used herein, "substrate" means any surface or object to which an ink or coating can be applied. Substrates include, but are not limited to, cellulosic substrates, paper, paperboard, fabrics (e.g., cotton), leather, textiles, felt, concrete, masonry, stone, plastics, plastic or polymer films, spunbond nonwovens (e.g., made of polypropylene, polyester, etc.), glass, ceramic, metal, wood, composites, combinations thereof, and the like. The substrate can have one or more layers of metal or metal oxide, or other inorganic materials. Nonwoven substrates are particularly preferred.

[0025] As used herein, the terms "article" or "articles" refer to a substrate or a product of manufacture. Examples of articles include, but are not limited to, substrates such as cellulosic substrates, paper, paperboard, plastic, plastic or polymer film, glass, ceramic, metal, composites, and other substrates, as well as articles of manufacture such as publications (e.g., booklets), labels, and packaging materials (e.g., corrugated sheets or cardboard), containers (e.g., bottles, cans), polyolefins (e.g., polyethylene or polypropylene), polyesters (e.g., polyethylene terephthalate), metallized foils (e.g., laminated aluminum foil), metallized polyesters, and metal containers.

[0026] As used herein, "inks and coatings," "ink," and "coatings" are used interchangeably and refer to the compositions of the present invention or, where specified, compositions found in the prior art (comparison). Inks and coatings typically contain resins, solvents, and optionally colorants. Coatings are often considered to be colorless or transparent, while inks typically contain colorants.

[0027] As used herein, "energy curing" refers to curing achieved under exposure to various electromagnetic radiation sources that produce actinic action. Such sources include, but are not limited to, electron beams, UV light, visible light, IR, or microwaves. When the composition is cured under the action of UV light, then non-limiting UV sources can be used, such as: low-pressure mercury lamps, medium-pressure mercury lamps, xenon lamps, excimer lamps, carbon arc lamps, metal halide lamps, UV-LED lamps, or sunlight. It should be understood by those skilled in the art that any UV light source can be used to cure the composition prepared according to the present invention. The composition of the present invention is particularly suitable for use in compositions that can be cured under the action of UV light and / or electron beams.

[0028] As used herein, "energy curable" refers to a composition that can be cured by exposure to one or more types of actinic radiation. The compositions of the present invention are particularly suitable for use in compositions that are curable under the action of UV light and / or electron beams.

[0029] As used herein, "(meth)acrylate" and "(meth)acrylic acid" include both acrylate and methacrylate, and both acrylic acid and methacrylic acid.

[0030] As used herein, "monofunctional" means having one functional group.

[0031] As used herein, "multifunctional" means having two or more functional groups. For example, a multifunctional monomer can be difunctional, trifunctional, tetrafunctional, or have a higher number of functional groups. The two or more functional groups can be the same or different.

[0032] As used herein, "monomer" refers to a small molecule having one or more functional groups. A monomer reacts with other monomers, whether identical or not, to form a monomer chain (oligomer and / or polymer). Each monomer in the chain is a monomer repeat unit. A monomer is the smallest unit that makes up an oligomer or polymer. A monomer is a low molecular weight molecule, typically having a weight average molecular weight (Mw) of 100 Daltons or less.

[0033] As used herein, "oligomer" refers to a chain of several repeating monomeric units. Oligomers are long chains of several monomeric units and have a weight average molecular weight in the mid-range of about 100 daltons to about 10,000 daltons.

[0034] As used herein, "polymer" refers to a macromolecule containing multiple repeating monomeric and / or oligomeric units. Polymers are high molecular weight molecules having a weight average molecular weight greater than about 10,000 daltons.

[0035] As used herein, "coefficient of friction" or "CoF" is the ratio of the frictional force resisting motion of the surface being tested to a force applied normal to that surface. "Kinetic CoF" is the ratio of the force resisting motion of the surface as the motion progresses to the normal force. "Static CoF" refers to the ratio of the force resisting the initial motion of the surface to the normal force.

[0036] As used herein, "weight percent of one or more acrylates" and "total weight of acrylates" exclude any weight percent, weight, or amount attributable to acrylate amine synergists, acrylate photoinitiators, or acrylate EC additives.

[0037] Energy curable coatings and methods of use thereof The labels, films, and packaging produced by employing the methods of the present invention are easier to recycle because the need for lamination with a second, different substrate is eliminated. For example, different substrates and lamination films, such as polyester and low density polyethylene, make recycle more difficult or impossible using locally available industrial methods.

[0038] In the method of the present invention, the use of suitable UV-polymerizable monomers and oligomers and UV photoinitiators allows for low-energy curing, minimizing the generation of undesirable molecular fragments (e.g., benzene) as by-products after UV curing photodecomposition and polymerization. The coatings of the present invention have the ability to cure efficiently using minimal UV light energy doses, producing coated labels and packaging with a low CoF, as needed, for example, when printing beverage bottle labels that experience face-to-face label contact during bottle and container filling, packaging, and shipping to their destination. The coatings of the present invention are used to protect the underlying print, instead of using a second laminated substrate to protect the print. The coating may also be described as a topcoat.

[0039] Advantageously, in some embodiments of the present invention, the coating may consist essentially of ethylenically unsaturated acrylate monomers and / or oligomers, and performance additives such as α-cleaved Norrish Type I and hydrogen-abstraction Norrish Type II photoinitiators, amine synergists, and copolymerizable amines, inorganic and organic fillers, surfactants, and waxes.

[0040] In some embodiments, certain copolymerizable amines, PIs and amine synergists are found to be particularly suitable. Such components include IGM resin, Omnirad 2959 (1-[4-(2-hydroxyethoxyl)-phenyl]-2-hydroxy-2-methylpropanone), Omnipol BP (a diester of carboxymethoxybenzophenone and polytetramethylene glycol 250), Allnex Ebecryl P39 (a polymeric benzophenone derivative diluted with 25% EBECRYL® LEO 10501 (a trifunctional diluent oligomer)), and GM resin Photomer 4250 (trimethylolpropane triacrylate and hexamethyleneimine / 1H-azepine-1-propanoic acid, hexahydro-, 2,2,bis[(1-oxo-2-propen-1-yl)oxy]methyl]butyl ester), Allnex Ebecryl P115 (a copolymerizable amine; an adduct of diethylamine and tripropylene glycol diacrylate), and Rahn Genomer 5161 (oligoamine, acrylate amine synergist; propylidine trimethanol, ethoxylated ester with acrylic acid, reaction product with diethylamine).

[0041] Base material Suitable substrates include printing substrates such as polyolefin packaging and label films on a printing press, hi some embodiments, the substrate is made of recyclable polyolefin.

[0042] Acrylate Although any ethylenically unsaturated monomers and oligomers can be used in the energy curable coating compositions of the present invention, UV polymerizable acrylate monomers and oligomers are primarily used as the energy curable compounds in the coating method of the present invention.

