Active energy ray-curable ink composition, printed matter using the ink composition, recording method, method for producing printed matter, and ink set

Abstract

To provide an active energy ray-curable ink composition which enables formation of a coated film that highly achieves both physical properties such as chemical resistance required for a hard type, and physical properties such as stretchability and flexibility required for a soft type, and is excellent in optical heat resistance, and a printed matter, a recording method, a method for manufacturing a printed matter using the ink composition.SOLUTION: An active energy ray-curable ink composition has coated film physical properties satisfying at least one of the following condition 1 and condition 2. Condition 1: (a) a change rate of glossiness after the coated film has been heated is less than 55% and (b) even when an elongation rate is 115% or more, cracks are not generated in the coated film after stretching. Condition 2: (c) apparent change is not generated on the surface of the coated film in 50 mass% or more of ethanol aqueous solution, and (d) cracks are not generated in the coated film even under bending conditions equal to or severer than a mandrel with a diameter of 2 mm at 25°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an actinic ray-curable ink composition, a printed matter using the ink composition, a recording method, a method for producing a printed matter, and an ink set. [Background technology]

[0002]

[0003] Conventionally, the development of actinic ray-curable ink compositions that are cured by ultraviolet rays, electron beams, or other actinic ray has been progressing. Actinic ray-curable ink compositions have a fast drying property, and therefore can prevent ink bleeding even when printed on substrates that do not absorb ink or absorb very little ink, such as plastic, glass, and coated paper. Actinic ray-curable ink compositions are composed of a polymerizable monomer, a polymerization initiator, other additives, and the like.

[0003] In recent years, there has been a demand for printing on flexible substrates such as polyethylene terephthalate resin, vinyl chloride resin, and elastomers, in addition to substrates made of plastic, glass, coated paper, etc. In such cases, since molding involves bending, stretching, and other processes, the ink after curing must have physical properties such as flexibility. As an example of such an actinic energy ray-curable ink composition, one containing a monofunctional monomer having a cyclic structure, a bifunctional monomer satisfying a specific relationship between molecular weight and number of functional groups, and a tetrafunctional or higher monomer satisfying a specific relationship between molecular weight and number of functional groups has been proposed (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2016-037582 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been a demand for an actinic radiation-curable ink composition that can be applied to both hard substrates such as the aforementioned plastics and glass, as well as flexible substrates such as those described above. Application to hard substrates requires coating film physical properties that are excellent in durability, such as scratch resistance and chemical resistance. On the other hand, application to flexible substrates requires coating film physical properties that are excellent in flexibility, such as stretchability and flexibility. However, since durability and flexibility are basically in a trade-off relationship, it has conventionally been necessary to selectively use a hard-type ink composition that is suitable for hard substrates and a soft-type ink composition that is suitable for flexible substrates. In addition, any of the above types of ink compositions is also required to have optical heat resistance, which means that optical properties such as glossiness are unlikely to deteriorate at high temperatures.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide an actinic ray-curable ink composition that can achieve a high degree of compatibility between physical properties such as chemical resistance required for hard types and physical properties such as stretchability and flexibility required for soft types, and that can form a coating film that is also excellent in optical heat resistance; and a printed matter, a recording method, a method for producing a printed matter, and an ink set that use the ink composition. [Means for solving the problem]

[0007] The present inventors have investigated many types of polymerizable compounds having different numbers of functional groups and combinations thereof as active energy ray-polymerizable compounds, and as a result, have found that the above-mentioned problems can be solved by using, for example, a combination of polymerizable compound B1): a tetrafunctional or higher polymerizable compound having a linear aliphatic hydrocarbon structure having from 4 to 12 carbon atoms, and B2): a bifunctional polymerizable compound having a cyclic structure and a glass transition point of 100°C or higher, thereby completing the present invention.

[0008] A first aspect of the present invention is an actinic ray-curable ink composition having coating film properties that satisfy at least one of the following conditions 1 and 2: Condition 1: (a) The change in gloss after heating the coating film is less than 55%, and (b) no cracks occur in the coating film after stretching even when the stretching ratio is 115% or more. Condition 2: (c) When exposed to an aqueous solution of 50% or more by mass of ethanol, there is no visible change in the surface of the coating film, and (d) even when subjected to severe bending conditions such as bending a 2 mm diameter mandrel at 25°C, no cracks occur in the coating film.

[0009] A second aspect of the present invention is a coating film comprising: an object; and a coating film formed on a surface of the object; The coating film is a printed material containing a cured product of the actinic ray-curable ink composition according to the first aspect.

[0010] A third aspect of the present invention is a recording method in which the actinic energy ray-curable ink composition according to the first aspect is ejected onto the surface of a substrate by an inkjet method.

[0011] A fourth aspect of the present invention is a method for producing a printed matter, which comprises ejecting the actinic ray-curable ink composition according to the first aspect onto the surface of a substrate by an inkjet method.

[0012] A fifth aspect of the present invention provides an ink jet recording medium comprising the actinic ray-curable ink composition according to the first aspect and a color ink composition, The actinic ray-curable ink composition does not contain a colorant, the color ink composition contains a colorant and has a viscosity of less than 100 mPa·s during printing; and In the ink set, the color ink composition is at least one selected from the group consisting of a yellow ink composition, a magenta ink composition, a cyan ink composition, a black ink composition, and a white ink composition. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an actinic ray-curable ink composition that can achieve a high degree of compatibility between physical properties such as chemical resistance required for hard types and physical properties such as stretchability and flexibility required for soft types, and that can form a coating film that also has excellent optical heat resistance; a printed matter using the ink composition; a recording method; and a method for producing a printed matter. DETAILED DESCRIPTION OF THE INVENTION

[0014] <Actinic energy ray-curable ink composition> An actinic ray-curable ink composition according to one embodiment of the present invention is an actinic ray-curable ink composition having coating film properties that satisfy at least one of the following conditions 1 and 2. Condition 1: (a) The change in gloss after heating the coating film is less than 55%, and (b) no cracks occur in the coating film after stretching even when the stretching ratio is 115% or more. Condition 2: (c) When exposed to an aqueous solution of 50% or more by mass of ethanol, there is no visible change in the surface of the coating film, and (d) even when subjected to severe bending conditions such as bending a 2 mm diameter mandrel at 25°C, no cracks occur in the coating film.

[0015] By using such an actinic energy ray-curable ink composition, it is possible to achieve a high level of compatibility between physical properties such as chemical resistance required for hard types and physical properties such as stretchability and flexibility required for soft types, and it is also possible to form a coating film that is excellent in optical heat resistance.

[0016] Conditions 1 and 2 will be explained in detail below.

[0017] (Condition 1) Condition 1 requires that the coating film satisfy both of the following physical properties: (a) the change in gloss after heating is less than 55%; and (b) the coating film does not crack even when stretched to a stretching ratio of 115% or more. Condition 1(a) and Condition 1(b) are explained below.

[0018] Condition 1(a) is a coating film physical property that the rate of change in gloss after heating is less than 55%. Condition 1(a) is a coating film physical property related to optical heat resistance. Satisfying the coating film physical property of Condition 1(a) indicates that the coating film has excellent optical heat resistance.

[0019] More specifically, the coating film properties of condition 1(a) mean that when a test coating film is heated at 60°C for 15 minutes, the rate of change in gloss of the test coating film after heating, as measured using a gloss meter, is less than 55% compared to the test coating film before heating. Here, the test coating film before heating was prepared by forming a color ink layer on a substrate using an inkjet recording device, and then forming a coating film of the above-described active energy ray-curable ink composition on the above-described color ink layer to a film thickness of 20 μm.

[0020] The rate of change in gloss is preferably 50% or more and less than 55%, more preferably 45% or more and less than 50%, even more preferably 40% or more and less than 45%, and particularly preferably less than 40%.

[0021] (Condition 1(b)) Condition 1(b) is a coating film physical property that does not cause cracks in the coating film after stretching, even at a stretching ratio of 115% or more. Condition 1(b) is a coating film physical property related to stretchability. Satisfying the coating film physical property of Condition 1(b) indicates that the coating film has excellent stretchability. More specifically, the coating film properties of condition 1(b) mean that when stretched coating films having different stretch ratios are prepared by stretching test coating films at a speed of 50.0 mm / min using an electric test stand and allowed to stand at room temperature for 7 days, no cracks occur in the stretched coating films, even when the stretch ratio is 115% or more, with the stretch ratio before stretching being 100%. The test coating film before stretching was prepared by forming a coating film of an active energy ray-curable ink composition on a substrate using an inkjet recording device so as to have a film thickness of 20 μm.

