UV-curable ink composition, and interior film comprising ink layer formed therefrom

Abstract

The present invention relates to a UV-curable ink composition and an interior film comprising an ink layer formed therefrom, the composition not only having excellent digital printing ink curability and adhesion but also being eco-friendly by excluding environmentally regulated substances.

Description

Interior film comprising a UV-curing ink composition and an ink layer formed therefrom

[0001] The present invention relates to an ultraviolet curable ink composition that is eco-friendly as it does not contain environmentally regulated substances, and has excellent digital printing ink curability and adhesion, and an interior film comprising an ink layer formed therefrom.

[0002]

[0003] Various printing methods, such as flexographic printing, gravure printing, inkjet printing, and screen printing, are utilized to apply specific colors or form patterns on various types of substrates. In particular, gravure printing is widely used because it enables mass production through high-speed production. However, gravure printing has disadvantages, such as incurring additional costs and time for design changes, insufficient image resolution after printing, and a high risk of safety accidents due to the time required for process changes and exposure to danger.

[0004] As an alternative to this, the use of digital printer printing and UV-curing inks has been proposed. For example, Japanese Registered Patent No. 5631588 discloses an inkjet ink comprising at least one irradiation-curing monomer, at least one inert thermoplastic resin, at least one radical photoinitiator, and at least one colorant. However, unlike gravure printing inks, digital printer inks suffer from performance variations due to factors such as the selection of raw materials suitable for digital printer printing, low viscosity, and nano-sized particle conditions, and there have been limitations in matching the manufacturing concept of the printed product. To solve these problems, research and development are being conducted on the composition of inks suitable for digital printing inkjets, the nozzle size of the print head, and the jetting speed of the print head, taking into account the compatibility between the material (PVC, PET, etc.) and the ink, as well as the compatibility with the print head.

[0005] Conventional ink compositions typically contain substances such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and tetrahydrofurfuryl acrylate (THFA), which were banned from use under the European Printing Association (EUPIA) regulatory agreement (version 6, March 2024). Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide plays a crucial role in ink curing; replacing it with another substance weakens ink curing, leading to blocking during product manufacturing or image damage during primer treatment. Tetrahydrofurfuryl acrylate is a monomer that enhances adhesion to polyvinyl chloride (PVC); replacing it with another substance results in reduced adhesion.

[0006] Accordingly, there is a need to develop an ink composition that is eco-friendly by not containing environmentally regulated substances such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and tetrahydrofurfuryl acrylate (THFA), while also having excellent digital printing ink curability and adhesion.

[0007]

[0008] The present invention provides a UV-curing ink composition that is eco-friendly as it does not contain environmentally regulated substances such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and tetrahydrofurfuryl acrylate (THFA), while also having excellent digital printing ink curability and adhesion.

[0009] In addition, the present invention provides an interior film comprising an ink layer formed from the above ink composition.

[0010]

[0011] The present invention provides a UV-curing ink composition comprising, based on the total weight of the UV-curing ink composition, 13 to 24 weight% of a pigment dispersion, 3 to 20 weight% of a urethane (meth)acrylate oligomer, 3 to 10 weight% of 1,6-hexanediol di(meth)acrylate, 15 to 25 weight% of benzyl (meth)acrylate, 10 to 20 weight% of phenoxyethyl (meth)acrylate, 10 to 20 weight% of an N-vinyl lactam-type monomer, and 5 to 9 weight% of a UV initiator.

[0012] In addition, the present invention provides an interior film comprising an ink layer formed from the above ink composition.

[0013]

[0014] The UV-curing ink composition of the present invention is eco-friendly as it does not contain environmentally regulated substances such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and tetrahydrofurfuryl acrylate (THFA), and at the same time, it has excellent digital printing ink curability and adhesion, making it applicable to digital printing methods. The ink layer formed from the ink composition according to the present invention has excellent ink curability, so no blocking occurs during product production, the image is not damaged during primer treatment, and it can maintain excellent adhesion with polyvinyl chloride (PVC).