[0043] Acrylates selected from the group consisting of pentaerythritol (5EO) tetraacrylate, propoxylated glycerol triacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, tripropylene glycol diacrylate, and blends thereof, facilitate low energy curing and are believed to comprise at least about 50 wt. % of the total weight of acrylates in the coating composition, e.g., at least about 55 wt. %, at least about 60 wt. %, at least about 70 wt. %, at least about 80 wt. %, at least about 90 wt. %, or at least about 99 wt. %.

[0044] The acrylate selected from the group consisting of pentaerythritol (5EO) tetraacrylate, propoxylated glycerol triacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, tripropylene glycol diacrylate, and blends thereof may comprise about 50% to about 99% by weight of the energy curable coating, such as about 55% to about 95% by weight, about 60% to about 90% by weight, about 65% to about 85% by weight, about 55% to about 99% by weight, about 60% to about 99% by weight, about 65% to about 99% by weight, about 70% to about 99% by weight, about 50% to about 95% by weight, about 50% to about 90% by weight, about 50% to about 85% by weight, about 50% to about 80% by weight, or about 50% to about 75% by weight, based on the total weight of the coating.

[0045] monomer Examples of suitable monofunctional ethylenically unsaturated monomers include the following (and combinations thereof):

[0046] Isobutyl acrylate, cyclohexyl acrylate, iso-octyl acrylate, n-octyl acrylate, isodecyl acrylate, iso-nonyl acrylate, octyl / decyl acrylate, lauryl acrylate, 2-propylheptyl acrylate, tridecyl acrylate, hexadecyl acrylate, stearyl acrylate, iso-stearyl acrylate, behenyl acrylate, tetrahydrofurfuryl acrylate, 4-t-butylcyclohexyl acrylate, 3,3,5 -Trimethylcyclohexane acrylate, ethylamine acrylate, dicyclopentyl acrylate, dihydrodicyclopentadienyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentanyl acrylate, benzyl acrylate, phenoxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, alkoxylated nonylphenol acrylate, cumylphenoxyethyl acrylate, cyclic trimethylolpropane formal acrylate, 2( 2-Ethoxyethoxy)ethyl acrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, caprolactone acrylate, ethoxylated methoxypolyethylene glycol acrylate, methoxytriethylene glycol acrylate, tripropylene glycol monomethyl ether acrylate, diethylene glycol butyl ether acrylate, alkoxylated tetrahydrofurfuryl acrylate, ethoxylated ethylhexyl acrylate, alkoxylated phenol acrylate, ethoxylated phenol acrylate, ethoxylated nonylphenol acrylate, propoxylated nonylphenol acylate, polyethylene glycol o-phenylphenyl ether acrylate, ethoxylated p-cumylphenol acrylate, ethoxylated nonylphenol acrylate, alkoxylated lauryl acrylate, ethoxylated tristyrylphenol acrylate, N-(acryloyloxyethyl)hexahydrophthalimide, N-butyl 1,Examples of the acrylates include, but are not limited to, 2(acryloyloxy)ethyl carbamate, acryloyloxyethyl hydrogen succinate, octoxypolyethylene glycol acrylate, octafluoropentyl acrylate, 2-isocyanatoethyl acrylate, acetoacetoxyethyl acrylate, 2-methoxyethyl acrylate, dimethylaminoethyl acrylate, 2-carboxyethyl acrylate, and 4-hydroxybutyl acrylate.

[0047] Examples of suitable polyfunctional ethylenically unsaturated monomers include the following (and combinations thereof):

[0048] 1,3-Butylene glycol diacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, ethoxylated neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, 2-methyl-1,3-propanediyl ethoxyacrylate, 2-methyl-1,3-propanediol diacrylate, ethoxylated 2-methyl-1,3-propanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, 1,6-hexanediol diacrylate, alkoxylated hexanediol diacrylate, ethoxylated hexanediol diacrylate, propoxylated hexanediol diacrylate, 1,9-nonanediol diacrylate, 1,10-decanediol diacrylate, ethoxylated hexa Hexanediol diacrylate, alkoxylated hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, propoxylated ethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, poly(tetramethylene glycol) diacrylate, cyclohexanedimethanol diacrylate, ethoxylated cyclohexanedimethanol diacrylate, alkoxylated cyclohexanedimethanol diacrylate, polybutadiene diacrylate, hydroxypivalyl hydroxypivalate diacrylate, tricyclodecane dimethanol diacrylate, 1,4-butanediylbis[oxy(2-hydroxy-3,1-propanediyl)] diacrylate, ethoxylated bisphenol A diacrylate, propoxylated bisphenol A diacrylate, propoxylated ethoxylated bisphenol A diacrylate, ethoxylated bisphenol F diacrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, dioxane glycol diacrylate, ethoxylated glycerol triacrylate, glycerol)ethylamino) triacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, caprolactone-modified trimethylolpropane triacrylate, ethoxylated trimethylolpropane Examples of the acrylates include, but are not limited to, propane triacrylate, propoxylated trimethylolpropane triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, e-caprolactone-modified tris(2-hydroxyethyl)isocyanurate triacrylate, melamine acrylate oligomer, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and ethoxylated dipentaerythritol hexaacrylate.

[0049] Equivalent methacrylate compounds can also be used, although one skilled in the art will appreciate that methacrylate compounds have lower reactivity than their equivalent acrylate counterparts.

[0050] Other functional monomer classes that can be partially used in these formulations include cyclic lactams such as N-vinylcaprolactam, N-vinyloxazolidinone and N-vinylpyrrolidone, and secondary or tertiary acrylamides such as acryloylmorpholine, diacetone acrylamide, N-methylacrylamide, N-ethylacrylamide, N-isopropylacrylamide, N-t-butylacrylamide, N-hexylacrylamide, N-cyclohexylacrylamide, N-octylacrylamide, N-t-octylacrylamide, N-dodecylacrylamide, N-benzylacrylamide, N-(hydroxymethyl)acrylamide, N-isobutoxymethyl ... acrylamide, N-butoxymethylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N,N-propylacrylamide, N,N-dibutylacrylamide, N,N-dihexylacrylamide, N,N-dimethylaminomethylacrylamide, N,N-dimethylaminoethylacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminohexylacrylamide, N,N-diethylaminomethylacrylamide, N,N-diethylaminoethylacrylamide, N,N-diethylaminopropylacrylamide, N,N-dimethylaminohexylacrylamide, and N,N'-methylenebisacrylamide.

[0051] Oligomer Oligomers are substances that provide the vehicle for UV inks. They are similar to monomers, except they are already partially polymerized, making them more viscous. During curing, the monomers react with the oligomers to form chains in three dimensions. In the printing industry, resins / oligomers with acrylate functionality are primarily used to provide the reactivity necessary to allow proper curing for modern high-speed presses.

[0052] The main classes of suitable acrylated oligomers include epoxy acrylates, urethane acrylates, polyester acrylates, acrylic acrylates, hyperbranched polyester acrylates, water-based UV polyurethane dispersions, and organic-inorganic hybrid materials.

