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 same, the ink composition comprising a pigment, a urethane (meth) acrylate oligomer, a (meth) acrylate monomer, a caprolactam-based compound, and an UV initiator, wherein the urethane (meth) acrylate oligomer comprises two functional groups and has a weight average molecular weight of 500 to 2,000 g / mol.

Description

Ultraviolet-curable ink composition and interior film comprising an ink layer formed therefrom

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0077001, filed June 15, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an ultraviolet-curable ink composition having excellent storage stability at room temperature and high temperature, and excellent design freedom and printability when printed using a digital printer, and an interior film including an ink layer formed therefrom.

[0003] Various printing methods such as flexo 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 and flexo printing are widely used because they can be mass-produced at high speeds. However, gravure printing and flexo printing have limitations such as requiring additional costs and time, such as producing copper plates, for design changes, and insufficient resolution of the image after printing. In addition, conventional printing methods typically use solvent-based inks containing organic solvents. These solvent-based inks have the problem of causing environmental problems by emitting large amounts of volatile organic compounds (VOCs) due to the organic solvents contained in the ink.

[0004] Alternatives to this have been proposed, such as digital printer printing and the use of UV-curable inks. For example, Japanese Patent No. 5631588 (Patent Document 1) discloses an inkjet ink comprising at least one radiation-curable 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 have performance variations due to factors such as the selection of printable raw materials for digital printers, low viscosity, and conditions for nano-sized particles, and there are also limitations in matching the manufacturing concept of the printed product.

[0005] Accordingly, there is a need for research and development on a UV-curable ink composition that is capable of digital printer printing, has excellent storage stability at room temperature and high temperature, and has excellent design freedom and printability when printed using a digital printer, and an interior film including a layer derived from the composition.

[0006] The present invention aims to provide an ultraviolet-curable ink composition that is capable of being printed by a digital printer, has excellent storage stability at room temperature and high temperature, and has excellent design freedom and printability when printed using a digital printer, and an interior film comprising an ink layer formed therefrom.

[0007] The present invention comprises a pigment, a urethane (meth)acrylate oligomer, a (meth)acrylate monomer, a caprolactam compound and an ultraviolet initiator,

[0008] The above urethane (meth)acrylate oligomer contains two functional groups and provides an ultraviolet-curable ink composition having a weight average molecular weight of 500 to 2,000 g / mol.

[0009] In addition, the present invention comprises a substrate layer;

[0010] An ink layer formed on the substrate layer and formed from the ultraviolet-curable ink composition;

[0011] An adhesive layer formed on the ink layer; and

[0012] An interior film is provided, including a transparent protective layer formed on the adhesive layer.

[0013] The ultraviolet-curable ink composition according to the present invention has excellent storage stability at room temperature (25°C) and high temperature (60°C), excellent image resolution after printing, and excellent design freedom and printability during printing.

[0014] In addition, the interior film according to the present invention including an ink layer formed from the above ultraviolet-curable ink composition has excellent image resolution and thus excellent appearance characteristics, and has excellent interlayer adhesiveness, so that defects such as interlayer peeling occur less frequently, resulting in excellent product properties and productivity.

[0015] The present invention is described in detail below.

[0016] In this specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0017] Additionally, in this specification, when it is said that a layer is located "on" another layer, this includes not only cases where the layer is in contact with the other layer, but also cases where another layer exists between the two layers.

[0018] Furthermore, in this specification, “weight average molecular weight” is measured by a conventional method known in the art, and can be measured by, for example, a GPC (gel permeation chromatography) method.

[0019] “Viscosity” is measured by a conventional method known in the art, and can be measured, for example, using a Brookfield viscometer (rotating spindle viscometer) at room temperature (25°C).

[0020] The "particle size", which is the diameter of the particle, is measured by a conventional method known in the relevant technical field, and can be measured by laser light scattering (LLS), for example, and the "average particle size" is the cumulative distribution 10% (D) of the particle size distribution measured as described above. 10 ) to 90%(D 90 ) may be the average value of the particle diameter.

[0021] Additionally, the “functional group” is a functional group involved in a polymerization reaction, and may be, for example, a (meth)acrylate group, and “(meth)acrylate” means “acrylate” and / or “methacrylate”.

[0022]

[0023] UV-curable ink composition

[0024] The ultraviolet curable ink composition according to the present invention comprises a pigment, a urethane (meth)acrylate oligomer, a (meth)acrylate monomer, a caprolactam-based compound, and an ultraviolet initiator.

[0025] Specifically, the ink composition of the present invention includes a urethane (meth)acrylate oligomer and a (meth)acrylate monomer, so that the ink composition has an appropriate viscosity and can be applied to a digital printing method, the ink composition has excellent storage stability, and the ink layer produced therefrom has excellent peeling strength.

