Energy-curable thermally activated inkjet adhesive for foil pressing

Abstract

An adhesive composition that can be applied to a substrate using an inkjet printhead, cured to a solid, tack-free state, and easily re-adhered to a tacky state by the application of heat and pressure, allowing for accurate transfer of a foil to the substrate, comprises one or more free-radical curable monomers, an oligomer-resin composition component that includes one or more oligomers soluble in the monomers and one or more inert thermoplastic resins, and, optionally, one or more free-radical photoinitiators.

Description

Technical Field

[0001] Embodiments of the present invention relate to an energy-curable inkjet adhesive composition containing an inert resin, a functional oligomer, a monomer, and other additives. This adhesive can be applied, inter alia, to substrates including paper, cardboard for cartons, plastic films, and plastic sheets. By irradiating one of UV, LED, or electron beam, the adhesive is fully cured to have a non-tacky (sticky, tacky) surface. The cured adhesive surface becomes tacky when heated and pressurized. By hot stamping foil onto the tacky surface of the cured adhesive, foil transfer without using a mold can be performed efficiently and accurately.

Background Art

[0002] 〔Cold Foil Processing〕 Cold foil processing and hot foil processing are commonly used for metal foil decoration of various substrates. Cold foil processing is basically performed in the following steps. (1) Apply an adhesive to the substrate according to the desired image shape, (2) Press the foil on the backing support material and the substrate together, and transfer the foil from the backing support material to the adhesive image portion of the substrate, (3) Peel off the foil in the area where the adhesive is not printed.

[0003] Currently available adhesives for cold foil processing include solvent-based, aqueous, oil-based, and ultraviolet curable formulations. Cold foil processing can be performed by an in-line process such as in-line offset printing or in-line flexographic printing. In recent years, inkjet printing has been used for hot stamping. UV curable inkjet adhesives are also used for in-line cold foil processing.

[0004] In an inkjet printing process, since a low viscosity is required, in the prior art, the adhesive ejected from an inkjet nozzle generally does not have a sufficiently high viscosity and adhesiveness when it reaches and deposits on a substrate. However, to smoothly transfer the foil in the foil pressing process, a high viscosity and high surface adhesiveness are indispensable. In the prior art method, the viscosity of the adhesive is manipulated, and the UV curing dose for initiating the adhesiveness of the adhesive is shorter than the dose required for the complete curing and solidification of the adhesive. This greatly increases the complexity and cost of the process. Also, due to the insufficient hardness of the adhesive layer when the foil is attached to the surface of the adhesive layer, image formation below the standard is caused.

[0005] In the prior art, the adhesive in the shape of an image does not completely cure and solidify after being applied to a substrate. For this reason, substrates having images formed by ejecting an adhesive are likely to adhere to each other, so it is difficult to store them before foil sticking whether in web form or sheet form. Also, when pressure is applied, they are likely to stretch, and moreover, they are very susceptible to the influence of moisture, so the images may soften and deteriorate, or the images may be in an under-cured state. Further, in the prior art, the images of the cured adhesive are not sufficiently cured to the extent that they do not stretch or deteriorate when pressure is applied to the foil, so the foil-pressed images often fall below the standard. Furthermore, many of such prior art systems need to first partially dry or partially cure and solidify the adhesive image and then apply it to the foil and then completely cure and solidify it. In this case, the images before complete curing and solidification may stretch, or the uncured or partially cured and solidified adhesive may deposit on rollers and other system components, which also causes the foil-pressed images to fall below the standard.

[0006] The cold foil process is carried out inline by printing. Usually, in this inline process, since the foil cannot be accurately positioned, there may be waste of the foil. For an adhesive image shape that is sticky and only partially cured with incomplete solidification, usually, the foil cannot be accurately positioned, so the waste of the foil increases in the inline process. When the adhesive image is formed only in the area of the substrate without small voids, an excessive amount of foil will be wasted if accurate positioning is not performed on the substrate.

[0007] Cold foil processing cannot be carried out offline by printing (for example, by a converter). This is because the adhesive image applied to the substrate is sticky and soft, so the transportation and storage of the substrate to the printing facility are not practical and not desirable.

[0008] 〔Hot Foil Processing〕 Hot foil processing is another method used when decorating various substrates with metal foil. Hot foil processing, also known as hot stamping, is conventionally carried out by a hot stamping device using a metal plate / die engraved with a designed pattern image.

[0009] The web materials for hot foil processing that can be used in this process are well-known and widely available. This material generally consists of a polyester or other plastic carrier film provided with a wax layer, a lacquer layer, a foil layer, and an adhesive layer formed on the foil layer. The adhesive layer on the foil layer is arranged to face the adhesive image on the substrate to which the foil is pressed.

[0010] In this process, a heated plate / die is applied to the back side of the roll or web of the foil-attached film to activate the release layer, and the foil is transferred to the foil-pressing area of the substrate. By combining hot foil processing with embossing / debossing, a tactile effect can be obtained.

Summary of the Invention

Problems to be Solved by the Invention

[0011] According to this hot foil technology, the pattern of the foil attached to the substrate is determined by the design engraved on the mold. It may take several days to several weeks to engrave the desired design on the mold and prepare the printing unit by attaching the mold so that the foil can be hot foil stamped onto the substrate. The mold engraving process is very costly, especially when there are multiple short-term operations that require a new image design for each. In hot foil stamping, high pressure and high temperature are required, and it is difficult to maintain accurate alignment and high image quality.

Means for Solving the Problem

[0012] The unique adhesive composition according to an embodiment of the present invention can be easily applied to a substrate using an inkjet print head, solidifies by complete curing, becomes non-sticky, has a dry feel, and is resistant to moisture. Then, if necessary, it can be easily made sticky by applying heat and pressure, enabling accurate transfer of the foil to the substrate. In embodiments of these unique adhesive compositions, by applying the adhesive in a desired image shape using an inkjet print head, a convenient, efficient, accurate, and reliable hot foil technology is made possible without using a mold.

[0013] Embodiments of the present invention address the problems in the cold foil and hot stamping systems in the prior art.

[0014] Embodiments of the present invention include a foil printing system using an adhesive composition applied to a substrate in a desired adhesive image shape using a non-contact printing process in inkjet printing. The substrate may be paper, cardboard, plastic film (e.g., polypropylene or polyethylene), and other materials in web or sheet form used in non-contact printing processes.

[0015] The adhesive composition of this embodiment, after being applied to a substrate in a desired image shape, is cured completely by irradiating the image with UV or LED light, or electron beam (EB) ionization radiation, and becomes solidified, non-tacky, and dry-feeling, and is resistant to moisture. When the image is irradiated with UV, LED, or EB, the adhesive composition changes almost instantaneously at room temperature from a liquid to a solidified non-sticky solid. In this system, there is no need or no requirement to further cure the solidified adhesive composition image. 〔Monomer component〕 The adhesive composition of the embodiment of the present invention is completely cured and solidified by irradiation with UV, LED, or EB, but when heat and pressure are applied during foil pressing, it softens along its exposed surface and can exhibit sufficient adhesiveness to accurately perform foil transfer. To achieve this unique property of being completely cured and solidified by irradiation with UV, LED, or EB, but softening along the exposed surface of the applied adhesive image when heat and pressure are applied and being able to exhibit sufficient adhesiveness to accurately perform foil transfer, the monomer component of the composition should be purely or initially a radiation-curable monofunctional monomer. If difunctional or trifunctional monomers are present, their concentrations should be carefully restricted, and other polyfunctional monomers (with functionality greater than trifunctional monomers) should not be included in the composition. More specifically, the concentration of difunctional and / or trifunctional radiation-curable monomers should be about 20% by weight or less, preferably about 10% by weight or less, of the monomer component in the composition, and the remaining monomer component must be one or more radiation-curable monofunctional monomers. Also, the low-functional free-radical-curable monomer must be able to solubilize the inert resin component of the composition, that is, the inert resin component must be soluble in the monomer. 〔Oligomer / resin component〕 This component in the composition may include only one or more functional oligomers, only one or more inert thermoplastic resins, or a combination of one or more functional oligomers and one or more inert thermoplastic resins. "Inert thermoplastic resin" is a thermoplastic resin that does not polymerize even when irradiated with UV, LED, or EB. The inert thermoplastic resin(s) and oligomer(s) used may be up to 100% solids, but the glass transition temperature T g of the oligomer(s) and resin(s) is desirably within 40%, preferably within 10%, of the glass transition temperature of the low-functional free radical curable monomer used. Although not a preferred embodiment, as long as the T g of the adhesive composition as a finished product is in the range of about 20 to 100 °C, preferably about 40 to 80 °C, inert thermoplastic resins and oligomers with glass transition temperatures other than the above may be used. Furthermore, in order to achieve the unique ability to both cure and soften along the image surface, the oligomer and / or resin further has a glass transition temperature T g of about -45 °C to 250 °C, and the softening point must be about 0 °C to 190 °C, preferably 60 °C to 120 °C. 〔Free radical photoinitiator〕 Free radical photoinitiators are necessary to achieve free radical curing of UV and LED curable compositions, but are not necessary for EB curable compositions. One of the objectives of the embodiments of the present invention is to provide an adhesive composition that can be cured by applying EB curing technology and does not require the use of a photoinitiator. EB curable adhesive compositions generally have less odor than UV / LED curable compositions, can be used for forming thicker coatings and convex images, and can form good-looking images with transfer foils, so they are preferred in many applications. Embodiments of EB curable thermally activated adhesives are also particularly well-suited for use on containers for food, pharmaceuticals, and consumer goods in both cold foil and hot foil processes.