[0022] The stretching ratio is preferably 115% or more and less than 120%, more preferably 120% or more and less than 125%, even more preferably 125% or more and less than 130%, and particularly preferably 130% or more.

[0023] (Condition 2) Condition 2 requires that the coating film satisfy both of the following physical properties: (c) no visible change in the surface of the coating film when exposed to an aqueous solution of 50% by mass or more of ethanol, and (d) no cracks occur in the coating film even when subjected to severe bending conditions of a mandrel having a diameter of 2 mm and at 25° C. Conditions 2(c) and 2(d) are explained below.

[0024] (Condition 2(c)) Condition 2(c) is a coating film physical property that the appearance of the coating film surface does not change when exposed to an ethanol aqueous solution of 50% by mass or more. Condition 2(c) is a coating film physical property related to ethanol resistance. Satisfying the coating film physical property of Condition 2(c) indicates that the coating film has excellent ethanol resistance. More specifically, the coating film properties of condition 2(c) mean that when the test coating film is rubbed back and forth 10 times with cotton swabs impregnated with aqueous ethanol solutions having different ethanol concentrations and the coating film surface is observed, there is no change in the coating film surface when exposed to 50% by mass or more of aqueous ethanol solutions. The test coating film was prepared by forming a coating film of an active energy ray-curable ink composition on a substrate using an inkjet recording device so as to have a film thickness of 20 μm.

[0025] The concentration of the aqueous ethanol solution is preferably 50% by mass or more and less than 60% by mass, more preferably 60% by mass or more and less than 70% by mass, even more preferably 70% by mass or more and less than 80% by mass, and particularly preferably 80% by mass or more.

[0026] (Condition 2(d)) Condition 2(d) is a coating film physical property that requires that the coating film does not crack even when bent under severe conditions, such as when bending a 2mm diameter mandrel at 25°C. Condition 2(d) is a coating film physical property related to flexibility. Meeting the coating film physical property of Condition 2(d) indicates that the coating film has excellent flexibility. More specifically, the coating film properties of condition 2(d) mean that no cracks occur in the test coating film even when the test coating film is bent under severe bending conditions of at least a 2 mm diameter mandrel at 25°C using a bending tester. The test coating film was prepared by forming a coating film of an active energy ray-curable ink composition on a substrate using an inkjet recording device so as to have a film thickness of 20 μm.

[0027] Regarding the bending conditions using a mandrel, it is preferable that no cracks occur in the coating film at a temperature of 25°C and a diameter of 2 mm, more preferably that no cracks occur in the coating film at a temperature of 0°C and a diameter of 6 mm, even more preferably that no cracks occur in the coating film at a temperature of 0°C and a diameter of 4 mm, and particularly preferably that no cracks occur in the coating film at a temperature of 0°C and a diameter of 2 mm.

[0028] The actinic energy ray-curable ink composition of one embodiment of the present invention has coating film physical properties that satisfy at least one of the above-mentioned condition 1 and condition 2, but it is more preferable that the coating film physical properties satisfy both of the above-mentioned condition 1 and condition 2. The actinic energy ray-curable ink composition that satisfies at least one of the coating film properties of the above condition 1 and the above condition 2 is not particularly limited. The actinic ray-curable ink composition of this embodiment may contain, for example, the following as the polymerizable compound B) which is an actinic ray-polymerizable compound: Polymerizable compound B1): a tetrafunctional or higher polymerizable compound having a linear aliphatic hydrocarbon structure with 4 to 12 carbon atoms, and / or Polymerizable compound B2): It is preferable to contain a bifunctional polymerizable compound having a cyclic structure and a glass transition point of 100° C. or higher. The polymerizable compound B1) and the polymerizable compound B2) will be described below.

[0062] The actinic ray-curable ink composition of this embodiment may contain components other than the polymerizable compound B1) and the polymerizable compound B2), as long as the desired effect is obtained. Essential and optional components that may be contained in the actinic ray-curable ink composition of this embodiment will be described below.

[0029] (Polymerizable compound B1)) The actinic energy ray-curable ink composition of this embodiment may contain a polymerizable compound B1) as needed. The polymerizable compound B1) is a tetrafunctional or higher functional polymerizable compound having a linear aliphatic hydrocarbon structure with 4 to 12 carbon atoms. A tetrafunctional or higher functional polymerizable compound is a compound having four or more ethylenically unsaturated double bonds that are polymerized by irradiation with actinic energy rays. In this specification, actinic energy rays include electromagnetic waves such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, visible light, infrared rays, X-rays, and gamma rays, as well as electron beams, proton beams, and neutron beams. The polymerizable compound B1) has a linear aliphatic hydrocarbon structure consisting of a specific number of carbon atoms, and therefore has a large number of crosslinking points in the coating film and a long distance between the crosslinking points, thereby improving the chemical resistance, flexibility, etc. of the coating film. In this specification, the polymerizable compound is a concept that includes compounds that are also called oligomers or polymers, in addition to monomers, depending on their molecular weight.

[0030] The linear aliphatic hydrocarbon structure is a highly flexible structure having a predetermined number of methylene chains. The lower limit of the number of carbon atoms in the linear aliphatic hydrocarbon structure, excluding the carbon atoms of the ethylenically unsaturated double bond, is preferably 5 or more, more preferably 6 or more, and even more preferably 7 or more. The upper limit of the number of carbon atoms in the linear aliphatic hydrocarbon structure, excluding the carbon atoms of the ethylenically unsaturated double bond, is preferably 11 or less, more preferably 10 or less, and even more preferably 9 or less.

[0031] The lower limit of the number of linear aliphatic hydrocarbon structures in the compound is preferably 4 or more. The upper limit of the number of linear aliphatic hydrocarbon structures in the compound is preferably 8 or less.

[0032] The number of functional groups of the polymerizable compound B1) is preferably 8 or less. When the number of functional groups is 8 or less, a decrease in reactivity due to steric hindrance or the like is less likely to occur compared to polymerizable compounds having more than 8 functional groups, and a high crosslink density can be achieved.

[0033] Examples of the polymerizable compound B1) include pentaerythritol tetraacrylates such as EO-modified (4) (number of functional groups = 4), EO-modified (35) (number of functional groups = 4), PO-modified (4) (number of functional groups = 4), and PO-modified (10) (number of functional groups = 4), ditrimethylolpropane tetraacrylates such as EO-modified (4) (number of functional groups = 4), and PO-modified (4) (number of functional groups = 4), dipentaerythritol pentaacrylates such as EO-modified (6) (number of functional groups = 6), EO-modified (12) (number of functional groups = 6), EO-modified (18) (number of functional groups = 6), EO-modified (24) (number of functional groups = 6), EO-modified (48) (number of functional groups = 6), and PO-modified (6) (number of functional groups = 6), caprolactone-modified (2) (number of functional groups = 6), and caprolactone-modified (2) (number of functional groups = 6). Examples of dipentaerythritol hexaacrylate include EO-modified (6) (number of functional groups = 6), caprolactone-modified (6) (number of functional groups = 6), caprolactone-modified (12) (number of functional groups = 6), and dipentaerythritol hexaacrylate, such as EO-modified (6) (number of functional groups = 6), EO-modified (12) (number of functional groups = 6), EO-modified (18) (number of functional groups = 6), EO-modified (24) (number of functional groups = 6), EO-modified (48) (number of functional groups = 6), PO-modified (6) (number of functional groups = 6), caprolactone-modified (2) (number of functional groups = 6), caprolactone-modified (3) (number of functional groups = 6), caprolactone-modified (6) (number of functional groups = 6), caprolactone-modified (12) (number of functional groups = 6), and (meth)acrylates with different numbers of modifications, different types of modifications, or different structures.

[0034] The polymerizable compound B1) may be used alone or in combination of two or more kinds, if necessary.