[0053] Photopolymerization initiator Free radical photoinitiators are classified into two main groups: Norrish Type I and Norrish Type II, depending on the type of reactive species formed. Norrish Type I photoinitiators are cleavage-type photoinitiators, in which exposure to actinic radiation results in lytic bond cleavage and the generation of two reactive fragments of the photoinitiator. Norrish Type II photoinitiators are hydrogen extractable and require a hydrogen donor to react. A synergist, such as an amine, is typically used in combination with Norrish Type II photoinitiators as a source of hydrogen donor. Type II photoinitiators abstract a hydrogen atom from the synergist to form two radicals.

[0054] There is no limitation on the type, blend, or concentration of photoinitiator used and can include any suitable type of photoinitiator, such as, but not limited to, α-hydroxyketones, acylphosphine oxides, α-aminoketones, thioxanthones, benzophenones, phenylglyoxylates, oxime esters, and combinations thereof.

[0055] Combinations of Norrish Type I alpha-cleaved and Norrish Type II hydrogen-abstraction PIs, along with amine synergists, are typically used to achieve a balance of rapid surface cure and bulk-through cure of the coating film, combined with no yellowing, low odor, low extractables, and other desirable properties for conversion and end use.

[0056] The energy curable coating compositions of the present invention include a Norrish Type I photoinitiator and a Norrish Type II photoinitiator, and include from about 1 wt % to about 20 wt %, such as from about 1.5 wt % to about 15 wt %, from about 2 wt % to about 10 wt %, from about 3 wt % to about 5 wt %, from about 2 wt % to about 15 wt %, from about 3 wt % to about 20 wt %, from about 1 wt % to about 15 wt %, from about 1 wt % to about 10 wt %, from about 1 wt % to about 5 wt %, or from about 1 wt % to about 3 wt %, of one or more photoinitiators, based on the total weight of the composition.

[0057] In some embodiments, the one or more photoinitiators are selected from the group consisting of oligomeric compounds, polymeric compounds, acrylated compounds, and mixtures thereof.

[0058] Norrish type I Norrish Type I photoinitiators include α-hydroxyketones, α-dialkoxy-acetophenones, α-hydroxy-alkyl-phenones, acylphosphine oxides, α-aminoketones, α-amino-alkyl-phenones, benzoin ethers, benzil ketals, and oxime esters.

[0059] Suitable Norrish Type I photoinitiators include the following:

[0060] α-Hydroxyketones, such as 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-2-methyl-4'-tert-butyl-propiophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methyl-propiophenone, 2-hydroxy-4'-(2-hydroxypropoxy)-2-methyl-propiophenone, oligo 2-hydroxy-2-methyl-1-[ 4-(1-methyl-vinyl)phenyl]propanone, bis[4-(2-hydroxy-2-methylpropionyl)phenyl]methane, 2-hydroxy-1-[1-[4-(2-hydroxy-2-methylpropanoyl)phenyl]-1,3,3-trimethylindan-5-yl]-2-methylpropan-1-one, and 2-hydroxy-1-[4-[4-(2-hydroxy-2-methylpropanoyl)-phenoxy]phenyl]-2-methylpropan-1-one,

[0061] acylphosphine oxides, such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl (2,4,6-trimethylbenzoyl)phenylphosphineate, and bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide;

[0062] α-amino ketones, such as 2-methyl-1-[4-methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, and 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one;

[0063] Oxime esters, such as 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime, [1-(4-phenylsulfanylbenzoyl)heptylideneamino]benzoate, and [1-[9-ethyl-6-(2-methylbenzoyl))ethylami-3-yl]-ethylideneamino]acetate, and

[0064] Polymeric photoinitiators and sensitizers, such as polymeric aminobenzoates (GENOPOL AB-1 (polymeric 4-dimethylaminobenzoic acid derivatives) or GENOPOL AB-2 (polyfunctional aminobenzoates; 1,3-propanediol, 2-ethyl-2-(hydroxymethyl)-, oxirane-containing polymer, 4-(dimethylamino)benzoate) from RAHN, Omnipol ASA (poly(ethylene glycol) bis(p-dimethylaminobenzoate) or polyethylene glycol(200) di(β-(4(acetylphenyl)piperazine))-propionate) from IGM), or Speedcure 7040 (1,3- Di({α-4-(dimethylamino)benzoylpoly[oxy(1-methylethylene)]}oxy)-2,2-bis(α-4-(dimethylamino)benzoylpoly[oxy(1-methylethylene)]}oxymethyl)propane and {α-4-(dimethylamino)benzoylpoly-(oxyethylene)-poly[oxy(1-methylethylene]poly(oxyethylene)}4-dimethylamino)benzoate), polymeric thioxanthone derivatives (GENOPOL TX-1 or TX-2; 9-oxo-9H-thioxanthene-carboxylate, esters with branched polyols) from RAHN, and Omnipol from IGM. polymeric aminoalkylphenones such as TX (a diester of carboxy-methoxythioxanthone and polytetramethylene glycol 250), or Speedcure 7010 (1,3-di(α-[1-chloro-9-oxo-9H-thioxanthen-4-yl)oxy]acetylpoly[oxy(1-methylethylene)]}oxy)-2,2-bis({α-[1-methylethylene)]}oxymethyl)propane) from Lambson, Omnipol 910 (polyethylene glycol (200) di(β-4[4-(2-dimethylamino-2-benzyl)butanoylphenyl]-piperazine) propionate) from IGM; polymeric benzoyl formate esters such as Omnipol 2712 (polymeric methylbenzoyl formate) from IGM; and polymeric sensitizers such as Omnipol 2712 (polymeric methylbenzoyl formate) from IGM. SZ (polyethylene glycol (200) di(β-(4(p-acetylphenyl)piperazine))propionate).

[0065] Other suitable photoinitiator examples include diethoxyacetophenone, benzil, benzil dimethyl ketal, and the like.

[0066] In some embodiments, the one or more Norrish Type I photoinitiators are selected from the group consisting of 1-[4-(2-hydroxyethoxyl)-phenyl]-2-hydroxy-2-methylpropanone, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]-propanone], 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropanoyl)phenoxy]phenyl}-2-methylpropan-1-one], ethyl(2,4,6-trimethylbenzoyl)phenylphosphinenate, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and mixtures thereof.

[0067] Norrish type II Norrish Type II photoinitiators include thioxanthones, benzophenones, aminobenzoates, and phenyl glyoxylates.

[0068] Suitable thioxanthones include, but are not limited to, 2-4-diethylthioxanthone, isopropylthioxanthone, 2-chlorothioxanthone, and 1-chloro-4-propoxythioxanthone, and combinations thereof.

[0069] Suitable benzophenones include, but are not limited to, benzophenone, 4-phenylbenzophenone, and 4-methylbenzophenone, methyl-2-benzoylbenzoate, 4-benzoyl-4-methyldiphenyl sulfide, 4-hydroxybenzophenone, 2,4,6-trimethylbenzophenone, 4,4-bis(diethylamino)benzophenone, benzophenone-2-carboxy(tetraethoxy)acrylate, 4-hydroxybenzophenone laurate, 1-[-4-[benzoylphenylsulfo]phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one, and combinations thereof.