[0016] The photoinitiator used in the UV-curable adhesive must absorb actinic rays in the wavelength band (e.g., 220 - 410 nm) generated and emitted by a conventional mercury UV lamp.

[0017] The photoinitiator used in the LED-curable adhesive must absorb actinic rays with a longer wavelength band (e.g., 395 nm, 365 nm) emitted from an LED lamp.

[0018] 〔Surface Tension and Viscosity of the Adhesive Composition〕 In a preferred embodiment, the adhesive composition has a surface tension at 25°C of about 22 mN / m to 34 mN / m, preferably about 25 mN / m to 32 mN / m, more preferably about 28 mN / m to 30 mN / m. Also, in a preferred embodiment, the viscosity at 25°C is between about 5 cps and 200 cps, preferably between about 10 cps and 100 cps, more preferably between 15 cps and 40 cps.

[0019] Embodiments of UV-curable and LED-curable inkjet thermally activated adhesives include the following. (1) Inert resin about 0 - 10% (2) Low-functional oligomer about 0 - 10% (3) Monofunctional monomer about 45 - 95% (4) Bifunctional monomer about 0 - 10% (5) Trifunctional monomer about 0 - 10% (6) Photoinitiator about 1 - 20% (7) Amine synergist about 0 - 20% (8) Antifoaming agent about 0.01 - 2.5% (9) Wetting and flow agent about 0.01 - 5.0% (10) Wax additive about 0 - 3% (11) Stabilizer about 0.05 - 3.0%

[0020] Embodiments of EB-curable inkjet thermally activated adhesives include the following. (1) Inert resin about 0 - 10% (2) Low-functional oligomer about 0 - 10% (3) Monofunctional monomer: about 40 - 95% (4) Bifunctional monomer: about 0 - 10% (5) Trifunctional monomer: about 0 - 10% (6) Amine synergist: about 0 - 20% (7) Antifoaming agent: about 0.01 - 2.5% (8) Wetting and fluidizing agent: about 0.01 - 5.0% (9) Wax additive: about 0 - 3% (10) Stabilizer: about 0.05 - 3.0%

Mode for Carrying Out the Invention

[0021] It should be understood that the foregoing general description and the following detailed description are intended only to be illustrative and explanatory, and are not intended to limit the subject matter claimed or protected herein.

[0022] 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 this invention belongs.

[0023] As used herein, the term "monomer" refers to a material that has a lower viscosity than an oligomer, a molecular weight of less than about 1000 g / mol, and a viscosity at 25°C of 500 cps or less. A monomer contains one or more unsaturated groups that can form an oligomer or polymer by polymerization.

[0024] As used herein, the term "monofunctional acrylate monomer" refers to a monomer that contains one acrylate functional group or one C=C double bond.

[0025] As used herein, the term "bifunctional acrylate monomer" refers to a monomer that contains two acrylate functional groups or two C=C double bonds.

[0026] As used herein, the term "trifunctional acrylate monomer" refers to a monomer that contains three acrylate functional groups or three C=C double bonds.

[0027] As used herein, the term "high-functional acrylate monomer" refers to an acrylate monomer containing four or more acrylate functional groups or four or more C=C double bonds.

[0028] As used herein, the terms "(meth)acrylate" and "(meth)acrylic acid" include both acrylate compounds and methacrylate compounds.

[0029] As used herein, the term "ethoxylation" refers to a compound whose chain is extended using ethylene oxide.

[0030] As used herein, the term "propoxylation" refers to a compound whose chain is extended using propylene oxide.

[0031] As used herein, the term "alkoxylation" refers to a compound whose chain is extended using either or both of ethylene oxide and propylene oxide.

[0032] As used herein, the term "oligomer" refers to a material having a higher viscosity than that of a monomer, a molecular weight of about 5000 g / mol to 200000 g / mol, having one or more unsaturated groups, and capable of polymerizing to form a higher molecular weight polymer. A "functional oligomer" is the above-described oligomer that is soluble in the monomers used in the embodiments of the present invention, rapidly cures upon irradiation with UV, LED, or EB, is flexible after curing, and exhibits adhesiveness when heated after curing.

[0033] As used herein, the term "molecular weight" means the number average molecular weight unless otherwise specified.

[0034] As used herein, the term "polymer" refers to a macromolecule having a molecular structure mainly or entirely formed by bonding a large number of similar molecular units.

[0035] As used herein, the term "inert resin" refers to a resin that does not contain C=C bonds or other reactive groups and does not react with monomers / oligomers upon irradiation with UV, LED, or EB.

[0036] As used herein, the term "thermoplastic resin" refers to a plastic material or polymer that is flexible or moldable at a specific temperature or higher and solidifies upon cooling.

[0037] As used herein, "energy curable" refers to curing that occurs in response to exposure to a suitable energy source, including ultraviolet (UV) irradiation, light-emitting diode (LED) irradiation, and electron beam irradiation.

[0038] As used herein, "cure (cure, curing)" refers to the process of polymerizing, solidifying, and / or crosslinking monomer and / or oligomer units to form a polymer.

[0039] As used herein, the term "room temperature" refers to an ambient temperature of 23°C to 25°C.

[0040] As used herein, "thermally activatable or thermally activated" refers to the activity of a cured resin or cured adhesive in response to heating and pressure.

[0041] As used herein, the term "coating amount" refers to the amount of adhesive applied to a predetermined side or surface of a substrate. This is usually expressed in grams of the composition per square meter of the substrate ("gsm").

[0042] As used herein, the term "inline" refers to a foil pressing system that is a separate unit in which a printing device and a foil pressing device are horizontally attached to each other and driven together.

[0043] As used herein, the term "offline" refers to a foil stamping system in which the printing device and the foil stamping device are separate units that are not commonly driven and are installed at different locations or horizontally with respect to each other.

[0044] In the present disclosure, unless otherwise specified, all are expressed in parts by weight and weight percentages (weight% based on the total weight), and all temperatures are in °C.

[0045] Inert thermoplastic resin The resin used in the embodiments of the adhesive composition is inert and does not react with monomers or oligomers in the composition of the embodiments. These carefully selected inert thermoplastic resins also contribute to the flexibility of the film, reduce film shrinkage during the curing process, improve surface softening, tackiness and adhesiveness, and help the cured adhesive composition adhere firmly to the substrate. However, thermosetting resins may not be used.