[0035] The lower limit of the content of the polymerizable compound B1) is preferably 2.5% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, relative to the total mass of the actinic energy ray-curable ink composition. The upper limit of the content of the polymerizable compound B1) is preferably 12.5% ​​by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less, relative to the total mass of the actinic energy ray-curable ink composition. When the content of the polymerizable compound B1) is within the above range, it is possible to achieve a high level of compatibility between physical properties such as stretchability and flexibility and physical properties such as chemical resistance, and it is also possible to form a coating film that is excellent in optical heat resistance.

[0036] (Polymerizable compound B2)) The actinic energy ray-curable ink composition of this embodiment may contain a polymerizable compound B2) as needed. The polymerizable compound B2) is a bifunctional polymerizable compound having a cyclic structure and a glass transition temperature of 100°C or higher. The bifunctional polymerizable compound is a compound having two ethylenically unsaturated double bonds that are polymerized by irradiation with actinic energy rays. The glass transition temperature means the glass transition temperature of the homopolymer of the polymerizable compound A). The polymerizable compound B2) has a cyclic structure, and therefore has a high glass transition point (hereinafter also referred to as "Tg"), and can improve the optical heat resistance, stretchability, etc. of the coating film. The glass transition temperature of each polymerizable compound is measured using a dynamic viscoelasticity measuring device. Specifically, a 90 / 10 mixture of polymerizable compound and monoacylphosphine oxide is applied to a loose substrate or applied using a mold, irradiated with a 385 nm LED lamp until completely cured, and then peeled off from the substrate to prepare a 1.0 cm x 5.0 cm, 0.1 cm thick test piece. The resulting coating is then measured using a dynamic viscoelasticity measuring device (RSA-G2, manufactured by TA Instruments Japan) at a frequency of 5 Hz, a heating rate of 5°C / min, a temperature range of -20 to 150°C, and a strain of 0.1%.

[0037] The cyclic structure may be a monocyclic structure having one cyclic structure per molecule, or a polycyclic structure having two or more cyclic structures per molecule. The cyclic structure may be an alicyclic structure or an aromatic ring structure, but from the viewpoint of the heat resistance and toughness of the coating film, an alicyclic structure is preferred. Compared to aromatic rings, alicyclic structures have higher transparency and are less susceptible to discoloration and heat sagging at high temperatures, improving the heat resistance of the coating film. Furthermore, aromatic rings have a tendency to stack, while alicyclic rings are more likely to exhibit flexibility in the coating film and improve toughness. More specifically, the alicyclic structure is preferably an aliphatic fused cyclic structure, an aliphatic bridged cyclic structure, or an aliphatic bridged fused cyclic structure.

[0038] The glass transition point is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 140°C or higher.

[0039] The polymerizable compound B2) is preferably a bifunctional polymerizable compound having a cyclic structure and a glass transition point of 100°C or higher, more preferably a bifunctional polymerizable compound having a cyclic structure and a glass transition point of 120°C or higher, and even more preferably a bifunctional polymerizable compound having a cyclic structure and a glass transition point of 140°C or higher.

[0040] Examples of the polymerizable compound B2) include dimethyloltricyclodecane diacrylate, ethoxylated bisphenol A di(meth)acrylate, and 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene diacrylate.

[0041] The polymerizable compound B2) may be used alone or in combination of two or more kinds, if necessary.

[0042] The lower limit of the content of the polymerizable compound B2) is preferably 10% by mass or more, more preferably 13% by mass or more, and even more preferably 15% by mass or more, relative to the total mass of the actinic energy ray-curable ink composition. The upper limit of the content of the polymerizable compound B2) is preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less, relative to the total mass of the actinic energy ray-curable ink composition. When the content of the polymerizable compound B2) is within the above range, it is possible to achieve a high level of compatibility between physical properties such as stretchability and flexibility and physical properties such as chemical resistance, and it is also possible to form a coating film that is excellent in optical heat resistance.

[0043] The above-described active energy ray-curable ink composition preferably has coating film properties that satisfy the following condition 3. Condition 3: The change in gloss after UV irradiation of the coating film is less than 55%.

[0044] By using such an actinic ray-curable ink composition, a coating film having excellent weather resistance can be formed. Condition 3 will be explained below.

[0045] (Condition 3) Condition 3 is a coating film physical property that the rate of change in gloss after UV irradiation of the coating film is less than 55%. Condition 3 is a coating film physical property related to weather resistance. Satisfying the coating film physical property of Condition 3 indicates that the coating film has excellent weather resistance.

[0046] More specifically, the coating film properties under Condition 3 were measured by irradiating the test coating with UV light using a weather resistance evaluation device at an output of 100 mW / cm. 2 This means that when a weather resistance test is conducted under the test conditions, the rate of change in gloss of the test coating film after the weather resistance test, as measured using a gloss meter, is less than 55% compared to the gloss of the test coating film before the weather resistance test. The test coating film before the weather resistance test was prepared by forming a coating film of an active energy ray-curable ink composition on a substrate using an inkjet recording device so as to have a film thickness of 20 μm.

[0047] The rate of change in gloss is preferably 50% or more and less than 55%, more preferably 45% or more and less than 50%, even more preferably 40% or more and less than 45%, and particularly preferably less than 40%.

[0048] (Polymerizable compound C)) The actinic ray-curable ink composition of this embodiment may contain a polymerizable compound C) as needed. The polymerizable compound C) is a monofunctional polymerizable compound having a cyclic structure. The monofunctional polymerizable compound is a compound having one ethylenically unsaturated double bond that can be polymerized by irradiation with active energy rays.

[0049] Examples of the polymerizable compound C) include acryloylmorpholine, isobornyl acrylate, 4-t-butylcyclohexyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, t-butyl acrylate, cyclic trimethylolpropane formal acrylate, 3-3-5-trimethylcyclohexyl acrylate, benzyl acrylate, phenyl acrylate, and the like. Examples of suitable acrylates include 2-acryloyloxyethyl acrylate, γ-butyrolactone acrylate, cresol acrylate, 2-acryloyloxyethyl phthalate, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, 2-acryloyloxyethyl hexahydrophthalate, 2-acryloyloxypropyl phthalate, para-cumylphenoxyethylene glycol acrylate, nonylphenoxypolyethylene glycol acrylate, 1-adamantyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, and (meth)acrylates thereof with different numbers of modifications, different types of modifications, or different structures.

[0050] The polymerizable compound C) may be used alone or in combination of two or more kinds, if necessary.

[0051] The lower limit of the content of the polymerizable compound C) is preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more, relative to the total mass of the actinic energy ray-curable ink composition. The lower limit of the content of the polymerizable compound C) is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less, relative to the total mass of the actinic energy ray-curable ink composition.

[0052] (ultraviolet absorber) The actinic ray-curable ink composition of this embodiment may contain an ultraviolet absorber as needed. The ultraviolet absorber is a compound (monomer, oligomer, polymer) that has an absorption wavelength in the ultraviolet region.

[0053] Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzoate-based ultraviolet absorbers, and hydroxyphenyltriazine-based ultraviolet absorbers.For example, benzophenone compounds such as 2-hydroxy-4-n-octoxy-benzophenone, 2-hydroxy-4-dodecyloxy-benzophenone, 2-hydroxy-4-octadecyloxy-benzophenone, 2-hydroxy-4-benzyloxy-benzophenone, and 1,4-bis(4-benzoyl-3-hydroxyphenoxy)-butane, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)benzotriazole, 2-(3,5-di-t-pentyl ... benzotriazole compounds such as 2-(2-hydroxy-4-octyloxyphenyl)-2-benzotriazole, 2-(2-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimidylmethyl)phenol, 2-(2-hydroxy-4-octyloxyphenyl)-2-benzotriazole, and 2-(2-hydroxy-5-t-octylphenyl)-2-benzotriazole; 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3-5-triazine; 2,4-diphenyl-6-( 2-hydroxy-4-methoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-ethoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-(2-hydroxy-4-propoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4 ,6-bis(4-phenylphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine, and 2,4-diphenyl-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine.

