Laminate containing an inorganic nanoparticle-containing surface layer exhibiting a low-gloss appearance, and radiation-curable ink containing inorganic nanoparticles.

Abstract

To provide a laminate having an inorganic nanoparticle-containing surface layer with a low-gloss appearance, and an inorganic nanoparticle-containing radiation-curable ink.SOLUTION: A laminate of an embodiment of the present disclosure includes a substrate and a surface layer containing a cured product of a radiation-curable ink. The radiation-curable ink contains inorganic nanoparticles, a polyether-modified polymer, and at least one selected from among radiation-curable polymerizable oligomers and radiation-curable polymerizable monomers. The surface layer has a 60° surface glossiness of 50.0 GU or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a laminate including a surface layer exhibiting a low-gloss appearance and a radiation-curable ink. [Background technology]

[0002] For example, light-diffusing sheets are used in display devices such as liquid crystal displays to minimize the reduction in screen visibility. Also known are embossed decorative films used for decorating the interior and exterior of buildings, vehicles, and other structures.

[0003] Patent Document 1 (Japanese Patent No. 3743624) describes a light-diffusing sheet comprising a light-diffusing layer made of a resin film layer having a fine uneven surface, wherein the 60° gloss value (JIS Z8741) of the fine uneven surface differs depending on the direction of incidence, and the maximum value (a) and minimum value (b) of the gloss value satisfy the formula: (ab)>{(a+b) / 2}×0.1.

[0004] Patent Document 2 (Japanese Patent Publication No. 2011-255552) describes an embossed decorative sheet in which an embossed surface is applied to the surface of the decorative sheet, wherein a surface protective layer made of a curable resin containing synthetic resin beads is provided on the surface side of the decorative sheet, the embossing has an average amplitude of 15 to 50 micrometers, and the synthetic resin beads are synthetic resin beads with an average particle size of 8 to 20 micrometers.

[0005] Patent Document 3 (Japanese Patent Publication No. 2019-072935) describes an stretchable film having a surface layer containing a binder containing urethane resin, urethane resin beads having an average particle size of 4 to 20 micrometers, and nanosilica particles, wherein the surface gloss is 5 GU or less at 60 degrees.

[0006] In recent years, there has been a demand for films with a low-gloss appearance, for example, in optical and decorative applications. When a low-gloss appearance is achieved through mechanical means such as embossing, maintenance of equipment such as embossing rolls is required, and since a new embossing roll is needed for each desired low-gloss appearance, this has led to increased costs.

[0007] While techniques for roughening the surface of printed or coated layers by incorporating resin beads into ink are known, there have been cases where a good low-gloss appearance could not be achieved due to the sedimentation of the resin beads within the layer. In recent years, it has become possible to produce low-gloss layers using inkjet technology, but due to limitations in inkjet head size, resin beads cannot be used, and viscosity limitations have made it difficult to achieve low gloss. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 3743624 [Patent Document 2] Japanese Patent Publication No. 2011-255552 [Patent Document 3] Japanese Patent Publication No. 2019-072935 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] This disclosure provides a laminate including an inorganic nanoparticle-containing surface layer exhibiting a low-gloss appearance, and an inorganic nanoparticle-containing radiation-curable ink. [Means for solving the problem]

[0010] According to one embodiment of the present disclosure, a laminate is provided comprising a substrate and a surface layer containing a cured product of a radiation-curable ink, wherein the radiation-curable ink comprises at least one selected from inorganic nanoparticles, polyether-modified polymers, and radiation-curable polymerizable oligomers and radiation-curable polymerizable monomers, and the surface layer exhibits a 60-degree surface gloss of 50.0 GU or less.

[0011] According to another embodiment of the present disclosure, a radiation-curable ink is provided comprising inorganic nanoparticles, a polyether-modified polymer, and at least one selected from radiation-curable polymerizable oligomers and radiation-curable polymerizable monomers. [Effects of the Invention]

[0012] According to this disclosure, it is possible to provide a laminate including an inorganic nanoparticle-containing surface layer exhibiting a low-gloss appearance, and an inorganic nanoparticle-containing radiation-curable ink.

[0013] The above description should not be considered to disclose all embodiments of the present invention or all advantages relating to the present invention. [Brief explanation of the drawing]

[0014] [Figure 1] (a) is a schematic cross-sectional view of a laminate of one embodiment of the present disclosure before irradiation, and (b) is a schematic cross-sectional view of the laminate after irradiation. [Figure 2] (a) is an SEM image of the upper surface of the laminate of Comparative Example 1, which has a surface layer containing a polyether-modified polymer but not inorganic nanoparticles, and (b) is an SEM image of the cross-section of the surface layer of the laminate of Comparative Example 1. [Figure 3] (a) is an SEM image of the upper surface of the laminate of Comparative Example 2, which has a surface layer containing inorganic nanoparticles but not polyether-modified polymer, and (b) is an SEM image of the cross-section of the surface layer of the laminate of Comparative Example 2. [Figure 4](a) is a SEM photograph of the upper surface of the laminate of Example 1 provided with a surface layer containing inorganic nanoparticles and a polyether-modified polymer, and (b) is a SEM photograph of the cross-section of the surface layer of the laminate of Example 1. [Figure 5] The upper left of (a) is a SEM photograph at a tilt angle of 10 degrees of the surface of the laminate of Comparative Example 3 provided with a conventional uneven surface layer prepared using an inkjet ink not containing a polyether-modified polymer and inorganic nanoparticles. The lower left is a SEM photograph of the upper surface of this uneven surface layer, and the right side is an optical photograph of the surface of the laminate of Comparative Example 3 provided with a conventional uneven surface layer. The upper right of (b) is a SEM photograph at a tilt angle of 10 degrees of the surface of the laminate of Example 14 provided with an uneven surface layer of an embodiment of the present disclosure prepared using an inkjet ink containing a polyether-modified polymer and inorganic nanoparticles. The lower right is a SEM photograph of the upper surface of this uneven surface layer, and the left side is an optical photograph of the surface of the laminate of Example 14 provided with a surface layer prepared using the ink of the present disclosure.

Mode for Carrying Out the Invention

[0015] Hereinafter, for the purpose of exemplifying typical embodiments of the present invention, a more detailed description will be given, but the present invention is not limited to these embodiments.

[0016] In the present disclosure, "nanoparticle" means a particle having a size on the order of nanometers, that is, less than 1000 nm.

[0017] In the present disclosure, "radiation curable" means the performance of being cured by radiation such as ultraviolet rays, electron beams, and X-rays.

[0018] In the present disclosure, "non-functional" means the performance of not exhibiting a curing reaction with the compound of Formula 1, a radiation curable oligomer or monomer, etc. contained in the ink even when exposed to radiation.

[0019] In this disclosure, "(meth)acrylic" means acrylic or methacrylic, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acryloyl" means acryloyl or methacryloyl.

[0020] In this disclosure, "monofunctional monomer" means a compound having only one reactive functional group, and generally its weight-average molecular weight is less than 1000.

[0021] In this disclosure, "oligomer" means a compound having multiple units derived from monomers, and generally has a weight-average molecular weight of 500 or more, or 1000 or more. For example, a urethane (meth)acrylate oligomer is a compound containing multiple units having urethane bonds and having a (meth)acryloyloxy group.

[0022] In this disclosure, for example, "on top of" in "the decorative layer is placed on top of the substrate" means either that the decorative layer is placed directly on top of the substrate, or that the decorative layer is placed indirectly on top of the substrate via another layer.

[0023] In this disclosure, for example, "below" in "the adhesive layer is placed below the substrate" means either that the adhesive layer is placed directly on the underside of the substrate, or that the adhesive layer is placed indirectly on the underside of the substrate film via another layer.

[0024] In this disclosure, the term "film" also includes articles referred to as "sheets."

[0025] In this disclosure, "omitted" means that variations caused by manufacturing tolerances, etc., are included, and it is intended that variations of approximately ±20% are acceptable.

[0026] In this disclosure, "transparent" means that the average transmittance in the visible light region (wavelength 400 nm to 700 nm), measured in accordance with JIS K 7375, is 80% or higher, preferably 85% or higher, or 90% or higher.

[0027] In this disclosure, "translucent" means that the average transmittance in the visible light region (wavelength 400nm to 700nm), measured in accordance with JIS K 7375, is less than 80%, preferably 75% or less, and may be 10% or more, or 20% or more, and is intended not to completely conceal the substrate.

[0028] Refer to the drawings for an example of the laminate of this disclosure.