[0046] The inert thermoplastic resin may be selected from rosin ester resins, cellulose resins, polyester resins, aldehyde resins, epoxy resins, acrylic resins, methacrylic resins, acrylate resins, methacrylate resins, urea-formaldehyde resins, vinyl chloride copolymers, melamine formaldehyde resins, polyurethane resins, polyimide resins, alkyd resins and phthalic resins. Currently, methacrylic resins are preferred. The inert resin should have a molecular weight in the range of about 800 g / mol to 200,000 g / mol, preferably in the range of about 10,000 g / mol to 60,000 g / mol.

[0047] Examples of acrylic, methacrylic, acrylate and methacrylate resins that may be used include Paraloid DM-55 (methyl methacrylate copolymer: molecular weight 6,000, Tg 70°C) manufactured by Dow, Paraliod B44 (MMA / EA copolymer: molecular weight 140,000, Tg 60°C), Elvacite 4036 (formerly Ineos Acrylics, molecular weight 60,000, Tg 50°C) manufactured by Lucite, Elvacite 2046 (isobutyl / n-butyl methacrylate copolymer: molecular weight 165,000, Tg 35°C), Elvacite 2013 (methyl methacrylate / n-butyl methacrylate copolymer: molecular weight 34,000, Tg 76°C), Elvacite 2043 (ethyl methacrylate copolymer: molecular weight 50,000, Tg 66°C), NeoCryl B735 (methyl methacrylate copolymer: molecular weight 40,000, Tg 74°C) manufactured by DSM, NeoCryl B300 (MMA / BMA copolymer: molecular weight 16,000, Tg 45°C), NeoCryl B302 (MMA copolymer: molecular weight 5,000, Tg 80°C), Dianal BR 106 (n-butyl methacrylate copolymer: molecular weight 60,000, Tg 60°C) manufactured by DAI, Degalan 64 / 12 (acrylic resin: molecular weight 68,000, Tg 58°C) manufactured by Evonik, Ebecryl 168 (acidic methacrylate copolymer, details of molecular weight and Tg unknown) manufactured by Ornex, Ebecryl 170 (acidic methacrylate copolymer, details of molecular weight and Tg unknown), Ebecryl 745 (acrylic polymer, details of molecular weight unknown, Tg 30°C), and LUMICRYL 1000 (acrylic resin, details of molecular weight and Tg unknown) manufactured by Estron Chemical.

[0048] Examples of aldehyde resins that may be used include Laropal A 81 (aldehyde resin: details of molecular weight unknown, Tg 57°C), Laropal A 101 (aldehyde resin: details of molecular weight unknown, Tg 73°C) manufactured by BASF, and resin SK (hydrogenated acetophenone formaldehyde resin: Tg 90°C) manufactured by Evonik.

[0049] Examples of vinyl resins that may be used include Vinnol E15 / 48H (hydroxyl-containing copolymer of about 84 wt% vinyl chloride (VC) and about 16 wt% acrylate ester) manufactured by Wacker, ELVAX150 (ethylene vinyl acetate copolymer: melting point 63°C), ELVAX40L-03 (ethylene vinyl acetate copolymer, melting point 58°C), ELVAX CE9619-1 (ethylene vinyl acetate copolymer, melting point 87°C) manufactured by DuPont, and VYHH (molecular weight 27,000, Tg 72°C), VMCC (molecular weight 19,000, Tg 72°C), VWCH (molecular weight 27,000, Tg 74°C) manufactured by Dow.

[0050] Examples of rosin ester resins that may be used include Sylvatac RE 40 (details of molecular weight and Tg unknown) manufactured by Arizona Chemical, and Filtrez526 (fumaric acid-modified rosin ester, details of molecular weight unknown, Tg 72°C), Filtrez 629 (phenol-modified rosin ester, details of molecular weight unknown, melting point 155°C) manufactured by Akzo.

[0051] Examples of polyester resins that may be used include CN-790 (Tg 55°C) manufactured by Sartomer, and SAIB100 (sucrose acetate isobutyrate: molecular weight 856) manufactured by Eastman.

[0052] Examples of cellulose-based resins that may be used include CAB551-0.01 (cellulose acetate butyrate: molecular weight 16,000, Tg 85°C) manufactured by Eastman.

[0053] Examples of hydrocarbon resins that may be used include Norsolene S135 (inert aromatic hydrocarbon resin: Tg 81.7°C), Norsolene S125 (inert aromatic hydrocarbon resin: Tg 71.1°C), Norsolene S105 (inert aromatic hydrocarbon resin: Tg 53.5°C), Norsolene S95 (inert aromatic hydrocarbon resin: Tg 46.3°C), Norsolene S85 (inert aromatic hydrocarbon resin: Tg 45°C), Norsolene A90 (inert aromatic hydrocarbon resin: Tg 46.4°C), Wingtack 86 (inert aromatic hydrocarbon resin: Tg 52°C), Wingtack 98 (aliphatic C-5 hydrocarbon resin: Tg 48°C), and NEVTAC 100 (C5 aliphatic hydrocarbon resin: molecular weight 2850) manufactured by Neville Chemical.

[0054] In this embodiment, one type of thermoplastic resin or a combination of two or more types of thermoplastic resins can be used. In many applications, it is preferable to use two or more different thermoplastic resins.

[0055] In an embodiment of the adhesive composition, the concentration of the inert resin in the oligomer / resin component is 0 to 100% by weight, preferably about 50% to 100% by weight, and the balance of the resin / oligomer component is oligomer, and the amount thereof is preferably about 80 to 100% by weight. The total amount of the inert resin present in the adhesive composition is about 0 to 10% by weight, preferably about 1 to 8% by weight, and more preferably about 2 to 6% by weight.

[0056] Preferred inert thermoplastic resins are thermoplastic resins having a glass transition temperature (Tg) of about -20°C to 250°C, preferably about 10°C to 100°C, more preferably about 20°C to 90°C, and a molecular weight of 800 g / mol to 200,000 g / mol, preferably about 7000 g / mol to 80,000 g / mol, and more preferably about 10,000 g / mol to 60,000 g / mol.

[0057] Currently, preferred inert thermoplastic resins are Paraloid B44 (solid acrylic resin (MMA copolymer): Tg 60°C), Elvacite 2013 (solid methacrylate resin: Tg 76°C), Dianal BR 106 (solid methacrylate resin: Tg 58°C), Laropal A 81 (aldehyde ketone resin: Tg 73°C), and SK resin (hydrogenated acetophenone-formaldehyde resin: Tg 90°C).

[0058] 〔Oligomer〕 One or more functional oligomers may be used. The oligomers contained in the adhesive composition of this embodiment are selected from epoxy (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and polyurethane (meth)acrylate.

[0059] The oligomer must have a molecular weight of less than about 100,000 g / mol and a viscosity at room temperature of less than about 100,000 cps. Even more preferred oligomers are monofunctional polyurethane acrylates with a molecular weight of less than about 75,000 g / mol and a viscosity at room temperature of less than about 50,000 cps. Another preferred oligomer is a monofunctional polyurethane acrylate with a molecular weight of less than about 10,000 g / mol and a viscosity at room temperature of less than 10,000 cps.

[0060] The oligomer may be one type of acrylate resin or a combination of two or more types of acrylate resins. The oligomer may have a glass transition temperature (Tg) of about -45°C to about 175°C, preferably about 10°C to 100°C, more preferably about 20°C to 80°C.

[0061] Examples of usable epoxy (meth) acrylates include Ebecryl 3702 (fatty acid-modified bisphenol A type epoxy diacrylate: Tg 56°C), Ebecryl 3703 (amine-modified bisphenol A type epoxy diacrylate: Tg 57°C), Ebecryl 3720 (bisphenol A type epoxy diacrylate: Tg 67°C), and Ebecryl 3721 (modified bisphenol A type epoxy diacrylate resin) manufactured by Ornex Co., Ltd.

