Ink set and method for producing printed matter

Abstract

To provide an active energy ray-curable inkjet ink set capable of providing a printed matter having a laminate which can achieve both excellent adhesion to a hard substrate and excellent scratch resistance, suppress an interlayer separation between a primer layer and a colored layer and improve hardness.SOLUTION: There is provided a printed matter 1 comprising a base material 2, a primer layer 6 formed on the base material 2 and a colored layer 7 formed on the primer layer 6, wherein the primer layer 6 is formed by a primer ink containing (A) acryloyl morpholine and (B) a monofunctional monomer containing a hydroxyl group at a mass ratio (A / B) of (A) acryloyl morpholine to 100 pts.mass of the monofunctional monomer of (B) of 10 to 50 pts.mass and the colored layer 7 is formed with a coloring ink containing a monomer containing at least one N group selected from a urethane (meth)acrylate, an amine modified (meth)acrylate and an acrylamide.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an ink set and a method for producing a printed matter. [Background technology]

[0002] Patent Documents that disclose ink compositions that teach the incorporation of acryloylmorpholine include Patent Document 1 and Patent Document 2.

[0003] For example, Patent Document 1 discloses a coating composition that contains 20.0 to 70.0 mass% of a water-soluble acrylamide monomer, 5.0 to 60.0 mass% of a water-soluble hydroxyl group-containing monofunctional monomer, and 8.0 to 35.0 mass% of a water-insoluble polymerizable compound, based on the total mass of all polymerizable components, and further contains 3.0 to 10.0 mass parts of a photopolymerization initiator and / or a sensitizer, based on 100 mass parts of the total mass of all polymerizable components, and further contains a pigment and water, in which the mass ratio of the water-soluble acrylamide monomer to the water-soluble hydroxyl group-containing monofunctional monomer (acrylamide monomer / hydroxyl group-containing monofunctional monomer) is 0.3 to 10.0, and is irradiated with an integrated light amount of 100 mJ / cm by a UV-LED having a peak wavelength of 365 to 405 nm. 2 The present invention discloses an ultraviolet-curable water-based ink jet printing ink composition for printing, which has a step of being provisionally cured by irradiation as described below.

[0004] Patent Document 2 discloses a radiation-curable inkjet ink set including a radiation-curable clear ink composition and a radiation-curable colored ink composition, the clear ink composition containing a hydrogen abstraction type photopolymerization initiator and a hydroxyl group-containing monomer, and the colored ink composition containing an intramolecular cleavage type photopolymerization initiator and a coloring material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-131834 A [Patent Document 2] JP 2020-100757 A Summary of the Invention [Problem to be solved by the invention]

[0006] 2. Description of the Related Art In recent years, attention has been focused on directly printing inkjet ink onto a hard substrate such as glass to provide the substrate with decorations such as letters, pictures, patterns, and the like.

[0007] However, when printing a laminate of a primer layer and a colored layer on a hard substrate, no study has been conducted to date on issues such as achieving both adhesion to the substrate and scratch resistance, as well as preventing delamination of the laminate and improving the hardness of the ink layer.

[0008] In this regard, Patent Document 1 discloses an ink composition containing acryloylmorpholine (ACMO (registered trademark)) and 4-hydroxybutyl acrylate (4HBA). The invention described in Patent Document 1 aims to provide an ink composition with excellent curability and water resistance. However, this ink composition is printed in a single layer on a substrate. Therefore, if the ink layer is formed in a form that also serves as a colored layer, the amount of monomer components that contribute to adhesion is reduced by the additional blending of pigments, etc., and there is a concern that adhesion will decrease. In addition, since this is an ink composition used for a single-layer ink layer, there is no suggestion about issues such as interlayer peeling in a laminate of ink layers. Furthermore, since the ink composition of Patent Document 1 is an aqueous ink, it contains a solvent (water) that requires time to dry. Therefore, there is also the issue that the ink cures slowly and printing efficiency decreases.

[0009] Patent Document 2 discloses an ink set that combines a clear ink that contains 4HBA and can contain ACMO (registered trademark) with a colored ink. The invention described in Patent Document 2 aims to provide an ink set that is low odor and has excellent curing properties. However, since the clear ink is an ink containing 4HBA as the main component, it has relatively good curing properties, but is not highly rated in terms of hardness such as pencil hardness. In addition, when the clear ink is printed as a colored layer in consideration of the adhesion of the ink layer to the substrate, the amount of monomer components that contribute to adhesion is reduced by the additional blending of pigments, etc., and there is a concern that the adhesion may decrease.

[0010] Furthermore, neither Patent Document 1 nor Patent Document 2 considers at all the scratch resistance of a laminate of a primer layer and a colored layer on a hard substrate.

[0011] Therefore, an object of the present invention is to provide an actinic ray-curable inkjet ink set which can provide a printed matter having a laminate that can achieve both excellent adhesion to a hard substrate and excellent scratch resistance, and further can suppress interlayer peeling between the primer layer and the colored layer and improve hardness.

[0012] Another object of the present invention is to provide a method for producing a printed item having a laminate obtained by using the active energy ray-curable inkjet ink set, which can achieve both excellent adhesion to a hard substrate and excellent scratch resistance, and further can suppress interlayer peeling between the primer layer and the colored layer and improve hardness. [Means for solving the problem]

[0013] The ink set of the present invention is an actinic ray-curable inkjet ink set comprising a combination of a clear primer ink and one or more types of colored inks, the primer ink containing (A) acryloylmorpholine and (B) a monofunctional monomer containing a hydroxyl group, in which the mass ratio (A / B) of (A) acryloylmorpholine to 100 parts by mass of (B) the monofunctional monomer containing a hydroxyl group is 10 parts by mass to 50 parts by mass, and the colored ink contains at least one monomer containing an N group selected from urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide.

[0014] In the ink set of the present invention, the monofunctional monomer constituting the primer ink may be 4-hydroxybutyl acrylate.

[0015] In the ink set of the present invention, the primer ink may further contain a silane coupling agent.

[0016] The ink set of the present invention may further include an ink containing a monomer having an isocyanurate structure as an overcoat ink to be printed on the color ink.

[0017] The method for producing a printed matter of the present invention is a method for producing a printed matter using an actinic energy ray-curable inkjet ink set comprising a combination of a clear primer ink and one or more colored inks, the method comprising a first step of printing the primer ink on a substrate, and a second step of printing the one or more colored inks on the primer ink, the primer ink comprising (A) acryloylmorpholine and (B) a monofunctional monomer containing a hydroxyl group, the mass ratio (A / B) of (A) acryloylmorpholine per 100 mass parts of (B) the monofunctional monomer containing a hydroxyl group being 10 mass parts to 50 mass parts, and the colored ink comprising at least one N-group-containing monomer selected from urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide.

[0018] The method for producing a printed matter of the present invention further includes a third step of printing an overcoat ink so as to cover the color ink, and the overcoat ink may include a monomer having an isocyanurate structure.

[0019] In the method for producing a printed matter of the present invention, the substrate may be a hard substrate. Effect of the Invention

[0020] According to the present invention, it is possible to provide an actinic ray-curable inkjet ink set which can provide a printed item having a laminate that can achieve both excellent adhesion to a hard substrate and excellent scratch resistance, and further can suppress interlayer peeling between the primer layer and the colored layer and improve hardness.

[0021]

[0023] Furthermore, according to the present invention, it is possible to provide a method for producing a printed item having a laminate obtained by using the active energy ray-curable inkjet ink set, which can achieve both excellent adhesion to a hard substrate and excellent scratch resistance, and further can suppress interlayer peeling between the primer layer and the colored layer and improve hardness. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic diagram of a printed matter produced by a method for producing a printed matter according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing a part of the method for producing the printed matter. [Diagram 3] FIG. 3 is a diagram showing a process subsequent to the process of FIG. [Figure 4] FIG. 4 is a diagram showing a process subsequent to the process of FIG. [Diagram 5] FIG. 5 is a diagram showing a process subsequent to the process of FIG. [Figure 6] FIG. 6 is a diagram showing a process subsequent to the process of FIG. [Figure 7] FIG. 7 is a diagram showing a process subsequent to the process of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] [Ink set] The ink set of the present invention is an actinic energy ray-curable inkjet ink set. The inks used in the actinic energy ray-curable inkjet ink set are, for example, UV inks containing polymerizable compounds such as monomers and oligomers (hereinafter, these may be collectively referred to simply as "monomers") that undergo a polymerization reaction and are cured by irradiation with ultraviolet light.