[0026] If the ink composition contains only a urethane (meth)acrylate oligomer and does not contain a (meth)acrylate monomer, the ink composition has a high viscosity at 25°C, making it difficult to apply to a digital printer, and a problem occurs in which printing from a digital printer head does not occur. On the other hand, if the ink composition contains only a (meth)acrylate monomer and does not contain a urethane (meth)acrylate oligomer, the ink composition has a low viscosity, making it difficult to print from a digital printer head. Even if printing is possible because it is composed only of high-viscosity monomers, problems such as insufficient adhesion and durability may occur, and the printed matter may not maintain its initial state over time, resulting in damage to the printed matter. In addition, if the ink composition contains only a (meth)acrylate monomer and does not contain a urethane (meth)acrylate oligomer, a problem in which it is difficult to commercialize the ink composition due to insufficient implementation of physical properties may occur. Therefore, the ink composition of the present invention prevents the above-described problem and obtains the above-described effect by including a urethane (meth)acrylate oligomer and a (meth)acrylate monomer in combination.

[0027]

[0028] pigment

[0029] Pigments serve to impart color to ink compositions. Here, the pigments may be, for example, colored pigments.

[0030] The above-mentioned coloring pigment serves to form an image by imparting color to the coating. At this time, the coloring pigment may be a black pigment, a white pigment, a blue pigment, a cyan pigment, a red pigment, a magenta pigment, a yellow pigment, a violet pigment, or a mixture thereof. At this time, any coloring pigment that can be commonly applied to ink may be used without special restrictions.

[0031] The pigment may be in the form of a pigment dispersion, and for example, the average particle size of the pigment dispersed in the dispersion may be 50 to 200 nm, 60 to 160 nm, or 80 to 140 nm. When the average particle size of the pigment in the dispersion is within the above range, the storage stability of the ink composition is excellent. In addition, when the average particle size of the pigment in the pigment dispersion is less than the above range, the shielding power of the ink containing it is reduced, so that the color density is lowered, which causes limitations in color expression, and also, due to the excessively low particle size of the pigment, the force of the pigment particles to re-aggregate is strong, so that the storage stability of the dispersion is reduced, and a phenomenon of easy gelation may occur. On the other hand, when the average particle size of the pigment in the pigment dispersion exceeds the above range, the problem of clogging of the head nozzle may occur when ejecting the ink containing it.

[0032] In addition, the pigment dispersion may have a viscosity at 25°C of 20 to 50 cps, 20 to 40 cps, or 25 to 35 cps. If the viscosity of the pigment dispersion at 25°C is less than the above range, the stability of the pigment dispersion may be compromised, and the viscosity may increase over time and gelation may occur. If the viscosity exceeds the above range, the viscosity of the ink containing the pigment dispersion may increase, and the output stability of the ink may be reduced.

[0033] The above UV-curable ink composition may contain 13 to 24 wt% or 15 to 21 wt% of a pigment based on the total weight of the ink composition. If the content of the pigment is less than the above range, the color development of the printed matter may be reduced, and if it exceeds the above range, the content of ink, which is a solid component in the composition, may be high, resulting in poor ink discharge properties.

[0034]

[0035] Urethane (meth)acrylate oligomer

[0036] Urethane (meth)acrylate oligomer is a main ingredient that controls the properties of an ink composition, and plays a role in controlling the dischargeability and storage stability of the ink, as well as the peel strength of the ink layer manufactured therefrom. Specifically, the urethane (meth)acrylate oligomer contains a soft urethane structure as a polymer, thereby improving the melting and adhesive properties of the ink composition, thereby enhancing the adhesion to the substrate layer, and has the effect of improving the flexibility and elongation of products such as manufactured interior films.

[0037] The above urethane (meth)acrylate oligomer contains two functional groups. When the above urethane (meth)acrylate oligomer contains two functional groups, the flexibility of the printed surface and the adhesion to the PVC substrate are excellent, which enables the commercialization of interior films. On the other hand, when the functional group is one or none, rather than two, the curing property of the ink composition may be insufficient, resulting in the ink not being cured and the adhesion being reduced. In addition, when the functional group is contained in excess of the above range and three or more, the hardness of the printed matter may increase, causing it to brittle and cracking.

[0038] In addition, the urethane (meth)acrylate oligomer has a weight average molecular weight (Mw) of 500 to 2,000 g / mol. When the weight average molecular weight of the urethane (meth)acrylate oligomer is within the above range, the amount of the oligomer used can be appropriately controlled, thereby improving the adhesiveness, which is a functionality of the printed coating surface.

[0039] Specifically, the urethane (meth)acrylate oligomer may have a weight average molecular weight of 700 to 1,700 g / mol, or 800 to 1,500 g / mol. If the weight average molecular weight of the urethane (meth)acrylate oligomer is less than the above range, the functionality of the oligomer itself may be limited, and as the functional groups decrease, the curing performance of the oligomer may also decrease, increasing the possibility of non-curing. If the weight average molecular weight exceeds the above range, the ink fluidity may decrease, causing a problem of not being ejected from a digital printing head, which may cause a problem in output stability.