[0015]

[0016] The present invention will be described in detail below. However, it is not limited to the following description, and each component may be modified in various ways or selectively combined as needed. Accordingly, it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0017] As used herein, “weight-average molecular weight” is measured by conventional methods known in the art, for example, by the gel permeation chromatography (GPC) method. “Viscosity” is measured by conventional methods known in the art, for example, by using a Brookfield rotational viscometer at room temperature (25 °C). “Particle size” is measured by conventional methods known in the art, for example, by laser light scattering (LLS).

[0018]

[0019] UV-curing ink composition

[0020] The UV-curing ink composition of the present invention comprises a pigment dispersion, a urethane (meth)acrylate oligomer, 1,6-hexanediol di(meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, N-vinyl lactam-type monomer, and a UV initiator.

[0021]

[0022] pigment dispersion

[0023] The UV-curing ink composition of the present invention comprises a pigment dispersion. The pigment dispersion serves to impart color to the ink composition and form an image.

[0024] As long as the pigment dispersion is in the form of a dispersion in which the pigment is dispersed, it may be used without any particular restrictions. For example, the pigment dispersion may include a pigment, a dispersant, and a (meth)acrylate monomer.

[0025] The above pigments are not particularly limited, and both organic and inorganic pigments can be used, and pigments of any color can be used. For example, Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48(Ca), 48(Mn), 57(Ca), 57:1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168, 170, 171, 175, 176, 178, 179, 184, 185, 187, 202, Magenta pigments such as 219, 245, Pigment Violet 19, 23, 32, 33, 36, 38, 43, 50; Cyan pigments such as Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:34, 15:4, 16, 18, 22, 25, 60, 65, 66; Yellow pigments such as Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 167, 172, 180; Pigment Black 7, as carbon black, for example, MCF88, No.2300, 2200 B, 900, 33, 40, 45, 52, MA7, 8, 100, etc. (Mitsubishi Chemical), Raven 5750, 5250, 5000, 3500, 1255, 700, etc. (Columbia Carbon), Regal 400 R, 330R, 660 R, Mogul L, Monarch 700, 800, 880, 900, 1000, 1100, 1300, 1400, etc. (Cabot), Color Black FW1, FW2, FW2V, FW18, FW200, S15, S160, S170, Printex 35, U, V, 140 U, ​​Special Black 6, 5, 4A, Black pigments such as those from 4 (De Good Co., Ltd.) may be used. These pigments may be used individually or in combination of two or more types.

[0026] The particle size (volume average) of the pigment in the pigment dispersion above may be 10 to 300 nm, for example, 50 to 200 nm. If the particle size of the pigment is less than the aforementioned range, re-aggregation between particles may occur or the hiding power may be reduced, and if it exceeds the aforementioned range, the coloring power and discharge stability may be reduced.

[0027] The above pigment is dispersed in (meth)acrylate monomers using a polymer dispersant. The polymer dispersant serves to adsorb the pigment and stably disperse it within the (meth)acrylate monomers.

[0028] As the above-mentioned dispersant, an amine value of 1 to 100 mgKOH / g, for example 5 to 50 mgKOH / g, and an acid value of 1 to 100 mgKOH / g, for example 5 to 50 mgKOH / g, may be used. When the amine value and acid value of the dispersant are within the aforementioned ranges, the dispersant is well adsorbed onto the surface of the pigment during pigment dispersion, which can result in a smaller average particle size of the pigment within the dispersion and a narrower distribution. Additionally, electrostatic repulsion between particles is imparted, thereby improving the storage stability of the dispersion. When the amine value and acid value of the dispersant fall outside the aforementioned ranges, the pigment adsorption capacity of the dispersant decreases, leading to reduced dispersibility and increased viscosity of the pigment dispersion. Furthermore, it becomes difficult to produce a dispersion with a desired particle size, and the resistance of the ink film may be reduced.

[0029] The above-mentioned dispersant may have a weight-average molecular weight of 1,000 to 60,000 g / mol, for example, 2,000 to 30,000 g / mol, or another example, 2,000 to 10,000 g / mol. When the weight-average molecular weight of the dispersant is within the aforementioned range, compatibility with the dispersion solvent is improved and the stability of the pigment dispersion can be enhanced.