[0024] The ink set of the present invention is a combination of (1) a primer ink, (2) one or more colored inks, and (3) an overcoat ink. The combination of overcoat inks is arbitrary.

[0025] (1) Primer ink The primer ink contains at least (A) acryloylmorpholine (ACMO (registered trademark)) and (B) a monofunctional monomer containing a hydroxyl group as radically polymerizable components.

[0026] (1-A) Acryloylmorpholine Acryloyl morpholine contains an N group, so it has good affinity with non-porous substrates such as glass, and contributes to improving the pencil hardness of the printed layer. In particular, acryloyl morpholine has a cyclic structure, so it has good scratch resistance. More specifically, when acryloyl morpholine is polymerized by UV curing, the cyclic structure becomes a steric hindrance, so that it does not adhere too closely to other monomers and curing shrinkage is relatively suppressed. This results in a flexible coating film with good scratch resistance.

[0027] The content of acryloylmorpholine in the primer ink is, for example, 10 parts by mass or more, preferably 15 parts by mass or more, as the mass ratio (A / B) of acryloylmorpholine to 100 parts by mass of the monofunctional monomer containing a hydroxyl group (B). The mass ratio (A / B) is, for example, 50 parts by mass or less, preferably 35 parts by mass or less. More specifically, the mass ratio (A / B) is, for example, 10 parts by mass or more and 50 parts by mass or less, preferably 15 parts by mass or more and 35 parts by mass or less. If it is less than 10 parts by mass, there is little acryloylmorpholine, which contributes to adhesion to the substrate and also contributes to improving pencil hardness, and the printed layer may not have sufficient scratch resistance and pencil hardness. On the other hand, if it exceeds 50 parts by mass, the coating film may become too hard and adhesion to the substrate may be insufficient.

[0028] (1-B) Monofunctional monomer containing a hydroxyl group Examples of the monofunctional monomer containing a hydroxyl group include (meth)acrylates containing a hydroxyl group. As the (meth)acrylate containing a hydroxyl group, various (meth)acrylates having a hydroxyl group in the molecule can be used. Specific examples of the (meth)acrylate containing a hydroxyl group include, but are not limited to, the following various compounds.

[0029] 4-hydroxybutyl acrylate (4HBA), 2-hydroxybutyl acrylate (2HBA), 2-hydroxyethyl acrylate (2HEA), 2-hydroxypropyl acrylate (2HPA), 2-hydroxyethyl methacrylate (2HEMA), 2-hydroxypropyl methacrylate (2HPMA). These can be used alone or in combination of two or more. Of these, 4-hydroxybutyl acrylate is preferable. Since 4-hydroxybutyl acrylate has a long crosslinking chain, it is possible to improve the flexibility of the primer layer and further increase the adhesion of the primer layer to the surface of a hard substrate.

[0030] The content of the monofunctional monomer containing a hydroxyl group in the primer ink is, for example, 45% by mass or more, preferably 50% by mass or more, based on the total mass of the monomers contained in the primer ink. The content of the monofunctional monomer containing a hydroxyl group in the primer ink is, for example, 90% by mass or less, preferably 85% by mass or less, based on the total mass of the monomers contained in the primer ink. More specifically, the content of the monofunctional monomer containing a hydroxyl group in the primer ink is, for example, 45% by mass or more and 90% by mass or less, preferably 50% by mass or more and 85% by mass or less, based on the total mass of the monomers contained in the primer ink. If it is less than 45% by mass, there is a small amount of the monofunctional monomer containing a hydroxyl group that contributes to adhesion to the substrate, and sufficient adhesion may not be obtained. On the other hand, if it exceeds 90% by mass, there is little room for blending other monomers. In particular, if the amount of acryloylmorpholine is insufficient, the scratch resistance and pencil hardness of the printed layer are reduced. When two or more types of monofunctional monomers containing a hydroxyl group are used in combination, the total content thereof may be within the above range.

[0031] (1-C) Other Monomers The primer ink may further contain other monomers other than acryloylmorpholine and monofunctional monomers containing a hydroxyl group. For example, known monofunctional, bifunctional, trifunctional or higher polyfunctional monomers and oligomers can be used as such monomers. For example, unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid, salts or esters thereof, urethane, amides and their anhydrides, acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes. For example, the oligomers include oligomers formed from the above monomers such as linear acrylic oligomers, epoxy (meth)acrylates, oxetane (meth)acrylates, aliphatic urethane (meth)acrylates, aromatic urethane (meth)acrylates, and polyester (meth)acrylates. These can be used alone or in combination of two or more.

[0032] The content of the other monomer in the primer ink is, for example, the remainder of acryloylmorpholine and the monofunctional monomer containing a hydroxyl group, that is, the blending ratio of acryloylmorpholine and the monofunctional monomer containing a hydroxyl group is set preferentially.

[0033] The primer ink is a clear ink in which the content of coloring materials such as pigments and dyes is less than 0.1% by mass, and preferably 0% by mass.

[0034] The primer ink may contain an additive (component) for a radical polymerizable component. The additive is not particularly limited, but examples thereof include a radical polymerization initiator, a sensitizer, a radical polymerization inhibitor, a surfactant, and a silane coupling agent.

[0035] (1-D) Radical polymerization initiator When the active energy ray irradiated to the primer ink is light such as ultraviolet light, the radical polymerization initiator imparts photocurability as active energy ray curability to the primer ink. As the radical polymerization initiator, various compounds that can generate radicals by irradiation with light of any wavelength and cause a radical polymerization reaction of the radically polymerizable component can be used.

[0036] The radical polymerization initiator is not particularly limited, but examples thereof include the various compounds shown below.

[0037] Benzophenones or salts thereof such as benzophenone, hydroxybenzophenone, 2-chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone (Michler's ketone), 4,4'-bisdimethylaminobenzophenone (Michler's ketone), 4-methoxy-4'-dimethylaminobenzophenone, and the benzophenone compound represented by the general formula (1) disclosed in JP2008-280427A.

[0038] Thioxantone compounds or salts thereof such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, 1-chloro-4-propoxythioxanthone, 2,4-diethylthioxanthone, 4-isopropylthioxanthone, isopropoxychlorothioxanthone, and thioxanthone compounds represented by the general formula (2) of JP2008-280427A.

[0039] Anthraquinones such as ethylanthraquinone, benzanthraquinone, aminoanthraquinone, and chloroanthraquinone.

[0040] Acetophenones such as acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxyphenylacetophenone, 4'-dimethylaminoacetophenone, and dimethylhydroxyacetophenone.

[0041] 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(m-methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-di(p-methoxyphenyl)-5-phenylimidazole Imidazoles such as midazole dimer, 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer, and 2,4,5-triarylimidazole dimer.

[0042] Benzoins such as benzyl dimethyl ketal, 2-benzyl-2-dimethylamino-1-(4-morpholinophenylbutan)-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenyl-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 9,10-phenanthrenequinone, benzoins, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-propyl ether, benzoin isobutyl ether, and benzoin-n-butyl ether.

[0043] Acridine derivatives such as 9-phenylacridine and 1,7-bis(9,9′-acridinyl)heptane.

[0044] Phosphine oxides such as bisacylphosphine oxide, bisphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

[0045] 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}2-methylpropan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)butan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, methylbenzoylformate, azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trihalomethyltriazine, benzyl, methylbenzoyl, methyl benzoylformate, 2-benzyl-2-dimethylamino-4-morpholinobutyrophenone, etc. The above-mentioned radical polymerization initiators can be used alone or in combination of two or more kinds.

[0046] The content of the radical polymerization initiator can be set arbitrarily. However, in consideration of imparting good photocurability to the primer ink, the content of the radical polymerization initiator is, for example, 0.1% by mass or more and 15% by mass or less, and preferably 1% by mass or more and 10% by mass or less, based on the total mass of the primer ink. When two or more kinds of radical polymerization initiators are used in combination, the total content may be set to the above range.