[0040] The viscosity of the urethane (meth)acrylate oligomer at 25°C may be 1,000 to 5,000 cps, 2,000 to 4,800 cps, or 3,000 to 4,500 cps. If the viscosity of the urethane (meth)acrylate oligomer at 25°C is below the above range, the adhesion of the manufactured ink layer may be reduced, and if it exceeds the above range, the viscosity of the ink composition may be increased, resulting in insufficient head ejection properties and reduced output stability.

[0041] In addition, the urethane (meth)acrylate oligomer may be included in an amount of 3 to 15 wt%, or 5 to 10 wt%, based on the total weight of the ink composition. If the amount of the urethane (meth)acrylate oligomer is less than the above range, the effective ingredient in the ink composition may be insufficient, and thus the physical properties of the manufactured ink layer may not be properly secured. If the amount exceeds the above range, the output stability of the inkjet head may deteriorate during printing.

[0042]

[0043] (meth)acrylate monomer

[0044] (Meth)acrylate monomer improves ink output properties by controlling the viscosity of the ink composition and plays a role in improving the adhesion of the ink layer when forming the ink layer.

[0045] The (meth)acrylate monomer may include a first (meth)acrylate monomer that is difunctional and comprises an aliphatic group, a second (meth)acrylate monomer that is monofunctional and comprises an aliphatic group, and a second (meth)acrylate monomer that is monofunctional and comprises an aromatic group.

[0046] The first (meth)acrylate monomer serves to improve adhesion to a substrate layer such as PVC. For example, the first (meth)acrylate monomer may be 1,6-hexanediol diacrylate (HDDA).

[0047] The above-mentioned 2-1 (meth)acrylate monomer serves to provide adhesion to the adhesive layer during the manufacture of the interior film. For example, the above-mentioned 2-1 (meth)acrylate monomer may be tetrahydrofurfuryl acrylate (THFA).

[0048] The above-mentioned 2-2 (meth)acrylate monomer plays a role in appropriately controlling the viscosity of the ink composition and improving the solubility of the ultraviolet initiator. For example, the above-mentioned 2-2 (meth)acrylate monomer may be phenoxyethyl acrylate (PHEA).

[0049] The above (meth)acrylate monomer may have a weight average molecular weight of 100 to 1,000 g / mol, 100 to 700 g / mol, or 100 to 500 g / mol. If the weight average molecular weight of the above (meth)acrylate monomer is less than the above range, the viscosity of the ink composition may be insufficient, which may cause problems in printing from the printer head during printing, and if it exceeds the above range, the viscosity of the ink composition may increase, which may cause problems in printing from the printer head during printing.

[0050] Additionally, the (meth)acrylate monomer may include a difunctional first (meth)acrylate monomer and a monofunctional second (meth)acrylate monomer in a weight ratio of 1:3 to 1:20, or a weight ratio of 1:5 to 1:16.

[0051] If the above (meth)acrylate monomer contains a smaller amount of the second (meth)acrylate monomer than the above-mentioned range for the first (meth)acrylate monomer, the adhesion between the ink layer and the adhesive layer may be reduced, resulting in insufficient adhesion of the interior film. In addition, if the above (meth)acrylate monomer contains an excess amount of the second (meth)acrylate monomer than the above-mentioned range for the first (meth)acrylate monomer, the adhesion between the digitally printed painted surface and the substrate layer may be reduced, resulting in insufficient adhesion of the interior film.

[0052] Additionally, the acrylate monomer may include a 2-1 (meth)acrylate monomer and a 2-2 (meth)acrylate monomer in a weight ratio of 1:0.8 to 1:2, or a weight ratio of 1:1 to 1:1.6.

[0053] In addition, the (meth)acrylate monomer may be included in an amount of 38 to 65 wt%, or 42 to 58 wt%, based on the total weight of the ink composition. If the amount of the (meth)acrylate monomer is less than the above range, the viscosity of the ink composition may increase due to an increase in the oligomer amount, which may result in a decrease in output stability during digital output, and if it exceeds the above range, the adhesion may deteriorate as the oligomer amount decreases.

[0054] Specifically, the ink composition may include 3 to 10 wt%, 3 to 9 wt%, or 3 to 8 wt% of a first (meth)acrylate monomer, and 35 to 55 wt%, or 39 to 50 wt% of a second (meth)acrylate monomer, based on the total weight of the ink composition. When the content of the first (meth)acrylate monomer is less than the above range, the adhesion of the ink-coated surface to the substrate layer, which is a digital printing surface, may be reduced, and when it exceeds the above range, the hardness of the ink-coated surface may increase, causing cracks (breakage of the ink layer) to occur during the embossing process when manufacturing an interior film. In addition, when the content of the second (meth)acrylate monomer is less than the above range, the adhesion of the ink layer and the adhesive layer-coated surface may be reduced, and when it exceeds the above range, the adhesion of the ink-coated surface to the substrate layer, which is a digital printing surface, may be reduced.