[0030] As the above-mentioned dispersant, commercially available dispersants may be used, such as a structured copolymer with a pigment-affinic group, e.g. BYKJET-9131; a high molecular weight block copolymer with a pigment-affinic group, e.g. DISPERBYK-161; and a high molecular weight polymer, e.g. BYKJET-9133, DISPERBYK-2200, 2205, TEGO Dispers 670, 685, Solsperse 13940, 32550, etc., and these may be used individually or in a mixture of two or more types.

[0031] The above (meth)acrylate monomer serves as a solvent for dispersing the pigment. As the above (meth)acrylate monomer, commercially available (meth)acrylate monomers, such as monofunctional (meth)acrylate monomers or difunctional (meth)acrylate monomers, may be used alone or in a mixture of two or more types. Examples of monofunctional (meth)acrylate monomers that may be used include PHEA (Phenol (EO)2Acrylate), EOEOEA (Ethoxy ethoxy ethyl Acrylate), CA (Caprolactone Acrylate), CTFA (Cyclic trimethylolpropane formal Acrylate), PBA (Phenoxy benzyl Acrylate), LA (Lauryl acrylate), THFA (Tetrahydrofurfuryl Acrylate), SA (Stearyl Acrylate), etc. Examples of difunctional (meth)acrylate monomers that can be used include HDDA (1,6-Hexanediol Diacrylate), DDDA (1,10-Decanediol Diacrylate), TPGDA (Triethylene glycol Diacrylate), BPA(EO)3DA (Bisphenol A (EO)3Diacrylate), TCDDA (Tricyclodecane dimethanol Diacrylate), PEGDA (Polyethylene glycol Diacrylate), etc.

[0032] The pigment dispersion may comprise, based on the total weight of the pigment dispersion, 5 to 30 weight% of the pigment, for example, 10 to 20 weight%, 1 to 40 weight% of the dispersant, for example, 2 to 20 weight%, and the remainder of the (meth)acrylate monomer. If the content of the pigment is below the aforementioned range, the color development may be insufficient during coloring, and if it exceeds the aforementioned range, the content of the ink, which is a solid component in the composition, is high, which may result in poor ink ejection performance. If the content of the dispersant is below the aforementioned range, the dispersion of the pigment may be insufficient, and if it exceeds the aforementioned range, the dispersion stability may be unstable, causing precipitation to occur over time, and an excessive increase in viscosity may lead to an increase in viscosity during ink manufacturing. If the content of the (meth)acrylate monomer deviates from the aforementioned range, the dispersion of the pigment may be insufficient.

[0033] Based on the total weight of the ink composition, the pigment dispersion may contain 13 to 24 weight%, for example, 15 to 21 weight%. If the content of the pigment dispersion is less than the aforementioned range, the color development may be insufficient when coloring, and if it exceeds the aforementioned range, the content of the solid ink in the composition may be high, resulting in poor ink ejection performance.

[0034]

[0035] Urethane (meth)acrylate oligomer

[0036] The UV-curing ink composition of the present invention comprises a urethane (meth)acrylate oligomer. The urethane (meth)acrylate oligomer serves as a primary raw material that governs the physical properties of the ink composition, playing a role in controlling the ink's ejectability, storage stability, and the peel strength of the ink layer produced therefrom. Specifically, the urethane (meth)acrylate oligomer improves the melting and adhesion characteristics of the ink composition by including a urethane structure with soft polymer properties. As a result, the ink composition of the present invention exhibits excellent adhesion to a substrate layer and can provide excellent flexibility and elongation to products such as interior films manufactured using it.

[0037] The above urethane (meth)acrylate oligomer may include two functional groups. In this case, the flexibility of the printed coating surface and the adhesion to the PVC substrate are excellent, allowing for the production of an interior film of even higher quality. On the other hand, if fewer than two functional groups are included or none are included, the curability of the ink composition is insufficient, which may result in the ink not curing or reduced adhesion. Meanwhile, if three or more functional groups are included, the hardness of the printed material increases, causing it to become brittle and potentially leading to cracking.