[0070] Suitable phenylglyoxylates include, but are not limited to, phenylglyoxylic acid methyl ester, oxy-phenyl-acetic acid 2-[hydroxyl-ethoxy]-ethyl ester, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester, and combinations thereof.

[0071] For example, polymeric benzophenone derivatives (GENOPOL BP-1 ([benzoyl benzoate, ester with branched polyol] or GENOPOL BP-2 (polyfunctional benzophenone derivative; benzoyl benzoate, ester with branched polyol]) from RAHN, Omnipol BP (diester of carboxymethoxybenzophenone and polytetramethylene glycol 250) from IGM, Omnipol Polymeric photoinitiators and sensitizers are also suitable, including BP2702 (bis(benzophenone-2-carboxylic acid) polyethylene glycol ester) or Omnipol 682 (a diester of carboxymethoxybenzophenone and polyethylene glycol 200), or Speedcure 7005 from Lambson (a mixture of 1,3-di({-2-(phenylcarbonyl)benzoylpoly[oxy(1-methylethylene)]}oxy-2,2-bis({α-2-phenylcarbonyl)-benzoylpoly[oxy(1-methylethylene)]}oxymethyl)propane and {α-2-(phenylcarbonyl)benzoylpoly(oxyethylene)poly[oxy(1-methylethylene)]-poly(oxyethylene)}2-(phenylcarbonyl)benzoate).

[0072] Other Norrish Type II photoinitiators include camphorquinone, 2-ethylanthraquinone, and 9-fluorenone.

[0073] In some embodiments, the one or more Norrish Type II photoinitiators are selected from the group consisting of oligomeric benzophenones, polymeric benzophenones, acrylated benzophenones, and derivatives and mixtures thereof.

[0074] In some embodiments, the one or more Norrish Type II photoinitiators are selected from the group consisting of 4-(4-methylphenylthio)benzophenone, carboxymethoxy-benzophenone and di-esters of polytetramethylene glycol 250, methyl-o-benzoylbenzoate, and mixtures thereof.

[0075] Additional Photoinitiators Titanium-bis

number

[0076] Amine Synergists The energy curable coating compositions of the present invention comprise from about 5 wt % to about 20 wt %, such as from about 5 wt % to about 18 wt %, from about 7 wt % to about 15 wt %, from about 10 wt % to about 13 wt %, from about 5 wt % to about 15 wt %, from about 5 wt % to about 10 wt %, from about 5 wt % to about 8 wt %, from about 10 wt % to about 20 wt %, from about 10 wt % to about 13 wt %, from about 15 wt % to about 20 wt %, or from about 17 wt % to about 20 wt %, based on the total weight of the composition.

[0077] Suitable examples of amine synergists include, but are not limited to, aromatic amines, aliphatic amines, aminoacrylates, and amine-modified polyether acrylates.

[0078] Examples of aromatic amines include 2-(dimethylamino)ethyl benzoate, N-phenylglycine, benzoic acid, 4-(dimethylamino)-, 1,1'-[(16-ethylamino)di-2,1-ethanediyl] ester, and simple alkyl esters of 4-(N,N-dimethylamino)benzoic acid. In some embodiments of the present invention, the ethyl, amyl, 2-butoxyethyl, and 2-ethylhexyl esters of 4-(N,N-dimethylamino)benzoic acid are particularly preferred. Other positional isomers of N,N-dimethylamino)benzoic acid esters are also suitable.

[0079] Suitable aliphatic amines include N-methyldiethanolamine, triethanolamine, and tri-isopropanolamine.

[0080] Suitable aminoacrylates and amine-modified polyether acrylates include EBECRYL 80, EBECRYL 81, EBECRYL 83, EBECRYL 85, EBECRYL 880, EBECRYL LEO10551, EBECRYL LEO10552, EBECRYL LEO10553, EBECRYL 7100, EBECRYL P115, and EBECRYL P116, all available from ALLNEX; CN501, CN550, CN560, CN570, CN580, CN590, CN600, CN610, CN620, CN630, CN640, CN650, CN660, CN670, CN680, CN690, CN691, CN692, CN693, CN694, CN695, CN696, CN697, CN698, CN69 ... UVA421, CN3705, CN3715 (propylidine trimethanol, ethoxylated ester with acrylic acid, reaction product with diethylamine), CN3755 (1,6-hexanediol diacrylate, 2-aminoethanol polymer), CN381 and CN386 (2-propenoic acid, 1,1'-((1-methyl-1,2-ethanediyl)bis(oxy(methyl-2,1-ethanediyl))) ester, reaction product with diethylamine), GENOMER 5142 from RAHN (2-propenoic acid, 1,1'-[(1-methyl-1,2-ethanediyl)bis[oxy(methyl-2,1-ethanediyl)] ester, reaction product with diethylamine), GENOMER 5161 (propenoic acid, 1,1'-[(1-methyl-1,2-ethanediyl)bis[oxy(methyl-2,1-ethanediyl)] ester, reaction product with diethylamine), PHOTOMER 4771 (polymer of 2-propenoic acid, 1,6-hexanediyl ester, 2-aminoethanol), PHOTOMER 4967 (2-propenoic acid, (1-methyl-1,2-ethanediyl)bis[oxy(methyl-2,1-ethanediyl)] ester, reaction product with diethylamine), PHOTOMER 5006 (propylidine trimethanol, ethoxylated ester with acrylic acid, reaction product with diethylamine), PHOTOMER 4775 (2-propenoic acid, 1,6-hexanediyl ester, reaction product with diethylamine), PHOTOMER 5006 (propylidine trimethanol, ethoxylated ester with acrylic acid, reaction product with diethylamine), PHOTOMER 5271, and GENOMER 5275, all available from IGM.LAROMER LR8996 (a polymer with propylidinetrimethanol, 6-hexanediyl ester, and 2-aminoethanol), PHOTOMER 5662, PHOTOMER 5850 (a mixture of propoxylated esters with glycerol, acrylic acid, and ethoxylated esters with propylidinetrimethanol, acrylic acid, and diethylamine), PHOTOMER 5930 (a polymer with 2-propenoic acid, 2-aminoethanol, 1,2-ethanediol, and 2-ethyl-2-(hydroxymethyl)-1,3-propanediol), and PHOTOMER 4250 (1H-azepine-1-propanoic acid, hexahydro-, 2,2-bis[[(1-oxo-2-propen-1-yl)oxy]methyl]butyl ester), all available from BASF. Examples of such polymers include LR8889, LAROMER LR8997, LAROMER PO83F, LAROMER PO84F, LAROMER PO94F (polymers of poly(oxy-1,2-ethanediyl), α-hydro-ω-[(1-oxo-2-propen-1-yl)oxy]-, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol), LAROMER PO9067, LAROMER PO9103 (polymers of 2-propenoic acid, 1,1′-(1,6-hexanediyl) ester, 2-aminoethanol), LAROMER PO9106, and LAROMER PO77F, as well as AGISYN701, AGISYN702, AGISYN703, NeoRad P-81, and NeoRad P-85, formerly of DSM-AGI.