[0055] More specifically, the ink composition may include 3 to 10 wt%, 3 to 9 wt%, or 3 to 8 wt% of the first (meth)acrylate monomer, 15 to 25 wt%, 15 to 24 wt%, or 17 to 23 wt% of the second-1 (meth)acrylate monomer, and 20 to 30 wt%, 21 to 28 wt%, or 22 to 27 wt% of the second-2 (meth)acrylate monomer, based on the total weight of the ink composition. When the content of the first (meth)acrylate monomer is less than the above range, the adhesion between the substrate layer, which is a digital printing surface, and the printed painting surface may be reduced, thereby reducing the adhesion of the interior film, and when it exceeds the above range, cracks (painting surface breakage phenomenon) may occur in the embossing process during the manufacturing of the interior film, thereby reducing the quality of the digital printing image. In addition, when the content of the 2-1 (meth)acrylate monomer is less than the above range, the adhesion between the digital printing surface and the adhesive layer may be insufficient, thereby reducing the adhesion of the interior film, and when it exceeds the above range, the adhesion between the substrate layer, which is the digital printing surface, and the printed painting surface may be reduced, thereby reducing the adhesion of the interior film. Furthermore, when the content of the 2-2 (meth)acrylate monomer is less than the above range, the solubility of the ultraviolet initiator may be reduced during ink manufacturing, and as time passes after ink manufacturing, recrystallization of the ultraviolet initiator may be caused, which may cause a nozzle clogging problem of the digital printer head. On the other hand, when it exceeds the above range, the viscosity of the ink composition may be reduced or the adhesion may be reduced due to a change in the content of the oligomer.

[0056]

[0057] caprolactam compounds

[0058] Caprolactam compounds play a role in improving the adhesion to the substrate layer when manufacturing an ink layer using an ink composition and improving the heat resistance of the manufactured ink layer.

[0059] The caprolactam compound may have a weight average molecular weight of 50 to 500 g / mol, 80 to 400 g / mol, or 100 to 300 g / mol. If the weight average molecular weight of the caprolactam compound is less than the above range, the adhesion and heat resistance of the ink composition may be reduced, and if it exceeds the above range, the color of the ink may change or the storage stability of the ink may be reduced.

[0060] Additionally, the caprolactam compound may be, for example, n-vinylcaprolactam.

[0061] The caprolactam-based compound may be included in an amount of 10 to 20 wt%, or 12 to 18 wt%, based on the total weight of the ink composition. If the content of the caprolactam-based compound is less than the above range, the adhesion of the ink composition may be reduced and the heat resistance may be low, which may cause a problem in that the color of the ink layer may change during the interior film lamination process. If the content exceeds the above range, the dispersion stability of the pigment in the ink may be reduced, so that the pigment may clump over time, increasing the particle size or causing the pigment to precipitate, which may cause a problem in the storage stability of the ink.

[0062]

[0063] UV initiator

[0064] The ultraviolet initiator absorbs ultraviolet rays to initiate polymerization and harden the ink composition, thereby forming a film and controlling the curing speed of the ink composition.

[0065] The above ultraviolet initiator may include a first phosphine oxide-based compound containing one acyl group, and a second phosphine oxide-based compound containing two or more acyl groups.

[0066] The above first phosphine oxide compound absorbs ultraviolet rays to initiate polymerization and harden the ink composition, thereby forming a coating film and controlling the curing speed of the ink composition.

[0067] Additionally, the first phosphine oxide compound may be, for example, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO).

[0068] The above second phosphine oxide compound absorbs ultraviolet rays to initiate polymerization, thereby controlling the curing speed of the ink composition and controlling the final degree of curing of the manufactured ink layer.

[0069] Additionally, the second phosphine oxide compound may be, for example, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO).

[0070] The above ultraviolet initiator may be included in an amount of 4 to 12 wt%, or 6 to 10 wt%, based on the total weight of the ink composition. If the amount of the ultraviolet initiator is less than the above range, the ink composition may not be cured, and if it exceeds the above range, the ultraviolet initiator may not be sufficiently dissolved, and the change in ink curing performance relative to the amount of the ultraviolet initiator is minimal, which is not desirable from an economic perspective.

[0071] Specifically, the ink composition may include 3 to 7 wt%, or 4 to 6 wt%, of a first phosphine oxide-based compound, and 1 to 5 wt%, or 2 to 4 wt%, of a second phosphine oxide-based compound, based on the total weight of the ink composition. If the content of the first phosphine oxide-based compound is less than the above range, the ink composition may not be cured, and if it exceeds the above range, the UV initiator may not be dissolved due to excessive loading, and the degree of improvement in ink curing performance relative to the amount of UV initiator may be insufficient, thereby reducing economic feasibility. In addition, if the content of the second phosphine oxide-based compound is out of the above range, the UV initiator may not be dissolved due to excessive loading, and the degree of improvement in ink curing performance relative to the amount of UV initiator may be insufficient, thereby reducing economic feasibility. In addition, recrystallization of the UV initiator may occur due to changes in time or temperature of the ink, which may cause clogging of the nozzle of a digital printer.