[0038] The above urethane (meth)acrylate oligomer may have a weight-average molecular weight (Mw) of 500 to 2,000 g / mol, for example, 700 to 1,700 g / mol, or for another example, 1,000 to 1,500 g / mol. When the weight-average molecular weight of the above urethane (meth)acrylate-based oligomer satisfies the aforementioned range, the amount of oligomer used can be appropriately controlled, thereby further improving the adhesion to the printed coating surface. If the weight-average molecular weight of the above urethane (meth)acrylate oligomer is below the aforementioned range, there is a limit to the functionalization of the oligomer itself, and the reduction in functional groups may decrease the curing performance of the oligomer, increasing the possibility of incomplete curing. If it exceeds the aforementioned range, the ink fluidity decreases, causing a problem where the ink does not eject from the digital printing head, which may lead to a decrease in output stability.

[0039] The above urethane (meth)acrylate oligomer may have a viscosity (25°C) of 1,000 to 5,000 cps, for example, 2,000 to 4,800 cps, or for another example, 3,000 to 4,500 cps. If the viscosity of the urethane (meth)acrylate oligomer is below the aforementioned range, the adhesion of the manufactured ink layer may be reduced, and if it exceeds the aforementioned range, the viscosity of the ink composition increases, which reduces head ejection performance and may result in inferior output stability.

[0040] Based on the total weight of the ink composition, the urethane (meth)acrylate oligomer may be included in an amount of 3 to 20 weight%, for example, 10 to 20 weight%. If the content of the urethane (meth)acrylate oligomer is less than the aforementioned range, the physical properties of the prepared ink layer may be insufficient due to a lack of content of the active ingredient in the ink composition, and if it exceeds the aforementioned range, the output stability of the inkjet head may be reduced when printing the ink composition.

[0041]

[0042] (Meta)acrylate monomer

[0043] The UV-curing ink composition of the present invention comprises a (meth)acrylate-based monomer. The (meth)acrylate monomer controls the viscosity of the ink composition to improve ink output performance and serves to improve the adhesion of the ink layer during ink layer formation.

[0044] The UV-curable primer composition of the present invention comprises 1,6-hexanediol di(meth)acrylate, benzyl (meth)acrylate, and phenoxyethyl (meth)acrylate as (meth)acrylate-based monomers. By using the three types of (meth)acrylates, the curability and adhesion of digital printing ink can be improved. In particular, by using the three types of (meth)acrylates, the present invention can improve the curability and adhesion of digital printing ink without using tetrahydrofurfuryl acrylate (THFA), which is an environmentally regulated substance.

[0045] 1,6-hexanediol di(meth)acrylate serves to improve adhesion to a substrate layer such as PVC and to strengthen the hardness of the ink printing layer. Based on the total weight of the ink composition, the 1,6-hexanediol di(meth)acrylate may be included in an amount of 3 to 10 weight%, for example, 3 to 7 weight%. If the content of the 1,6-hexanediol di(meth)acrylate is less than the aforementioned range, the hardness and adhesion may decrease, and if it exceeds the aforementioned range, the hardness and adhesion may improve, but cracks may occur in the printed material during the embossing process.

[0046] Benzyl (meth)acrylate improves adhesion to a substrate layer such as PVC and lowers the viscosity of the ink, thereby enabling an increase in the proportion of oligomers used to improve the functionality of the ink. Based on the total weight of the ink composition, the benzyl (meth)acrylate may contain 15 to 25 weight%, for example, 18 to 22 weight%. If the content of the benzyl (meth)acrylate falls outside the aforementioned range, the adhesion may decrease.

[0047] Phenoxyethyl (meth)acrylate plays a role in appropriately controlling the viscosity of the ink composition and improving the solubility of the UV initiator. Based on the total weight of the ink composition, the phenoxyethyl (meth)acrylate may be included in an amount of 10 to 20 weight%, for example, 14 to 16 weight%. If the content of the phenoxyethyl (meth)acrylate is less than the aforementioned range, the solubility of the UV initiator may decrease, and curing may not proceed sufficiently; if it exceeds the aforementioned range, the content of the monomer capable of imparting adhesion may decrease, and the adhesion may be reduced.