[0054] In particular, it is preferable to select an ultraviolet absorber that has a maximum absorption wavelength in the wavelength range of 315 nm to 400 nm and a large absorbance area Ab in the wavelength range of 315 nm to 400 nm. Generally, short-wavelength ultraviolet rays such as UV-C and UV-B contained in sunlight are mostly absorbed by the ozone layer in the atmosphere, and therefore the ultraviolet rays that actually reach the ground have wavelengths of approximately 315 to 400 nm (so-called UV-A). By incorporating an ultraviolet absorber having an absorption wavelength in the range of 315 nm to 400 nm, the ultraviolet rays that actually reach the ground can be effectively absorbed by the coating film, which is the cured product of the active energy ray-curable ink composition, thereby reducing the amount of ultraviolet rays that reach the substrate, thereby effectively improving the weather resistance of the substrate. In this specification, the substrate may be a substrate (recording medium) itself or a substrate (recording medium) with a colored layer laminated on part or the entire surface of the substrate (recording medium).

[0055] The lower limit of the content of the ultraviolet absorber is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and even more preferably 1.7% by mass or more, relative to the total mass of the actinic energy ray-curable ink composition, which can more effectively improve the weather resistance of the substrate. The upper limit of the content of the ultraviolet absorber is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, and even more preferably 3.0% by mass or less, relative to the total mass of the actinic energy ray-curable ink composition, which improves the solubility of the ultraviolet absorber contained in the ink composition and improves the ejection properties of the ink composition.

[0056] (light stabilizer) The actinic energy ray-curable ink composition of this embodiment may contain a light stabilizer as needed. The light stabilizer preferably contains, for example, a hindered amine. The hindered amine is preferably a NOR hindered amine. The NOR hindered amine has a structure as shown in the following formula, and is capable of capturing peroxy radicals by the NOR group.

[0057] [ka]

[0058] Specific examples of such NOR-type hindered amines include dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine, decanedioic acid bis(2.2.6.6-tetramethyl-1-(octyloxy)-4-piperidinyl)ester, 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamino)-1,3,5-triazine, and bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate.

[0059] Light stabilizers other than NOR-type hindered amines may also be contained, including, for example, conventionally known light stabilizers such as NR-type hindered amine compounds.

[0060] The lower limit of the content of the light stabilizer is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, relative to the total mass of the actinic energy ray-curable ink composition. The upper limit of the content of the light stabilizer is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less, relative to the total mass of the actinic energy ray-curable ink composition.

[0061] (antioxidant) The actinic energy ray-curable ink composition of this embodiment may contain an antioxidant as needed. An antioxidant is a compound that captures hydroperoxides. By including an antioxidant in the actinic energy ray-curable ink composition, it becomes possible to effectively suppress discoloration (yellowing) of a coating film that is a cured product of the actinic energy ray-curable ink composition.

[0062] The compound that captures hydroperoxides preferably contains, for example, a hindered amine. Examples of the hindered amine include NH-type hindered amines. NH-type hindered amines are compounds that have one or more piperidine structures in the molecule, in which a hydrogen atom is bonded to the nitrogen atom of a 2,2,6,6-tetramethylpiperidine skeleton, and have a structure as shown in the following formula, making it possible to capture hydroperoxides by the NH group.

[0063] [ka]

[0064] Examples of such NH-type hindered amines include 2,2,6,6-tetramethyl-4-piperidyl stearate, 2,2,6,6-tetramethyl-4-piperidyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}]hexamethyl, bis(1-octoxy-2,2,6,6-tetramethyl-4 -piperidyl) sebacate, 2,2,6,6-tetramethyl-piperidyl methacrylate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)di(tridecyl)-1,2,3,4-butanetetracarboxylate, 3,9-bis[1,1-dimethyl-2-{tris(2,2,6,6-tetramethyl-4-piperidyloxycarbonyloxy)butylcarbonyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, and the like.

[0065] As the antioxidant, an antioxidant other than the above-mentioned NH-type hindered amine may be used. For example, at least one of a thioether-based antioxidant and a phenol-based antioxidant can be used as such an antioxidant. A thioether-based antioxidant is an antioxidant consisting of an organic compound in which sulfur is substituted with an organic group. A phenol-based antioxidant is an antioxidant having a phenol group in its chemical structure. At least one of a thioether-based antioxidant and a phenol-based antioxidant can capture hydroperoxides.

[0066] Examples of the thioether antioxidant include dialkylthiodipropionates such as dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate, and pentaerythritol tetra(β-alkylthiopropionic acid) esters.Examples of phenolic antioxidants include monophenolic antioxidants such as 2,6-t-butylphenol, 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and methylhydroquinone; and 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2 ,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5.5]undecane, 2,2'-dihydroxy-3,3'-di(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane, and other bisphenols. Phenolic antioxidants; trisphenolic antioxidants such as 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane and 1,3,5-trimethyl-2,4,6-tris(3,5-t-butyl-4-hydroxybenzyl)benzene; tetrakis-phenolic antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane and tetrakis-[ethylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane antioxidants; tocopherol-based antioxidants such as D-α-tocopherol, L-α-tocopherol, D-β-tocopherol, L-β-tocopherol, D-γ-tocopherol, L-γ-tocopherol, D-δ-tocopherol, and L-δ-tocopherol; tocotrienol-based antioxidants such as D-α-tocotrienol, L-α-tocotrienol, D-β-tocotrienol, L-β-tocotrienol, D-γ-tocotrienol, L-γ-tocotrienol, D-δ-tocotrienol, and L-δ-tocotrienol.

[0067] The lower limit of the antioxidant content is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, relative to the total mass of the actinic energy ray-curable ink composition, which can more effectively improve the weather resistance of the substrate. The upper limit of the content of the antioxidant is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less, relative to the total mass of the actinic energy ray-curable ink composition, which improves the dispersibility (or solubility) of the antioxidant contained in the ink composition and improves the ejection properties of the ink composition.

[0068] (Polymerization initiator) The actinic energy ray-curable ink composition of this embodiment may contain a polymerization initiator as needed. The polymerization initiator is not particularly limited as long as it promotes the polymerization reaction of the polymerizable compound in the ink composition upon irradiation with actinic energy rays. Note that a polymerization initiator is not necessarily essential in the ink composition according to this embodiment, and for example, a polymerization initiator may not be used when an electron beam is used as the actinic energy ray.

[0069] Specific examples of the polymerization initiator include aromatic ketones including thioxanthone and the like, α-aminoalkylphenones, α-hydroxyketones, acylphosphine oxides, aromatic onium salts, organic peroxides, thio compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

[0070] The lower limit of the content of the polymerization initiator may be any amount that can appropriately initiate the polymerization reaction of the polymerizable compound, and is preferably 5.0% by mass or more, more preferably 6.0% by mass or more, and even more preferably 7.0% by mass or more, relative to the total mass of the active energy ray-curable ink composition. The upper limit of the content of the polymerization initiator is preferably 20.0 mass % or less, more preferably 18.0 mass % or less, and even more preferably 15.0 mass % or less, relative to the total mass of the actinic energy ray-curable ink composition.

[0071] (polymerization inhibitor) The actinic energy ray-curable ink composition of this embodiment may contain a polymerization inhibitor as needed. The polymerization inhibitor is not particularly limited, and examples of polymerization inhibitors that can be used include diphenylpicrylhydrazide, tri-p-nitrophenylmethyl, p-benzoquinone, p-tert-butylcatechol, picric acid, copper chloride, methylhydroquinone, methoquinone, tert-butylhydroquinone, phenothiazines, and nitrosamines.

[0072] (colorant) The actinic ray-curable ink composition of this embodiment may contain an ink containing a coloring material as needed. The coloring material is not particularly limited as long as it is a dye or pigment used in a typical ink composition. The ink containing a coloring material may be an actinic energy ray-curable ink, a solvent-based ink containing a coloring material and a solvent, or a water-based ink containing a coloring material and water. The color of the ink containing the coloring material is not particularly limited, and examples include yellow, magenta, cyan, black, light colors of each color, and white. In the embodiment of the printed matter described below, when a colored layer is provided, or in the embodiment of the ink set described below, the actinic ray-curable ink composition of this embodiment does not contain a colorant.

[0073] (Other additives) The actinic ray-curable ink composition of this embodiment may contain various other additives such as a solvent, a plasticizer, a leveling agent, a resin, and a surface conditioner.