[0072] Meanwhile, if only the first phosphine oxide compound is used without using the second phosphine oxide compound, the ink composition may not be cured during curing after digital printing output, which may result in a decrease in peel strength or a blocking problem when the printed material is placed.

[0073]

[0074] additives

[0075] The above ultraviolet curable ink composition may additionally contain additives such as a surface tension control agent, a surfactant, and a preservative, and may also contain additives that are typically applicable to ink.

[0076] For example, the surface tension modifier improves the surface tension of the ink composition by controlling the wetting of the ink composition with respect to the substrate layer. Specifically, the surface tension modifier may be a polyether-modified polydimethylsiloxane. In addition, the surface tension modifier may be included in an amount of 0.001 to 0.3 wt% based on the total weight of the ink composition. If the amount of the surface tension modifier exceeds the above range, the surface tension of the ink composition may be insufficient, resulting in poor printing of the ink composition.

[0077] The above UV-curable ink composition may have a viscosity of 15 to 23 cps at 25°C. If the viscosity of the UV-curable ink composition at 25°C is below the above range, ink may scatter when ejected from an inkjet printer head, resulting in a large amount of satellites being generated on the printed matter. If it exceeds the above range, ink may not be completely ejected from a micro-tubular nozzle during printing, resulting in a nozzle failure phenomenon.

[0078] In addition, the above UV-curable ink composition may have an average particle size of dispersed particles of 50 to 200 nm, or 100 to 150 nm. When the average particle size of the dispersed particles in the UV-curable ink composition is within the above range, stable head ejection performance can be exhibited as inkjet ink. On the other hand, when the average particle size of the dispersed particles in the UV-curable ink composition is outside the above range, the head may be clogged during printing or the shielding power (color density) of the printed matter may be reduced, which may lower the color development of the ink composition and cause nozzle clogging.

[0079] The above ultraviolet-curable ink composition may have a glass transition temperature (Tg) of -70 to -30°C, or -60 to -40°C. When the glass transition temperature of the ultraviolet-curable ink composition is within the above range, the ink curing performance is excellent and the output stability during digital printing is excellent. On the other hand, when the glass transition temperature of the ultraviolet-curable ink composition is below the above range, the ink curing performance is insufficient and the output stability during digital printing may be reduced, and when it exceeds the above range, the output stability during digital printing may be reduced or ink fluidity problems may occur within the printer.

[0080] The ultraviolet-curable ink composition according to the present invention as described above has excellent storage stability at room temperature (25°C) and high temperature (60°C), and excellent image resolution after printing, and is capable of interlayer lamination with a substrate layer such as PVC, and has excellent design freedom and printability during printing.

[0081]

[0082] Interior film

[0083] In addition, an interior film according to the present invention includes a substrate layer; an ink layer formed on the substrate layer and formed from the ultraviolet-curable ink composition; an adhesive layer formed on the ink layer; and a transparent protective layer formed on the adhesive layer.

[0084]

[0085] Substrate layer

[0086] The above-mentioned substrate layer can be used without any special restrictions as long as it is generally applicable to interior films or decorative films, and may include, for example, a vinyl chloride-based resin.

[0087] The above vinyl chloride resin may be at least one selected from the group consisting of polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and vinyl chloride and a vinyl chloride copolymer containing a monomer copolymerized therewith.

[0088] The above-mentioned substrate layer may be a commercially available product that is typically applicable to interior films or decorative films, and may have an average thickness of, for example, 30 to 200 ㎛ or 50 to 150 ㎛.

[0089]

[0090] ink layer

[0091] The ink layer is formed from the ultraviolet-curable ink composition described above.

[0092] The ink layer may be formed by digitally printing the ultraviolet-curable ink composition. For example, the ink layer may be formed by digitally printing the ultraviolet-curable ink composition on a substrate layer.

[0093]

[0094] adhesive layer

[0095] The adhesive layer is formed on the ink layer and serves to bond the ink layer and the transparent protective layer.

[0096] The adhesive layer may be used without any particular limitation as long as it is generally applicable to interior films or decorative films, and may include, for example, a UV-curable adhesive. Specifically, the adhesive layer may include an oligomer, a monomer, a UV-initiator, and the like.

[0097] Additionally, the adhesive layer can be applied in a thickness that is typically applicable to interior films or decorative films, for example, the average thickness can be 1 to 20 μm, or 2 to 10 μm.

[0098]

[0099] transparent protective layer

[0100] The transparent protective layer can be used without any special restrictions as long as it is generally applicable to interior films or decorative films, and may include, for example, a vinyl chloride-based resin.

[0101] The above vinyl chloride resin may be at least one selected from the group consisting of polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and vinyl chloride and a vinyl chloride copolymer containing a monomer copolymerized therewith.

[0102] The above transparent protective layer can be formed by a method that is typically applicable to interior films or decorative films, and for example, can be formed by laminating it on the adhesive layer and then curing it by irradiating it with ultraviolet rays.