[0048] The above (meth)acrylate-based monomer may further include a (meth)acrylate-based monomer (a fourth (meth)acrylate-based monomer) used in the relevant technical field in addition to the aforementioned 1,6-hexanediol di(meth)acrylate, benzyl (meth)acrylate, and phenoxyethyl (meth)acrylate.

[0049] The above-mentioned fourth (meth)acrylate monomer may have a molecular weight of 100 to 1,000 g / mol, for example, 100 to 700 g / mol, or for another example, 100 to 500 g / mol. If the molecular weight of the above-mentioned (meth)acrylate monomer is less than the aforementioned range, the viscosity of the ink composition is low, which may cause problems with output from the printer head during printing, and if it exceeds the aforementioned range, the viscosity of the ink composition increases, which may cause problems with output from the printer head during printing.

[0050] Based on the total weight of the ink composition, the fourth (meth)acrylate-based monomer may be included in an amount of 1 to 20 weight%, for example, 5 to 15 weight%. If the content of the fourth (meth)acrylate-based monomer falls outside the aforementioned range, the adhesion strength may be reduced.

[0051]

[0052] N-vinylactam type monomer

[0053] The UV-curing ink composition of the present invention comprises an N-vinylactam type monomer. When an ink layer is manufactured using the ink composition, the N-vinylactam type monomer serves to improve adhesion to the substrate layer and enhance the heat resistance of the manufactured ink layer.

[0054] The above N-vinylactam type monomer may have a molecular weight of 50 to 500 g / mol, for example, 80 to 400 g / mol, or another example, 100 to 300 g / mol. If the molecular weight of the above N-vinylactam type monomer is less than the aforementioned range, the adhesion and heat resistance of the ink composition may be reduced, and if it exceeds the aforementioned range, the color of the ink may change or the storage stability of the ink may be reduced.

[0055] The above-mentioned N-vinyl lactam type monomers may include N-vinylpyrrolidone, N-vinylpiperidone, N-vinylmorpholone, N-vinylcaprolactam, N-vinyl-1,3-oxazine-2-one, N-vinyl-3,5-morpholindione, etc. These may be used alone or in a mixture of two or more types.

[0056] Based on the total weight of the ink composition, the above-mentioned ink composition may contain 10 to 20 weight percent, for example, 12 to 18 weight percent, of the N-vinyl lactam-type monomer. If the content of the N-vinyl lactam-type monomer is less than the aforementioned range, the adhesion of the ink composition may be reduced, and the heat resistance may be reduced, which may cause a problem where the color of the ink layer changes during the interior film lamination process. If the content of the N-vinyl lactam-type monomer exceeds the aforementioned range, the dispersion stability of the pigment in the ink is reduced, causing the pigment to clump together over time, increase in particle size, or cause pigment precipitation, which may result in poor storage stability of the ink.

[0057]

[0058] UV initiator

[0059] The UV-curing ink composition of the present invention includes a UV initiator. The UV initiator absorbs ultraviolet light to initiate polymerization, thereby curing the ink composition to form a coating film and controlling the curing speed of the ink composition.

[0060] The above-mentioned ultraviolet initiator may include a phosphine oxide-based compound containing an acyl group. For example, the above-mentioned ultraviolet initiator may include phenylacylphosphine, 2,4-diethyl-9H-thioxanthen-9-one (DETX), 2-isopropylthioxanthone, ethyl 4-(dimethylamino)benzoate, etc. These may be used alone or in a mixture of two or more.

[0061] The present invention can improve the curability and adhesion of digital printing ink without using UV initiators that can cause environmental problems, such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), by including 1,6-hexanediol di(meth)acrylate, benzyl (meth)acrylate, and phenoxyethyl (meth)acrylate in specific amounts.

[0062] Based on the total weight of the ink composition, the above-mentioned ink composition may contain 5 to 9 weight percent, for example, 6 to 9 weight percent, of the ultraviolet initiator. If the content of the ultraviolet initiator is less than the aforementioned range, an incomplete curing phenomenon may occur in the ink composition, and if it exceeds the aforementioned range, the ultraviolet initiator may not be sufficiently dissolved, and the change in ink curing performance relative to the content of the ultraviolet initiator may be insignificant, which may reduce economic efficiency.