[0074] (viscosity) The viscosity of the actinic ray-curable ink composition of this embodiment at 40°C is preferably 3 mPa·s or more and 25 mPa·s or less, and more preferably 3 mPa·s or more and 20 mPa·s or less. A viscosity of 3 mPa·s or more is preferable in that it provides good ejection properties when ejected using an inkjet device. Good ejection properties mean that ink dots are less likely to be missing during continuous printing, and ejection disturbances and the like are less likely to occur, making it easier to obtain normal printing. A viscosity of 25 mPa·s or less is preferable in that it is less likely to cause ejection defects due to missing dots, even if the inkjet device head does not incorporate a mechanism for reducing viscosity by heating, and therefore reduces the possibility of the ink composition not being ejected normally.

[0075] <Method of manufacturing active energy ray-curable ink composition> The method for producing an actinic ray-curable ink composition according to one embodiment of the present invention is not particularly limited, and a conventionally known method can be used. For example, a disperser is used to disperse polymerizable compound B1) and polymerizable compound B2), and if necessary, polymerizable compound C), an ultraviolet absorber, an antioxidant, a light stabilizer, and the like, and then, if necessary, a polymerization initiator, a polymerization inhibitor, a leveling agent, and the like are added and stirred uniformly to obtain a mixture, which is then filtered through a filter to obtain an actinic ray-curable ink composition.

[0076] <Printed material> A printed matter according to one embodiment of the present invention includes at least a substrate and a coating film laminated on the surface of the substrate. The coating film contains a cured product of the actinic ray-curable ink composition described above. By forming such a coating film on the surface of a substrate, it is possible to achieve a high degree of compatibility between the physical properties required for soft types, such as stretchability and flexibility, and the physical properties required for hard types, such as chemical resistance, and it is possible to provide a printed matter with a coating film that also has excellent optical heat resistance. Furthermore, by exposing the coating film for a long period of time, fading (yellowing) of the coating film can be effectively suppressed. As mentioned above, the substrate may be the substrate (recording medium) itself, or a substrate (recording medium) with a colored layer laminated on part or the entire surface.

[0077] Each layer constituting the printed matter will be described below.

[0078] (Base material (recording medium)) The substrate (recording medium) is not particularly limited, and may be a non-absorbent substrate such as a resin substrate or a metal plate glass, an absorbent substrate such as paper or fabric, or a substrate with a surface coating such as a substrate with a receiving layer, and various substrates can be used.

[0079] Examples of non-absorbent substrates include resin substrates such as polyester resins, polypropylene synthetic paper, vinyl chloride resins, polyimide resins, polycarbonate resins, styrene resins, acrylic resins, ABS resins, and polyurethane resins, as well as metals, metal foil-coated paper, glass, synthetic rubber, and natural rubber.

[0080] Examples of absorbent substrates include woody paper, medium-quality paper, fine paper, cotton, synthetic fiber fabrics, silk, hemp, woven fabrics, nonwoven fabrics, and leather.

[0081] Examples of surface-coated substrates include coated paper, art paper, cast paper, lightweight coated paper, and lightly coated paper.

[0082] (colored layer) The printed matter of this embodiment may optionally include a colored layer. The colored layer is a layer containing a colorant (dye or pigment) typically used in ink compositions, and is formed primarily from an ink composition applied to the surface of a substrate or a layer formed on the surface of the substrate (such as a primer layer, coating layer, or receiving solution layer). The ink composition forming this colored layer may be an actinic radiation-curable ink composition, a solvent-based ink composition containing a colorant and a solvent, or an aqueous ink composition containing a colorant and water. The colored layer may consist of a single layer or multiple layers (e.g., multiple layers including yellow ink, magenta ink, cyan ink, black ink, etc.). Forming a coating film on the surface of a substrate on which the colored layer is formed over part or the entire surface of a recording medium can enhance the weather resistance of the colored layer. Furthermore, fading (yellowing) of the coating film due to prolonged exposure can be effectively suppressed, thereby preventing changes to the design of the image. The substrate to which the ink composition of the above embodiment is applied may be the surface of the recording medium itself. However, the ink composition of the above embodiment is preferably applied to the surface of a colored layer to form a coating film.

[0083] The colored layer may contain a resin. When the colored layer contains a resin, the resin may be a binder resin, a resin emulsion, or a polymer dispersant contained in the actinic energy ray-curable ink composition, which may directly become the resin of the ink layer, or may be a cured product formed by polymerizing a polymerizable compound contained in the actinic energy ray-curable ink composition by irradiating it with actinic energy rays after it has been ejected onto the surface of a substrate (recording medium).

[0084] The method for applying the active energy ray-curable ink composition for forming the colored layer is not particularly limited. Examples include spraying, coating, inkjet, gravure, and flexography. Among these, the inkjet method is preferred for ejection (application). The inkjet method makes it easy to eject (apply) the ink to any desired location on the substrate or to the entire surface of the substrate.

[0085] The coloring material of the ink composition forming the colored layer is not particularly limited, and may be a dye-based or pigment-based coloring material. It is preferable to use a pigment-based ink composition that provides good resistance to water and light of the colored layer. The pigment that can be used in the ink composition forming the colored layer is not particularly limited. Examples include organic pigments and inorganic pigments that are used in conventional ink compositions. These may be used alone or in combination of two or more. Specific examples of organic pigments include insoluble azo pigments, soluble azo pigments, dye derivatives, phthalocyanine organic pigments, quinacridone organic pigments, perylene organic pigments, dioxazine organic pigments, nickel azo pigments, isoindolinone organic pigments, pyranthrone organic pigments, thioindigo organic pigments, condensed azo organic pigments, benzimidazolone organic pigments, quinophthalone organic pigments, isoindoline organic pigments, quinacridone solid solution pigments, and organic solid solution pigments such as perylene solid solution pigments; inorganic pigments include titanium oxide and zinc oxide; and other pigments such as carbon black. The pigments that can be used in the ink composition may be a combination of multiple organic and inorganic pigments, or a combination of a pigment dispersion dispersed in an aqueous solvent using a pigment dispersant and a self-dispersing pigment.

[0086] (paint film) The coating film contains a cured product of the above-described actinic energy ray-curable ink composition.

[0087] The lower limit of the coating thickness is not particularly limited, but is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm. A coating thickness of 10 μm or more more effectively improves the weather resistance of the substrate, resulting in a printed matter with higher weather resistance. The upper limit of the coating thickness is not particularly limited, but from the viewpoint of productivity and cost of the printed matter, is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less.

[0088] Furthermore, when a coating film formed from the above-described active energy ray-curable ink composition contains an ultraviolet absorber and a predetermined light stabilizer, it is possible to impart high weather resistance to the substrate. Therefore, if the coating film formed from the above-described active energy ray-curable ink composition is a thin coating film, for example, about 10 μm thick, it is possible to impart sufficiently high weather resistance to the substrate.

[0089] The coating film may have a uniform thickness (for example, the thickness of the coating film described above), or may have a non-uniform thickness. For example, the surface may have a matte or glossy finish, or may have a textured finish such as wood grain, leather, linen, or fallen leaves. A coating film of such a non-uniform thickness effectively prevents yellowing and cracking due to long-term exposure and can have a highly aesthetic design. A coating film of non-uniform thickness can be obtained by adjusting conditions such as the amount of the actinic energy ray-curable ink composition ejected (applied) and the time between ejection (application) of the ink composition and irradiation with actinic energy rays.

[0090] Such a coating film of uneven thickness may be obtained by increasing or decreasing the amount of ink composition ejected (applied) at one time depending on the location of ejection (application), or by ejecting (applying) multiple ink compositions at the same location to create unevenness.

[0091] The method for applying the active energy ray-curable ink composition to form a coating film is not particularly limited. Examples include spraying, coating, inkjet printing, gravure printing, and flexography. Among these, inkjet printing is preferred. The inkjet printing method makes it easy to apply the ink to any desired location on a substrate or to the entire surface of the substrate.

[0092] <Recording method> A recording method according to one embodiment of the present invention includes a step of applying the above-described actinic energy ray-curable ink composition to the surface of a substrate.