[0029] Figure 1 is a cross-sectional view of a laminate 100 before irradiation and a laminate 110 after irradiation according to one embodiment of the present disclosure. Laminate 100 in Figure 1(a) comprises a surface layer 102 before irradiation on a substrate 101, and laminate 110 in Figure 1(b) comprises a surface layer 105 after irradiation on a substrate 101. Both surface layers contain inorganic nanoparticles 103 and a binder resin 104 cured from at least one selected from radiation-curable polymerizable oligomers and radiation-curable polymerizable monomers.

[0030] Hereinafter, for the purpose of illustrating typical embodiments of this disclosure, details of each component will be described, with some reference numerals omitted.

[0031] The laminate of this disclosure comprises a surface layer prepared from an inorganic nanoparticle, a polyether-modified polymer, and a radiation-curable ink comprising at least one selected from radiation-curable polymerizable oligomers and radiation-curable polymerizable monomers.

[0032] In the radiation-curable ink of this disclosure, the inorganic nanoparticles are not substantially aggregated or coalesced within the ink, and when such ink is applied to a substrate surface, the inorganic nanoparticles can be dispersed substantially uniformly in the surface layer, as shown in Figure 1(a). Surprisingly, the inventors have found that when a radiation-curable ink containing inorganic nanoparticles and a polyether-modified polymer is used, at least a portion of the inorganic nanoparticles in the surface layer applied to the substrate surface can migrate to the vicinity of the surface layer upon irradiation with radiation, as shown in Figure 1(b), resulting in a low-gloss appearance.

[0033] The radiation-curable inks of this disclosure are less prone to aggregation and coalescence of inorganic nanoparticles within the ink, thus reducing or preventing clogging of ink discharge nozzles or wires wound around coating rolls. For example, conventional inks that produce a low-gloss appearance by incorporating coarse particles on the order of micrometers have limitations in printing or coating methods, and methods such as inkjet printing could not be used. However, since the radiation-curable inks of this disclosure can coarseize particles by aggregating or densifying them after application to the substrate, they are not subject to the limitations of printing or coating methods, and are advantageous in terms of productivity and other factors.

[0034] There are no particular restrictions on the inorganic nanoparticles used; for example, at least one particle selected from silica, alumina, titanium dioxide, zinc oxide, zirconium oxide, tin-doped indium oxide, cesium tungstate, and antimond-doped tin oxide can be used. Among these, silica nanoparticles are preferred from the viewpoint of interaction with any compound of formula 1 or non-functional silane coupling agent that can be incorporated into the ink, the development of a low-gloss appearance after irradiation, and abrasion resistance. Herein, "inorganic nanoparticles" in this disclosure does not include inorganic pigments such as carbon black used in inkjet inks.

[0035] As silica nanoparticles, for example, silica sol obtained using water glass (sodium silicate solution) as a starting material can be used. For example, when using a dispersion in which silica nanoparticles are dispersed in isopropanol or the like, from the viewpoint of the development of a low-gloss appearance after irradiation, or from the viewpoint of reducing or preventing problems such as gelation of the ink, it is preferable that the dispersion of the starting material contains little or no acidic components, alkaline components, and ionic components, especially ammonia, acetic acid, hydrochloric acid, sodium ions, potassium ions, and calcium ions. Therefore, in the ink prepared using such a dispersion, or in the surface layer formed by such ink, the content of acidic components, alkaline components, and ionic components, especially ammonia, acetic acid, hydrochloric acid, sodium ions, potassium ions, and calcium ions, is preferably 500 ppm or less, 300 ppm or less, 100 ppm or less, 10 ppm or less, or 1 ppm or less, based on the total solid weight of the ink or the total weight of the surface layer (dry coating amount), and it is more preferable that these components are not present.

[0036] From the viewpoint of achieving a low-gloss appearance after irradiation, or from the viewpoint of reducing or preventing ink gelation, it is advantageous that the silica nanoparticles in such a dispersion are unmodified particles whose surfaces have not been altered by surface treatment agents such as silanes, amines, carboxylic acids, sulfonic acids, phosphonic acids, and titanates, and it is advantageous to use isopropanol as the dispersion. Dispersions containing unmodified silica nanoparticles with acidic, alkaline, and ionic components within the above ranges can be commercially available, for example, IPA-ST, IPA-ST-L, and IPA-ST-ZL manufactured by Nissan Chemical Corporation.

[0037] There are no particular restrictions on the amount of inorganic nanoparticles used, and they can be adjusted as appropriate based on the required low-gloss appearance, ink viscosity, etc. The amount of inorganic nanoparticles used can be 2% by mass or more, 4% by mass or more, or 6% by mass or more, or 20% by mass or less, 15% by mass or less, or 10% by mass or less, based on the total weight of the surface layer (dry coating amount) or the total weight of the ink (solid content).

[0038] Low-gloss appearance is generally more susceptible to the influence of fine irregularities on the surface of the surface layer caused by inorganic nanoparticles than to inorganic nanoparticles within the surface layer. The radiation-curable ink of this disclosure can migrate inorganic nanoparticles that contribute to a low-gloss appearance to the vicinity of the surface of the surface layer by radiation irradiation, thereby reducing the amount of inorganic nanoparticles used compared to inorganic nanoparticle-containing inks that do not have such properties. As a result, the radiation-curable ink of this disclosure can contribute to reducing manufacturing costs and improving elongation properties, etc.

[0039] There are no particular restrictions on the average particle size of inorganic nanoparticles. For example, from the viewpoint of low-gloss appearance, ejection from inkjet nozzles, and coating properties, it can be 5 nm or larger, 7 nm or larger, 10 nm or larger, 12 nm or larger, 20 nm or larger, 30 nm or larger, or 50 nm or larger, and it can be 150 nm or smaller, 120 nm or smaller, or 100 nm or smaller. The average particle size of inorganic nanoparticles is the average of the diameters of 10 or more particles, for example, 10 to 100 particles, measured using a transmission electron microscope (TEM).

[0040] The radiation-curable ink of this disclosure contains a polyether-modified polymer, which allows inorganic nanoparticles to be migrated to the vicinity of the surface layer by radiation irradiation.

[0041] There are no particular restrictions on the polyether-modified polymer; for example, a polyether-modified polymer having siloxane bonds can be used. Examples of such polymers include polyether-modified siloxane polymers, such as "TEGO® Flow 425" from Evonik Industries; polyether-modified polydimethylsiloxanes, such as "BYK-UV3510" from BIC Chemie Japan Co., Ltd.; polyether-modified polysiloxanes or polyether-modified polydimethylsiloxanes having one or more (meth)acrylic functional groups, such as "BYK-UV3500", "BYK-UV3505", "BYK-UV3530", "BYK-UV3570", "BYK-UV3575", and "BYK-UV3576" from BIC Chemie Japan Co., Ltd.; and silicone (meth)acrylates, such as "TEGO® Rad 2250", "TEGO® Rad 2300", and "TEGO® Rad 2600" from Evonik Industries. In addition, silicone-free modified polyethers that do not contain siloxane bonds, such as "BYK-UV3535" manufactured by BIC Chemie Japan Co., Ltd., can also be used.

[0042] There are no particular restrictions on the content of the polyether-modified polymer in the radiation-curable ink or the surface layer formed by such ink. For example, from the viewpoint of the ability to produce a low-gloss appearance, the content can be 0.5 parts by mass or more, 0.8 parts by mass or more, 1.0 part by mass or more, 3.0 parts by mass or more, 5.0 parts by mass or more, 7.0 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, or 20 parts by mass or more per 100 parts by mass of inorganic nanoparticles. There are no particular restrictions on the upper limit of the polyether-modified polymer content. For example, it can be 50 parts by mass or less, 40 parts by mass or less, 35 parts by mass or less, or 30 parts by mass or less.

[0043] The principle by which the use of polyether-modified polymers produces a low-gloss appearance upon irradiation is not entirely clear, but we believe the following: For example, considering the photograph in Figure 4, we believe that irradiation changes the surface energy of inorganic nanoparticles, and that the polyether-modified polymer acts on the particle surface to promote aggregation or densification of the inorganic nanoparticles. Furthermore, we believe that the movement of aggregated or densified inorganic nanoparticles toward the surface is due to the fact that the curing rate of radiation-curable oligomers or monomers near the surface of the surface layer is slower than the curing rate inside the surface layer, due to the influence of oxygen in the atmospheric environment. In other words, we believe that aggregates of inorganic nanoparticles formed from the inside of the surface layer near the substrate side are immediately held in place by the cured binder resin component immediately after irradiation. On the other hand, we believe that aggregates near the surface of the surface layer can move toward the surface even after irradiation because the curing rate of radiation-curable oligomers, etc. is slow. As a result, we believe that these migrated aggregates roughen the surface layer on a micrometer order, and the inorganic nanoparticles constituting the aggregates also form nanometer-order fine irregularities on the surface layer, thus enabling the development of an excellent low-gloss appearance as shown in Figure 5(b).