[0081] In some embodiments, the one or more amine synergists are selected from the group consisting of copolymerizable tertiary amines, aminoacrylates, amine-modified polyether acrylates, and mixtures thereof.

[0082] In some other embodiments, the amine synergist is selected from the group consisting of propylidine trimethanol, ethoxylated esters with acrylic acid, reaction products with diethylamine, 1H-azepine-1-propanoic acid, hexahydro-, 2,2-bis[[(1-oxo-2-propen-1-yl)oxy]methyl]butyl ester, and mixtures thereof.

[0083] EC Coating Additives The radiation curable compositions and inks of the present invention may contain conventional additives to modify the flow, surface tension, gloss, and abrasion resistance of the cured coating or printed ink. These additives include copolymerizable amines (crosslinkers), inert, non-curable resins, extenders, surfactants, surface tension modifiers, waxes, antiblock release agents, leveling agents, wetting agents, slip agents, flow agents, dispersants, degassing agents, stabilizers (e.g., in-can stabilizers), inorganic and organic fillers, and blends thereof.

[0084] In some embodiments, preferred additives include fluorocarbon surfactants, silicone and organic polymer surfactants, and inorganic materials such as talc.

[0085] These additives are typically used in amounts of about 0.1% to about 5% by weight, based on the total weight of the composition.

[0086] Suitable examples of such additives include the Tegorad product line (Tegorad is a trademark and a commercially available product of Tego Chemie, Essen, Germany) and the Solsperse product line (Solsperse is a trademark and a commercially available product of Lubrizol Company).

[0087] Examples of suitable copolymerizable amines (crosslinkers) include those used above as amine synergists, such as Allnex Ebecryl P115 (an adduct of diethylamine and tripropylene glycol diacrylate), as well as copolymerizable tertiary amines, dialkylenetriamines such as diethylenetriamine and di-hexamethylene-triamine, dialkylenetetraamines, dialkylenepentamines, and mixtures thereof.

[0088] Suitable surfactants, surface tension modifiers, wetting agents, flow agents, leveling agents, and dispersing agents include phosphate polyesters, fluorocarbon surfactants, silicone polyether acrylates such as Evonik Tego® Rad2250 (a radically crosslinkable organically modified silicone acrylate), and organic polymeric surfactants.

[0089] Suitable stabilizers include in-can stabilizers such as a mixture of glycerol, propoxylated esters with acrylic acid, 2,6-di-tert-butyl-p-cresol, tris(N-hydroxy-N-isophenylaminato-O,O')aluminum, and 4-methoxyphenol; a mixture of glycerol, propoxylated esters with acrylic acid, 4,4'-isopropylidenediphenol, oligomeric reaction products with 1-chloro-2,3-epoxypropane, esters with acrylic acid, 2,6-tert-butyl-p-cresol, tris(N-hydroxy-N-nitrosophenylaminato-O,O')aluminum, and 4-methoxyphenol; and a mixture of ethoxylated trimethylpropane triacrylate, 4-methoxyphenol, and phenothiazine.

[0090] Waxes include polypropylene waxes, synthetic polyethylene wax alloys, slip and controlled release waxes such as Shamrock LoAngle 5413 (also known as S-413; a synthetic wax that exhibits multiple peaks in the range of 107-142°C), and combinations thereof.

[0091] Suitable anti-blocking release agents include surface treated precipitated silica, untreated fumed silica, calcium stearate, for example, United Guardian B-122 calcium stearate powder.

[0092] Suitable slip agents include primary and secondary fatty acid amides, including erucamide, oleamide, oleyl palmitamide, and mixtures thereof.

[0093] Suitable degassing and antifoaming agents include organically modified polysiloxanes such as ICM1051, ICM I-1042, Foamtrol 110, polydimethylsiloxanes, modified polydimethylsiloxanes such as BYK-373, polyalkylene oxide modified heptamethyltrisiloxanes.

[0094] The method of the present invention may use conventional extenders such as clay, talc, calcium carbonate, magnesium carbonate, or silica, as well as inorganic and organic fillers for coatings, to adjust gloss, misting, and color strength.

[0095] The radiation-curable coating of the present invention may contain an inert, non-curable resin having no curable acrylic groups and a weight number average of 1,000 to 30,000 daltons, such as 1,000 to 4,000 daltons. Suitable inert resins include poly(acrylates), poly(esters), poly(urethanes), poly(amides), ketone resins, aldehyde resins, alkyd resins, phenolic resins, phenol-formaldehyde resins, nitrocellulose, vinyl resins, acrylics, epoxy resins, styrenes, urea resins, melamine-formaldehyde, rosin resins, rosin esters, hydrocarbon resins, and mixtures thereof. Such resins may improve pigment wetting, gloss, rheology, and / or flexibility.

[0096] Hardening Mechanism The radiation-curable compositions of the present invention can be cured by a light source such as a high-voltage mercury lamp, a medium-voltage mercury lamp, a xenon lamp, a carbon arc lamp, a metal halide lamp, a UV-LED lamp, or UV light provided by sunlight. The wavelength of the applied radiation is typically within the range of 100 to 500 nm or 250 to 350 nm.

[0097] After being applied to a printing substrate, such as a polyolefin packaging or label film, on a printing press, the liquid-phase coating is cured into a solid dry film by free-radical polymerization initiated by absorption of UV light radiation, subsequent photolytic breakdown of the PI, and reaction with unsaturated monomers and oligomers.

[0098] Ultraviolet radiation, including ultraviolet A, ultraviolet B, and ultraviolet C radiation (Uva+Uvb+Uvc), is typically used. The UV energy is advantageously, for example, between 40 and 80 mJ / cm 2 , 50-100mJ / cm 2 , 50-75mJ / cm 2 , or 50-60mJ / cm 2 40 to 100 mJ / cm 2 This applies within the scope of

[0099] In addition, the lamp may be appropriately selected according to the absorption spectrum of the radiation-curable composition. Furthermore, the inks of the present invention may be cured under inert conditions, for example, in an environment of one or more inert gases such as nitrogen or carbon dioxide.

[0100] In some embodiments, to enable the press to operate at high line speeds, the coating provides radiation in the range of 40-100 mJ / cm from an industry standard medium pressure mercury (Hg) arc lamp (with a life of less than 1,000 hours of use) and reflector housing, as measured with an EIT Power Puck II radiometer. 2 (UV a +UV b +UV c ), or 50-100mJ / cm 2, or 50 to 75 mJ / cm 2 , or 50-60mJ / cm 2 The low UV energy dose curing is achieved by using the coating composition of the present invention in combination with low extractable benzene.