[0093] The method for applying the actinic energy ray-curable ink composition is not particularly limited. Examples include spraying, coating, inkjet, gravure, and flexography. Among these, inkjet ejection (application) is preferred. With the inkjet method, it is easy to eject (apply) the ink to any desired location on the substrate or to the entire surface of the substrate.

[0094] When the inkjet method is employed, an inkjet recording apparatus can be used, and the inkjet recording apparatus can be any of a piezo type, a thermal type, an electrostatic type, or the like.

[0095] The inkjet method is not particularly limited and may be a serial head method or a line head method.

[0096] Next, the actinic energy ray-curable ink composition applied to the surface of the substrate is irradiated with actinic energy rays. This irradiation forms a coating film containing a cured product of the ink composition on the surface of the substrate. Examples of actinic energy rays include electromagnetic waves such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, visible light, infrared rays, X-rays, and gamma rays, as well as electron beams, proton beams, and neutron beams. The light source for irradiating the actinic energy rays is not particularly limited, and examples include high-pressure mercury lamps, metal halide lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, ultraviolet lasers, sunlight, and LED lamps. From the viewpoints of energy conservation and high flexibility in the design and equipment of the printing device, it is more preferable to use an LED lamp as the light source.

[0097] A printed matter can be obtained by this recording method. The embodiment of the printed matter is not particularly limited, and may be an embodiment in which a coating film is formed directly on a substrate, or an embodiment in which the above-mentioned colored layer is formed on a substrate and a coating film is formed on this colored layer.

[0098] When obtaining a printed matter having the above-described colored layer, the application method and order are not particularly limited. Generally, a method can be used in which an ink composition for obtaining a colored layer is applied to a substrate and cured to form a colored layer, and then the above-described active energy ray-curable ink composition is applied to the obtained colored layer and cured to form a coating film. Alternatively, a method can be used in which the ink composition for obtaining a colored layer and the above-described active energy ray-curable ink composition are applied simultaneously, as necessary.

[0099] <Manufacturing method for printed matter> The recording method of applying the ink composition according to the above embodiment to the surface of a substrate can also be defined as a method for producing a printed matter.

[0100] <Ink set> An ink set according to one embodiment of the present invention comprises the above-described actinic energy ray-curable ink composition and a color ink composition.

[0101] The actinic ray-curable ink composition may or may not contain a colorant, but preferably does not contain a colorant. In this specification, when the actinic ray-curable ink composition does not contain a colorant, it is also referred to as a clear ink composition.

[0102] The color ink composition contains a colorant and has a viscosity of less than 100 mPa·s during printing. The viscosity during printing refers to the viscosity when the ink is discharged onto the surface of the substrate. The viscosity during printing is preferably less than 80 mPa·s, and more preferably less than 50 mPa·s.

[0103] The color ink composition is at least one selected from the group consisting of a yellow ink composition, a magenta ink composition, a cyan ink composition, a black ink composition, and a white ink composition.

[0104] When an ink set is used, for example, a color ink composition is ejected (applied) onto a substrate by an inkjet method and cured by ultraviolet light to form a colored layer, and then a clear ink composition is ejected (applied) onto the resulting colored layer and cured by ultraviolet light to form a coating film, thereby producing a printed product. The coating film of the resulting printed product can highly combine physical properties such as chemical resistance required for hard types with physical properties such as stretchability and flexibility required for soft types, and also has excellent optical heat resistance and weather resistance. [Example]

[0105] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0106] [Examples 1 to 54 and Comparative Example 1] (Preparation of Ink Composition) The following polymerizable compound B1), the following polymerizable compound b1, the following polymerizable compound B2), the following polymerizable compound b2, the following polymerizable compound C), the following polymerizable compound c, the following polymerization initiator, the following polymerization inhibitor, the following leveling agent, the following UV absorber, the following light stabilizer, and the following antioxidant were uniformly mixed in the amounts shown in Tables 1 to 4 below to prepare the ink compositions of Examples 1 to 54 and Comparative Example 1. The content of each component in Tables 1 to 4 is expressed in mass%. The following ultraviolet absorbers were used: UA1: Triazine ultraviolet absorber (2,4-bis(2-hydroxy-4-butyloxyphenyl)-6-(2,4-bis-butyloxyphenyl)-1,3,5-triazine) (CAS number 208343-47-9, maximum absorption wavelength: 349 nm, absorbance area Ab 50.8) UA2: Benzotriazole-based ultraviolet absorber (2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole) As antioxidants, the following AO1 to AO16 were used. AO1 (thioether): Dilauryl thiodipropionate AO2 (thioether): Distearyl thiodipropionate AO3 (thioether): Pentaerythritol tetra(β-alkylthiopropionic acid) ester AO4 (monophenolic): 2,6-t-butylphenol AO5 (monophenolic): 2-t-butyl-4-methoxyphenol AO6 (bisphenol): 2,2'-methylenebis(4-methyl-6-t-butylphenol) AO7 (bisphenol): 2,2'-methylenebis(4-ethyl-6-t-butylphenol) AO8 (Trisphenol): 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane AO9 (Trisphenol): 1,3,5-trimethyl-2,4,6-tris(3,5-t-butyl-4-hydroxybenzyl)benzene A10 (Tetrakisphenol): Tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane A11 (Tetrakisphenol): Tetrakis-[ethylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane A12 (Tocotrienol): D-α-Tocotrienol A13 (tocopherols): D-α-tocopherol A14 (NH-type hindered amine): Tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate A15 (NH-type hindered amine): 6,6-tetramethyl-piperidyl methacrylate A16 (NH-type hindered amine): Bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate

[0107] [Table 1]

[0108] [Table 2]

[0109] [Table 3]

[0110] [Table 4]

[0111] (Preparation of ink composition for colored layer) An ink composition for a colored layer was prepared by mixing the following polymerizable compound, polymerization initiator, polymerization inhibitor, leveling agent, pigment, and pigment dispersant in the proportions shown in Table 5. The content of each component in Table 5 is expressed in mass%.

[0112] [Table 5]

[0113] (evaluation) <Optical heat resistance> Each printed matter was produced using the ink compositions of the Examples and Comparative Examples. Specifically, an inkjet recording device was used to eject a color ink composition (yellow) for the colored layer onto the surface of each substrate, and the colored layer was formed by irradiating it with an LED lamp having a wavelength of 385 nm as active energy rays. Next, an inkjet recording device was used to eject the ink compositions of the Examples and Comparative Examples onto the surface of the substrate from above the colored layer, and the coating was formed by irradiating it with an LED lamp having a wavelength of 385 nm, thereby obtaining each printed matter. The coating thickness of each printed matter was 20 μm. Each printed material was heated at 60°C for 15 minutes, and the gloss of each printed material was measured before and after heating using an appearance analyzer Rhopoint IQ-S (manufactured by Rhopoint Instruments). The rate of change in gloss of the printed material before and after heating was calculated, and the optical heat resistance of each coating film was evaluated based on the following evaluation criteria. Among the evaluation criteria of 2 or more, the closer to 5 the coating film's optical heat resistance is, the higher the evaluation. Evaluation criteria of 1 indicates that the coating film's optical heat resistance is poor, and the evaluation is low. The results are shown in Tables 6 to 9. (Evaluation criteria) 5: Gloss change rate is less than 40% 4: Gloss change rate is 40% or more but less than 45% 3: Gloss change rate is 45% or more but less than 50% 2: Gloss change rate is 50% or more but less than 55% 1: Gloss change rate is 55% or more

[0114] <Stretchability> Using an inkjet recording device, the ink compositions of the examples and comparative examples were ejected onto the surface of each substrate, and then irradiated with an LED lamp having a wavelength of 385 nm to form a coating film, thereby obtaining each printed matter. The coating film thickness of each printed matter was 20 μm. Using an electric test stand MX2-500N (Imada), each printed material was stretched at a speed of 50.0 mm / min, and by varying the stretching time, five types of stretched printed materials were produced with stretch ratios ranging from less than 115% to 130%, with the unstretched material being considered 100%. Each of the resulting stretched printed materials was left at room temperature for 7 days, and the presence or absence of cracks in the coating film was visually inspected. The stretchability of each coating film was evaluated based on the following evaluation criteria. Among the evaluation criteria of 2 or more, the closer to 5 the coating film has excellent stretchability and the higher the evaluation. Evaluation criteria of 1 indicates that the coating film has poor stretchability and the lower the evaluation. The results are shown in Tables 6 to 9. (Evaluation criteria) 5: No cracks occur even when the elongation rate is 130% or more 4: No cracks occur even when the elongation rate is between 125% and 130% 3: No cracks occur even when the elongation rate is between 120% and 125% 2: No cracks occur even when the elongation rate is between 115% and 120% 1: Cracks occur even when the elongation rate is less than 115%