[0044] In one embodiment, the surface layer of the present disclosure after irradiation with radiation can be substantially covered by the aggregation or density of inorganic nanoparticles, as shown in Figure 4(b), while within the surface layer, there can be a distribution of areas where the aggregates of inorganic nanoparticles are present (which may be called "island areas") and areas where they are not present (which may be called "sea areas") (which may be called a "sea-island structure"). For example, when a surface layer is prepared using an ink that already contains aggregates of inorganic nanoparticles, the aggregates are generally distributed substantially uniformly within the surface layer, so such a surface layer does not exhibit the structure shown in Figure 4(b), that is, a structure in which the density of aggregates is less in the areas below the surface of the surface layer, for example, in the middle section, than near the surface.

[0045] Herein, in this disclosure, "aggregate" refers to an aggregate or densely packed body of primary inorganic nanoparticles, for example, consisting of 5 or more, 7 or more, or 10 or more particles, and "near the surface of the surface layer" refers to the region from the top of the surface of the surface layer to the bottom of the portion where inorganic nanoparticles are aggregated or densely packed in the thickness direction. Furthermore, the density of aggregates can be determined by measuring the thickness-direction cross-section of the surface layer using a scanning electron microscope (SEM). For example, differences in the density of aggregates can be determined by observing the presence or absence of areas formed near the surface of the surface layer where aggregates are densely packed and arranged substantially continuously in the planar and thickness directions of the surface layer.

[0046] The radiation-curable inks of this disclosure comprise at least one selected from radiation-curable polymerizable oligomers and radiation-curable polymerizable monomers.

[0047] In one embodiment, the radiation-curable ink is advantageous as a radical polymerization type (meth)acrylic ink employing a (meth)acrylic radiation-curable polymerizable oligomer and radiation-curable polymerizable monomer, from the viewpoint of compatibility with the compound of Formula 1 described later and curing reactivity. The surface layer formed using the (meth)acrylic ink has excellent strength and weather resistance, and is advantageous, for example, when the laminate is used as an interior material for decorative films.

[0048] In one embodiment, the radiation-curable ink includes a difunctional urethane (meth)acrylate oligomer, which is a radiation-curable polymerizable oligomer, and optionally a radiation-curable monofunctional monomer that can also function as a diluent. For example, in inkjet printing, due to the configuration of the equipment, it is difficult to purge with nitrogen, and generally, the ink is radiation-cured in an air atmosphere. Compared to polyfunctional monomers with three or more functions, difunctional or monofunctional monomers or oligomers are generally susceptible to oxygen inhibition and tend to be difficult to cure in an air atmosphere. However, inks containing difunctional urethane (meth)acrylate oligomers are easily cured even in an air atmosphere, and the cured binder resin component has excellent elongation properties, etc., making it advantageous, for example, when the laminate is used as an interior material for decorative films.

[0049] The bifunctional urethane (meth)acrylate oligomer is a urethane oligomer, which is a reaction product of a diol and a diisocyanate, with (meth)acryloyl groups introduced at both ends. The (meth)acryloyl groups react with other bifunctional urethane (meth)acrylate oligomers and the (meth)acryloyl groups or monofunctional monomers of the compound of formula 1 to form a cured product. The bifunctional urethane (meth)acrylate oligomer can impart flexibility, impact resistance at low temperatures of approximately 0-10°C (sometimes simply referred to as "low-temperature impact resistance"), and chemical resistance to the cured product of radiation-curable inks. The bifunctional urethane (meth)acrylate oligomer may be one type or a combination of two or more types. The diol and diisocyanate constituting the urethane oligomer may each be one type or a combination of two or more types.

[0050] Examples of diols include polyester polyols, polyether polyols, polycarbonate polyols, and polycaprolactone polyols.

[0051] The diol may include low molecular weight diols. Examples of low molecular weight diols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, 1,2-cyclopentanediol, and tricyclo[5.2.1.0 2,6 Decandimethanol is one example.

[0052] Examples of diisocyanates include aliphatic isocyanates and aromatic isocyanates. Examples of aliphatic isocyanates include tetramethylene diisocyanate, hexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, decamethylene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, and 4,4'-methylenebis(cyclohexyl isocyanate). Examples of aromatic isocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, methylenediphenyl 4,4'-diisocyanate, 1,3-phenylenediisocyanate, 1,4-phenylenediisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, diphenylmethane-2,2'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 1,5-naphthalenediisocyanate, and 2-methyl-1,5-naphthalenediisocyanate.

[0053] By using aliphatic compounds for both the diol and the diisocyanate, the weather resistance of the cured product of the radiation-curable ink and the surface layer containing the cured product can be improved.

[0054] The introduction of (meth)acryloyl groups can be achieved by reacting a hydroxyl group-containing (meth)acrylate with the isocyanate terminus of a urethane oligomer. Examples of hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, dipropylene glycol monoacrylate, and dipropylene glycol monomethacrylate. The hydroxyl group-containing (meth)acrylates can be used alone or in combination of two or more. In this embodiment, it is desirable to use an excess of diisocyanate relative to the diol during the synthesis of the urethane oligomer, i.e., to make the molar ratio of NCO group / OH group greater than 1.

[0055] The introduction of (meth)acryloyl groups can also be carried out by reacting an isocyanato group-containing (meth)acrylate with the hydroxyl group terminus of the urethane oligomer. Examples of isocyanato group-containing (meth)acrylates include 2-isocyanatoethyl acrylate and 2-isocyanatoethyl methacrylate. In this embodiment, it is desirable to use an excess of diol relative to diisocyanate during the synthesis of the urethane oligomer, i.e., to keep the molar ratio of NCO group / OH group to less than 1.

[0056] Examples of bifunctional urethane (meth)acrylate oligomers include polyester urethane di(meth)acrylate oligomers, polycarbonate urethane di(meth)acrylate oligomers, and polyether urethane di(meth)acrylate oligomers.

[0057] From the viewpoint of curability in an air atmosphere and elongation characteristics, a bifunctional aliphatic urethane acrylate oligomer is advantageous. A bifunctional aliphatic urethane acrylate oligomer can provide a cured product with excellent weather resistance and a surface layer containing such a cured product.

[0058] The number-average molecular weight Mn of the bifunctional urethane (meth)acrylate oligomer can be 500 or more, 1,000 or more, or 1,200 or more, and can be 5,000 or less, 4,000 or less, or 3,000 or less. The weight-average molecular weight Mw of the bifunctional urethane (meth)acrylate oligomer can be 500 or more, 1,000 or more, or 1,200 or more, and can be 5,000 or less, 4,000 or less, or 3,000 or less. The number-average molecular weight Mn and weight-average molecular weight Mw are standard polystyrene equivalent values ​​obtained by gel permeation chromatography.

[0059] Radiation-curable inks preferably contain 20 parts by mass or more, 25 parts by mass or more, or 30 parts by mass or more of a bifunctional urethane (meth)acrylate oligomer, based on 100 parts by mass of the radiation-curable component. By setting the content of the bifunctional urethane (meth)acrylate oligomer to 20 parts by mass or more, based on 100 parts by mass of the radiation-curable component, the flexibility, low-temperature impact resistance, and chemical resistance of the cured product of the radiation-curable ink can be further improved. Radiation-curable inks preferably contain 50 parts by mass or less, 45 parts by mass or less, or 40 parts by mass or less of a bifunctional urethane (meth)acrylate oligomer, based on 100 parts by mass of the radiation-curable component. By setting the content of the bifunctional urethane (meth)acrylate oligomer to 50 parts by mass or less, based on 100 parts by mass of the radiation-curable component, good inkjet ejection or coating properties can be obtained. Herein, in this disclosure, "radiation-curable component" includes other radiation-curable polymerizable monomers and oligomers such as bifunctional urethane (meth)acrylate oligomers, monofunctional monomers having a dioxane moiety or dioxolane moiety as described later, and the compound of Formula 1 as described later.

[0060] In some embodiments, the radiation-curable ink may contain other radiation-curable polymerizable oligomers or monomers, for example, monofunctional monomers having a dioxane moiety or a dioxolane moiety. Such other radiation-curable polymerizable oligomers and monomers can be used alone or in combination of two or more.