[0062] Examples of usable polyester (meth) acrylates include CN-299 (tetrafunctional acrylated polyester oligomer: Tg 15°C) manufactured by Sartomer Co., Ltd., Genorad 40 (methacrylated phosphate ester: details of Tg unknown) manufactured by Rahn Co., Ltd., Ebecryl 83 (amine-modified polyester acrylate: Tg 6°C), Ebecryl 436 (reactive chlorinated polyester resin diluted 40% with reactive diluent trimethylolpropane triacrylate: Tg 54°C), Ebecryl 438 (reactive chlorinated polyester resin diluted 40% with reactive diluent OTA-480: Tg 37°C), Ebecryl 450 (fatty acid-modified polyester hexaacrylate: Tg 17°C), Ebecryl 452 (low-viscosity polyester acrylate oligomer: details of Tg unknown), Ebecryl 810 (polyester tetraacrylate: Tg 31°C), Ebecryl 812 (low-viscosity polyester acrylate: Tg 72°C), Ebecryl 820 (low-viscosity polyester acrylate: details of Tg unknown), Ebecryl 870 (fatty acid-modified polyester hexaacrylate: Tg 41°C), Ebecryl 4744 (polyester acrylate: Tg 23°C), and Ebecryl 5849 (bio-derived polyester acrylate, Tg 84°C).

[0063] Examples of polyether (meth) acrylates that can be used include Ebecryl 80 (amine-modified polyether tetraacrylate: Tg 50°C), Ebecryl 81 (amine-modified polyether acrylate: Tg -18°C), and Ebecryl 85 (low-viscosity amine-modified polyether acrylate: Tg details unknown) manufactured by Ornex Co., Ltd.

[0064] Examples of polyurethane (meth) acrylates that can be used include CN-131 (aromatic monoacrylate oligomer: Tg 4°C) manufactured by Sartomer Co., Ltd., Geneomer 4188 / M22 (monofunctional urethane acrylate with 35% IBOA (monomer): Tg -3°C) manufactured by Rahn Co., Ltd., Ebecryl 271 (bifunctional aliphatic urethane acrylate: Tg 19°C), Ebecryl 242 (aliphatic urethane acrylate oligomer diluted with 30% by weight of the reactive diluent IBOA: Tg 46°C), Ebecryl 1291 (hexafunctional aliphatic urethane acrylate: Tg 80°C), Ebecryl 4100 (aliphatic urethane triacrylate: Tg 22°C), Ebecryl 4200 (aliphatic urethane acrylate, Tg 12°C), Ebecryl 5129 (hexafunctional aliphatic urethane acrylate: Tg 30°C), Ebecryl 8210 (aliphatic urethane acrylate, Tg 68°C), Ebecryl 8296 (aliphatic urethane acrylate, Tg -1°C), Ebecryl 8402 (aliphatic urethane diacrylate: Tg 14°C), Ebecryl 8411 (aliphatic urethane diacrylate diluted with 20% by weight of the reactive diluent isobornyl acrylate: Tg -18°C), Ebecryl 8465 (aliphatic urethane triacrylate oligomer: Tg 36°C), Eatecryl 8604 (aliphatic urethane tetraacrylate: Tg 79°C), Ebecryl 220 (hexafunctional aromatic urethane acrylate: Tg 49°C), Ebecryl 4500 (aromatic urethane acrylate: Tg 9°C), and Ebecryl 4849 (aromatic urethane diacrylate diluted with 15% by weight of the reactive diluent 1,6-hexanediol diacrylate (HDDA): Tg 29°C).

[0065] The total amount of the functional oligomer present in the adhesive composition of this embodiment must be at a concentration of 0 to 10%, preferably about 1% to 8%, more preferably about 2% to 6% with respect to the weight of the adhesive composition.

[0066] Examples of currently preferred oligomers include Geneomer 4188 (monofunctional urethane acrylate diluted with IBOA (monomer): Tg -3°C), Ebecryl 242 (aliphatic urethane acrylate oligomer diluted with IBOA (monomer): Tg 46°C), and CN 131 (aromatic monoacrylate oligomer: Tg 4°C).

[0067] [Monofunctional Monomer] The monofunctional monomer must contain one acrylate functional group or one C=C double bond. Examples of monofunctional monomers that may be used include aliphatic mono(meth)acrylate, aromatic mono(meth)acrylate, alkoxylated (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, alkoxylated tetrahydrofurfuryl (meth)acrylate, monoacrylic acid, N-vinyl compounds, and acrylamide compounds. These are available from suppliers such as Sartomer, Ornex, BASF, Rahn, etc., and for example, there are the following. (1) Laromer TBCH from BASF: t-butylcyclohexyl acrylate (molecular weight 210, Tg 84°C, viscosity 8 cps, surface tension: 28.5) (2) SR203 from Sartomer: tetrahydrofurfuryl methacrylate (molecular weight 170, viscosity 5 cps, surface tension: 35) (3) SR285 T from Sartomer: tetrahydrofurfuryl acrylate (molecular weight 156, Tg -15°C, viscosity 6 cps, surface tension: 36) (4) SR257 from Sartomer: stearyl acrylate (molecular weight 314, Tg 35°C, viscosity 3 cps, surface tension: 30.9) (5) Sartomer's SR324: Stearyl methacrylate (molecular weight 339, Tg 38 °C, viscosity 14 cps, surface tension: 30.6) (6) Sartomer's SR339: 2-Phenoxyethyl acrylate (molecular weight 192, Tg 5 °C, viscosity 12 cps, surface tension: 39) (7) Sartomer's SR340: 2-Phenoxyethyl methacrylate (molecular weight 206, Tg 54 °C, viscosity 10 cps, surface tension: 38) (8) Sartomer's SR420: 3,3,5-Trimethylcyclohexyl acrylate (molecular weight 196, Tg 29 °C, viscosity 6 cps, surface tension: 27) (9) Sartomer's CD421 A: 3,3,5-Trimethylcyclohexyl methacrylate (molecular weight 210, Tg 145 °C) (10) Sartomer's SR531: Cyclic trimethylolpropane formal acrylate (molecular weight 200, Tg 10 °C, viscosity 15 cps, surface tension: 33) (11) Sartomer's SR423A: Isobornyl methacrylate (molecular weight 222, Tg 110 °C, viscosity 10 cps, surface tension: 31) (12) Sartomer's SR506: Isobornyl acrylate (molecular weight 208, Tg 88 °C, viscosity 8 cps, surface tension: 32) (13) BASF's 4HBA: 4-Hydroxybutyl acrylate (molecular weight 144, Tg -40 °C, viscosity 11 cps, surface tension: 35) (14) ACMO of KJ Chemicals Co., Ltd. (Japan): N-Acryloylmorpholine (molecular weight 141, Tg 145 °C, viscosity 12 cps, surface tension: 45) (15) BASF's NVC: N-Vinylcaprolactam (molecular weight 139, Tg 147 °C, viscosity 5 cps, surface tension: 43.9) (16) BASF's NVP: N-Vinylpyrrolidone (molecular weight 111, Tg 150 °C, viscosity 2.5 cps, surface tension: 32.5) (17) Eastman's DMAC: Dimethylacetamide (molecular weight 87.2, MP 14 °C, viscosity 2.5 cps, surface tension: 32) (18) DAAM of Nippon Kasei Co., Ltd.: Diacetone acrylamide (molecular weight 229, Tg 77°C, viscosity 18 cps, surface tension: 30.6)