[0047] (1-E) Sensitizer The photocurable primer ink preferably contains an optional sensitizer as necessary. The sensitizer becomes excited by irradiation with ultraviolet light or the like, and interacts with the radical polymerization initiator to help generate radicals in the radical polymerization initiator. In particular, when an LED is used as a light source, the wavelength range is narrow. Therefore, it is preferable to contain a sensitizer to expand the wavelength range to which the primer ink is sensitive and improve the sensitivity, i.e., to sensitize the ink.

[0048] Examples of the sensitizer include, among the above-mentioned radical polymerization initiators, thioxanthones or salts thereof, such as 2,4-diethylthioxanthone, 1-chloro-4-propoxythioxanthone, a mixture of 2-isopropylthioxanthone and 4-isopropylthioxanthone, and the like; eutectic mixtures of benzophenone and 2,3- and 4-methylbenzophenone; benzophenones or salts thereof, such as methyl-2-benzophenone, benzophenone, 4-benzoyl-4'-methylphenyl sulfide, 4-methylbenzophenone, and 4-phenylbenzophenone; 2-ethylanthraquinone; and 4,4'-bisdiethylaminobenzophenone (Michler's ketone).

[0049] Other sensitizers include, for example, benzoate compounds such as ethyl-4-(dimethylamino)benzoate and 2-ethyl-4-(dimethylaminobenzoate), naphthalene benzoxazolyl derivatives, thiophene benzoxazolyl derivatives, stilbene benzoxazolyl derivatives, coumarin derivatives, styrene biphenyl derivatives, pyrazolone derivatives, stilbene derivatives, styryl derivatives of benzene and biphenyl, bis(benzazol-2-yl) derivatives, carbostyril, naphthalimide, dibenzothiophene-5,5'-dioxide derivatives, pyrene derivatives, pyridotriazole, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, ethanolamine, diethanolamine, triethanolamine, and the like.

[0050] As the sensitizer, a compound having an absorption wavelength range suitable for sensitization can be selected from the various sensitizers described above according to the wavelength range of light from the light source and the absorption wavelength range of the radical polymerization initiator. The above sensitizers can be used alone or in combination of two or more kinds.

[0051] The content of the sensitizer can be set arbitrarily. However, in consideration of the well manifestation of the sensitizing effect of the sensitizer, the content of the sensitizer is, for example, 0.1% by mass or more and 5% by mass or less, and preferably 0.5% by mass or more and 4% by mass or less, based on the total mass of the primer ink. When two or more kinds of sensitizers are used in combination, the total content may be set to the above range.

[0052] (1-F) Radical polymerization inhibitors The primer ink may contain a radical polymerization inhibitor as necessary. The radical polymerization inhibitor prevents the primer ink from gelling due to a radical polymerization reaction of the radically polymerizable component during storage of the primer ink or during storage sealed in a package. As the radical polymerization inhibitor, various compounds capable of preventing the above-mentioned gelling can be used.

[0053] Examples of the radical polymerization inhibitor include nitrosamine compounds, hydroquinones, catechols, hindered amines, phenols, phenothiazines, and quinones having a condensed aromatic ring.

[0054] Examples of the nitrosoamine compound include the ammonium salt of N-nitrosophenylhydroxylamine (ammonium-N-nitrosophenylhydroxylamine), the aluminum salt of N-nitrosophenylhydroxylamine (aluminum-N-nitrosophenylhydroxylamine), and the like.

[0055] Examples of hydroquinones include hydroquinone, hydroquinone monomethyl ether, 1-o-2,3,5-trimethylolhydroquinone, 2-tert-butylhydroquinone, etc. Examples of catechols include catechol, 4-methylcatechol, 4-tert-butylcatechol, etc.

[0056] Examples of the hindered amines include any hindered amines having a polymerization inhibitory effect. Examples of the phenols include phenol, butylhydroxytoluene, butylhydroxyanisole, pyrogallol, alkyl gallate, hindered phenols, etc. Examples of the phenothiazines include phenothiazine, etc. Examples of the quinones having a condensed aromatic ring include naphthoquinone, etc. The above-mentioned radical polymerization inhibitors can be used alone or in combination of two or more kinds.

[0057] The content of the radical polymerization inhibitor can be set arbitrarily. The content of the radical polymerization inhibitor is, for example, 0.01% by mass or more and 3% by mass or less, preferably 0.05% by mass or more and 0.5% by mass or less, based on the total mass of the primer ink. When two or more kinds of radical polymerization inhibitors are used in combination, the total content may be set to the above range.

[0058] (1-G) Surfactant Examples of the surfactant include various surfactants such as silicone-based, fluorine-based, anionic, cationic, nonionic and amphoteric surfactants. Of these, silicone-based and fluorine-based surfactants are preferred.

[0059] Examples of commercially available silicone surfactants include BYK (registered trademark) 307, 310, 320, 330, 333, 342, and 377 manufactured by BYK Japan Co., Ltd.; and 8029 ADDITIVE, 8054 ADDITIVE, 205SL, 8032 ADDITIVE, 57 ADDITIVE, and 8526 ADDITIVE manufactured by Dow Corning Toray Co., Ltd.

[0060] Examples of commercially available fluorine-based surfactants include Megafac (registered trademark) F-553, F-554, F-556, F-558, and F-559 manufactured by DIC Corporation, fluorine-containing oligomers and fluorine-containing reactive oligomers of Futergent (registered trademark) manufactured by Neos Co., Ltd., Surflon (registered trademark) manufactured by AGC Sei Chemical Co., Ltd. that does not contain water as a solvent, and LE-604 and LE-605 manufactured by Kyoeisha Chemical Co., Ltd. The above surfactants can be used alone or in combination of two or more kinds.

[0061] The content of the surfactant can be set arbitrarily. The content of the surfactant is, for example, 0.1% by mass or more and 3% by mass or less, and preferably 0.2% by mass or more and 2% by mass or less, based on the total mass of the primer ink, calculated as the amount of the active ingredient in the surfactant. When two or more types of surfactants are used in combination, the total content may be set to the above range.

[0062] (1-H) Silane coupling agent The primer ink may contain a silane coupling agent as necessary. The incorporation of a silane coupling agent can improve the hot and cold water resistance of the printed layer. Therefore, even after the printed layer is immersed in hot and cold water, the adhesion to the substrate, the adhesion between the primer layer and the colored layer, and the pencil hardness can be maintained at a high level.

[0063] Silane coupling agents, for example, contain, in the same molecule, an organic functional group X for ensuring adhesion with the resin forming the hard substrate, and a hydrolyzable group OR for hydrolyzing and bonding with the silica sol by a sol-gel reaction. 1 and having the formula (1): XSi(OR 1 )3(1) Any of various compounds represented by the following formula can be used.

[0064] Of these, the hydrolyzable group OR 1Examples of the organic functional group X include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, a t-butoxy group, etc. Examples of the organic functional group X include groups having a functional group in its structure, such as a vinyl group, an epoxy group, a styryl group, a methacryloxy group, an acryloxy group, an amino group, a ureido group, a chloropropyl group, a mercapto group, a sulfide group, etc.

[0065] Among these, an amino group-containing silane coupling agent having an amino group as the organic functional group X is used. The amino group in the silane coupling agent has a high affinity for radical polymerizable components, and in particular, with (meth)acrylates containing hydroxyl groups, hydrogen bonds are formed between the hydroxyl groups in the molecule. Therefore, when the primer ink is printed on the surface of a hard substrate, the amino group-containing silane coupling agent in the printed primer precursor layer is unevenly distributed at the interface with the glass substrate, and acts to increase the adhesion of the primer layer to the surface of the glass substrate after the curing reaction.

[0066] The amino group-containing silane coupling agent is not particularly limited, but examples thereof include the various compounds shown below.

[0067] N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride. The above-mentioned silane coupling agents can be used alone or in combination of two or more kinds.

[0068] The content of the silane coupling agent can be set arbitrarily. The content of the silane coupling agent is, for example, 0.1% by mass or more and 1.3% by mass or less, preferably 0.3% by mass or more and 1.3% by mass or less, based on the total mass of the primer ink. When two or more kinds of silane coupling agents are used in combination, the total content of the agents may be set to the above range.

[0069] (1-I) Other Additives The primer ink of the present invention may contain additives other than the above-mentioned additives, such as known polymerization accelerators, penetration accelerators, wetting agents (moisturizing agents), fixing agents, antifungal agents, preservatives, antioxidants, chelating agents, thickeners, etc.

[0070] (2) Colored ink The color ink contains, as a radically polymerizable component, at least a monomer containing an N group.