[0061] A monofunctional monomer having a dioxane moiety or a dioxolane moiety is a compound having at least one of a dioxane moiety and a dioxolane moiety in its molecule, and having only one reactive functional group. When used in combination with a bifunctional urethane (meth)acrylate oligomer, a monofunctional monomer having a dioxane moiety or a dioxolane moiety can improve the low-temperature impact resistance of the cured product and the surface layer containing the cured product. Examples of reactive functional groups include a (meth)acryloyl group, a (meth)acrylamide group, and a vinyl group. Due to its high reactivity with the bifunctional urethane (meth)acrylate oligomer, it is advantageous for the monofunctional monomer having a dioxane moiety or a dioxolane moiety to have a (meth)acryloyl group, particularly an acryloyl group. The monofunctional monomer having a dioxane moiety or a dioxolane moiety may be one type or a combination of two or more types.

[0062] Monofunctional monomers having a dioxane moiety or dioxolane moiety include, for example, (5-ethyl-1,3-dioxan-5-yl)methyl (meth)acrylate (also called cyclic trimethylolpropane formal acrylate), (2-methyl-5-ethyl-1,3-dioxan-5-yl)methyl (meth)acrylate, (2,2-dimethyl-5-ethyl-1,3-dioxan-5-yl)methyl (meth)acrylate, (2-methyl-2,5-diethyl-1,3-dioxan-5-yl)methyl (meth)acrylate, (2,2,5-triethyl-1,3-dioxan-5-yl)methyl (meth)acrylate, (2,5-diethyl-1,3-dioxan-5-yl)methyl (meth)acrylate, and polyethylene glycol (meth)acrylate having a 1,3-dioxane ring, etc. Functional monomers, and (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-cyclohexyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-2-isobutyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl Examples of monofunctional monomers having a dioxolane moiety include (2-2-acetonyl-1,3-dioxolan-4-yl)methyl(meth)acrylate, (2-oxo-1,3-dioxolan-4-yl)methyl(meth)acrylate, 2-(2-oxo-1,3-dioxolan-4-yl)ethyl(meth)acrylate, and 3-(2-oxo-1,3-dioxolan-4-yl)propyl(meth)acrylate.

[0063] The monofunctional monomer having a dioxane or dioxolane moiety is preferably (5-ethyl-1,3-dioxan-5-yl)methyl (meth)acrylate or (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, and more preferably (5-ethyl-1,3-dioxan-5-yl)methyl acrylate or (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate due to its high reactivity with the bifunctional urethane (meth)acrylate oligomer, and particularly preferably (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate because it gives a cured product with excellent low-temperature impact resistance.

[0064] Radiation-curable inks preferably contain 10 parts by mass or more, 20 parts by mass or more, or 30 parts by mass or more, and preferably 80 parts by mass or less, 70 parts by mass or less, or 50 parts by mass or less, of monofunctional monomers having a dioxane or dioxolane moiety, based on 100 parts by mass of the radiation-curable component. Good low-temperature impact resistance can be obtained by setting the content of monofunctional monomers having a dioxane or dioxolane moiety to 10 parts by mass or more, based on 100 parts by mass of the radiation-curable component. Good weather resistance can be obtained by setting the content of monofunctional monomers having a dioxane or dioxolane moiety to 80 parts by mass or less, based on 100 parts by mass of the radiation-curable component.

[0065] In some embodiments, the radiation-curable ink may also contain other radiation-curable polymerizable monomers. Examples of other radiation-curable polymerizable monomers include linear alkyl(meth)acrylates such as methyl(meth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, isoamyl(meth)acrylate, 2-methylbutyl(meth)acrylate, n-hexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, isononyl(meth)acrylate, decyl(meth)acrylate, and dodecyl(meth)acrylate; alicyclic(meth)acrylates such as cyclohexyl(meth)acrylate, trimethylcyclohexyl(meth)acrylate, and isobornyl(meth)acrylate; and phenoxyethyl(meth)acrylate. Examples include phenoxyalkyl (meth)acrylates such as methoxypropyl (meth)acrylate, 2-methoxybutyl (meth)acrylate, and 2-(2-ethoxyethoxy)ethyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as methoxypropyl (meth)acrylate, 2-methoxybutyl (meth)acrylate, and 2-(2-ethoxyethoxy)ethyl (meth)acrylate; cyclic ether-containing (meth)acrylates such as glycidyl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate; hydroxyl-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; nitrogen-containing (meth)acryloyl compounds such as (meth)acrylamide and N,N-diethyl (meth)acrylamide; and monofunctional monomers such as (meth)acrylic acid. Other radiation-curable polymerizable monomers include vinyl compounds such as vinyl acetate, vinyl propionate, styrene, and vinyltoluene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; and monofunctional monomers such as unsaturated carboxylic acids such as crotonic acid, itaconic acid, fumaric acid, citraconic acid, and maleic acid. Among these, n-octyl (meth)acrylate and trimethylcyclohexyl (meth)acrylate are preferred from the viewpoint of developing a low-gloss appearance after radiation irradiation, reducing ink viscosity, and improving storage stability, and it is even more preferable to use them in combination.

[0066] Other radiation-curable polymerizable monomers may be polyfunctional monomers. Polyfunctional monomers can function as crosslinking agents to enhance the strength and durability of the cured product. Crosslinking with polyfunctional monomers can also improve the adhesion between the surface layer containing the cured product and the substrate or other layers on the surface layer. From the viewpoint of elongation properties and impact resistance, the content of polyfunctional monomers is preferably 5 parts by mass or less, or 3 parts by mass or less, based on 100 parts by mass of the radiation-curable component.

[0067] Examples of polyfunctional monomers that can be used include difunctional (meth)acrylates such as 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate; trifunctional (meth)acrylates such as glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate; and (meth)acrylates having four or more functional groups such as ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and pentaerythritol tetra(meth)acrylate.

[0068] For example, other radiation-curable polymerizable monomers are advantageous to have a (meth)acryloyl group, particularly an acryloyl group, because they exhibit high reactivity with bifunctional urethane (meth)acrylate oligomers and monofunctional monomers having any dioxane or dioxolane moieties, and form cured products with excellent adhesion to other materials such as substrate layers and decorative layers.

[0069] In some embodiments, the radiation-curable ink may not contain other radiation-curable polymerizable monomers, including the monofunctional monomers and polyfunctional monomers described above, or it may contain such radiation-curable polymerizable monomers in amounts of more than 0 parts by mass, 10 parts by mass or more, or 20 parts by mass or more, and 70 parts by mass or less, 60 parts by mass or less, or 50 parts by mass or less, based on 100 parts by mass of the radiation-curable component.

[0070] Other radiation-curable polymerizable oligomers besides bifunctional urethane (meth)acrylate oligomers can be used, such as polyester (meth)acrylate and epoxy (meth)acrylate. These radiation-curable polymerizable oligomers may be monofunctional or polyfunctional.

[0071] In some embodiments, the radiation-curable ink may not contain other radiation-curable polymerizable oligomers, or it may contain more than 0 parts by mass, 5 parts by mass or more, or 10 parts by mass or more, and 50 parts by mass or less, 40 parts by mass or less, or 30 parts by mass or less, based on 100 parts by mass of the radiation-curable component.

[0072] In some embodiments, the total content of other radiation-curable polyfunctional monomers and radiation-curable polyfunctional oligomers in the radiation-curable ink can be 30 parts by mass or less, 20 parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, 3 parts by mass or less, or 1 part by mass or less, based on 100 parts by mass of the radiation-curable component, or these polyfunctional monomers and polyfunctional oligomers may not be incorporated into the ink at all. By not using polyfunctional monomers and polyfunctional oligomers, or by setting the total content to 10 parts by mass or less, the migration of inorganic nanoparticles to the surface of aggregates can be improved, and the flexibility or elongation properties of the cured product can be enhanced.

[0073] As a photopolymerization initiator, for example, known compounds that induce radical polymerization reactions can be used. As photopolymerization initiators, both intramolecular cleavage type and hydrogen abstraction type can be used, for example, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethylbenzoyldiphenylphosphine oxide, benzoyldiethoxyphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, benzoin alkyl ether (for example, benzoin methyl ether, Examples include benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, n-butylbenzoin ether, etc.), methylbenzoyl formate, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, p-tert-butyltrichloroacetophenone, p-tert-butyldichloroacetophenone, benzyl, acetophenone, thioxanthone compounds (2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone), camphorquinone, 3-ketocoumarin, anthraquinone compounds (e.g., anthraquinone, 2-ethylanthraquinone, α-chloroanthraquinone, 2-tert-butylanthraquinone, etc.), acenaphthene, 4,4'-dimethoxybenzyl, and 4,4'-dichlorobenzyl. Photopolymerization initiators can be used alone or in combination of two or more types.