[0063]

[0064] additives

[0065] The above UV-curing ink composition may further include additives commonly used in the relevant technical field. For example, it may additionally include surface tension modifiers, surfactants, preservatives, etc.

[0066] A surface tension modifier improves the surface tension of an ink composition by controlling the wetting of the ink composition with respect to a substrate layer. Polyether-modified polydimethylsiloxane, etc., may be used as the surface tension modifier.

[0067] Based on the total weight of the ink composition, the surface tension modifier may be included in an amount of 0.001 to 0.3 weight percent. If the content of the surface tension modifier falls outside the aforementioned range, the surface tension of the ink composition may be insufficient, which may result in a failure of the ink composition's output.

[0068]

[0069] The above UV-curing ink composition may have a viscosity (25°C) of 15 to 22 cps. If the viscosity of the UV-curing ink composition is below the aforementioned range, the ink may scatter when ejected from the inkjet printer head, and a large amount of satellites may be generated on the printed material. If it exceeds the aforementioned range, the ink may not be fully ejected from the microtube-shaped nozzle during printing, and nozzle detachment may occur.

[0070] The above UV-curing ink composition may have a glass transition temperature (Tg) of -70 to -30 ℃, for example, -60 to -40 ℃. When the glass transition temperature of the UV-curing ink composition satisfies the aforementioned range, the ink curability is excellent and the output stability during digital printing is excellent. On the other hand, if the glass transition temperature of the UV-curing ink composition is below the aforementioned range, the ink curing performance is insufficient and output stability during digital printing may be reduced, and if it exceeds the aforementioned range, output stability during digital printing may be reduced or problems with ink flowability within the printer may occur.

[0071] The UV-curing ink composition according to the present invention is eco-friendly as it does not contain environmentally regulated substances such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and tetrahydrofurfuryl acrylate (THFA), and at the same time has excellent digital printing ink curability and adhesion.

[0072]

[0073] Interior Film

[0074] An interior film according to the present invention comprises: a substrate layer; an ink layer formed on the substrate layer and formed from the UV-curing ink composition; an adhesive layer formed on the ink layer; and a transparent protective layer formed on the adhesive layer.

[0075]

[0076] material layer

[0077] The above substrate layer can be used without special restrictions as long as it is typically applicable to interior films or deco films, and, for example, may include vinyl chloride resin.

[0078] The above vinyl chloride resin may be one or more selected from the group consisting of polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), vinyl chloride, and vinyl chloride copolymers containing monomers copolymerized therewith.

[0079] For the above substrate layer, a commercially available product applicable to interior films or deco films can be used, for example, one having an average thickness of 30 to 200 μm or 50 to 150 μm can be used.

[0080]

[0081] Ink layer

[0082] The ink layer is formed from the aforementioned UV-curing ink composition. The ink layer can be formed by printing the UV-curing ink composition using a digital printing method.

[0083]

[0084] adhesive layer

[0085] The adhesive layer is formed on the ink layer and serves to bond the ink layer and the transparent protective layer.

[0086] The adhesive layer is formed from an adhesive composition, and the adhesive composition may be used without special limitations as long as it is typically applicable to interior films or deco films. For example, a UV-curing adhesive composition may be used. The adhesive composition may include an oligomer, a monomer, a UV initiator, etc.

[0087] The thickness of the adhesive layer is not subject to any special limitations as long as it is a thickness that is typically applicable to interior films or deco films, for example, the average thickness may be 1 to 20 μm or 2 to 10 μm. If the average thickness of the adhesive layer deviates from the aforementioned range, the adhesion between the ink layer and the transparent protective layer weakens, causing delamination between layers, or the thick adhesive layer may adversely affect the color development of the ink layer.

[0088]

[0089] Transparent protective layer

[0090] The transparent protective layer can be used without special restrictions as long as it is applicable to interior films or deco films, and, for example, may include vinyl chloride resin.

[0091] The above vinyl chloride resin may be one or more selected from the group consisting of polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), vinyl chloride, and vinyl chloride copolymers containing monomers copolymerized therewith.

[0092] The above transparent protective layer can be formed in a manner typically applicable to interior films or deco films, for example, by laminating on the adhesive layer and then curing by irradiating with ultraviolet rays.