[0071] (2-A) Monomers containing N groups The N-group-containing monomer contributes to improving the scratch resistance of the printed layer. The N-group-containing monomer is at least one selected from the group consisting of urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide.

[0072] Examples of the urethane (meth)acrylate include urethane (meth)acrylate obtained by reacting a polyisocyanate with a (meth)acrylate having a hydroxyl group, urethane (meth)acrylate obtained by reacting a polyester of polyisocyanate and a terminal diol with a (meth)acrylate having a hydroxyl group, and urethane (meth)acrylate obtained by reacting a polyisocyanate obtained by reacting a polyol with an excess of diisocyanate with a (meth)acrylate having a hydroxyl group. These can be used alone or in combination of two or more kinds.

[0073] Specific examples of urethane (meth)acrylates include CN961E75, CN961H81, CN962, CN963, CN963A80, CN963B80, CN963E75, CN963E80, CN963J85, CN964, CN964E75, CN964A85, CN965, CN965A80, CN966A80, CN966H90, CN966J75, CN966R60, CN980, CN981, and CN982 manufactured by Sartomer Corporation. , CN982A75, CN982B88, CN982E75, CN983, CN985B88, CN996, CN9001, CN9002, CN9178, CN9788, CN9893, and 230, 244, 245, 270, 280 / 15IB, 284, 285, 4858, 8307, 8411, 8804, 8807, 9270, etc., among the EBECRYL (registered trademark) series manufactured by Daicel-Allnex Co., Ltd., are listed, and CN983 is particularly preferred. These may be used alone or in combination of two or more kinds.

[0074] As the amine-modified (meth)acrylate, for example, various compounds capable of radical polymerization, which have a structure in which a (meth)acrylate monomer or oligomer is modified with an amino group, can be used. Specific examples of the amine-modified (meth)acrylate include CN371, CN373, CN383, CN386, etc., all of which are amine-modified acrylates manufactured by Sartomer Corporation, and CN371 is particularly preferred. These can be used alone or in combination of two or more kinds.

[0075] Examples of acrylamide include (meth)acrylamides such as N,N-dimethylacrylamide (DMAA), hydroxyethylacrylamide, N,N-diethylacrylamide (DEAA), N-isopropylacrylamide (NIPAM), N-[3-(dimethylamino)propyl]acrylamide (DMAPAA), diacetoneacrylamide (DAAM), N-tert-butylacrylamide, N-phenylacrylamide, N-ethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylmethacrylamide, N-(isobutoxymethyl)methacrylamide, and N-(triphenylmethyl)methacrylamide. These can be used alone or in combination of two or more.

[0076] As the N-group-containing monomer, any one of urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide may be selectively used, but it is preferable to use two or more of urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide. In particular, it is preferable to use three of urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide.

[0077] By using a combination of multiple types, the scratch resistance of the printing layer can be improved compared to the case of selectively using only one type. In particular, it is preferable to use three types of urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide in combination. When using three types in combination, two or more types of each of urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide may be used in combination.

[0078] The content of the N-group-containing monomer is, for example, 20% by mass or more, preferably 30% by mass or more, based on the total mass of the monomers contained in the color ink. The content of the N-group-containing monomer is, for example, 70% by mass or less, preferably 60% by mass or less, based on the total mass of the monomers contained in the color ink. More specifically, the content of the N-group-containing monomer is, for example, 20% by mass or more and 70% by mass or less, preferably 30% by mass or more and 60% by mass or less, based on the total mass of the monomers contained in the color ink. If it is less than 20% by mass, the amount of the N-group-containing monomer is small, and sufficient scratch resistance may not be obtained. On the other hand, if it exceeds 70% by mass, there is little room for blending other monomers. In particular, if the VEEA (VEEM) described later is insufficient, the curability of the color ink decreases, and interlayer peeling is likely to occur between the primer layer and the color layer. In addition, if the monomer containing an N group is in excess, the N groups in the color ink are consumed through polymerization, and the number of N groups facing the outside of the color layer and adhering to the substrate or primer layer decreases, resulting in, for example, a decrease in adhesion between the primer layer and the color layer. When two or more types of monomers containing an N group are used in combination, the total content thereof may be within the above range.

[0079] The mixing ratio of each of the three types of urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide when used in combination will be explained. These three types each play a different role in the colored layer. For example, urethane (meth)acrylate is mainly responsible for adhesion and coating strength, amine-modified (meth)acrylate is mainly responsible for promoting curing (assisting the reaction of the polymerization initiator), and acrylamide is mainly responsible for adjusting the viscosity. It is necessary to adjust the viscosity of the ink according to the specifications of the printing device in which the ink set is installed. Therefore, the mixing ratio of the above three types may be appropriately adjusted so that the viscosity of the colored ink matches the specifications of the printing device within the range of the preferred content (total amount) of the N-group-containing monomer.

[0080] (2-B) 2-(2-vinyloxyethoxy)ethyl (meth)acrylate The color ink preferably further contains 2-(2-vinyloxyethoxy)ethyl (meth)acrylate (VEEA (VEEM)).

[0081] VEEA (VEEM) is preferably the main component in the colored ink, that is, VEEA (VEEM) is preferably the monomer contained in the colored ink in the largest proportion.

[0082] If the color ink contains little or no VEEA (VEEM), the color ink will not cure well and will not adhere well to the primer layer, which may cause delamination between the primer layer and the color ink. On the other hand, if the color ink contains a lot of VEEA (VEEM), the color ink will shrink during curing and float, resulting in insufficient adhesion to the primer layer.

[0083] The content of VEEA (VEEM) in the color ink is, for example, 40% by mass or more, and preferably 66% by mass or more, based on the total mass of the N-group-containing monomers (100). The content of VEEA (VEEM) is, for example, 400% by mass or less, and preferably 234% by mass or less, based on the total mass of the N-group-containing monomers (100). More specifically, the content of VEEA (VEEM) is, for example, 40% by mass or more and 400% by mass or less, and preferably 66% by mass or more and 234% by mass or less, based on the total mass of the N-group-containing monomers (100).

[0084] If the content is less than 40% by mass, the ink viscosity becomes too high due to the increase in the amount of other highly viscous monomers, and the curability tends to decrease. If the curability decreases, the adhesion to the primer layer and scratch resistance at the initial stage are both insufficient, and as a result, it becomes difficult to improve the adhesion and scratch resistance after immersion in hot and cold water. On the other hand, if the content exceeds 400% by mass, the ink will cure too much, making the colored layer too hard and the viscosity too low. If the colored ink cures too much, the colored ink will cure and shrink, causing it to float, and the adhesion to the primer layer may be insufficient. If the ink viscosity is too high, continuous ejection becomes difficult, and if the ink viscosity is too low, mist (scattering) may occur on the printed matter. In other words, a large change in the ink viscosity may have a large effect on the ejection properties of the ink.

[0085] (2-C) Other Monomers The color ink may further contain other monomers other than the N-group-containing monomer and VEEA (VEEM). As such monomers, for example, monofunctional, difunctional, trifunctional or higher polyfunctional monomers and oligomers exemplified in "(1-C) Other Monomers" of the primer ink described above can be used.

[0086] The content of other monomers in the color ink is, for example, the remainder of the N-group-containing monomer and VEEA (VEEM). In other words, the blending ratio of the N-group-containing monomer and VEEA (VEEM) is set preferentially.

[0087] (2-D) Colorants As the coloring agent in the color ink, various pigments, dyes, etc. of various colors according to the color of the color ink can be used.

[0088] In particular, in consideration of improving the light resistance of the pattern layer, various inorganic pigments and / or organic pigments are preferred.

[0089] Among these, examples of inorganic pigments include metal compounds such as iron oxide, and various types of neutral, acidic, basic, etc. carbon black produced by known methods such as the contact method, furnace method, and thermal method.

[0090] Examples of organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments), polycyclic pigments (such as phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, diketopyrrolopyrrole pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments), dye chelates (such as basic dye chelates and acid dye chelates), nitro pigments, nitroso pigments, and aniline black.

[0091] Specific examples of the pigment include the following pigments.