[0074] In some embodiments, the radiation-curable ink can contain a photoinitiator in an amount of 1 part by mass or more, or 2 parts by mass or more, based on 100 parts by mass of the radiation-curable component, and can contain 20 parts by mass or less, or 15 parts by mass or less.

[0075] In some embodiments, the radiation-curable ink of the present disclosure can contain a compound of Formula 1 shown below.

[0076] For example, in the inkjet printing method, generally, inkjet ink is ejected from a discharge nozzle and applied to a substrate. Therefore, the required performance of such ink includes, for example, having a low viscosity and being an ink that is less likely to clog with few foreign substances. When inorganic nanoparticles are simply contained in the ink, generally, in a direction opposite to such required performance, that is, it tends to have a high viscosity, and a situation where the discharge nozzle and the like are likely to clog due to aggregation of the nanoparticles occurs. Under such circumstances, the present inventor has found that by using the compound of Formula 1 described later together with inorganic nanoparticles, while reducing or suppressing the aggregation and coalescence of the inorganic nanoparticles in the ink, the viscosity of the ink can be reduced to such an extent that it can be printed or coated by an inkjet printing method, a gravure coating method, a bar coating method, or the like.

[0077] The compound of Formula 1 can be represented by the following chemical formula: R 1 -R 2 -Si(OR 3 )3…Formula 1

[0078] In the formula, R 1 is an acryloyl group or a methacryloyl group, R 2 is an alkylene group having 5 to 12 carbon atoms, and R 3 is an alkyl group having 1 to 4 carbon atoms. From the viewpoint of viscosity reduction, R 1 is preferably a methacryloyl group, R 2 is preferably an alkylene group having 6 to 10 carbon atoms, more preferably an alkylene group having 8 to 10 carbon atoms, and R 3The alkyl group is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably an alkyl group having 1 to 2 carbon atoms. Among these, 8-(meth)acryloxyoctyltrimethoxysilane is particularly preferred as the compound of formula 1. The compounds represented by formula 1 can be used alone or in combination of two or more.

[0079] The reason why the compound in Equation 1 can reduce the viscosity of the ink is not clear, but R 2 We believe this is due to the longer chain length of R compared to typical silane coupling agents. In other words, the longer chain length of the compound of formula 1 bonded to inorganic nanoparticles... 2 We believe that by making it more difficult for particles to come into close proximity in certain areas, the fluidity of the particles improves, which can reduce the viscosity of the ink.

[0080] There are no particular restrictions on the amount of compound in Formula 1 that can be incorporated. Although this compound is a type of silane coupling agent, unlike general silane coupling agents, it is not used to improve adhesion to substrates, etc., but rather to reduce viscosity. Therefore, the amount used can be lower than that used for general silane coupling agents. For example, from the viewpoint of reducing viscosity, the amount of compound in Formula 1 can be 0.030 mmol or more, 0.040 mmol or more, or 0.050 mmol or more per gram of inorganic nanoparticles, and can be 0.090 mmol or less, 0.080 mmol or less, or 0.070 mmol or less.

[0081] In some embodiments, the radiation-curable inks of the present disclosure may further include a non-functionalized silane coupling agent. Such a non-functionalized silane coupling agent can also contribute to lowering the viscosity of the ink.

[0082] The compound in formula 1 is R 1Because it has an acryloyl group or a methacryloyl group, it can form a crosslinked structure with, for example, radiation-curable polymerizable oligomers and / or radiation-curable polymerizable monomers in the ink when exposed to radiation. This can improve the hardness or abrasion resistance of the surface layer, but may reduce the elongation properties required in, for example, decorative films. When it is desirable to reduce the viscosity of the ink while simultaneously reducing the formation of crosslinked structures and imparting elongation properties, it is advantageous to use the compound of Formula 1 in combination with a non-functional silane coupling agent.

[0083] There are no particular restrictions on such non-functionalized silane coupling agents, but examples include n-propyltrimethoxysilane, isopropyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, n-pentyltrimethoxysilane, isopentyltrimethoxysilane, n-hexyltrimethoxysilane, isohexyltrimethoxysilane, n-heptyltrimethoxysilane, isoheptyltrimethoxysilane, n-octyltrimethoxysilane, and isooctyltrimethoxysilane. Among these, n-propyltrimethoxysilane, n-hexyltrimethoxysilane, and isooctyltrimethoxysilane are preferred, and isooctyltrimethoxysilane is more preferred. These can be used alone or in combination of two or more.

[0084] There are no particular restrictions on the amount of non-functionalized silane coupling agent used, but, similar to the compound in Formula 1, from the viewpoint of reducing viscosity, it can be 0.030 mmol or more, 0.040 mmol or more, or 0.050 mmol or more per gram of inorganic nanoparticles, and can be 0.090 mmol or less, 0.080 mmol or less, or 0.070 mmol or less.

[0085] When reducing the viscosity of ink, it is common to dilute it by adding organic or aqueous solvents. However, the use of organic solvents, for example, worsens the working environment, and both solvents require a drying process after printing or coating, which tends to reduce productivity. When an ink containing a large amount of solvent is printed on a resin substrate, for example, by an inkjet printing method, the deposited ink tends to wet and spread on the substrate surface, which may prevent the desired printing performance from being fully achieved. On the other hand, with an ink that contains little or no solvent, the deposited ink does not wet and spread easily on the substrate surface, allowing for good printing performance. For example, it is possible to impart three-dimensional irregularities to the substrate surface that match the design of a texture or decorative film with a realistic feel. The radiation-curable ink of this disclosure can achieve low viscosity by using the specific compound of Formula 1 described above, and optionally a non-functional silane coupling agent. Therefore, the solvent content can be 5% by mass or less, 3% by mass or less, or 1% by mass or less, relative to the total amount of ink, or it may not contain any solvent at all.

[0086] For example, in the case of conventional inks that contain a high concentration of solvent and microbeads, when such ink is applied to a substrate surface to form a surface layer, and then the solvent in this surface layer is dried, the volume of the surface layer decreases, causing some of the microbeads to precipitate on the surface layer, thus easily producing a low-gloss appearance. However, when the solvent content in the ink is 5% by mass or less, this volume reduction effect of the surface layer does not occur, making it difficult to precipitate some of the microbeads on the surface layer, and thus difficult to produce a low-gloss appearance. In this case, for example, it is conceivable to use beads that are larger than the thickness of the surface layer, but inks containing beads of such size are likely to clog inkjet nozzles and the like. On the other hand, the radiation-curable ink of this disclosure can produce a low-gloss appearance even if the solvent content in the ink is 5% by mass or less, by irradiating the surface layer applied to the substrate with radiation.

[0087] Radiation-curing inks may contain additives as optional components, such as light stabilizers, polymerization inhibitors, UV absorbers, defoamers, antifouling agents, surface modifiers, pigments, and dyes.

[0088] The radiation-curable inks of this disclosure can achieve a low-gloss appearance without using beads, such as micrometer-order resin beads or glass beads, which were used in conventional inks, but this does not preclude the use of such beads. When such beads are used, the amount used can be, for example, 10% by mass or less, 7% by mass or less, 5% by mass or less, 3% by mass or less, or 1% by mass or less, based on the total weight (solids) of the ink or the total weight (dry coating amount) of the surface layer.

[0089] A surface layer prepared by irradiating with radiation using the radiation-curable ink of this disclosure can exhibit an excellent low-gloss appearance.

[0090] The low-gloss appearance of the surface layer can be evaluated, for example, by the 60-degree surface gloss when the measurement angle is set to 60 degrees. The 60-degree surface gloss can be 50.0 GU or less, 40.0 GU or less, 30.0 GU or less, 20.0 GU or less, or 15.0 GU or less. There is no particular limit to the lower limit of the 60-degree surface gloss, but for example, it can be 1.0 GU or more, 3.0 GU or more, or 5.0 GU or more. The surface gloss in this disclosure is measured using a portable gloss meter BYK Gardner Micro-Tri-Gloss (BYK Chemie Japan Co., Ltd.) in accordance with JIS Z8741. This surface gloss is a value measured on the surface layer in a state where no mechanical means such as embossing has been applied.

[0091] In some embodiments, the surface gloss of the surface layer of the laminate can be evaluated by the 20-degree surface gloss when the measurement angle is set to 20 degrees. The 20-degree surface gloss can be 20.0 GU or less, 15.0 GU or less, or 10.0 GU or less. There is no particular limit to the lower limit of the 20-degree surface gloss, but for example, it can be 0.1 GU or more, 0.3 GU or more, or 0.5 GU or more.