[0093] As the above transparent protective layer, a commercially available product applicable to interior films or deco films can be used, for example, one with an average thickness of 50 to 200 μm or 80 to 130 μm can be used. If the average thickness of the above transparent protective layer falls outside the aforementioned range, a deep embossing effect cannot be achieved, resulting in inferior texture, or the thick thickness may increase the price of the film, thereby reducing economic efficiency.

[0094]

[0095] The present invention will be explained in more detail below through examples. However, these examples are intended only to aid in understanding the invention and do not limit the scope of the invention in any way.

[0096]

[0097] [Examples 1-3]

[0098] UV-curing ink compositions for each example were prepared according to the composition of Table 1 below.

[0099]

[0100] [Comparative Example 1-7]

[0101] UV-curing ink compositions for each comparative example were prepared according to the composition of Table 2 below.

[0102]

[0103]

[0104]

[0105]

[0106] Pigment dispersion: Ink Tech, CIB-N (PB 15:4 dispersion, pigment concentration 15 wt%, average particle size 120 nm, viscosity (25 ℃) 28 cps)

[0107] Oligomer 1: Difunctional urethane acrylate oligomer (Mw 1,000 g / mol, viscosity (25 ℃) 3,550 cps)

[0108] Oligomer 2: Trifunctional urethane acrylate oligomer (Mw 2,500 g / mol, viscosity (25 ℃) 5,200 cps)

[0109] Monomer 1: 1,6-Hexanediol Diacrylate (HDDA)

[0110] Monomer 2: Benzyl Acrylate (BZA)

[0111] Monomer 3: Phenoxyethyl Acrylate (PHEA)

[0112] Monomer 4: N-vinylcaprolactam (NVC)

[0113] UV Initiator 1: Phenyl Acrylphosphine (Irgacure 819)

[0114] UV initiator 2: 2,4-diethyl-9H-thioxanthen-9-one (DETX)

[0115] Additives: Surface tension modifier (polyether-modified polydimethylsiloxane, BYK-UV3510)

[0116]

[0117] [Physical Property Evaluation]

[0118] The physical properties of the ink compositions of each example and comparative example were measured as follows, and the results are shown in Tables 3 and 4 below.

[0119]

[0120] Average particle size

[0121] After measuring the particle size distribution of particles dispersed in the composition using laser light scattering (LLS), the cumulative distribution of 10% (D) in the particle size distribution 10 ) to 90%(D90 The average value of the particle diameter of ) was set as the average particle size.

[0122]

[0123] viscosity

[0124] Measurements were taken at room temperature (25 ℃) using a viscometer (Brookfield spindle viscometer, Brookfield Viscometer LVDV-II, CPE-40 spindle).

[0125]

[0126] Storage stability

[0127] After storing the UV-curing ink compositions of each example and comparative example at 25°C or 60°C for 2 weeks, the average particle size of the dispersed particles and the viscosity at 25°C or 60°C were measured according to the average particle size and viscosity measurement method described above. Storage stability was evaluated as good if the change amount was 10% or less compared to the initial measurement value, and poor if the change amount exceeded 10%.

[0128]

[0129] Output

[0130] Using the ink compositions of each example and comparative example, the printability was evaluated by checking the number of nozzle failures in the head corresponding to the single-color unit while continuously printing for 1 hour using digital printing equipment (KONIKA, 1024i series, RICHO GEN5 head). A case where the number of nozzle failures was 3 or fewer was evaluated as good.

[0131]

[0132] Peel strength

[0133] An ink layer was formed by printing the ink compositions of each example and comparative example in a single color on a colored PVC substrate film (Kumkang Enterprise, KKP PRINT, thickness 80 μm) using digital printing equipment (KONIKA, 1024i series, RICHO GEN5 head). Subsequently, a UV adhesive (Permabond, Permabond UV640) of 7-8 μm was applied onto the ink layer, a transparent PVC film (Kumkang Enterprise, KKP DECO, thickness 110 μm) was placed over it, and a specimen was prepared by irradiating ultraviolet light using an LED light source with a wavelength of 395 nm. At this time, by using a UV adhesive with an adhesive strength of 5 kgf / inch or more, the part that separates during the peel strength measurement was set to be the ink layer, and the measured strength was set to be the measured strength of the ink layer.