[0068] 〔Bifunctional monomer〕 When using a bifunctional monomer, it must contain two acrylate functional groups or two C=C double bonds. In embodiments of adhesives containing these bifunctional monomers, they usually cure faster than embodiments of adhesives containing only monofunctional monomers. Examples of bifunctional monomers that may be used include aliphatic di(meth)acrylates, aromatic di(meth)acrylates, alkoxylated aliphatic di(meth)acrylates, alkoxylated aromatic di(meth)acrylates, glycol di(meth)acrylates, cyclohexanedimethanol di(meth)acrylates. These are available from suppliers such as Sartomer, Ornex, BASF, Rahn, etc., and for example, there are the following. (1) CD564: Alkoxylated hexanediol diacrylate, molecular weight 401, viscosity 25 cps, surface tension 33, Tg 14 degrees (2) PR01131: Propoxylated neopentyl glycol diacrylate, viscosity 15 cps, surface tension 32, Tg 32°C (3) SR213: 1,4-Butanediol diacrylate, molecular weight 198, viscosity 8 cps, surface tension 36, Tg 45°C (4) SR214: 1,4-Butanediol dimethacrylate, molecular weight 226, viscosity 7 cps, surface tension 34, Tg 55°C (5) SR230: Diethylene glycol diacrylate, molecular weight 214, viscosity 12 cps, surface tension 38, Tg 100°C (6) SR231: Diethylene glycol dimethacrylate, molecular weight 242, viscosity 8 cps, surface tension 35, Tg 66°C (7) SR238b: 1,6-Hexanediol diacrylate, molecular weight 118, viscosity 9 cps, surface tension 36, Tg 43°C (8) SR239: 1,6-Hexanediol dimethacrylate, molecular weight 254, viscosity 8 cps, surface tension 34, Tg 30°C (9) SR247: Neopentyl glycol diacrylate, molecular weight 212, viscosity 10 cps, surface tension 33, Tg 107 °C (10) SR272: Triethylene glycol diacrylate, molecular weight 259, viscosity 15 cps, surface tension 39, Tg 48 °C (11) SR297: 1,3-Butylene glycol dimethacrylate, molecular weight 226, viscosity 7 cps, surface tension 32, Tg 85 °C (12) SR306F: Tripropylene glycol diacrylate, molecular weight 300, viscosity 15 cps, surface tension 33, Tg 62 °C (13) SR349: Ethoxylated (3) bisphenol A diacrylate, molecular weight 469, viscosity 1600 cps, surface tension 44, Tg 67 °C (14) SR508: Dipropylene glycol diacrylate, molecular weight 242, viscosity 10 cps, surface tension 33, Tg 104 °C (15) SR540: Ethoxylated (4) bisphenol A dimethacrylate, molecular weight 541, viscosity 555 cps, surface tension 35, Tg 108 °C (16) SR541: Ethoxylated (6) bisphenol A dimethacrylate, molecular weight 629, viscosity 440 cps, surface tension 35, Tg 54 °C (17) SR601: Ethoxylated (4) bisphenol A diacrylate, molecular weight 513, viscosity 1080 cps, surface tension 37, Tg 60 °C (18) SR602: Ethoxylated (10) bisphenol A diacrylate, molecular weight 777, viscosity 610 cps, surface tension 38, Tg 2 °C (19) SR833S: Tricyclodecane dimethanol diacrylate, molecular weight 304, viscosity 130 cps, surface tension 38, Tg 186 °C (20) SR9003B: Propoxylated (2) neopentyl glycol diacrylate, molecular weight 212, viscosity 15 cps, surface tension 32, Tg 32 °C (21) SR9209a: Alkoxylated aliphatic diacrylate, viscosity 15 cps, surface tension 35, Tg 48 °C

[0069] [Trifunctional monomer] The trifunctional monomer, if present, contains three acrylate functional groups or three C=C double bonds. In embodiments of the adhesive containing the trifunctional monomer, it usually cures faster than embodiments of the adhesive containing only the bifunctional monomer. Examples of trifunctional monomers that may be used are as follows. (1) SR350: Trimethylolpropane trimethacrylate, molecular weight 338, viscosity 44 cps, surface tension 34, Tg 27 °C (2) SR351H: Trimethylolpropane triacrylate, molecular weight 296, viscosity 106 cps, surface tension 36, Tg 62 °C (3) SR368D: Tris(2-hydroxyethyl) isocyanurate triacrylate, molecular weight 375, viscosity 330 cps, surface tension 37, Tg 61 °C (4) SR444: Pentaerythritol triacrylate, molecular weight 298, viscosity 520 cps, surface tension 39, Tg 103 °C (5) SR454: Ethoxylated(3) trimethylolpropane triacrylate, molecular weight 429, viscosity 110 cps, surface tension 40, Tg 103 °C (6) SR501: Propoxylated(6) trimethylolpropane triacrylate, molecular weight 645, viscosity 125 cps, surface tension 33, Tg 21 °C (7) SR9020: Propoxylated(3) glyceryl triacrylate, molecular weight 422, viscosity 95 cps, surface tension 36, Tg 18 °C

[0070] In embodiments of the adhesive composition, the monomer must have a molecular weight of less than about 1000 g / mol and a viscosity of less than about 100 cps, preferably a molecular weight of less than about 500 g / mol and a viscosity of less than about 50 cps, more preferably a molecular weight of less than about 250 g / mol and a viscosity of less than about 20 cps.

[0071] Also, the monomer must have a surface tension of 26 - 43 dyn / cm, preferably 26 - 36 dyn / cm, more preferably 26 - 32 dyn / cm.

[0072] The monomer must have a glass transition temperature (Tg) after polymerization of about -20°C to 175°C, preferably about 10°C to 100°C, more preferably about 20°C to 90°C.

[0073] The total concentration of the monomer(s) used in the adhesive composition embodiment must be in the range of about 45% to 95%, more preferably in the range of about 60% to 80%, based on the weight of the adhesive composition.

[0074] The monomer used in the adhesive composition embodiment may be 100% monofunctional monomer. Isobornyl acrylate such as Sartomer's SR506 (molecular weight 208, Tg 88°C, viscosity 8 cps, surface tension: 32) has been found to be a particularly preferred monofunctional monomer from the viewpoints of curing rate, adhesiveness, and foil transfer quality. t-Butylcyclohexyl acrylate such as BASF's Laromer TBCH (molecular weight 210, Tg 84°C, viscosity 8 cps, surface tension: 28.5) is another particularly preferred monofunctional monomer from the viewpoints of curing rate, adhesiveness, and foil transfer quality.

[0075] Also, the monomer used in the embodiment may contain vinyl-containing monomers or acrylamide monomers such as N-vinylcaprolactam (molecular weight 139, Tg 147°C, viscosity 5 cps, surface tension: 43.9), N-vinylpyrrolidone (molecular weight 111, Tg 150°C, viscosity 2.5 cps, surface tension: 32.5), diacetoneacrylamide (molecular weight 229, Tg 77°C, viscosity 18 cps, surface tension: 30.6), etc., and may be contained in an amount of less than 25%, preferably less than 15%, more preferably less than 10% of the total monomer composition to increase the curing rate and improve the surface properties of the cured film.

[0076] In some examples of embodiments of the adhesive composition, up to 20% by weight, preferably 10% by weight or less of a bifunctional or trifunctional monomer (e.g., SR-833: tricyclodecane dimethanol diacrylate and SR-454: ethoxylated trimethylolpropane triacrylate (manufactured by Sartomer), VEEA (manufactured by Nippon Shokubai, 2-(2-vinyloxyethoxy)ethyl acrylate) may be included.

[0077] By not adding a polyfunctional monomer, or preferably, although not suitable, limiting the polyfunctional monomer to bifunctional and trifunctional monomers and restricting its concentration to 20% or less, preferably 10% or less of the total monomer components in the composition and not adding higher functionality monomers, it is an unexpected discovery in the embodiments of the present invention that good curing speed and desirable printed image characteristics can be obtained. This discovery is contrary to the current situation where high functional monomers are sometimes generally used to achieve the desired rapid curing speed in currently recognized conventional adhesives, inks, and coating products.

[0078] 〔Other composition components〕 Other components included in the embodiments of the present invention generally include photoinitiators (for UV and LED curable compositions), synergists, stabilizers, wetting agents / flow agents, defoamers, and wax compounds.

[0079] 〔Photoinitiator〕 The photoinitiator initiates free radical photopolymerization during UV or LED curing. Both type I (cleavage type) and type II (hydrogen abstraction type) photoinitiators can be used. For EB curable adhesive compositions, there is no need to use a photoinitiator.