[0115] <Ethanol resistance> Using an inkjet recording device, the ink compositions of the examples and comparative examples were ejected onto the surface of each substrate, and then irradiated with an LED lamp having a wavelength of 385 nm to form a coating film, thereby obtaining each printed matter. The coating film thickness of each printed matter was 20 μm. The coating film of each printed material was rubbed back and forth 10 times with a cotton swab soaked in five different types of ethanol aqueous solutions, with ethanol concentrations ranging from less than 50% by mass to 80% by mass, and the presence or absence of scratches on the coating surface was visually confirmed. The ethanol resistance of each coating film was evaluated based on the following evaluation criteria. Among the evaluation criteria of 2 or more, the closer to 5 the coating film has excellent ethanol resistance and the higher the evaluation. Evaluation criteria of 1 indicates that the coating film has poor ethanol resistance and the lower the evaluation. The results are shown in Tables 6 to 9. (Evaluation criteria) 5: No change to the coating film even when rubbed with an ethanol solution of 80% or more by mass 4: No change to the coating when rubbed with an aqueous solution of ethanol with a concentration of 70% by mass or more but less than 80% by mass 3: No change to the coating when rubbed with an aqueous solution of ethanol with a concentration of 60% by mass or more but less than 70% by mass 2: No change to the coating when rubbed with an aqueous solution of ethanol with a concentration of 50% by mass or more but less than 60% by mass Scratches will occur on the coating when rubbing with an ethanol solution of less than 1:50% by mass.

[0116] <Flexibility> Using an inkjet recording device, the ink compositions of the examples and comparative examples were ejected onto the surface of each substrate, and then irradiated with an LED lamp having a wavelength of 385 nm to form a coating film, thereby obtaining each printed matter. The coating film thickness of each printed matter was 20 μm. Using a cylindrical mandrel bending tester, each printed material was bent around five types of mandrels with different temperatures and diameters according to the cylindrical mandrel method specified in JIS-K5600-5-1. The presence or absence of cracks in the coating film was then visually confirmed, and the flexibility of each coating film was evaluated based on the following evaluation criteria. Among the evaluation criteria of 2 or more, the closer to 5 the coating film is in terms of excellent flexibility and the higher the evaluation. Evaluation criteria of 1 indicates that the coating film is in terms of poor flexibility and the lower the evaluation. The results are shown in Tables 6 to 9. (Evaluation criteria) 5: No cracks occur even when bent at 0°C with a 2mm diameter mandrel 4: No cracks occur even when bent at 0°C with a 4mm diameter mandrel 3: No cracks occur even when bent at 0°C with a 6mm diameter mandrel 2: No cracks occur even when bent at 25°C with a 2mm diameter mandrel 1: When bent at 25°C with a 2mm diameter mandrel, cracks occur. In the above evaluation criteria, the lower the mandrel temperature and the smaller the mandrel diameter, the more severe the bending conditions.

[0117] <Weather resistance> Using an inkjet recording device, the ink compositions of the examples and comparative examples were ejected onto the surface of each substrate, and then irradiated with an LED lamp having a wavelength of 385 nm to form a coating film (clear ink layer), thereby obtaining each printed matter. The coating film thickness of each printed matter was 20 μm. Using a weather resistance evaluation device (Iwasaki Electric Co., Ltd.'s Eye Super UV Tester), UV was irradiated from the clear ink layer side of each printed item, with an output of 100 mW / cm 2 The weather resistance test was carried out under the following test conditions. The gloss of the coating film before and after the test was measured using an appearance analyzer Rhopoint IQ-S (manufactured by Rhopoint Instruments), and the rate of change between before the test and after 100 hours of testing was calculated, and the weather resistance of each coating film was evaluated based on the following evaluation criteria. Among the evaluation criteria of 2 or more, the closer to 5 the rating, the better the gloss of the coating film after the weathering test, and the higher the evaluation. Evaluation criteria of 1 indicates that the gloss of the coating film after the weathering test is poor, and the lower the evaluation. The results are shown in Tables 6 to 9. (Evaluation criteria) 5: Gloss change rate is less than 40% 4: Gloss change rate is 40% or more but less than 45% 3: Gloss change rate is 45% or more but less than 50% 2: Gloss change rate is 50% or more but less than 55% 1: Gloss change rate is 55% or more

[0118] [Table 6]

[0119] [Table 7]

[0120] [Table 8]

[0121] [Table 9]

[0122] The comparison results of Example 24 in Table 7 and Examples 53 and 54 in Table 9 show that when polymerizable compound B1) and polymerizable compound B2) are used in combination, the optical heat resistance, stretchability, ethanol resistance, flexibility, and weather resistance of the coating film are synergistically improved.

[0123] [Prints 1-15 and comparison prints 1-5] (Production of printed materials using ink set 1) Printed items were produced using the clear ink compositions of Examples 1, 24, and 53 described above and the color ink compositions for the colored layers described above. Specifically, an inkjet recording device was used to eject one of the color ink compositions (yellow, magenta, cyan, black, or white) shown in Table 5 onto the surface of each substrate, and each colored layer was formed by irradiating the substrate with active energy rays from an LED lamp having a wavelength of 385 nm. Next, using an inkjet recording device, the clear ink compositions of Examples 1, 24, and 53 described above were ejected onto the substrate surface over the colored layer, and a coating film was formed by irradiating the substrate with an LED lamp having a wavelength of 385 nm, resulting in printed items 1 to 15. The coating film thickness of each printed item was 20 μm. In addition, in the production of the above printed matter, comparative printed matters 1 to 5 were printed matters on which only a colored layer was formed.

[0124] [Prints 16-18 and comparison print 6] (Production of printed materials using ink set 2) Printed items were produced using the clear ink compositions of Examples 1, 24, and 53 described above and the color ink compositions for the colored layers described above. Specifically, an inkjet recording device was used to eject the color ink compositions shown in Table 5 (yellow, magenta, cyan, black, and white) onto the surface of each substrate in this order. After ejecting each color ink composition, the substrate was repeatedly irradiated with an LED lamp having a wavelength of 385 nm as active energy rays, thereby forming five colored layers. Next, using an inkjet recording device, the clear ink compositions of Examples 1, 24, and 53 described above were ejected onto the substrate surface over the colored layers, and a coating was formed by irradiating the substrate with an LED lamp having a wavelength of 385 nm, thereby obtaining printed items 16 to 18. The coating thickness of each printed item was 30 μm. Furthermore, in the production of the above printed matter, a printed matter in which only a colored layer was formed was designated as comparative printed matter 6. The thickness of the coating film of comparative printed matter 6 was 10 μm.