[0092] (Yellow pigment) CI Pigment Yellow 1, 2, 3, 12, 13, 14, 14C, 16, 17, 20, 24, 73, 74, 75, 83, 86, 93, 94, 95, 97, 98, 109, 110, 114, 117, 120, 125, 128, 129, 130, 137, 138, 139, 147, 148, 150, 151, 154, 155, 166, 168, 180, 185, 213, 214 (Magenta pigment) CI Pigment Red 5, 7, 9, 12, 48(Ca), 48(Mn), 49, 52, 53, 57(Ca), 57:1, 97, 112, 122, 123, 149, 168, 177, 178, 179, 184, 202, 206, 207, 209, 242, 254, 255 (cyan pigment) CI Pigment Blue 1, 2, 3, 15, 15:1, 15:3, 15:4, 15:6, 15:34, 16, 22, 60 (Black pigment) CI Pigment Black 7 (Orange pigment) CI Pigment Orange 36, 43, 51, 55, 59, 61, 71, 74 (Green pigment) CI Pigment Green 7, 36 (Violet pigment) CI Pigment Violet 19, 23, 29, 30, 37, 40, 50 One or more pigments can be used depending on the color of the colored ink.

[0093] For example, when carbon black is used to produce the color black, a cyan pigment may be added to make the color appear more blue-black.

[0094] The pigment may be surface-treated to improve the dispersion stability in the colored ink. The pigment may be used in the production of the colored ink in the form of a liquid pigment dispersion in which the pigment is dispersed in an arbitrary dispersion medium. A dispersant or the like may be added to the pigment dispersion to disperse the pigment well.

[0095] As the dispersant, any of various dispersants such as polymeric dispersants, surfactants, etc. can be used. As the dispersion medium, any organic solvent or any of various radical polymerizable components can be used, and it is particularly preferable to use at least one of the above-mentioned radical polymerizable components.

[0096] In addition, when a radical polymerizable component is used as the dispersion medium, the ratio of each of the above-described various radical polymerizable components is expressed as a value determined by taking into consideration the radical polymerizable component as the dispersion medium. The ratio of the colorant such as a pigment can be set arbitrarily depending on the type of the colorant, the color of the color ink, etc.

[0097] The color ink may contain a radical polymerizable additive (component) like the primer ink. The additive is not particularly limited, but examples thereof include a radical polymerization initiator, a sensitizer, a radical polymerization inhibitor, a surfactant, and the like.

[0098] (2-E) Radical polymerization initiator Specific examples of the radical polymerization initiator include various photoradical polymerization initiators exemplified in "(1-D) Radical Polymerization Initiator" for the primer ink described above. It is preferable to select the same radical polymerization initiator as that used in the primer ink as the radical polymerization initiator used. This allows the primer precursor layer made of the primer ink and the color precursor layer made of the color ink to undergo a curing reaction simultaneously.

[0099] The content of the radical polymerization initiator can be set arbitrarily. In consideration of imparting good photocurability to the color ink, the content of the photoradical polymerization initiator is preferably 3% by mass or more, particularly 5% by mass or more, and 12% by mass or less, particularly 10% by mass or less, of the total mass of the color ink. When two or more types of radical polymerization initiators are used in combination, the total content may be set to the above range.

[0100] (2-F) Sensitizer Specific examples of the sensitizer include the various sensitizers exemplified in the above-mentioned primer ink "(1-E) Sensitizer". Among them, it is preferable to select and use any sensitizer having the same absorption wavelength range as the sensitizer of the primer ink, especially the same sensitizer used in the primer ink. One or more of these sensitizers can be used.

[0101] The content of the sensitizer can be set arbitrarily. In order to satisfactorily exert the sensitizing effect of the sensitizer, the content of the sensitizer is preferably 0.1% by mass or more, particularly 1% by mass or more, and preferably 10% by mass or less, particularly 5% by mass or less, of the total mass of the color ink. When two or more types of sensitizers are used in combination, the total content may be within the above range.

[0102] (2-G) Radical polymerization inhibitor Specific examples of the radical polymerization inhibitor include the various radical polymerization inhibitors exemplified in "(1-F) Radical Polymerization Inhibitor" for the primer ink described above, and among them, it is preferable to select and use the same radical polymerization inhibitor as that used in the primer ink. One or more of these radical polymerization inhibitors can be used.

[0103] The content of the radical polymerization inhibitor is preferably 0.01% by mass or more, particularly preferably 0.05% by mass or more, and 3% by mass or less, particularly preferably 2% by mass or less, of the total mass of the color ink. When two or more kinds of radical polymerization inhibitors are used in combination, the total content thereof may be within the above range.

[0104] (2-H) Surfactants Specific examples of the surfactant include the various surfactants exemplified in the above-mentioned primer ink "(1-G) Surfactant", and among them, it is preferable to select and use the same surfactant as that used in the primer ink. One or more of these surfactants can be used.

[0105] The content of the surfactant can be set arbitrarily. The content of the surfactant is, for example, 0.1% by mass or more and 3% by mass or less, and preferably 0.2% by mass or more and 2% by mass or less, based on the total mass of the color ink, calculated as the amount of the active ingredient in the surfactant. When two or more types of surfactants are used in combination, the total content of the surfactants may be set to the above range.

[0106] (2-I) Other Additives The color ink of the present invention may contain additives other than the above-mentioned additives, such as known polymerization accelerators, penetration accelerators, wetting agents (moisturizing agents), fixing agents, antifungal agents, preservatives, antioxidants, chelating agents, thickeners, etc.

[0107] (3) Overcoat ink The overcoat ink contains at least a monomer containing an N group as a radical polymerizable component. In particular, it is preferable to contain a monomer having an isocyanurate structure. The monomer having an isocyanurate structure has a relatively high glass transition temperature Tg and can form a hard coating film by active energy ray curing. On the other hand, the flexibility derived from the isocyanurate structure contributes to improving the pencil hardness of the printed layer. Furthermore, since the isocyanurate structure contains an N group, it has a high affinity with the monomer containing an N group contained in the color ink, and suppresses interlayer peeling between the color layer and the overcoat layer.

[0108] Examples of monomers having an isocyanurate structure include tris(2-hydroxyethyl)isocyanurate diacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, isocyanuric acid EO modified diacrylate, isocyanuric acid EO modified triacrylate, etc. These can be used alone or in combination of two or more. Among these, monomers having an isocyanurate structure with three functions, such as tris(2-hydroxyethyl)isocyanurate triacrylate and isocyanuric acid EO modified triacrylate, are preferred. If it is trifunctional, it has a high glass transition temperature Tg and can form a harder coating film. This can improve the pencil hardness of the printing layer compared to the case of two functions.

[0109] The content of the monomer having an isocyanurate structure is, for example, 15% by mass or more, preferably 20% by mass or more, based on the total mass of the monomers contained in the overcoat ink. The content of the monomer having an isocyanurate structure is, for example, 30% by mass or less, preferably 25% by mass or less, based on the total mass of the monomers contained in the overcoat ink. More specifically, the content of the monomer having an isocyanurate structure is, for example, 15% by mass or more and 30% by mass or less, preferably 20% by mass or more and 25% by mass or less, based on the total mass of the monomers contained in the overcoat ink. If it is less than 15% by mass, it is not possible to sufficiently suppress interlayer peeling due to affinity with the monomer containing an N group contained in the colored ink, and adhesion may decrease. On the other hand, if it exceeds 30% by mass, the cured product of the overcoat ink (overcoat layer) itself becomes too hard, and marks made by a pencil or the like tend to remain. When two or more types of monomers having an isocyanurate structure are used in combination, the total content may be within the above range.

[0110] (3-B) 2-(2-vinyloxyethoxy)ethyl (meth)acrylate The overcoat ink preferably further comprises 2-(2-vinyloxyethoxy)ethyl (meth)acrylate (VEEA (VEEM)).

[0111] VEEA (VEEM) is preferably the main component in the overcoat ink, that is, VEEA (VEEM) is preferably the monomer contained in the overcoat ink in the largest proportion.

[0112] If the overcoat ink contains little or no VEEA (VEEM), the curing of the color ink is insufficient, and the adhesion to the color layer is insufficient, which may cause peeling between the color layer and the overcoat layer, such as interlayer delamination. On the other hand, if the overcoat ink contains a lot of VEEA (VEEM), the color ink may shrink during curing and float, resulting in insufficient adhesion to the color layer.