[0080] UV and LED curable inkjet compositions may contain one or more photoinitiators. Examples of photoinitiators applicable to UV and LED curable adhesive compositions include, but are not limited to, benzophenone, benzoin ether and their derivatives. These include benzophenone, chlorobenzophenone, 4-phenylbenzophenone, trimethylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether, and alkyl benzoins such as methyl benzoin, ethyl benzoin, propyl benzoin. These photoinitiators are available from IGM as Omnirad BP, Omnirad 4MBZ, Omnirad 4PBZ, Omnirad OMBB, Omnirad 4HBL, Omnirad BEM, Omnirad EMK, Omnirad MBF and Omnirad BDK. Other photoinitiators that may be used include α-hydroxyketones such as 1-hydroxy-cyclohexyl-phenylketone, 2-hydroxy-2-methyl-1-phenylpropanone and 2-hydroxy-2-methyl-1-(4-isopropylphenyl)propanone. These photoinitiators are products available from IGM as Omnirad 73 and Omnirad 481. Still other photoinitiators that may be used include α-aminoketones and their derivatives such as Irgacure 369, 907, 1300, etc. which are commercially available from IGM, thioxanthones such as Omnirad ITX and Omnirad DETX which are commercially available from IGM, thioxanthones and their derivatives including isopropylthioxanthone, 2-chlorothioxanthone and 2-ethylthioxanthone, and acylphosphines and their derivatives such as Omnirad TPO, Omnirad TPO-L and Omnirad 380 which are commercially available from IGM.

[0081] Polymeric benzophenone derivatives, polymeric aminobenzoates, polymeric thioxanthone derivatives, and polymeric α-hydroxyketones are photoinitiators suitable for UV and LED curable adhesive compositions. Examples of commercially available products include GENOPOL BP-1 from Rahn and Omnipol BP from IGM for polymeric benzophenone derivatives, GENOPOL AB-1 from Rahn and Omnipol ASA from IGM for polymeric aminobenzoates, GENOPOL TX-1 from Rahn and Omnipol TX from IGM for polymeric thioxanthone derivatives, and Chivacure 150 and 70 from Chitec for polymeric α-hydroxyketones.

[0082] The photoinitiators used in embodiments of UV curable adhesives absorb broadband actinic rays (e.g., from 220 nm to 410 nm) generated by conventional mercury UV lamps. The photoinitiators used in embodiments of LED curable adhesives absorb actinic rays with longer wavelengths (e.g., 395 nm, 365 nm) emitted from LED lamps.

[0083] The amount of photoinitiator present in the adhesive should usually be less than 20% by weight of the adhesive composition, and may be less than 15%, less than 10%, or between 5 - 10% by weight of the adhesive composition. Currently, a concentration of about 10 - 15% is preferred.

[0084] As photoinitiators for UV curable thermally activatable inkjet adhesives for hot foil stamping, Omnirad 481 (1-hydroxycyclohexyl-phenyl ketone) and Omnirad ITX (2-isopropylthioxanthone) from IGM are currently more preferred.

[0085] As photoinitiators for hot foil stamping UV curable thermally activatable inkjet adhesives, Irgacure 907 (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one), Omnirad ITX (2-isopropylthioxanthone), Irgacure 819 (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide), Irgacure 369 (2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone) and Omnirad TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide) from IGM are preferred.

[0086] Synergist In an embodiment of the composition, it is preferable to include a synergist in order to suppress oxygen inhibition during photopolymerization and improve the curing rate. A free amine synergist may be included. Examples of suitable free amine synergists include, but are not limited to, triethanolamine, N-methyldiethanolamine, N,N-dimethylethanolamine, 2-(dimethylamino)ethyl benzoate, ethyl 4-(dimethylamino)benzoate, 2-ethylhexyl 4-dimethylaminobenzoate. A synergist of a monofunctional amine and an acrylic acid amine is a more preferred synergist at present. Examples thereof include EHA (monofunctional amine) from IGM, CN3175 from Sartomer, and GENOPOL AB-1 from Rahn.

[0087] An acrylic acid amine synergist or a polymer amine synergist may also be blended into the adhesive. Examples of commercially available acrylic acid amine synergists include Ebecryl 7100, Ebecryl 115 and Ebecryl p116 from Ornex, CN374, CN381, CN-1002, CN3705, CN3715, CN3735, CN3755 from Sartomer, Laromer PO 94F, Laromer P077F from BASF. Examples of commercially available polymer amine synergists include Omnipol ASA, Omnipol SZ from IGM, and GENOPOL AB-1 from Rahn.

[0088] The synergist is preferably contained in the adhesive composition in an amount of 0 to 20% by weight, preferably 2% to 15% by weight, more preferably 3% to 10% by weight, based on the weight of the adhesive composition.

[0089] 〔Stabilizer / Polymerization inhibitor〕 In embodiments of the adhesive composition, one or more polymerization inhibitors or stabilizers are included to prevent aggregation of the adhesive and conventional gelation during manufacture, storage, and transportation, and to help suppress / eliminate surface cracking of the cured composition. Examples of suitable inhibitors include phenolic materials (e.g., benzoquinone, hydroquinone, hydroquinone monomethyl ether, butylated hydroxytoluene), phenothiazine, nitrosophenylhydroxylamine aluminum salt, benzotriazole aluminum salt amine complex, aromatic amines, nitroxyl compounds.

[0090] A currently preferred stabilizer / polymerization inhibitor is Genorad-16 (which contains an inhibitor in an acrylate ester), and it is used at a concentration of about 0.05% to 3.0%, preferably about 0.1% to 2.0%, most preferably about 0.2% to about 1.0%.

[0091] 〔Wetting agent / Flow agent〕 Conventional wetting agents / flow agents can be included in the adhesive composition to change the surface tension, control the flow properties / leveling properties, properly wet the substrate, and enable the adhesive to flow and level properly during application. The wetting agent / flow agent can be of a silicone-free type (e.g., acrylate polymer) or a silicone-containing type (e.g., polyether-modified polydimethylsiloxane). The concentration of the wetting agent / flow agent (e.g., Radadd 1116 available from Trilogy Group, Ebecryl 1360 available from Ornex) varies depending on the specific agent used, but generally ranges from at least about 0.1% to about 5% or less by weight of the adhesive composition.

[0092] 〔Degassing agent / Antifoaming agent〕 In an embodiment of the adhesive composition, a conventional antifoaming agent or defoaming agent may be contained as a degassing agent and / or an antifoaming agent. An antifoaming agent is generally included to suppress the formation of large bubbles on the liquid surface. A degassing agent is generally included to remove the air mixed into the coating film during coating as quickly as possible. Examples of these materials include polyacrylate, polyglycol, polyol, polysiloxane, oxyalkyleneamine, silicone oils and fluids, polyether-modified methylalkylpolysiloxane copolymers, and combinations thereof.

[0093] Examples of degassing agents that can be used include TEGO 910 (silicone-free polymer), TEGO 920 (silicone-free air venting agent), TEGO 900 (organically modified polysiloxane) manufactured by Evonik, and Byk-500 (silicone-free air venting agent) manufactured by Byk.

[0094] Examples of antifoaming agents that can be used include TEGO Foamex N (dimethylpolysiloxane), TEGO 810 (polyether siloxane copolymer), TEGO 845 (organically modified polysiloxane) manufactured by Evonik, Byk-535 (silicone-free polymer), Byk-055 (silicone-free solution of defoaming polymer), Byk-1790 (silicone-free polymer-based antifoaming agent), Byk-1791 (silicone-free and aromatic-free polymer-based antifoaming agent) manufactured by BYK, and Foam blast UVD (silicone / silica concentrated foam control agent) manufactured by Emerald Performance Materials.

[0095] In an embodiment of the adhesive composition, the degassing agent Byk-500 (silicone-free air venting agent), Byk-535 (silicone-free polymer), or Byk-1791 (silicone-free and aromatic-free polymer-based antifoaming agent) may be contained in an amount of 0.01% to 2.5%, preferably 0.1% to 2.0%, more preferably 0.25% to 1.5% based on the weight of the adhesive composition.

[0096] 〔Wax〕 In embodiments of the adhesive composition, a wax selected from synthetic wax, semi-crystalline wax, petroleum wax, microcrystalline wax, paraffin wax, animal wax, vegetable wax, carnauba wax, and mineral wax may be included. The wax (when used) after dispersion is required to be compatible with other components used in the embodiments of the adhesive composition so that the composition remains stable and the print head does not clog when applying the adhesive by an inkjet process.