[0103] In addition, the transparent protective layer may be a commercially available product that is typically applicable to interior films or decorative films, and may have an average thickness of, for example, 50 to 200 μm or 80 to 130 μm. If the average thickness of the transparent protective layer is outside the above range, the deep embossing effect may not be achieved, resulting in poor texture, or the film may become expensive due to its thick thickness, resulting in poor economic efficiency.

[0104] The interior film according to the present invention as described above has excellent image resolution of the ink layer and excellent adhesion between each layer, so that the physical properties and productivity of the product are excellent.

[0105] Hereinafter, the present invention will be described in more detail through examples.

[0106] [Example]

[0107] Experimental Examples 1 to 21. Preparation of UV-curable ink composition

[0108] A UV-curable ink composition was prepared by adjusting the composition as described in Tables 1 to 4.

[0109] Ingredients (% by weight) Experimental Example 1 Experimental Example 2 Experimental Example 3 Experimental Example 4 Experimental Example 5 Pigment dispersion 20.00 20.00 20.00 20.00 20.00 Oligomer 15.00 8.00 10.00 8.00 Oligomer 2 5.00 Oligomer 3 Oligomer 4 Oligomer 5 Monomer 15.00 5.00 5.00 3.00 Monomer 2 20.00 20.00 20.00 20.00 23.00 Monomer 3 23.99 23.99 23.99 23.99 22.99 Monomer 4 Monomer 5 Monomer 6 Caprolactam compound 18.00 15.00 13.00 18.00 15.00 Ultraviolet initiator 15.005.005.005.005.005.00UV initiator 23.003.003.003.003.00Surface tension control agent 0.010.010.010.010.01Total 100100100100100

[0110] Ingredients (% by weight) Experimental Example 6 Experimental Example 7 Experimental Example 8 Experimental Example 9 Experimental Example 10 Pigment dispersion 20.00 20.00 20.00 20.00 20.00 Oligomer 18.00 8.00 13.00 3.00 Oligomer 2 Oligomer 3 5.00 Oligomer 4 Oligomer 5 Monomer 18.00 5.00 5.00 5.00 5.00 Monomer 2 17.00 17.00 20.00 20.00 Monomer 3 23.99 26.99 23.99 23.99 Monomer 4 Monomer 5 Monomer 6 Caprolactam compound 15.00 15.00 10.00 20.00 18.00 Ultraviolet initiator 15.005.005.005.005.005.00UV initiator 23.003.003.003.003.00Surface tension control agent 0.010.010.010.010.01Total 100100100100100

[0111] Ingredients (% by weight) Experimental Example 11 Experimental Example 12 Experimental Example 13 Experimental Example 14 Experimental Example 15 Pigment dispersion 20.00 20.00 20.00 20.00 20.00 Oligomer 1 5.00 5.00 5.00 Oligomer 2 Oligomer 3 Oligomer 45.00 Oligomer 5 5.00 Monomer 15.00 5.00 5.00 Monomer 2 20.00 20.00 5.00 20.00 Monomer 3 23.99 23.99 20.00 23.99 Monomer 4 43.99 Monomer 5 23.99 Monomer 6 5.00 Caprolactam compound 18.00 18.00 18.00 18.00 18.00 Ultraviolet initiator 15.005.005.005.005.005.00UV initiator 23.003.003.003.003.00Surface tension control agent 0.010.010.010.010.01Total 100100100100100

[0112] Ingredients (% by weight) Experimental Example 16 Experimental Example 17 Experimental Example 18 Experimental Example 19 Experimental Example 20 Experimental Example 21 Pigment dispersion 20.00 20.00 20.00 20.00 20.00 20.00 Oligomer 15.00 1.00 16.00 23.00 5.00 Oligomer 2 Oligomer 3 Oligomer 4 Oligomer 5 Monomer 1 2.00 5.00 20.00 Monomer 238.99 25.00 25.00 51.99 20.00 20.00 Monomer 3 23.99 23.99 23.00 Monomer 4 Monomer 55.00 Monomer 65.00 Caprolactam compound 18.00 22.00 7.00 18.00 7.00 UV Initiator 15.00 5.00 5.00 5.00 5.00 5.00 UV Initiator 23.00 3.00 3.00 3.00 3.00 Surface Tension Control Agent 0.01 0.01 0.01 0.01 0.01 Total 100 100 100 100 100

[0113]

[0114] The manufacturer, product name, and other characteristics of each component used in the above experimental examples are shown in Table 5 below. In addition, Mw is the weight average molecular weight, and the average particle size of the dispersed particles is a value measured using the same method as item (1) of the following test examples.