[0101] Printing method The coatings of the present invention can be formulated for printing by any of the methods well known in the art for curable polymer coatings, such as flexographic printing, gravure printing, screen printing, spray coating, inkjet printing, lithographic printing, roll coating, curtain coating, etc. In some embodiments, flexographic coating is the preferred method. In some embodiments, the coating is applied by flexography at flexographic press speeds of about 600 feet per minute (FPM) or greater.

[0102] EC Coating Parameters Similar to laminate structures, the method of the present invention provides EC coatings that have acceptable performance for the following parameters listed in Table 1 in a wide range of gloss / matt effects when applied at low coat weights while requiring low UV energy doses for cure, thereby effectively replacing the need for laminate film and label structures.

[0103] The coatings and methods of the present invention enhance ease of recyclability by avoiding the need to separate the multiple plastic film layers required for laminate construction, while resulting in unsafe levels of undesirable by-products in packaging, particularly benzene.

[0104] The coatings and methods of the present invention maximize conversion efficiency, economy, and sustainability for printer-converters by enabling conversion at high press speeds (e.g., 600 FPM or greater) using low levels of UV light curing energy without the need to print and laminate multiple non-recyclable layers to achieve the required gloss, coefficient of friction (CoF), mechanical durability, and chemical resistance.

[0105] In some embodiments, the weight of the cured coating is about 1 g / m 2 ~about 5g / m 2 is.

[0106] In some embodiments, the cured coating exhibits a low odor of about 1 or less. [Table 1]

[0107] 1 Low odor (i.e., ≦1) is subjectively defined by a panel of odor test subjects based on a scale of 0 to 5, where 0 = no discernible odor, 1 = very slight odor, 2 = slight odor, 3 = moderate odor, 4 = strong odor, and 5 = very strong odor.

[0108] Fewer unwanted by-products and residues Certain PIs undergo UV-induced decomposition and produce greater amounts of benzene than other types, which produce less benzene depending on their molecular structure and subsequent decomposition reaction pathway. UV-curable formulations can be developed to minimize photolytic benzene production. These formulations have low residual benzene content (see Table 2), can be UV-cured at low UV energy doses, and produce low levels of photolytic benzene production after UV curing, such as in flexographic printing (1.0-4.5 g / 2 When applied to printed film at a coat weight typical of that used in ), and UV cured, the concentration was 0.1 ng / cm as measured by a Shimadzu QP2020 gas chromatograph with mass spectrometry (GC / MS). 2Thus, in some embodiments, the cured coating results in a coating having an overall extractable benzene level of about 0.1 ng / cm 2 With the following extractable benzene levels:

[0109] Advantageously, the coatings obtained by the methods of the present invention have low residual and photolytic production of undesirable products, such as benzene. Thus, the converted films or labels of the present invention have low levels of residual and undesirable by-products generated from the UV curing reaction, particularly benzene, which is limited in many packaged products, such as bottled water. The maximum contaminant level (MCL) of benzene allowed in public drinking water is 0.005 milligrams per liter (mg / L), as set by the U.S. Environmental Protection Agency (EPA) and the U.S. Food and Drug Administration (FDA).

[0110] dynamic surface tension Label and packaging films are designed to be print receptive and produce high-quality graphics with good intercoat adhesion of inks and coatings to the film surface. The surface energy of label and packaging films must be high enough to allow printing inks and coatings to transfer from the printing unit to the substrate film, promoting rapid wetting, leveling, and interlayer bond formation.

[0111] Typical biaxially oriented packaging label films, such as Taghleef Industries' LMW1 white voided polypropylene, have printable surface treatment levels of at least 38 dynes / cm (ASTM D2578), and often greater than 50 dynes / cm, as measured with Jemmco Accu-Flo Dyne pen solution. This results in a very high print-to-print coefficient of friction (CoF) of greater than 1.0 (ASTM D1894). High-CoF films are not suitable for applications where the printed label and packaging come into direct face-to-face contact in downstream converting processes, such as label applicators, bottle filling, and packaging lines, where the labeled bottle and film must slide freely against each other at high speeds with minimal friction and without damaging the graphics printed on the surface.

[0112] In some embodiments, the cured coatings of the present invention have a viscosity of 32 dynes / cm or greater to enhance substrate wetting, flow, and leveling. 2 For example, approximately 38 dynes / cm 2 It has a reduced dynamic surface tension of:

[0113] In some embodiments, the dynamic surface tension of the coating is increased to 38 dynes / cm using a silicone polyether acrylate such as Evonik Tego® Rad2250 (a radically crosslinkable organically modified silicone acrylate) or other surface tension modifier. 2 Less than or equal to 32 dynes / cm 2 is reduced to less than

[0114] Coefficient of Friction (CoF) Coat weight 1.1g / m 2 More than 1.5g / m 2When applied to labels and films printed with UV inks, the coating compositions obtained by the methods of the present invention may advantageously exhibit a face-to-face static CoF of 0 to 0.5, or 0.1 to 0.5, or 0.20 to 0.40, and a kinetic CoF of 0 to 0.5, or 0.1 to 0.5, or 0.15 to 0.35, as measured using a TMI Slip and Friction Tester Model 32-07 at a speed of 6 inches / minute, using a 200 g sled, and a 5 inch sweep length.

[0115] In some embodiments, the cured coating exhibits a static coefficient of friction (Static CoF) of ≦about 0.4, such as about 0.20-0.40. In some embodiments, the cured coating exhibits a kinetic coefficient of friction (Kinematic CoF) of about 0.35 or less, such as about 0.15-0.35.

[0116] CoF reduction can be achieved, for example, by using a combination of slip and release control waxes such as Shamrock LoAngle 5413 (also known as S-413; a synthetic wax that exhibits multiple peaks in the 107-142°C range) and an anti-blocking release agent such as United Guardian B-122 calcium stearate powder.

[0117] Gloss Level The desired gloss level of the coating is engineered by adjusting the formulation weight percentage ratio of high-gloss resins, polymers, monomers, and oligomers, using a combination of matte-effect resins, polymers, oligomers, and particle fillers to achieve the same range of gloss effects as the laminated film. The coated gloss typically ranges from 50 to 90 gloss units for high-gloss coatings, and from 10 to 20 gloss units, such as less than 10, for low-gloss matte effects, depending on the substrate quality and coating application process. A range of intermediate gloss levels is easily achieved by adjusting the ratio of gloss and matte components in the formulation and adjusting the coating application process conditions.

[0118] In some embodiments, the cured coating exhibits a low gloss in the range of about 1-50, such as about 5-25.

[0119] In some other embodiments, the cured coating exhibits a high gloss in the range of about 50-90. [Example]

[0120] The present invention is further described by the following non-limiting examples, which further illustrate the present invention and are not intended, nor should they be construed, to limit the scope of the invention.

[0121] method Gross Measurement Gloss was measured at 60° using a BYK-Gardner Model 4561 Micro-gloss Meter (ASTM D523 and D2457).