[0134] A specimen was prepared by laminating a colored PVC film, an ink layer, an adhesive layer, and a transparent PVC film in that order, and the 180° peel strength between the ink layer and the transparent PVC film was measured using a tensile testing machine (Universal Testing Machine, SALT, ST-1003).

[0135]

[0136] Whether cracks occur

[0137] After preparing a specimen using the same method as the aforementioned specimen for evaluating peel strength, the specimen was passed through a SUS roller with a depth of 200 μm at 170°C under a pressure of 6 MPa to create an embossed texture. Subsequently, it was visually checked whether the printed surface of the part pressed to a depth of 200 μm remained intact.

[0138]

[0139]

[0140]

[0141]

[0142] As shown in Tables 3 and 4 above, the UV-curing ink compositions of Examples 1-3 according to the present invention exhibited excellent physical properties across all measured parameters. In contrast, the UV-curing ink compositions of Comparative Examples 1-7, which did not contain the oligomer or monomer according to the present invention, or which contained the oligomer and monomer according to the present invention but in amounts outside the scope of the present invention, exhibited inferior physical properties compared to Examples 1-3 across all measured parameters. In particular, the UV-curing ink compositions of Comparative Examples 1-7 showed cracking, storage stability, or peel strength.

[0143]

[0144] The present invention provides a UV-curing ink composition that is eco-friendly as it does not contain environmentally regulated substances such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) and tetrahydrofurfuryl acrylate (THFA), while also having excellent digital printing ink curability and adhesion.

Claims

1. A UV-curing ink composition comprising, based on the total weight of the UV-curing ink composition, 13 to 24 weight% of a pigment dispersion, 3 to 20 weight% of a urethane (meth)acrylate oligomer, 3 to 10 weight% of 1,6-hexanediol di(meth)acrylate, 15 to 25 weight% of benzyl (meth)acrylate, 10 to 20 weight% of phenoxyethyl (meth)acrylate, 10 to 20 weight% of an N-vinyl lactam-type monomer, and 5 to 9 weight% of a UV initiator.

2. In claim 1, the pigment dispersion comprises a pigment, a dispersant, and a (meth)acrylate monomer, and The particle size (volume average) of the pigment in the pigment dispersion is 10 to 300 nm, and The amine value of the above dispersant is 1 to 100 mgKOH / g, the acid value is 1 to 100 mgKOH / g, and the weight-average molecular weight is 1,000 to 60,000 g / mol, and UV-curing ink composition having a viscosity (25°C) of 20 to 50 cps of the pigment dispersion above.

3. A UV-curing ink composition according to claim 1, wherein the weight-average molecular weight (Mw) of the urethane (meth)acrylate oligomer is 500 to 2,000 g / mol and the viscosity (25 ℃) is 1,000 to 5,000 cps.

4. A UV-curing ink composition according to claim 1, wherein the molecular weight of the N-vinylactam type monomer is 50 to 500 g / mol.

5. A UV-curing ink composition according to claim 1, wherein the N-vinyl lactam type monomer comprises one or more selected from the group consisting of N-vinylpyrrolidone, N-vinylpiperidone, N-vinylmorpholone, N-vinylcaprolactam, N-vinyl-1,3-oxazine-2-one, and N-vinyl-3,5-morpholindione.

6. A UV-curing ink composition according to claim 1, wherein the UV initiator comprises one or more selected from the group consisting of phenylacylphosphine, 2,4-diethyl-9H-thioxanthen-9-one (DETX), 2-isopropylthioxanthone, and ethyl 4-(dimethylamino)benzoate.

7. A UV-curing ink composition according to claim 1, wherein the viscosity (25 ℃) is 15 to 22 cps and the glass transition temperature (Tg) is -70 to -30 ℃.

8. Recording layer; An ink layer formed on the above substrate layer and formed from a UV-curing ink composition of any one of claims 1 to 7; An adhesive layer formed on the above ink layer; and A transparent protective layer formed on the adhesive layer. Interior film containing

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