[0092] In some embodiments, the surface gloss of the surface layer of the laminate can be evaluated by the 80-degree surface gloss when the measurement angle is set to 80 degrees. The 80-degree surface gloss can be 90.0 GU or less, 85.0 GU or less, or 80.0 GU or less. There is no particular limit to the lower limit of the 80-degree surface gloss, but for example, it can be 10.0 GU or more, 13.0 GU or more, or 15.0 GU or more.

[0093] In some embodiments, the initial viscosity of the radiation-curable ink can be, for example, 35.0 mPa·s or less, 30.0 mPa·s or less, 25.0 mPa·s or less, 20.0 mPa·s or less, 18.0 mPa·s or less, 17.0 mPa·s or less, 16.0 mPa·s or less, 15.0 mPa·s or less, 14.0 mPa·s or less, 13.0 mPa·s or less, or 12.0 mPa·s or less at 55°C, from the viewpoint of ejection from inkjet nozzles, coating properties, etc. There are no particular restrictions on the lower limit of the initial viscosity, but from the viewpoint of printability, etc., it can be, for example, 1.0 mPa·s or more, 3.0 mPa·s or more, or 5.0 mPa·s or more. Radiation-curable inks having such a viscosity range can be prepared, for example, by using the compound of Formula 1 and / or a non-functional silane coupling agent described above.

[0094] In some embodiments, the radiation-curable inks of the present disclosure exhibit excellent storage stability at high temperatures. Such storage stability can be indirectly evaluated by the viscosity of the ink at 55°C after one week of storage at 60°C. A radiation-curable ink of one embodiment of the present disclosure can achieve a viscosity of 30.0 mPa·s or less, 25.0 mPa·s or less, 20.0 mPa·s or less, 18.0 mPa·s or less, 17.0 mPa·s or less, 16.0 mPa·s or less, 15.0 mPa·s or less, 14.0 mPa·s or less, 13.0 mPa·s or less, or 12.0 mPa·s or less at 55°C after one week of storage at 60°C. There is no particular limit to the lower limit of such viscosity, but for example, it could be 1.0 mPa·s or more, 3.0 mPa·s or more, or 5.0 mPa·s or more.

[0095] The surface layer can be formed by applying radiation-curable ink directly onto a substrate or via another layer using various printing or coating methods, and then curing it by irradiation with radiation such as ultraviolet light or electron beams. When radiation irradiation is performed, it is generally carried out under a nitrogen atmosphere to prevent a decrease in curing speed or curing failure due to oxygen. However, as mentioned above, if the curing speed of radiation-curable oligomers, etc., near the surface of the surface layer differs from the curing speed inside, aggregates of inorganic nanoparticles are likely to migrate towards the surface. Therefore, it is advantageous to perform radiation irradiation under an air atmosphere containing oxygen. For example, in inkjet printing, due to the configuration of the equipment, it is difficult to purge with nitrogen, and generally the ink is radiation-cured under an air atmosphere. Therefore, the radiation-curable ink of this disclosure can be suitably used in inkjet printing.

[0096] Generally, high-viscosity inks are more effective at reducing or suppressing the aggregation and coalescence of inorganic particles within the ink, while low-viscosity inks are less effective at reducing or suppressing this aggregation. The radiation-curable ink of this disclosure is low-viscosity yet can reduce or suppress the aggregation and coalescence of inorganic nanoparticles within the ink, and can therefore be used for various printing or coating methods that require the use of low-viscosity inks, such as inkjet printing, gravure coating, bar coating, knife coating, capillary coating, spray coating, and stereolithography (sometimes referred to as "additive manufacturing"). In particular, the radiation-curable ink of this disclosure is particularly suitable for inkjet printing, which is susceptible to the effects of aggregates. Surface layers prepared in this manner can be distinguished, for example, from inkjet printing surface layers, gravure coating surface layers, and so on.

[0097] Radiation-curable inks may be printed or coated on at least a portion of a substrate, or on the entire substrate. The surface layer before irradiation may have a substantially smooth surface, or it may have an uneven surface such as an embossed pattern. When such a surface layer is irradiated with radiation, fine irregularities on the nanometer order and irregularities on the micrometer order, based on inorganic nanoparticles, can be formed on the surface of the surface layer, which are different from the uneven surface such as an embossed pattern.

[0098] There are no particular restrictions on the thickness of the surface layer, and it can be adjusted as appropriate depending on the development of a low-gloss appearance after irradiation, design, etc. For example, the thickness of the surface layer can be at least 7 micrometers, 20 micrometers, or 30 micrometers in some parts. By having a portion of the surface layer with a thickness of 7 micrometers or more, for example, when the laminate is used as a decorative film, it is possible to impart a texture with a realistic feel or three-dimensional irregularities to the surface of the decorative film that match the design of the decorative film.

[0099] In some embodiments, the maximum thickness of the surface layer can be, for example, 500 micrometers or less, 300 micrometers or less, or 100 micrometers or less. By setting the maximum thickness of the surface layer to 500 micrometers or less, the flexibility of the surface layer, such as its elongation and bending properties, can be optimized.

[0100] The thickness of the surface layer can be adjusted as appropriate, for example, by repeatedly printing or coating a radiation-curable ink locally or over the entire surface multiple times. Here, the thickness of each layer in the laminate of this disclosure can be defined as the average value of the thickness of at least five arbitrary locations on the target layer of the laminate, for example, the surface layer, by measuring the cross-sectional thickness of the laminate using a scanning electron microscope (SEM).

[0101] The surface layer may be transparent, translucent, or opaque in whole or in part in the visible range in order to provide the desired appearance.

[0102] The substrate constituting the laminate of this disclosure can be used, for example, as a support for the surface layer. The substrate may be subjected to surface treatment such as corona treatment or plasma treatment on its surface.

[0103] There are no particular restrictions on the material of the base material, and various resin materials can be used, such as polyvinyl chloride resin, polyurethane resin, polyolefin resins such as polyethylene (PE) and polypropylene (PP), polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polycarbonate resin, polyimide resin, polyamide resin, (meth)acrylic resins such as polymethyl methacrylate (PMMA), fluororesin, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, acrylonitrile-butadiene rubber (NBR), and copolymers such as acrylonitrile-butadiene-styrene copolymer (ABS). These can be used individually or in combination of two or more. Inorganic base materials such as glass and metallic base materials such as aluminum can also be used as the base material.

[0104] There are no particular restrictions on the shape or configuration of the substrate; for example, it may be in the shape of a film, a plate, a curved surface, an irregular shape, or a three-dimensional shape, and it may be a single-layer configuration, a laminated configuration, or a composite configuration in which multiple substrates of different shapes are combined.

[0105] The substrate may be colored or colorless. The substrate may be opaque, translucent, or transparent. The substrate may have a substantially smooth surface or a structured surface that can be formed by surface treatment such as embossing.

[0106] The thickness of the substrate can be, for example, 50 micrometers or more, 80 micrometers or more, or 100 micrometers or more. There is no particular upper limit on the thickness, but from the viewpoint of conformability, manufacturing cost, etc., it can be, for example, 500 micrometers or less, 300 micrometers or less, or 200 micrometers or less.

[0107] In some embodiments, the laminate of the present disclosure may further comprise at least one selected from the group consisting of, for example, a decorative layer, a glossy layer, a bonding layer, an adhesive layer, and a release liner, depending on the intended use. In the present disclosure, for example, a laminate comprising a colored substrate and / or a surface layer, or a laminate comprising a decorative layer and / or a glossy layer, may be referred to as a decorative film.

[0108] The laminate of this disclosure may, for example, have a decorative layer placed on or below the substrate. The decorative layer may, for example, be applied to the entire surface or to a portion of the substrate.

[0109] Decorative layers include, but are not limited to, the following: color layers exhibiting paint colors, such as light colors like white and yellow, and dark colors like red, brown, green, blue, gray, and black; pattern layers that impart patterns such as wood grain, stone patterns, geometric patterns, and leather patterns, as well as logos and illustrations to the article; relief layers with raised or recessed shapes on the surface; and combinations thereof.

[0110] The materials used for the color layer include, but are not limited to, inorganic pigments such as carbon black, lead yellow, yellow iron oxide, red iron oxide, etc.; phthalocyanine pigments such as phthalocyanine blue, phthalocyanine green, etc.; organic pigments such as azolake pigments, indigo pigments, perinone pigments, perylene pigments, quinophthalone pigments, dioxazine pigments, quinacridone pigments such as quinacridone red, etc., in which these pigments are dispersed in a binder resin such as (meth)acrylic resin or polyurethane resin.

[0111] The color layer can be formed using such materials by coating methods such as gravure coating, roll coating, die coating, bar coating, or knife coating, or by printing methods such as inkjet printing.