[0115] Ingredient Ratio Pigment Dispersion Manufacturer: Ink Tech, Product Name: CIB-N (PB 15:4 Dispersion: Pigment Concentration 15 wt%, Average Particle Size: 120 nm, Viscosity (25°C): 28 cps) Oligomer 12-Functional Urethane Acrylate Oligomer (Mw 1,000 g / mol, Viscosity (25°C) 3,550 cps) Oligomer 22-Functional Urethane Acrylate Oligomer (Mw 1,500 g / mol, Viscosity (25°C) 4,470 cps) Oligomer 31-Functional Urethane Acrylate Oligomer (Mw 440 g / mol, Viscosity (25°C) 910 cps) Oligomer 42-Functional Urethane Acrylate Oligomer (Mw 3,700 g / mol, Viscosity (25°C) 7,630 cps) Oligomer 53-Functional Epoxy Acrylate Oligomer (Mw 1,800 g / mol, viscosity (25℃) 4,830 cps) Monomer 12-functional monomer (1,6-hexanediol diacrylate, HDDA) Monomer 21-functional monomer (tetrahydrofurfuryl methacrylate, THFA) Monomer 31-functional monomer (phenoxyethyl acrylate, PHEA) Monomer 43-functional monomer (trimethylolpropane triacrylate, TMPTA) Monomer 53-functional monomer (ethoxylated trimethylolpropane triacrylate, ETPTA)) Monomer 64-functional monomer (pentaerythritol tetraacrylate, PETA) Caprolactam compound N-vinylcaprolactam (NVC) UV initiator 1 Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide UV initiator 2-Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide surface tension modifier polyether-modified polydimethylsiloxane (Manufacturer: BYK, Product name: BYK-UV3510)

[0116]

[0117] Test Example: Characteristic Evaluation

[0118] The properties of the UV-curable ink composition of the experimental example were measured using the following method, and the results are shown in Table 6.

[0119] (1) Average particle size of particles dispersed in the composition

[0120] After measuring the particle size distribution of the particles dispersed in the composition by laser light scattering (LLS), the cumulative distribution of 10% (D) in the particle size distribution 10 ) to 90%(D 90 ) was used as the average particle size.

[0121]

[0122] (2) Viscosity at 25℃

[0123] Measurements were made using a viscometer (Brookfield spindle viscometer, Brookfield Viscometer LVDV-II, CPE-40 spindle) at room temperature (25°C).

[0124]

[0125] (3) Storage stability

[0126] After storing the UV-curable ink composition at 25°C or 60°C for two weeks, the average particle size of the dispersed particles and the viscosity at 25°C or 60°C were measured in the same manner as in items (1) and (2) above, and the storage stability was evaluated based on the following criteria.

[0127] Specifically, if the change was less than 10% compared to the initial measurement value, it was evaluated as good, and if the change exceeded 10%, it was evaluated as bad.

[0128]

[0129] (4) Output

[0130] Using the ink compositions of each experimental example, the printability was evaluated by checking the number of nozzle failures in the head corresponding to the monochrome unit while continuously printing for one hour using digital printing equipment equipped with a KONIKA 1024i series and a RICHO GEN5 head. A printability evaluation was performed when the number of nozzle failures was three or fewer.

[0131]

[0132] (5) Peel strength

[0133] The ink composition of the experimental example was printed in a single color on a colored PVC substrate film (Manufacturer: Geumgang Enterprise, Product Name: KKP PRINT, Thickness: 80㎛) using the same equipment as the digital printing equipment as in Item (4) to form an ink layer. Then, a UV adhesive (Manufacturer: Permabond, Product Name: Permabond UV640) was applied 7 to 8㎛ thick on the ink layer, a PVC transparent film (Manufacturer: Geumgang Enterprise, Product Name: KKP DECO, Thickness: 110㎛) was covered, and a specimen was manufactured by irradiating ultraviolet rays using an LED light source with a wavelength of 395nm. At this time, the adhesive strength of the UV adhesive was set so that a product having an adhesive strength of 5kgf / inch or more was used so that the part that comes off when measuring the peel strength becomes the ink layer, and the measured strength is also set so that the measured strength is the measured strength of the ink layer.

[0134] The manufactured lamination sequence was as follows: colored PVC film, ink layer, adhesive layer, and PVC transparent film. Subsequently, the manufactured specimens were tested for 180° peel strength between the ink layer and the PVC transparent film using a tensile tester (Universal Testing Machine, manufacturer: SALT, model number: ST-1003).

[0135]

[0136] (6) Whether cracks occur

[0137] After manufacturing the specimen in the same manner as in item (5), the specimen was passed through a 200㎛ deep roll made of SUS at 170℃ under a pressure of 6MPa to create an embossed texture. Afterwards, it was visually inspected to confirm that the printed surface of the part pressed to a depth of 200㎛ was maintained intact.