[0097] For example, in embodiments containing Carnauba wax Lanco® 1955 SF (available from Lubrizol), it must be present in an amount of 0.02% to 1.0%, preferably 0.05% to 0.5%, more preferably 0.10% to 0.30% based on the weight of the adhesive composition. Also, in embodiments, for example, polyethylene wax S-395-N5 (available from Shamrock) may also be included in an amount of 0.02% to 1.0%, preferably 0.05% to 0.5%, more preferably 0.10% to 0.30% based on the weight of the adhesive composition.

[0098] 〔Flexographic printing applications〕 Embodiments of the adhesive composition can be used for foil processing by flexographic printing by increasing the concentration of the inert resin and / or oligomer to make the viscosity about 100 to 3000 cps, preferably about 400 to 2000 cps.

[0099] The inert resin may be one or more of acrylic resin, methacrylic resin, acrylate resin, methacrylate resin, urea-formaldehyde resin, rosin ester resin, cellulose resin, polyester resin, aldehyde resin, epoxy resin, vinyl chloride copolymer, melamine formaldehyde resin, polyurethane resin, polyimide resin, alkyd resin, and phthalic acid resin. Among these, those more commonly used in the adhesive / painting / ink industry are acrylic resin, acrylate resin, methacrylate resin, aldehyde resin, vinyl resin, rosin ester resin, cellulose resin, and hydrocarbon resin.

[0100] The inert resin has a glass transition temperature (Tg) of -40°C to 300°C, preferably 10°C to 150°C, more preferably 20°C to 100°C, and a molecular weight of about 2000 to 300000 g / mol, preferably about 10000 to 200000 g / mol, more preferably about 20000 to 100000 g / mol.

[0101] The inert resin can be present in an amount of 0 to 100%, preferably 50% to 100%, more preferably 80 to 100% based on the weight of the resin composition (i.e., the total of the oligomer and the inert resin formulated in the adhesive).

[0102] The total amount of the inert resin composition present in the adhesive composition is about 0 to 45%, preferably 5% to 30%, more preferably 8% to 20% based on the weight of the adhesive composition.

[0103] 〔Oligomer〕 The oligomer may be one or more of epoxy (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and polyurethane (meth)acrylate.

[0104] Among the above, the oligomers preferably used are polyurethane acrylate, polyester acrylate, polyether acrylate, and epoxy acrylate having a molecular weight of less than about 100000 g / mol and a viscosity at room temperature of less than about 100000 cps. Preferred oligomers are polyurethane acrylates having a molecular weight of less than about 75000 g / mol and a viscosity at room temperature of less than about 50000 cps. Even more preferred oligomers are polyurethane acrylates having a molecular weight of less than about 20000 g / mol and a viscosity at room temperature of less than 20000 cps.

[0105] The oligomer contained in the adhesive can be either one type of acrylate resin or a combination of two or more types of acrylate resins. These must have a glass transition temperature (Tg) of from about -35°C to about 250°C, preferably from about 10°C to 120°C, more preferably from about 20°C to 100°C.

[0106] The oligomer can be present in an amount of 0 to 100%, preferably 50% to 100%, more preferably 80 to 100%, based on the weight of the resin composition (i.e., the total amount of the oligomer and the inert resin formulated in the adhesive).

[0107] The total amount of the low-functional oligomer present in the adhesive composition is about 0 to 45%, preferably 5% to 30%, more preferably 8% to 20%, based on the weight of the adhesive composition.

Examples

[0108] The following examples are presented for illustrative purposes only and should not be construed as limiting the subject matter of the claims in any way. 〔Example 1: UV-curable thermally activatable inkjet adhesive〕 (1) Formulation and curing characteristics in the embodiment of the UV-curable thermally activatable inkjet adhesive Many inert resins are in the form of powders or pellets. To facilitate the preparation of the adhesive, these resins can be dissolved in a suitable monomer to form a uniform solution. An inert resin (in this example, 30 g of Dianal BR-106) together with a stabilizer (in this example, 1 g of Genorad 16) was charged into a 200 ml iron container containing a monofunctional monomer (in this example, 69 g of Laromer TBCH 105 manufactured by BASF). This mixture was mixed with stirring at 60 to 90°C for about 2 to 4 hours (at 1000 rpm to 2500 rpm) until a homogeneous resin solution was formed. The active resin solution used was a 30% solution of Dianal BR-106 resin. The Dianal BR-106 resin itself is an n-butyl methacrylate copolymer (manufactured by DAI) with a molecular weight of 60,000 and a glass transition temperature (Tg) of 58°C. The UV-curable adhesive was prepared with the formulation shown in Table 1 below. Unless otherwise specified, all amounts are in weight percent (wt%). Each component to be formulated was placed in a 100-ml plastic container. The container was covered and sealed, and mixed at 2500 rpm until a homogeneous adhesive solution was formed. The homogeneous adhesive solution was filtered through a 0.5-μm microfilter to remove insoluble particles. The viscosities of the solution were recorded at 25°C and 45°C respectively using a Brookfield DV-E viscometer from Polystat Cole-Parmer. Thereafter, the adhesive composition was supplied using a Meyer rod No. 8 at a coating amount of 20 gsm (grams per square meter) and printed onto double-sided coated paper (Productolith C2S). The printed adhesive was UV-cured using a UV curing device manufactured by AMS (AIR Motion System) equipped with a 300 w / inch UV lamp. The surface tackiness was evaluated by touching the printed pattern with a finger at two stages: immediately after curing and 30 minutes after curing. The dose required to obtain a cured printed pattern without surface tackiness was recorded. The adhesion of the cured film to the paper substrate was evaluated by the 810 tape test, which is an adhesion test well recognized in the ink and paint field. The results are shown as "pass" or "fail" below. "Pass" indicates that there is no peeling of the adhesive from the substrate, and "fail" indicates that the peeling of the adhesive from the substrate exceeds 10%. As shown in the results of Table 2, the adhesive of the present invention is shown to be cured by UV irradiation at a dose of 350 mj / cm 2 and substantially lose surface tackiness. The cured surface becomes non-tacky within 30 minutes. The adhesion between the cured film and the 810 tape was satisfactory.

Table 1

Table 2

Table 3

Table 4

Table 5

Table 6

Claims

1. A monomer component present at a concentration of about 45 to 95% by weight based on the weight of the adhesive composition, comprising one or more free radical curable monofunctional monomers, and further comprising difunctional and / or trifunctional free radical curable monomers at a concentration of about 20% by weight or less based on the total amount of the monomer component. One or more oligomers at a concentration of more than about 0% by weight and at most about 10% by weight of the adhesive composition, one or more inert thermoplastic resins at a concentration of at least about 1% by weight and at most about 8% by weight of the adhesive composition, or an oligomer-resin component soluble in the one or more monofunctional monomers comprising a combination thereof. One or more free radical photoinitiators for curing the one or more monofunctional monomers by UV or LED irradiation. Comprising The adhesive composition does not contain polyfunctional monomers having a functionality greater than that of trifunctional monomers. An adhesive composition, characterized in that when cured by UV or LED irradiation, it forms a non-sticky solid at room temperature, and exhibits adhesiveness when heat and pressure are applied after curing.

2. The adhesive composition according to claim 1, wherein the monomer component further comprises difunctional and / or trifunctional free radical curable monomers at a concentration of about 10% by weight or less based on the total amount of the monomer component.

3. The adhesive composition according to claim 1, wherein the oligomer-resin component consists only of the one or more inert thermoplastic resins.

4. The adhesive composition according to claim 1, wherein the oligomer-resin component consists only of the one or more oligomers.

5. The adhesive composition according to claim 1, wherein the oligomer-resin component consists of a combination of the one or more oligomers and the one or more inert thermoplastic resins.

6. The adhesive composition according to claim 1, wherein the glass transition temperature Tg of the one or more inert thermoplastic resins and the one or more oligomers is within ±40% of the glass transition temperature of the one or more free radical curable monofunctional monomers.

7. The adhesive composition according to claim 1, wherein the glass transition temperature Tg of the one or more inert thermoplastic resins and the one or more oligomers is within ±10% of the glass transition temperature of the one or more free radical curable monofunctional monomers.