[0112] The pattern layer is not limited to the following, but for example, patterns such as designs, logos, and illustrations may be directly applied to the substrate using printing methods such as gravure direct printing, gravure offset printing, inkjet printing, laser printing, and screen printing. Alternatively, films, sheets, etc., having designs, logos, and illustrations formed by coatings such as gravure coating, roll coating, die coating, bar coating, and knife coating, as well as by die-cutting and etching, may be used. As for the material of the pattern layer, for example, the same material used for the color layer may be used.

[0113] As the relief layer, a thermoplastic resin film having an uneven surface shape achieved by conventionally known methods, such as embossing, scratching, laser processing, dry etching, or hot pressing, can be used. Alternatively, a thermosetting or radiation-curable resin, such as a curable (meth)acrylic resin, can be applied to a release liner having an uneven surface, cured by heating or radiation, and then the release liner can be removed to form the relief layer.

[0114] The thermoplastic resin, thermosetting resin, and radiation-curable resin used in the relief layer are not particularly limited, but examples include fluororesins, polyester resins such as PET and PEN, (meth)acrylic resins, polyolefin resins such as polyethylene and polypropylene, thermoplastic elastomers, polycarbonate resins, polyamide resins, ABS resins, acrylonitrile-styrene resins, polystyrene resins, vinyl chloride resins, and polyurethane resins. The relief layer may also contain at least one of the pigments used in the color layer.

[0115] The thickness of the decorative layer is not particularly limited and can be adjusted as appropriate according to the required decorative properties, opacity, etc., but for example it can be 1 micrometer or more, 3 micrometers or more, or 5 micrometers or more, and can be 50 micrometers or less, 40 micrometers or less, 30 micrometers or less, 20 micrometers or less, or 15 micrometers or less.

[0116] The lustrous layer is not limited to the following, but may be a layer containing a metal selected from aluminum, nickel, gold, silver, copper, platinum, chromium, iron, tin, indium, titanium, lead, zinc, germanium, or an alloy or compound thereof, formed on the entire surface or part of the substrate or decorative layer by vacuum deposition, sputtering, ion plating, plating, etc. The thickness of the lustrous layer can be appropriately selected according to the required decorative properties and brightness.

[0117] A bonding layer (sometimes called a "primer layer") may be used to join the layers constituting the laminate. As the bonding layer, commonly used adhesives such as (meth)acrylic, polyolefin, polyurethane, polyester, and rubber-based adhesives can be used, including solvent-type, emulsion-type, pressure-sensitive, heat-sensitive, thermosetting, or UV-curing types. The bonding layer can be applied by known coating methods.

[0118] The thickness of the bonding layer can be, for example, 0.05 micrometers or more, 0.5 micrometers or more, or 5 micrometers or more, and can be 100 micrometers or less, 50 micrometers or less, 20 micrometers or less, or 10 micrometers or less.

[0119] The laminate may further include an adhesive layer for attaching the laminate to a substrate. The adhesive layer can be made of the same material as the bonding layer. The adhesive layer may be applied to the substrate instead of the laminate.

[0120] The thickness of the adhesive layer is not limited to the following, but can be, for example, 5 micrometers or more, 10 micrometers or more, or 20 micrometers or more, and can be 200 micrometers or less, 100 micrometers or less, or 80 micrometers or less.

[0121] The substrate, decorative layer, bonding layer, and adhesive layer of this disclosure may contain, as an optional component, fillers, reinforcing agents, antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, tackifiers, dispersants, plasticizers, flow enhancers, surfactants, leveling agents, silane coupling agents, catalysts, pigments, dyes, and the like, to the extent that they do not impair the effects and decorative properties of this disclosure.

[0122] Any suitable release liner can be used to protect the adhesive layer. Typical release liners are those prepared from paper (e.g., kraft paper), polymer materials (e.g., polyolefins such as polyethylene or polypropylene, polyesters such as ethylene vinyl acetate, polyurethane, and polyethylene terephthalate), etc. The release liner may be coated with a layer of release agent, such as a silicone-containing material or a fluorocarbon-containing material, as needed.

[0123] The thickness of the release liner can be, for example, 5 micrometers or more, 15 micrometers or more, or 25 micrometers or more, and 300 micrometers or less, 200 micrometers or less, or 150 micrometers or less. The thickness of the release liner can be defined as the average value calculated by measuring the thickness of any part of the release liner at least five times using a high-precision digital micrometer (MDH-25MB, manufactured by Mitutoyo Corporation) after removing the release liner from the adhesive layer.

[0124] The laminates of this disclosure can be prepared as appropriate by using known methods, such as printing methods including inkjet printing, gravure direct printing, gravure offset printing, and screen printing; coating methods including gravure coating, roll coating, die coating, bar coating, knife coating, and extrusion coating; lamination methods; and transfer methods, either individually or in combination.

[0125] There are no particular limitations on the product form of the laminate described herein. For example, it may be a single-sheet product, a laminate made by stacking multiple sheets, or a roll made by winding sheets into a roll.

[0126] In some embodiments, the surface layer of the Disclosure is stretchable, and a laminate comprising this surface layer can exhibit excellent elongation properties. Such elongation properties can be evaluated, for example, by an elongation test at break. The surface layer of the laminate in some embodiments can exhibit an elongation at break of 50% or more, 70% or more, 80% or more, 85% or more, or 90% or more at 20°C. There is no particular upper limit to the elongation at break, but it can be, for example, 200% or less, 180% or less, 160% or less, or 150% or less. Breakage refers to the occurrence of a visually observable change in appearance, such as a crack or a change in gloss, on the surface of the surface layer. Laminates having such elongation properties can be suitably used, for example, as decorative films.

[0127] In the elongation at break test, the laminate is cut into pieces 100 mm long and 25 mm wide to prepare test samples. Using a tensile testing machine (Tensilon universal tester, model number: RTC-1210A, manufactured by A&D Co., Ltd.), the elongation at the point when the surface layer of the test sample breaks is measured with a clamping distance of 50 mm, a tensile speed of 300 mm / min, and at 20°C. The elongation at break is determined using the formula: (length of test sample at break - length of test sample before elongation) / (length of test sample before elongation) × 100 (%).

[0128] The applications of the laminates of this disclosure are not particularly limited. For example, the laminates of this disclosure can be used for decorative purposes, optical purposes, etc. For example, the laminates of this disclosure can be used as interior materials such as interior walls, stairs, windows, doors, floors, ceilings, columns, partitions, etc., or exterior materials such as exterior walls of buildings such as office buildings, apartments, and houses, and can be used as interior or exterior parts for various types of vehicles such as automobiles, trains, aircraft, and ships. In addition, they can be used for electrical appliances such as personal computers, smartphones, mobile phones, refrigerators, and air conditioners, stationery, furniture, desks, various containers such as cans, road signs, and billboards. Furthermore, the laminates of this disclosure can also be used as light diffusing members used in display devices such as liquid crystal displays and organic EL displays, for example, light diffusing films or light diffusing plates to ensure uniformity of backlight brightness, or anti-glare (AG) films to reduce or prevent reflections of light from fluorescent lamps, etc. [Examples]

[0129] The following examples illustrate specific embodiments of the present disclosure, but the present invention is not limited thereto. All parts and percentages are by mass unless otherwise specified.

[0130] Table 1 shows the materials, reagents, etc., used in this example.

[0131] [Table 1]

[0132] <Preparation of surface-modified silica sol> Surface-modified silica sol was prepared by the following method.

[0133] (Zol 1) 0.452 g of KBM5803, 0.832 g of isooctyltrimethoxysilane, and 0.0045 g of 4-hydroxy-TEMPO free radicals were added to a glass bottle containing 30 g of IPA. This mixture was added to a glass bottle containing 150 g of IPA-ST-ZL and stirred at room temperature for 10 minutes. The glass bottle was sealed and left to stand in a 60°C oven for 16 hours. After transferring this mixture to a flask, 113.40 g of Viscoat® 196 was mixed in. Then, the IPA was removed from the mixture using a rotary evaporator while heating to 55°C until the solid content of the mixture was approximately 30% by mass. Subsequently, Viscoat® 196 was added to this mixture to prepare Sol 1, so that the silica nanoparticle concentration was 28.94% by mass.

[0134] (Zol 2) 0.8927 g of KBM5803, 1.6423 g of isooctyltrimethoxysilane, and 0.0089 g of 4-hydroxy-TEMPO free radicals were added to a glass bottle containing 30 g of IPA. This mixture was added to a glass bottle containing 150 g of IPA-ST-L and stirred at room temperature for 10 minutes. The glass bottle was sealed and left to stand in a 60°C oven for 16 hours. After transferring this mixture to a flask, 114.90 g of Viscoat® 196 was mixed in. Then, the IPA was removed from the mixture using a rotary evaporator while heating to 55°C until the solid content of the mixture was approximately 30% by mass. Subsequently, Viscoat® 196 was added to this mixture to prepare Sol 2, so that the concentration of silica nanoparticles was 29.21% by mass.