[0138] Average particle size (nm)Viscosity (25℃) (cps)25℃ storage stability60℃ storage stabilityPrintabilityCrack occurrencePeeling strength (kgf / inch)Average particle size (nm)Viscosity (cps)EvaluationAverage particle size (nm)Viscosity (cps)EvaluationExperimental example 112318.012417.6Good12117.5Good0X3.1Experimental example 212719.612519.4Good12219.3Good0X3.5Experimental example 312922.112622.0Good12021.5Good0X3.6Experimental example 412117.512317.1Good12417.00Good1X3.2Experimental example 512318.612118.2Good12318.0Good0X3.0Experimental example 612519.912919.4Good12119.0Good0X3.4Experimental example 712719.212418.9Good12818.7Good0X3.3Experimental example 812622.812422.5Good12522Good3X3.1Experimental example 912216.112315.5Good12415.1Good2X3.4Experimental example 1012414.212314.0Good12213.9Good3X0.9Experimental example 1112325.012124.3Good12324.1Good13X3.2Experimental example 1212120.112519.6Good12119.8Good1O1.2Experimental example 1312326.112225.6Good12225.7Good2403.1Experimental example 1412521.612420.4Good12320.6Good1203.2Experimental example 1512319.712419.5Good12019.40Good103.0Experimental example 1612622.312521.9Good12721.50Good103.3Experimental example 1712216.114217.3Poor15818.30Poor2X0.4Experimental example 1812423.012122.9Good12622.5Good10X3.6Experimental example 1912413.412113.0Good12313.10Good2X0.7Experimental example 2012427.012626.5Good12526.10Good16X3.7Experimental example 2112016.512216.2Good12016.00Good102.7

[0139]

[0140] As shown in Table 6, the compositions of Experimental Examples 1 to 9 had an appropriate average particle size of dispersed particles, an appropriate viscosity at 25°C, excellent storage stability and output properties, no cracks in the manufactured ink layer, and excellent peel strength.

[0141] On the other hand, Experimental Example 10 including oligomer 3 including a monofunctional urethane acrylate oligomer and Experimental Example 19 not including a urethane acrylate oligomer had low viscosity at 25°C, resulting in poor ink discharge properties and poor peeling strength of the manufactured ink layer.

[0142] In addition, Experimental Example 11 including oligomer 4 having high viscosity and weight average molecular weight at 25°C, Experimental Examples 13 and 14 including monomer 4 or monomer 5, which are trifunctional acrylate monomers, and Experimental Example 20 including an excessive amount of urethane acrylate oligomer had high viscosity at 25°C and / or poor ink ejection and printability. In particular, cracks occurred in the ink layers produced in Experimental Examples 13 and 14.

[0143] Experimental Example 12, which included oligomer 5 containing a trifunctional epoxy acrylate oligomer, and Experimental Example 21, which used a small amount of a caprolactam-based compound and did not include a surface tension control agent, showed cracks in the manufactured ink layer and insufficient peel strength.

[0144] Experimental Example 15, which includes Monomer 6, a tetrafunctional acrylate monomer, and Experimental Example 16, which includes Monomer 5, a trifunctional acrylate monomer, and Monomer 6, a tetrafunctional acrylate monomer, showed cracks in the manufactured ink layer.

[0145] In addition, Experimental Example 17, which contained a small amount of urethane acrylate oligomer and did not contain a bifunctional first acrylate monomer, had poor storage stability at room temperature (25°C) and high temperature (60°C), resulting in a large viscosity change and poor peel strength of the manufactured ink layer.

[0146] Experimental Example 18, which contained an excess of urethane acrylate oligomer and did not contain a bifunctional first acrylate monomer, had poor printability of the ink composition, resulting in nozzle failure during printing.

Claims

1. Contains pigment, urethane (meth)acrylate oligomer, (meth)acrylate monomer, caprolactam compound and ultraviolet initiator, A UV-curable ink composition, wherein the above urethane (meth)acrylate oligomer contains two functional groups and has a weight average molecular weight of 500 to 2,000 g / mol.

2. In claim 1, The viscosity of the above urethane (meth)acrylate oligomer at 25°C is 1,000 to 5,000 cps, An ultraviolet-curable ink composition wherein the weight average molecular weight of the above (meth)acrylate monomer is 100 to 1,000 g / mol.

3. In claim 1, The above (meth)acrylate monomer comprises a difunctional first (meth)acrylate monomer and a monofunctional second (meth)acrylate monomer, An ultraviolet-curable ink composition, wherein the above (meth)acrylate monomer comprises a difunctional first (meth)acrylate monomer and a monofunctional second (meth)acrylate monomer in a weight ratio of 1:3 to 1:

20.

4. In claim 1, An ultraviolet-curable ink composition, wherein the ultraviolet initiator comprises a first phosphine oxide-based compound containing one acyl group and a second phosphine oxide-based compound containing two or more acyl groups.

5. In claim 1, A UV-curable ink composition comprising 13 to 24 wt% of a pigment, 3 to 15 wt% of a urethane (meth)acrylate oligomer, 38 to 65 wt% of a (meth)acrylate monomer, 10 to 20 wt% of a caprolactam-based compound, and 4 to 12 wt% of an UV-initiator.

6. Base layer; An ink layer formed on the substrate layer and formed from the ultraviolet curable ink composition of any one of claims 1 to 5; An adhesive layer formed on the ink layer; and An interior film comprising a transparent protective layer formed on the adhesive layer.