[0113] The content of VEEA (VEEM) in the overcoat ink is, for example, 20% by mass or more, and preferably 25% by mass or more, based on the total mass of the monomers contained in the overcoat ink. The content of VEEA (VEEM) is, for example, 75% by mass or less, and preferably 70% by mass or less, based on the total mass of the monomers contained in the overcoat ink. More specifically, the content of VEEA (VEEM) is, for example, 20% by mass or more and 75% by mass or less, and preferably 25% by mass or more and 70% by mass or less, based on the total mass of the monomers contained in the overcoat ink.

[0114] If the content is less than 20% by mass, the ink viscosity becomes too high due to the increase in the amount of other highly viscous monomers, and the curability tends to decrease. If the curability decreases, both the adhesion and scratch resistance to the colored layer at the initial stage are insufficient, and as a result, it becomes difficult to improve the adhesion and scratch resistance after immersion in hot and cold water. On the other hand, if the content exceeds 75% by mass, the ink is cured too much, making the overcoat layer too hard and the viscosity too low. If the overcoat ink is cured too much, the overcoat ink may harden and shrink, causing it to float, resulting in insufficient adhesion to the colored layer. If the ink viscosity is too high, continuous ejection becomes difficult, and if the ink viscosity is too low, mist (scattering) may occur on the printed matter. In other words, a large change in the ink viscosity may have a large effect on the ejection properties of the ink.

[0115] (3-C) Other Monomers The overcoat ink may further contain other monomers other than the monomer having an isocyanurate structure and VEEA (VEEM). As such monomers, for example, monofunctional, bifunctional, trifunctional or higher polyfunctional monomers and oligomers exemplified in "(1-C) Other Monomers" of the primer ink described above can be used.

[0116] In particular, it is preferable to use phenoxyethyl (meth)acrylate, which is highly flexible and resistant to scratches, and therefore contributes to improving the pencil hardness of the printed layer.

[0117] The content of phenoxyethyl (meth)acrylate in the overcoat ink is, for example, 50% by mass or more, and preferably 100% by mass or more, relative to the total mass 100 of the monomers having an isocyanurate structure. The content of phenoxyethyl (meth)acrylate is, for example, 200% by mass or less, and preferably 150% by mass or less, relative to the total mass 100 of the monomers having an isocyanurate structure. More specifically, the content of phenoxyethyl (meth)acrylate is, for example, 50% by mass or more and 200% by mass or less, and preferably 100% by mass or more and 150% by mass or less, relative to the total mass 100 of the monomers having an isocyanurate structure.

[0118] In the overcoat ink, the content of other monomers excluding the monomer having an isocyanurate structure, VEEA (VEEM), and phenoxyethyl (meth)acrylate is, for example, the remainder of the monomer having an isocyanurate structure, VEEA (VEEM), and phenoxyethyl (meth)acrylate. In other words, the blending ratio of the monomer having an isocyanurate structure, VEEA (VEEM), and phenoxyethyl (meth)acrylate is set preferentially.

[0119] The overcoat ink is a clear ink in which the content of coloring materials such as pigments and dyes is less than 0.1% by mass, and preferably 0% by mass.

[0120] The overcoat ink may contain an additive (component) of a radical polymerizable component. The additive is not particularly limited, but examples thereof include a radical polymerization initiator, a sensitizer, a radical polymerization inhibitor, a surfactant, and a silane coupling agent.

[0121] (3-D) Radical Polymerization Initiator Specific examples of the radical polymerization initiator include various photoradical polymerization initiators exemplified in "(1-D) Radical Polymerization Initiator" of the primer ink described above. It is preferable to select the same radical polymerization initiator as that used in the primer ink as the radical polymerization initiator used in the primer ink. This allows the primer precursor layer made of the primer ink, the color precursor layer made of the color ink, and the overcoat precursor layer made of the overcoat ink to undergo a curing reaction simultaneously. The content of the radical polymerization initiator can be set as desired.

[0122] Considering the need to impart good photocurability to the overcoat ink, the content of the photoradical polymerization initiator is preferably 3% by mass or more, particularly 5% by mass or more, and 12% by mass or less, particularly 10% by mass or less, of the total mass of the overcoat ink. When two or more types of radical polymerization initiators are used in combination, the total content thereof may be within the above range.

[0123] (3-E) Sensitizer Specific examples of the sensitizer include the various sensitizers exemplified in the above-mentioned primer ink "(1-E) Sensitizer". Among them, it is preferable to select and use any sensitizer having the same absorption wavelength range as the sensitizer of the primer ink, especially the same sensitizer used in the primer ink. One or more of these sensitizers can be used.

[0124] The content of the sensitizer can be set arbitrarily. In order to satisfactorily exert the sensitizing effect of the sensitizer, the content of the sensitizer is preferably 0.1% by mass or more, particularly 1% by mass or more, and preferably 10% by mass or less, particularly 5% by mass or less, of the total mass of the overcoat ink. When two or more types of sensitizers are used in combination, the total content may be within the above range.

[0125] (3-F) Radical polymerization inhibitors Specific examples of the radical polymerization inhibitor include the various radical polymerization inhibitors exemplified in "(1-F) Radical Polymerization Inhibitor" for the primer ink described above, and among them, it is preferable to select and use the same radical polymerization inhibitor as that used in the primer ink. One or more of these radical polymerization inhibitors can be used.

[0126] The content of the radical polymerization inhibitor can be set arbitrarily. The content of the radical polymerization inhibitor is preferably 0.01% by mass or more, particularly 0.05% by mass or more, and is preferably 3% by mass or less, particularly 2% by mass or less, of the total mass of the overcoat ink. When two or more kinds of radical polymerization inhibitors are used in combination, the total content may be within the above range.

[0127] (3-G) Surfactant Specific examples of the surfactant include the various surfactants exemplified in the above-mentioned primer ink "(1-G) Surfactant", and among them, it is preferable to select and use the same surfactant as that used in the primer ink. One or more of these surfactants can be used.

[0128] The content of the surfactant can be set arbitrarily. The content of the surfactant is, for example, 0.1% by mass or more and 3% by mass or less, and preferably 0.2% by mass or more and 2% by mass or less, based on the total mass of the overcoat ink, calculated as the amount of the active ingredient in the surfactant. When two or more types of surfactants are used in combination, the total content of the surfactants may be set to the above range.

[0129] (3-H) Silane coupling agent Specific examples of the silane coupling agent include the various silane coupling agents exemplified in the above-mentioned primer ink "(1-H) Silane Coupling Agent", and among them, it is preferable to select and use the same silane coupling agent as used in the primer ink. One or more of these silane coupling agents can be used.

[0130] The content of the silane coupling agent can be set arbitrarily. The content of the silane coupling agent is, for example, 0.1% by mass or more and 2.0% by mass or less, preferably 0.3% by mass or more and 1.5% by mass or less, based on the total mass of the overcoat ink. When two or more kinds of silane coupling agents are used in combination, the total content of them may be set to the above range.

[0131] (3-I) Other Additives The overcoat ink of the present invention may contain additives other than those mentioned above, such as known polymerization promoters, penetration promoters, wetting agents (moisturizing agents), fixing agents, antifungal agents, preservatives, antioxidants, chelating agents, thickeners, etc.

[0132] [Printed material] 1 is a schematic diagram of a printed matter 1 produced by a method for producing a printed matter according to one embodiment of the present invention. The printed matter 1 of the present invention produced by the ink set described above includes a substrate 2 and a printed layer 3 formed on the substrate 2.

[0133] The substrate 2 is, for example, a hard substrate, and is preferably a glass substrate or a hard substrate containing glass (for example, a glass-containing ceramic substrate such as a ceramic tile). The substrate 2 may have a smooth or uneven printed surface 4, and may be transparent, translucent, or opaque. A peelable adhesive layer or the like may be provided on the back surface 5 opposite the printed surface 4 of the substrate 2. After the printed layer 3 is formed, an adhesive layer or the like may be provided to cover the printed layer 3.

[0134] The printed layer 3 includes a primer layer 6, a colored layer 7, and an overcoat layer 8, which are laminated in this order from the printing surface 4 of the substrate 2. The primer layer 6 is a printed layer formed from the primer ink described above. The colored layer 7 is a printed layer formed from the colored ink described above. The overcoat layer 8 is a printed layer formed from the overcoat ink described above.