[0135] (Zol 3) 1.8817 g of KBM5803, 3.4618 g of isooctyltrimethoxysilane, and 0.0188 g of 4-hydroxy-TEMPO free radicals were added to a glass bottle containing 30 g of IPA. This mixture was added to a glass bottle containing 150 g of IPA-ST and stirred at room temperature for 10 minutes. The glass bottle was sealed and left to stand in a 60°C oven for 16 hours. After transferring this mixture to a flask, 123.65 g of Viscoat® 196 was mixed in. Next, the IPA was removed from the mixture using a rotary evaporator while heating to 55°C until the solid content of the mixture was approximately 30% by mass. Then, Viscoat® 196 was added to this mixture to prepare sol 3, so that the concentration of silica nanoparticles was 28.80% by mass.

[0136] <Preparation of radiation-curable ink> Radiation-curable inks were prepared using the materials listed in Table 2 by the following method. All amounts in Table 2 are in parts by mass.

[0137] (UV ink-C1) 2,500 g of CN991NS, 6,500 g of Viscoat® 196, and 1,000 g of NOAA were mixed in a glass bottle. To this mixture, 1,000 g of Omnirad® 184 was added as a photopolymerization initiator, and 0.010 g of TEGO® Rad 2250 was added as a polyether-modified polymer to prepare UV ink-C1.

[0138] (UV ink-C2) 2.073 g of Sol 1, 2.350 g of CN991NS, 4.656 g of Viscoat® 196, and 0.940 g of NOAA were mixed in a glass bottle. 1.000 g of Omnirad® 184 was added to this mixture as a photopolymerization initiator to prepare UV ink-C2.

[0139] (UV ink-C3) 2,500 g of CN991NS, 5,500 g of Viscoat® 196, and 2,000 g of MEDOL-10 were mixed in a glass bottle. To this mixture, 1,000 g of Omnirad® 184 was added as a photopolymerization initiator, and 0.100 g of TEGO® Flow 425 and 0.100 g of Genorad® 22 were added as polyether-modified polymers to prepare UV ink-C3.

[0140] (UV ink - E1~E13) UV inks E1 to E13 were prepared in the same manner as UV ink C2, except that the composition ratios were changed as shown in Table 2. [Table 2]

[0141] <Reference example> We used CosmoShine® A4100, a PET substrate film with a thickness of 50 micrometers.

[0142] <Comparative Example 1> Using a #20 Meyer rod, UV-C1 radiation-curable ink was applied to the primer-treated side of a 50-micrometer thick substrate film, CosmoShine® A4100, forming a coating layer approximately 10 micrometers thick. The substrate film with the coated layer was then passed twice through an ultraviolet irradiator (Fusion UV System Inc.'s H-bulb (DRS model)) in an air atmosphere to cure the coating layer. The irradiance at this time was 700 mW / cm². 2 , cumulative light intensity 900 mJ / cm 2 Under these conditions, ultraviolet light (UV-A) was irradiated onto the coating layer. In this way, a laminate of Comparative Example 1 having a coating layer with a thickness of approximately 10 micrometers was fabricated.

[0143] <Comparative Example 2, Examples 1-13> Laminates for Comparative Example 2 and Examples 1-13 were prepared in the same manner as for Comparative Example 1, except that the radiation-curable ink was changed from UV-C1 to one of the inks listed in Tables 3-1 to 3-3.

[0144] <Example 14> Using an inkjet printer (inkjet head KM1024iLMHB, 720 x 720 dpi, manufactured by Konica Minolta, Inc.), an inkjet print layer approximately 10 micrometers thick was printed onto a base film, BK646420, using UV-E13 radiation-curing ink while heating it to 55°C. The base film with the inkjet print layer applied was then passed twice through a UV irradiator (H-bulb (DRS model) from Fusion UV System Inc.) in an air atmosphere to cure the inkjet print layer. The irradiance at this time was 700 mW / cm². 2 , cumulative light intensity 900 mJ / cm 2 Under these conditions, ultraviolet light (UV-A) was irradiated onto the inkjet printed layer. In this way, a laminate of Example 14 having an inkjet printed layer with a thickness of approximately 10 micrometers was fabricated.

[0145] <Comparative Example 3> The laminate of Comparative Example 3 was prepared in the same manner as in Example 14, except that the radiation-curable ink was changed from UV-E13 to UV-C3.

[0146] The following evaluations were performed on each sample of Reference Example, Examples 1-14, and Comparative Examples 1-2, and the results are shown in Tables 3-1 to 3-3. Here, "SiO2 particle content" in the tables is based on the total weight (dry coating amount) of the coating layer or inkjet printed layer. Furthermore, scanning electron microscope images of the coating layers in the laminates of Comparative Examples 1 and 2, and Example 1 are shown in Figures 2 to 4, and scanning electron microscope images and optical images of the inkjet printed layers in the laminates of Example 14 and Comparative Example 3 are shown in Figure 5.

[0147] (Initial viscosity) The initial viscosity of radiation-curable ink at 55°C was measured using a Discovery HR-2 (DHR-2) rheometer (TA Instruments) with a 20mm cone-plate type parallel plate (TA Instruments) at a rotation speed of 150 revolutions / minute.

[0148] (Changes in appearance after UV irradiation) The appearance of the coating layer or inkjet printed layer was visually observed before and after UV irradiation to check for any changes in appearance. If the glossy appearance of the coating layer or inkjet printed layer changed to a low-gloss appearance after UV irradiation, it was determined as "yes," and if there was no change to a low-gloss appearance, it was determined as "no."

[0149] (Surface gloss) In accordance with JIS Z8741, the surface gloss of each sample was measured at measurement angles of 20°, 60°, and 80° using a portable gloss meter, BYK Gardner Micro-Tri-Gloss (BYK Chemie Japan Co., Ltd.).

[0150] (Adhesiveness) The adhesion performance between the base film and the coating layer or inkjet printing layer was evaluated using the cross-cut method in accordance with JIS K 5600. A 5x5 grid with a grid spacing of 1 mm and cellophane tape (trademark) CT-24 (manufactured by Nichiban Co., Ltd.) were used. The result was judged as "good" if no peeling or / or chipping occurred in the coating layer or inkjet printing layer, and as "poor" if peeling or / or chipping occurred.

[0151] [Table 3] [Table 4] [Table 5]

[0152] It will be apparent to those skilled in the art that the above embodiments and examples can be modified in various ways without departing from the basic principles of the present invention. Furthermore, it will be apparent to those skilled in the art that various improvements and modifications of the present invention can be implemented without departing from the spirit and scope of the invention. [Explanation of Symbols]

[0153] 100 Laminate before radiation irradiation 101 Base material 102 Surface layer before radiation irradiation 103 Inorganic Nanoparticles 104 Binder resin 105 Surface layer after radiation irradiation 110 Laminate after radiation irradiation

Claims

1. A radiation-curable ink comprising inorganic nanoparticles, a polyether-modified polymer, a compound of the following formula 1, and at least one selected from radiation-curable polymerizable oligomers and radiation-curable polymerizable monomers, After curing, the inorganic nanoparticles form aggregates and exhibit a 60-degree surface gloss of 50.0 GU or less. Radiation-curable ink for surface layers: R １ -R ２ -Si(OR ３ ) ３ … Formula 1 In the formula, R １ is an acryloyl group or a methacryloyl group, R ２ This is an alkylene group with 5 to 12 carbon atoms. R ３ These are alkyl groups having 1 to 4 carbon atoms.

2. The ink according to claim 1, wherein the initial viscosity at 55°C is 35.0 mPa·s or less.

3. The ink according to claim 1 or 2, wherein the compound of formula 1 is 8-(meth)acryloxyoctyltrimethoxysilane.

4. The ink according to any one of claims 1 to 3, further comprising a non-functionalized silane coupling agent.

5. An ink according to any one of claims 1 to 4, comprising a radiation-curable polymerizable oligomer with a bifunctional urethane (meth)acrylate oligomer.

6. The ink according to any one of claims 1 to 5, wherein the amount of the compound of formula 1 and, if present, the non-functionalized silane coupling agent is in the range of 0.030 to 0.090 mmol per gram of inorganic nanoparticles.

7. The ink according to any one of claims 1 to 6, wherein the solvent content is 5% by mass or less.

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