8. The one or more inert thermoplastic resins and the one or more oligomers are selected such that, when combined with other components in the composition, the glass transition temperature Tg in the composition is in the range of about 20 to 100 °C. The adhesive composition according to claim 1.

9. The inert thermoplastic resin has a molecular weight in the range of about 800 g / mol to 200,000 g / mol and is selected from the group consisting of rosin ester resin, cellulose resin, polyester resin, aldehyde resin, epoxy resin, acrylic resin, methacrylic resin, acrylate resin, methacrylate resin, urea-formaldehyde resin, vinyl chloride copolymer, melamine formaldehyde resin, polyurethane resin, polyimide resin, alkyd resin and phthalic acid resin. The adhesive composition according to claim 1.

10. The one or more inert thermoplastic resins have a glass transition temperature Tg of about -20 °C to 250 °C and a molecular weight of about 800 g / mol to 60,000 g / mol. The adhesive composition according to claim 1.

11. The one or more oligomers have a glass transition temperature Tg of about -45 °C to 175 °C, a molecular weight of less than about 100,000 g / mol, and a viscosity of less than about 100,000 cps. The adhesive composition according to claim 1.

12. The oligomer is selected from the group consisting of epoxy (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate and polyurethane (meth)acrylate. The adhesive composition according to claim 1.

13. The monofunctional monomer is selected from the group consisting of aliphatic mono(meth)acrylate, aromatic mono(meth)acrylate, alkoxylated (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, alkoxylated tetrahydrofurfuryl (meth)acrylate, monoacrylic acid, N-vinyl compound and acrylamide compound. The adhesive composition according to claim 1.

14. The bifunctional monomer is selected from the group consisting of hybrid monomers such as aliphatic di(meth)acrylate, aromatic di(meth)acrylate, alkoxylated aliphatic di(meth)acrylate, alkoxylated aromatic di(meth)acrylate, glycol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and vinyl oxyethoxy)ethyl acrylate, and the adhesive composition according to claim 2.

15. The trifunctional monomer is selected from the group consisting of trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, pentaerythritol triacrylate, ethoxylated(3)trimethylolpropane triacrylate, propoxylated(6)trimethylolpropane triacrylate, and propoxylated(3)glyceryl triacrylate, and the adhesive composition according to claim 2.

16. The one or more monomers have a molecular weight of less than about 1000 g / mol and a viscosity of less than about 100 cps, and the adhesive composition according to claim 1.

17. The monomer component is present at a concentration of about 60 to 80% by weight based on the weight of the adhesive composition, and the adhesive composition according to claim 1.

18. The one or more monomers include isobornyl acrylate and / or t-butylcyclohexyl acrylate, and the adhesive composition according to claim 1.

19. The adhesive composition according to claim 1 further includes one or more of a polymerization inhibitor, a stabilizer, a wetting agent / flow agent, a degassing agent, an antifoaming agent, and a wax.

20. A monomer component containing one or more free radical curable monofunctional monomers cured by electron beam irradiation and present at a concentration of about 45 to 95% by weight based on the weight of the adhesive composition, the monomer component further including a bifunctional and / or trifunctional free radical curable monomer at a concentration of about 20% by weight or less based on the total amount of the monomer component, An oligomer resin component soluble in the one or more monofunctional monomers including one or more oligomers at a concentration of more than about 0% by weight and less than about 10% by weight of the adhesive composition, one or more inert thermoplastic resins at a concentration of about 1% by weight or more and less than about 8% by weight of the adhesive composition, or a combination thereof, comprising The adhesive composition does not contain a polyfunctional monomer having a functionality greater than that of a trifunctional monomer, and is an adhesive composition characterized in that when cured by electron beam irradiation, it forms a non-sticky solid that solidifies at room temperature and exhibits adhesiveness when heat and pressure are applied after curing.

21. The adhesive composition according to claim 20, wherein the monomer component further contains a bifunctional and / or trifunctional free radical curable monomer at a concentration of about 10% by weight or less based on the total amount of the monomer component.

22. The adhesive composition according to claim 20, wherein the oligomer resin component consists only of the one or more inert thermoplastic resins.

23. The adhesive composition according to claim 20, wherein the oligomer resin component consists only of the one or more oligomers.

24. The adhesive composition according to claim 20, wherein the oligomer resin component consists of a combination of the one or more oligomers and the one or more inert thermoplastic resins.

25. The adhesive composition according to claim 20, wherein the glass transition temperature Tg of the one or more inert thermoplastic resins and the one or more oligomers is within ±40% of the glass transition temperature of the one or more free radical curable monofunctional monomers.

26. The adhesive composition according to claim 20, wherein the glass transition temperature Tg of the one or more inert thermoplastic resins and the one or more oligomers is within ±10% of the glass transition temperature of the one or more free radical curable monofunctional monomers.

27. The adhesive composition according to claim 20, wherein the one or more inert thermoplastic resins and the one or more oligomers are selected such that, when combined with other components in the composition, the glass transition temperature Tg of the composition is in the range of about 20 to 100°C.

28. The inert thermoplastic resin has a molecular weight in the range of about 800 g / mol to 200,000 g / mol, and is selected from the group consisting of rosin ester resin, cellulose resin, polyester resin, aldehyde resin, epoxy resin, acrylic resin, methacrylic resin, acrylate resin, methacrylate resin, urea-aldehyde resin, vinyl chloride copolymer, melamine formaldehyde resin, polyurethane resin, polyimide resin, alkyd resin, and phthalic acid resin. The adhesive composition according to claim 20.

29. The one or more oligomers are present at a concentration of about 1 to 8% by weight of the adhesive composition. The adhesive composition according to claim 20.

30. The one or more inert thermoplastic resins have a glass transition temperature Tg of about -20°C to 250°C and a molecular weight of about 800 g / mol to 60,000 g / mol. The adhesive composition according to claim 20.

31. The one or more oligomers have a glass transition temperature Tg of about -45°C to 175°C, a molecular weight of less than about 100,000 g / mol, and a viscosity of less than about 100,000 cps. The adhesive composition according to claim 20.

32. The oligomers are selected from the group consisting of epoxy (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and polyurethane (meth)acrylate. The adhesive composition according to claim 20.

33. The monofunctional monomer is selected from the group consisting of aliphatic mono(meth)acrylate, aromatic mono(meth)acrylate, alkoxylated (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, alkoxylated tetrahydrofurfuryl (meth)acrylate, monoacrylic acid, N-vinyl compound, and acrylamide compound. The adhesive composition according to claim 20.

34. The difunctional monomer is selected from the group consisting of hybrid monomers such as aliphatic di(meth)acrylate, aromatic di(meth)acrylate, alkoxylated aliphatic di(meth)acrylate, alkoxylated aromatic di(meth)acrylate, glycol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and vinyloxyethoxy)ethyl acrylate. The adhesive composition according to claim 21.

35. The trifunctional monomer is selected from the group consisting of trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, pentaerythritol triacrylate, ethoxylated(3)trimethylolpropane triacrylate, propoxylated(6)trimethylolpropane triacrylate, and propoxylated(3)glyceryl triacrylate, and the adhesive composition according to claim 21.

36. The one or more monomers have a molecular weight of less than about 1000 g / mol and a viscosity of less than about 100 cps, and the adhesive composition according to claim 20.

37. The monomer component is present at a concentration of about 60 to 80% by weight based on the weight of the adhesive composition, and the adhesive composition according to claim 20.

38. The one or more monomers include isobornyl acrylate and / or t-butylcyclohexyl acrylate, and the adhesive composition according to claim 20.

39. The adhesive composition according to claim 20, further comprising one or more of a polymerization inhibitor, a stabilizer, a wetting agent / fludizing agent, a degassing agent, an antifoaming agent, and a wax.

40. Using an inkjet print head, applying the adhesive composition according to claim 1 or 20 to a substrate in accordance with an image pattern, irradiating the image pattern with UV, LED, or an electron beam to cure the adhesive composition to a non-sticky solidified state, placing the substrate holding the cured image pattern opposite to the foil of the web of the foil bearing, applying heat and pressure to make the adhesive composition sticky, and transferring the foil to the image pattern, A method of transferring a foil to a substrate.

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