[0122] Odor measurement Odor was subjectively defined by a panel of odor test subjects on a scale of 0 to 5, where 0 = no discernible odor, 1 = very slight odor, 2 = slight odor, 3 = moderate odor, 4 = strong odor, and 5 = very strong odor. In this subjective test, low odor was determined as 1 or less.

[0123] Determination of Benzene Levels To determine benzene levels, all tested materials were prepared in the same manner, regardless of their physical state at room temperature. To maximize sample homogeneity, each material was mixed before sampling. Approximately 1 gram of sample was then transferred to a tared 20 milliliter screw-cap headspace vial. The sample weight was measured and recorded. The sample vial was sealed and labeled for analysis. Samples were analyzed on a Shimadzu QP2020 gas chromatograph using mass spectrometry equipped with an Rtx-5 MS column (30 m × 0.25 mm, df = 1.0 micron) [Restek Corporation, Bellefonte, PA]. The instrument was also equipped with an AOC-6000 multifunction autosampler with SPME, heated headspace, and liquid injection hand. Each sample was equilibrated at 130 °C for 30 minutes with stirring. A volume of 1000 μL was removed from the equilibrated sample using a heated gas-tight syringe hand and injected into the split / splitless injection port (split mode with a split ratio of 10:1) and the analysis was initiated. The injection port was maintained at 250°C.

[0124] Elution was facilitated by temperature programming during the analysis. The oven temperature was initially held at 50 °C for 1.5 min and then increased to 95 °C at a rate of 10 °C / min. This temperature was then increased at a rate of 25 °C / min to a final temperature of 280 °C, which was held for an additional 1.6 min. The total analysis time was 15 min. The carrier gas was helium at a linear velocity of 37.0 cm / s. A Shimadzu SMART source was installed and operated in electron impact (EI) mode. The ion source was maintained at 230 °C. The mass spectrometer was operated in selected ion monitoring (SIM) mode, collecting responses at 78 m / z for 2.5–6.5 min.

[0125] The instrument response was calibrated in the following manner. A certified solution of benzene was purchased from Ultra Scientific [EPA-1003, benzene in methanol, lot number CP-5617, 5024 ± 25 μg / mL]. The entire contents of the ampoule (1 mL) were then transferred to a 10-milliliter volumetric flask and diluted to the final volume with methanol to create a working calibration stock solution with a nominal concentration of 500 μg / mL. This calibration stock was serially diluted to generate calibration standards of known composition ranging from 0.05 to 50 micrograms / milliliter. The instrument response of the 78 m / z ion was used for all quantitative measurements. All results were calculated as nanograms on the column. The method level of quantitation (LOQ) was determined to be 0.15 nanograms, and the limit of detection (MDL) was 0.03 nanograms. Calibration was performed with an r > 0.999. 2 The peak peaks were found to be linear over the calibrated range. Samples that displayed elevated signals within the retention time window of the benzene standard were reanalyzed using scan mode to generate searchable mass spectra. These spectra were matched to entries in the NIST14 mass spectral library for benzene to confirm their identification as benzene. [Table 2]

[0126] *Trace benzene determination by static headspace GCMS on homogeneously prepared samples equilibrated at 130°C for 30 minutes. Benzene signal spectra matched and confirmed to the NIST14 mass spectral library [CAS71-43-2] using Agilent Ultra Scientific EPA-1003 certified benzene calibration solution. [Table 3]

[0127] **2% PI dissolved in 3-ethoxytrimethylolpropane triacrylate, 550 lines per inch (LPI), 3.04 billion cubic microns per square inch (BCM / in 2 The films were coated using a laboratory Harper QD Flexo Proofing System with a 1000 psi anilox roll and cured on aluminum foil at increasing energy doses. Table 3 shows the benefit of using lower UV curing energy in terms of producing extractable benzene.

[0128] Example 1. Comparative UV-curable coatings A comparative UV curable coating (Example 1) was prepared according to the formulation shown in Table 4. [Table 4]

[0129] The composition of Comparative Example 1 was coated, applied, and cured on a commercial UV-flexo and rotary screen narrow-web label press operating at typical production speeds of 50-200 fpm onto clear biaxially oriented polypropylene (BOPP) film, and then analyzed for extractable benzene. Note that Comparative Example 1 failed both the extractable benzene and odor tests.

[0130] Example 2. UV-curable coating of the present invention A UV curable coating of the present invention (Example 2) was prepared according to the formulation shown in Table 5. [Table 5]

[0131] The composition of Inventive Example 1 was applied via various UV flexographic pigmented inks onto a 38 micron (μm) thick white voided biaxially oriented polypropylene (BOPP) film on a commercial UV-flexographic narrow web label press operating at typical production speeds between 400 and 800 feet per minute (fpm), cured, and then analyzed for extractable benzene. Inventive Example 2 exhibited passing results for all of the properties shown in Table 1 and had acceptable levels of extractable benzene.

[0132] Example 3. UV-curable coating of the present invention A UV curable coating of the present invention (Example 3) was prepared according to the formulation shown in Table 6. [Table 6]

[0133] The composition of Inventive Example 3 was applied to biaxially oriented polypropylene (BOPP) film on a commercial UV-flexo narrow web label press running at production speed, cured, and then analyzed in the laboratory in triplicate and the results averaged. Inventive Example 3 exhibited passing results for all of the properties shown in Table 1 and had acceptable levels of extractable benzene. Inventive Example 3 also exhibited reduced gloss due to the addition of a matting agent.

[0134] Example 4. Comparative UV-curable coating A comparative UV curable coating (Example 4) was prepared according to the formulation shown in Table 7. [Table 7]

[0135] The coating composition of Comparative Example 4 was applied to a 300 line per inch, 4.8 billion cubic microns per square inch (BCM / in 2 ) anilox roll on a Harper QD flexo proofing system in the laboratory, and applied at 60mJ / cm 2 The coating was cured on aluminum foil with a UVa+b+c energy dose of 1000 VA. Note that Comparative Example 4 failed both the extractable benzene and odor tests.

[0136] Example 5. UV-curable coating of the present invention Inventive Example 5 was prepared according to the formulation shown in Table 8. [Table 8]

[0137] The coating is applied at 300 lines per inch (LPI) and 4.8 billion cubic microns per square inch (BCM / in 2 ) anilox roll on a Harper QD flexo proofing system in the laboratory, and applied at 60mJ / cm 2 The coating was cured on aluminum foil using a UVa+b+c energy dose of 1000 ppm.

[0138] The composition of Inventive Example 5 exhibited passing results for all of the properties shown in Table 1 and had acceptable levels of extractable benzene.