[0135] [Manufacturing method for printed matter] 2 to 5 are schematic diagrams showing some steps in the method for producing the printed matter 1 in order of steps.

[0136] The printed matter 1 can be produced, for example, by forming the printed layer 3 on the substrate 2 using a known industrial inkjet printer. More specifically, first, an inkjet ink (for example, a cartridge) having the above-mentioned ink set is set in the inkjet printer. As the ejection head for the inkjet ink, for example, an on-demand or continuous type ejection head of either a thermal type or a piezoelectric type can be used. However, in consideration of improving the stability of ejection, it is preferable to employ an on-demand type piezoelectric type ejection head as the ejection head.

[0137] Referring to FIG. 2, the above-mentioned primer ink is ejected from an ejection head onto the substrate 2 to form a primer precursor layer 9. Next, referring to FIG. 3, a primer layer 6 is formed by irradiating an active energy ray (ultraviolet ray) from an active energy ray source to polymerize and harden a monomer in the ink of the primer precursor layer 9. The active energy ray source can be incorporated, for example, in the head of an inkjet printer, or prepared separately from the inkjet printer. Examples of the active energy ray source include an ultraviolet lamp, an ultraviolet light emitting diode, and an ultraviolet laser diode. Here, the emission peak wavelength of the active energy ray is preferably in the range of, for example, 350 nm to 420 nm.

[0138] Next, referring to Fig. 4, the above-mentioned color inks are ejected from an ejection head onto the substrate 2 to form a color precursor layer 10 on the primer layer 6. As the color inks, three colors of cyan (C), magenta (M), and yellow (Y), four colors obtained by adding black (K) to the above three colors, or multiple colors of more than three colors can be used. By ejecting such multiple color inks simultaneously or sequentially from multiple nozzles of an on-demand inkjet printer, any color precursor layer 10, from full color to monochrome, can be printed on the primer layer 6.

[0139] Next, referring to FIG. 5, the colored layer 7 is formed by irradiating the colored precursor layer 10 with active energy rays (ultraviolet rays) from an active energy ray source to polymerize and harden the monomer in the ink. The active energy ray source can be incorporated in the head of the inkjet printer, or can be prepared separately from the inkjet printer. Examples of the active energy ray source include an ultraviolet lamp, an ultraviolet light emitting diode, and an ultraviolet laser diode. Here, the emission peak wavelength of the active energy ray is preferably in the range of, for example, 350 nm or more and 420 nm or less.

[0140] Next, referring to FIG. 6, the above-mentioned overcoat ink is ejected from an ejection head onto the substrate 2 to form an overcoat precursor layer 11 on the colored layer 7. Next, referring to FIG. 7, the overcoat layer 8 is formed by polymerizing and curing the monomer in the ink of the overcoat precursor layer 11 by irradiation with active energy rays (ultraviolet rays) from an active energy ray source. The active energy ray source can be incorporated, for example, in the head of an inkjet printer, or prepared separately from the inkjet printer. Examples of the active energy ray source include an ultraviolet lamp, an ultraviolet light emitting diode, and an ultraviolet laser diode. Here, the emission peak wavelength of the active energy ray is preferably in the range of, for example, 350 nm to 420 nm.

[0141] Through the above steps, the printed matter 1 shown in Fig. 1 is obtained. In the above method, the primer precursor layer 9, the color precursor layer 10, and the overcoat precursor layer 11 are each cured in an independent active energy ray irradiation step, but at least two of the primer precursor layer 9, the color precursor layer 10, and the overcoat precursor layer 11 may be laminated in succession, and then the multiple precursor layers may be cured simultaneously in the same active energy ray irradiation step. EXAMPLES

[0142] The present invention will be further described below based on examples and comparative examples, but the configuration of the present invention is not limited to these examples.

[0143] [Primer Ink 1~14] The components were mixed so as to obtain the composition (mass %) shown in Table 1 and stirred until fully dissolved. After that, the mixture was filtered using a 5 μm membrane filter to prepare clear primer inks 1 to 14.

[0144] The information on the components used in Table 1 is as follows:

[0145] The cyclic structure and / or N-group containing monomer is Acryloylmorpholine (ACMO (registered trademark)) (manufactured by KJ Chemicals Co., Ltd.), Diethylacrylamide (DEAA) (KJ Chemicals Co., Ltd.), Phenoxyethyl acrylate (manufactured by Sartomer Corporation, product name "SR339NS").

[0146] The hydroxyl group-containing monomer is 4-Hydroxybutyl acrylate (4HBA) (Osaka Organic Chemical Industry Ltd.), 2-Hydroxyethyl acrylate (2HEA) (Osaka Organic Chemical Industry Ltd.) Phenoxyethyl acrylate (manufactured by Sartomer Corporation, product name "SR339NS").

[0147] 1,6-Hexanediol diacrylate is manufactured by Sartomer Corporation under the trade name "SR238."

[0148] The polymerization initiator was 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by Lambson, trade name "A-TPO").

[0149] The sensitizer is 2-isopropylthioxanthone (Lambson, trade name "2-ITX").

[0150] The polymerization inhibitor is manufactured by Kromachem under the trade name "Florstab UV-5".

[0151] The surfactant is a silicone-based surfactant (manufactured by BYK Japan Co., Ltd., product name "BYK-UV3510").

[0152] The silane coupling agent was manufactured by Shin-Etsu Chemical Co., Ltd. under the trade name "KBM903."

[0153] [Table 1]

[0154] [Colored ink 1~9] First, the following components were mixed in the ratios shown in Table 2, stirred, and then dispersed using a bead mill to prepare a cyan pigment (blue pigment) dispersion.

[0155] Cyan pigment: CI Pigment Blue 15:4 (BASF Heliogen (registered trademark) Blue, product name "D7110F" Dispersant: Lubrizol Corporation, product name "Solsperse 32000" Dispersion medium: VEEA (manufactured by Nippon Shokubai Co., Ltd., product name "VEEA-AI")

[0156] [Table 2]

[0157] Next, each component was mixed so as to obtain the composition (mass %) shown in Table 3, and stirred until sufficiently dissolved. After that, the mixture was filtered using a 5 μm membrane filter to prepare a cyan (C) colored ink.

[0158] The information on the ingredients used in Table 3 is as follows:

[0159] VEEA is manufactured by Nippon Shokubai Co., Ltd. under the trade name "VEEA-AI."

[0160] The amide bond-containing monomer is Amine-modified acrylate (manufactured by Sartomer, product name "CN371"), Diethylacrylamide (DEAA) (KJ Chemicals Co., Ltd.), - Urethane acrylate (manufactured by Sartomer Corporation, product name "CN983").

[0161] 1,6-Hexanediol diacrylate is manufactured by Sartomer Corporation under the trade name "SR238."

[0162] The polymerization initiator was 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by Lambson, trade name "A-TPO").

[0163] The sensitizer is 2-isopropylthioxanthone (Lambson, trade name "2-ITX").

[0164] The polymerization inhibitor is manufactured by Kromachem under the trade name "Florstab UV-5".

[0165] The surfactant is a silicone-based surfactant (manufactured by BYK Japan Co., Ltd., product name "BYK-UV3510").

[0166] In Table 3, the blending ratio of the pigment dispersion indicates only the pigment content, and the amount of VEEA in the pigment dispersion is shown in total with VEEA as the radical polymerizable component.

[0167] [Table 3]

[0168] [Examples 1 to 16 and Comparative Examples 1 to 6] Ink sets according to the examples and comparative examples were prepared in the combinations shown in Tables 4 and 5, and were set in a piezo inkjet printer equipped with a piezo head. Next, the primer ink was ejected onto the substrate 2 so as to form a solid pattern, and the primer precursor layer 9 was printed. A colorless and transparent glass substrate was used as the substrate 2. The printing conditions were a printing speed of 50 m / min, a resolution of 600×600, and a number of passes of 4. Thereafter, the substrate 2 on which the primer precursor layer 9 was formed was transferred to an ultraviolet irradiation device, and the primer ink was cured by performing a curing process by ultraviolet irradiation, thereby forming the primer layer 6. The ultraviolet irradiation conditions were a wavelength of 350 nm to 420 nm, and a conveying speed of 25 m / min.