[0125] (evaluation) <Gloss level 1 (before heat resistance test)> The 20° gloss of each printed matter was measured using an appearance analyzer Rhopoint IQ-S (manufactured by Rhopoint Instruments). The gloss of each printed matter was evaluated based on the following evaluation criteria. Among the evaluation criteria of 2 or above, the closer to 5 the printed matter is, the higher the glossiness and the higher the evaluation. Evaluation criteria of 1 indicates that the printed matter is low in glossiness and the lower the evaluation. The results are shown in Tables 10 and 11. (Evaluation criteria) 5: 20° gloss level is 70 or more 4: 20° gloss level is 60 or more but less than 70 3: 20° gloss level is 50 or more but less than 60 2: 20° gloss level is 40 or more and less than 50 1:20°glossiness less than 40

[0126] <Gloss level 2 (after heat resistance test)> Each printed material was heated at 60°C for 15 minutes, and the 20° gloss of each printed material after heating was measured using an appearance analyzer Rhopoint IQ-S (manufactured by Rhopoint Instruments). The gloss of each printed material was evaluated based on the following evaluation criteria. Among the evaluation criteria of 2 or above, the closer to 5 the printed matter is, the higher the glossiness and the higher the evaluation. Evaluation criteria of 1 indicates that the printed matter is low in glossiness and the lower the evaluation. The results are shown in Tables 10 and 11. (Evaluation criteria) 5: 20° gloss level is 70 or more 4: 20° gloss level is 60 or more but less than 70 3: 20° gloss level is 50 or more but less than 60 2: 20° gloss level is 40 or more and less than 50 1:20°glossiness less than 40

[0127] <Ethanol resistance> The coating film of each printed material was rubbed back and forth 10 times with a cotton swab soaked in five different types of ethanol aqueous solutions, with ethanol concentrations ranging from less than 50% by mass to 80% by mass, and the presence or absence of scratches on the coating surface was visually confirmed. The ethanol resistance of each coating film was evaluated based on the following evaluation criteria. Among the evaluation criteria of 2 or more, the closer to 5 the coating film has excellent ethanol resistance and the higher the evaluation. Evaluation criteria of 1 indicates that the coating film has poor ethanol resistance and the lower the evaluation. The results are shown in Tables 10 and 11. 5: No change to the coating film even when rubbed with an ethanol solution of 80% or more by mass 4: No change to the coating when rubbed with an aqueous solution of ethanol with a concentration of 70% by mass or more but less than 80% by mass 3: No change to the coating when rubbed with an aqueous solution of ethanol with a concentration of 60% by mass or more but less than 70% by mass 2: No change to the coating when rubbed with an aqueous solution of ethanol with a concentration of 50% by mass or more but less than 60% by mass Scratches will occur on the coating when rubbing with an ethanol solution of less than 1:50% by mass.

[0128] <Stretchability>

[0129] Using an electric test stand MX2-500N (Imada), each printed material was stretched at a speed of 50.0 mm / min, and by varying the stretching time, five types of stretched printed materials were produced with stretch ratios ranging from less than 115% to 130%, with the unstretched material being considered 100%. Each of the resulting stretched printed materials was left at room temperature for 7 days, and the presence or absence of cracks in the coating film was visually inspected. The stretchability of each coating film was evaluated based on the following evaluation criteria. Among the evaluation criteria of 2 or more, the closer to 5 the coating film has excellent stretchability and the higher the evaluation. Evaluation criteria of 1 indicates that the coating film has poor stretchability and the lower the evaluation. The results are shown in Tables 10 and 11. (Evaluation criteria) 5: No cracks occur even when the elongation rate is 130% or more 4: No cracks occur even when the elongation rate is between 125% and 130% 3: No cracks occur even when the elongation rate is between 120% and 125% 2: No cracks occur even when the elongation rate is between 115% and 120% 1: Cracks occur even when the elongation rate is less than 115%

[0130] <Weather resistance> Using a weather resistance evaluation device (Iwasaki Electric Co., Ltd.'s Eye Super UV Tester), UV was irradiated from the clear ink layer side of each printed item, with an output of 100 mW / cm 2 The weather resistance test was carried out under the following test conditions. The gloss of the coating film before and after the test was measured using an appearance analyzer Rhopoint IQ-S (manufactured by Rhopoint Instruments), and the rate of change between before the test and after 100 hours of testing was calculated, and the weather resistance of each coating film was evaluated based on the following evaluation criteria. Among the evaluation criteria of 2 or more, the closer to 5 the rating, the better the gloss of the coating film after the weathering test, and the higher the evaluation. Evaluation criteria of 1 indicates that the gloss of the coating film after the weathering test is poor, and the lower the evaluation. The results are shown in Tables 10 and 11. (Evaluation criteria) 5: Gloss change rate is less than 40% 4: Gloss change rate is 40% or more but less than 45% 3: Gloss change rate is 45% or more but less than 50% 2: Gloss change rate is 50% or more but less than 55% 1: Gloss change rate is 55% or more

[0131] [Table 10]

[0132] [Table 11]

Claims

1. An actinic ray-curable ink composition having coating film properties that satisfy at least one of the following conditions 1 and 2: Condition 1: (a) The change in 20° gloss after heating the coating film is less than 55%, and (b) no cracks occur in the coating film after stretching even when the stretching ratio is 115% or more. Condition 2: (c) When exposed to an aqueous solution of 50% by mass or more of ethanol, the surface of the coating film shows no change in appearance, and (d) when bent around a mandrel having a diameter of 2 mm at 25°C, no cracks occur in the coating film.

2. The actinic ray-curable ink composition according to claim 1 , further having coating film properties that satisfy the following condition 3: Condition 3: The change in 20° gloss after UV irradiation of the coating film is less than 55%.

3. As the polymerizable compound B) which is an active energy ray polymerizable compound, Polymerizable compound B1): A polymerizable compound having 4 or more functionalities and a linear aliphatic hydrocarbon structure having 4 to 12 carbon atoms, The actinic ray-curable ink composition according to claim 1 or 2.

4. The polymerizable compound B1) contains a tetrafunctional to octafunctional polymerizable compound having a linear aliphatic hydrocarbon structure having 4 to 12 carbon atoms, The actinic ray-curable ink composition according to claim 3 .

5. the content of the polymerizable compound B1) is 2.5% by mass or more and 12.5% ​​by mass or less with respect to the total mass of the actinic energy ray-curable ink composition; The actinic ray-curable ink composition according to claim 3 or 4.

6. As the polymerizable compound B) which is an active energy ray polymerizable compound, Polymerizable compound B2): Contains a bifunctional polymerizable compound having a cyclic structure and a glass transition temperature of 100°C or higher, The actinic ray-curable ink composition according to claim 1 or 2.

7. The polymerizable compound B2) contains a bifunctional polymerizable compound having a cyclic structure and a glass transition temperature of 120°C or higher. The actinic ray-curable ink composition according to claim 6 .

8. The polymerizable compound B2) contains a bifunctional polymerizable compound having an aliphatic fused ring structure, an aliphatic bridged ring structure, or an aliphatic bridged fused ring structure, The actinic ray-curable ink composition according to claim 6 or 7.

9. the content of the polymerizable compound B2) is 10% by mass or more and 30% by mass or less with respect to the total mass of the active energy ray-curable ink composition; The actinic ray-curable ink composition according to any one of claims 6 to 8.

10. As the active energy ray polymerizable compound, Furthermore, polymerizable compound C): a monofunctional polymerizable compound having a cyclic structure containing The actinic ray-curable ink composition according to any one of claims 3 to 9.

11. Further, the composition contains at least one selected from the group consisting of an ultraviolet absorber, a light stabilizer, and an antioxidant. The actinic ray-curable ink composition according to any one of claims 3 to 10.

12. The antioxidant contains at least one selected from the group consisting of thioether-based antioxidants, monophenol-based antioxidants, bisphenol-based antioxidants, trisphenol-based antioxidants, tetrakisphenol-based antioxidants, tocotrienol-based antioxidants, tocopherol-based antioxidants, and NH-type hindered amine-based antioxidants. The actinic ray-curable ink composition according to claim 11.

13. The ultraviolet absorber contains a triazine-based ultraviolet absorber. The actinic ray-curable ink composition according to claim 11 or 12.

14. The antioxidant contains an NH-type hindered amine. The actinic ray-curable ink composition according to any one of claims 11 to 13.

15. A coating film formed on a surface of a substrate, The coating film contains a cured product of the active energy ray-curable ink composition according to any one of claims 1 to 14. printed matter.

16. The actinic ray-curable ink composition according to any one of claims 1 to 14 is ejected onto a surface of a substrate by an inkjet method. Recording method.

17. The actinic ray-curable ink composition according to any one of claims 1 to 14 is ejected onto a surface of a substrate by an inkjet method. Methods for producing printed materials.

18. An ink set comprising the actinic ray-curable ink composition according to any one of claims 1 to 14 and a color ink composition, the actinic ray-curable ink composition does not contain a colorant, the color ink composition contains a colorant and has a viscosity of less than 100 mPa·s during printing; the color ink composition is at least one selected from the group consisting of a yellow ink composition, a magenta ink composition, a cyan ink composition, a black ink composition, and a white ink composition; Ink set.

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