[0139] Test Results of the UV-Curable Coatings of the Invention and Comparative UV-Curable Coatings The gloss, odor, and benzene extractable levels were measured for Examples 1-5. The results of these tests are shown in Table 9. [Table 9]

[0140] The data in Table 9 show that excellent results were obtained for all parameters when using selected acrylates of the present invention in the amounts required by the method of the present invention along with the photoinitiator and amine synergist required by the method of the present invention (see Inventive Examples 2, 3 and 5). Table 9 also shows that:

[0141] In Comparative Example 4, only about 45 wt. % of the acrylates selected from pentaerythritol (5EO) tetraacrylate, propoxylated glycerol triacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, and tripropylene glycol diacrylate were present, based on the total weight of the acrylates (excluding the acrylate amine synergist and EC additive from the total weight of the acrylates), and only about 35 wt. % of the acrylates, based on the total weight of the composition, exhibited high odor and an EC concentration of 0.1 ng / cm. 2 had extractable benzene levels of > 1000kJ / L.

[0142] In Comparative Example 1, only about 2.2 wt. % of an acrylate selected from pentaerythritol (5EO) tetraacrylate, propoxylated glycerol triacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, and tripropylene glycol diacrylate was present, based on the total weight of the acrylates (excluding the acrylate amine synergist and EC additive from the total weight of the acrylates), and only about 1.9 wt. % of the above acrylates, based on the total weight of the composition, were found to have high odor and a 5.2 ng / cm 2 had very high extractable benzene levels of <1.

[0143] UV coating formulations such as Comparative Examples 1 and 4, which contain lower molecular weight and more volatile photoinitiators such as benzophenone and tertiary amines such as methyldiethanolamine, were rated as high odor.

[0144] The materials used in Examples 2, 3, and 5 are less volatile and have higher molecular weights, e.g., oligomeric and polymeric benzophenones, and acrylated and copolymeric tertiary amines, are less likely to produce strong odors and are rated between 0 and 1 depending on the other materials and the composition they are combined with.

[0145] Although the present invention has been described in detail, including various embodiments thereof, it will be appreciated that those skilled in the art, upon consideration of this disclosure, may make modifications and / or improvements to the present invention which are within the scope and spirit of the invention.

Claims

1. 1. A method for preparing a monoweb label, comprising: (a) providing a substrate; (b) depositing an energy curable coating composition onto the substrate, the energy curable coating composition comprising: i. from about 50% to about 99% by weight of one or more acrylates, based on the total weight of the composition, wherein at least about 50% by weight of the total weight of the acrylates is selected from the group consisting of pentaerythritol (5EO) tetraacrylate, propoxylated glycerol triacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, tripropylene glycol diacrylate, and blends thereof; ii. about 1 wt % to about 20 wt % of one or more photoinitiators, including Norrish Type I and Norrish Type II photoinitiators, based on the total weight of the composition; iii. depositing an energy curable coating composition comprising: from about 5 wt % to about 20 wt % of one or more amine synergists, based on the total weight of the composition; (c) treating the deposited coating with about 30 to about 100 mJ / cm2 of UV-A, UV-B, and UV-C radiation; ２ and curing the composition with ultraviolet radiation of A method that does not require a multi-layer lamination process to prepare the label.

2. 10. The method of claim 1, wherein the acrylate selected from the group consisting of pentaerythritol (5EO) tetraacrylate, propoxylated glycerol triacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, tripropylene glycol diacrylate, and blends thereof comprises from about 60 wt% to about 99 wt% of the energy curable coating, based on the total weight of the coating.

3. 10. The method of any one of the preceding claims, wherein the one or more photoinitiators are selected from the group consisting of oligomeric compounds, polymeric compounds, acrylate compounds, and mixtures thereof.

4. 10. The method of any one of the preceding claims, wherein the one or more Norrish Type II photoinitiators are selected from the group consisting of oligomeric benzophenones, polymeric benzophenones, acrylated benzophenone derivatives, and mixtures thereof.

5. 10. The method of any one of the preceding claims, wherein the one or more Norrish Type I photoinitiators are selected from the group consisting of 1-[4-(2-hydroxyethoxyl)-phenyl]-2-hydroxy-2-methylpropanone, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]-propanone], 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropanoyl)phenoxy]phenyl}-2-methylpropan-1-one], ethyl(2,4,6-trimethylbenzoyl)phenylphosphinenate, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and mixtures thereof.

6. 10. The method of any one of the preceding claims, wherein the one or more Norrish Type II photoinitiators are selected from the group consisting of 4-(4-methylphenylthio)benzophenone, diesters of carboxymethoxy-benzophenone and polytetramethylene glycol 250, methyl-o-benzoylbenzoate, and mixtures thereof.

7. 10. The method of any one of the preceding claims, wherein the one or more amine synergists are selected from the group consisting of copolymerizable tertiary amines, aminoacrylates, amine-modified polyether acrylates, and mixtures thereof.

8. 10. The method of any one of the preceding claims, wherein the amine synergist is selected from the group consisting of propylidine trimethanol, ethoxylated esters with acrylic acid, reaction products with diethylamine, 1H-azepine-1-propanoic acid, hexahydro-, 2,2-bis[[(1-oxo-2-propen-1-yl)oxy]methyl]butyl ester, and mixtures thereof.

9. 10. The method of any one of the preceding claims, wherein the energy curable coating further comprises additives selected from the group consisting of copolymerizable amines, inert, non-curable resins, extenders, surfactants, surface tension modifiers, waxes, antiblock release agents, leveling agents, wetting agents, slip agents, flow agents, dispersants, degassing agents, stabilizers, inorganic and organic fillers, and blends thereof.

10. 10. The method of claim 9, wherein the filler is selected from the group consisting of clay, talc, calcium carbonate, magnesium carbonate, silica, and mixtures thereof.

11. The weight of the cured coating is about 1 g / m ２ ~Approx. 5g / m ２ 10. The method of any one of the preceding claims, wherein:

12. 10. The method of any one of the preceding claims, wherein the substrate is a recyclable polyolefin.

13. 10. The method of any one of the preceding claims, wherein the coating is applied by flexography at a flexographic press speed of about 600 feet per minute or greater.

14. 10. The method of any one of the preceding claims, wherein the cured coating exhibits a static coefficient of friction of about 0.4 or less.

15. 10. The method of any one of the preceding claims, wherein the cured coating exhibits a dynamic coefficient of friction of about 0.35 or less.

16. 10. The method of any one of the preceding claims, wherein the cured coating exhibits a low odor of about 1 or less.

17. The cured coating has a viscosity of about 38 dynes / cm ２ 10. The method of any one of the preceding claims, exhibiting a dynamic surface tension of:

18. 10. The method of any one of the preceding claims, wherein the cured coating exhibits a low gloss in the range of about 1 to 50.

19. 10. The method of any one of the preceding claims, wherein the cured coating exhibits a high gloss in the range of about 50-90.

20. The cured coating has a viscosity of about 0.1 ng / cm ２ 10. The method of any one of the preceding claims, having an extractable benzene level of:

21. A monoweb label prepared by the method of any one of the preceding claims.

22. 21. A method for providing an easily recycled label that does not require separation of layers or laminations, the method comprising preparing a monoweb label according to the method of any of claims 1 to 20.

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