[0169] Next, under normal temperature and pressure, color inks were ejected onto the base material 2 on which the primer layer 6 was formed in a solid pattern, and the color precursor layer 10 was printed on the primer layer 6. The printing conditions were printing speed: 50 m / min, resolution: 600 x 600, and number of passes: 4. Thereafter, the base material 2 on which the color precursor layer 10 was formed was transferred to an ultraviolet ray irradiation device, and a curing process was performed by ultraviolet ray irradiation to cure the color ink, thereby forming the color layer 7. The ultraviolet ray irradiation conditions were wavelength: 350 nm to 420 nm, and conveying speed: 25 m / min.

[0170] As a result, an evaluation sample was prepared in which an A4 solid pattern sample image consisting of a laminate (printed layer 3) of a primer layer 6 and a colored layer 7 was recorded on a substrate 2 consisting of a glass substrate. The obtained evaluation sample was then evaluated as follows.

[0171] [Evaluation test] (1) Cellophane tape adhesion evaluation Each evaluation sample was prepared according to the Japanese Industrial Standard JIS K5600-5-6 :1999 The cross-cut test described in "General Test Methods for Paints - Part 5: Mechanical Properties of Coatings - Section 6: Adhesion (Cross-cut Method)" was carried out. The evaluation criteria for adhesion are as follows. The evaluation results are shown in Tables 4 and 5. "Good": Classification was 0 to 2. "△": Classification was 3 to 4. "X": Classification was 5. (2) Scratch test evaluation The coating film of each evaluation sample was rubbed back and forth five times with a paper clip (Gachadama (registered trademark)) and the change in the coating film before and after the rub was evaluated. The evaluation criteria for the scratch test are as follows. The evaluation results are shown in Tables 4 and 5. "Good": No change in the coating. "△": Slight (thin or intermittent) scratches remained on the coating. "X": A (clear or solid) scratch remained on the coating film.

[0172] [Table 4]

[0173] [Table 5]

[0174] [Evaluation Results] First, referring to Tables 4 and 5, the results of Examples 1 to 16 show that if the primer ink contains (A) acryloylmorpholine and (B) a monofunctional monomer containing a hydroxyl group, and the mass ratio (A / B) of acryloylmorpholine (A) to 100 mass parts of the monofunctional monomer containing a hydroxyl group (B) is 10 mass parts to 50 mass parts, and the colored ink contains at least one type of N-group-containing monomer selected from urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide, then it is possible to achieve both excellent adhesion to the glass substrate 2 and excellent scratch resistance, and further to suppress interlayer delamination between the primer layer 6 and the colored layer 7.

[0175] More specifically, referring to Table 4, a comparison of Example 1 and Comparative Examples 1 and 2 reveals that the monomer to be combined with (B) the monofunctional monomer containing a hydroxyl group is optimally acryloylmorpholine, which is a monomer containing both a cyclic structure and an N group, and that if either the cyclic structure or the N group is missing, the above-mentioned effect cannot be achieved.

[0176] For example, as in Comparative Example 1 and Comparative Example 2, when diethylacrylamide (without a cyclic structure) or phenoxyethyl acrylate (without an N group) was used in place of acryloylmorpholine at the same content, neither of them could impart sufficient scratch resistance to the printed layer 3 (scratch test "x"). In Comparative Example 1, since diethylacrylamide does not have a cyclic structure, it is believed that it adheres to other monomers during polymerization, which promotes hardening shrinkage, resulting in poor flexibility and reduced scratch resistance. On the other hand, in Comparative Example 2, since phenoxyethyl acrylate does not have an N group, it has low adhesion to the glass substrate 2 and the colored layer 7 (layer containing an N group) and is prone to interlayer peeling, so it is believed that it was easily peeled off by cellophane tape peeling. In addition, in Comparative Example 2, since the adhesion between adjacent layers is low, the scratch resistance of the coating film is also believed to have decreased.

[0177] Furthermore, a comparison of Example 1, Examples 3 to 6, Comparative Example 4, and Comparative Example 5 revealed that even if the primer ink contains (A) acryloylmorpholine and (B) a monofunctional monomer containing a hydroxyl group, the above-mentioned effect cannot be achieved unless the mass ratio (A / B) is within the range of 10 parts by mass to 50 parts by mass.

[0178] For example, as in Comparative Example 4, when the content of acryloylmorpholine was low and the mass ratio (A / B) was 5.3 parts by mass (<10 parts by mass), the amount of acryloylmorpholine contributing to adhesion to the glass substrate 2 was small, and sufficient scratch resistance could not be imparted to the printed layer 3 (scratch test: "x"). On the other hand, as in Comparative Example 5, when the content of acryloylmorpholine was high and the mass ratio (A / B) was 53.8 parts by mass (>50 parts by mass), the adhesion to the glass substrate 2 and the colored layer 7 was insufficient (cellophane tape adhesion: "x"). This is thought to be because the N groups of the acryloylmorpholine in the primer ink were consumed by polymerization, and the N groups facing the outside of the primer layer 6 and adhering to the glass substrate 2 and the colored layer 7 became fewer, resulting in a decrease in adhesion to the glass substrate 2 and the colored layer 7.

[0179] In addition, from a comparison between Example 1 and Example 2, it was found that the monofunctional monomer containing a hydroxyl group to be combined with acryloylmorpholine is preferably 4-hydroxybutyl acrylate (4HBA) among (meth)acrylates containing a hydroxyl group. For example, the evaluation of cellophane tape adhesion was superior to Example 2, which used 2-hydroxyethyl acrylate (2HEA). This is believed to be because the crosslinking chains of 4HBA are longer than those of 2HEA, and sufficient flexibility was imparted to the primer layer 6. It is believed that the improved flexibility further enhanced the adhesion of the primer layer 6 to the surface of the glass substrate 2.

[0180] Furthermore, from a comparison of Examples 3 to 6, it was found that the mass ratio (A / B) of (A) acryloylmorpholine and (B) monofunctional monomer containing a hydroxyl group is particularly preferably 15 to 35 parts by mass within the range of 10 to 50 parts by mass. For example, as in Example 3, when the mass ratio (A / B) approaches 10 parts by mass, the amount of acryloylmorpholine, which is responsible for the hardness of the primer ink, decreases, and scratch resistance tends to decrease (scratch test: "△"). On the other hand, as in Example 6, when the mass ratio (A / B) approaches 50 parts by mass, the hardness of the coating film increases, and adhesion to the glass substrate 2 tends to become insufficient (cellophane tape adhesion: "△").

[0181] In contrast, in Examples 4 and 5, the composition has a good balance of acryloylmorpholine, which imparts hardness to the coating film, and 4HBA, which imparts flexibility to the coating film and improves adhesion, and it is believed that this allows for both excellent adhesion to the glass substrate 2 and excellent scratch resistance (both cellophane tape adhesion and scratch tests were rated "Good").

[0182] Furthermore, referring to Table 5, a comparison between Example 1, Examples 10 to 16, and Comparative Example 6 reveals that if a monomer containing an N group is absent from the monomers used in the colored ink to be combined with the above-mentioned primer ink, the above-mentioned effects cannot be achieved.

[0183] For example, in the case of Comparative Example 6, when the colored layer 7 is formed only from monomers consisting of VEEA and 1,6-hexanediol acrylate, the results of both the cellophane tape adhesion and the scratch test were "x". This is thought to be because the monomer does not contain an N group that has a high affinity with the N group of acryloylmorpholine, so that delamination is likely to occur between the primer layer 6 and the colored layer 7, resulting in the cellophane tape adhesion result being "x". In addition, VEEA is a material with excellent curing properties. Therefore, when cured with settings suited to VEEA, 1,6-hexanediol acrylate becomes insufficiently cured, and a cured layer with excellent strength is not formed, resulting in the scratch test result being "x".

[0184] Furthermore, from the comparison of Example 1 and Examples 10 to 12, it was found that from the viewpoint of improving scratch resistance, it is preferable to use three types of N-group-containing monomers for color inks together, rather than selectively using any one of urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide.

[0185] In addition, from a comparison between Example 1 and Examples 13 to 16, it was found that the content of the N-group-containing monomer is preferably 20% by mass to 70% by mass, and particularly preferably 30% by mass to 60% by mass, based on the total mass of the monomers contained in the color ink. For example, as in Example 13, when the content of the N-group-containing monomer approaches 20% by mass, it is considered that the amount of the N-group-containing monomer is small and sufficient scratch resistance cannot be obtained (scratch test "△"). On the other hand, as in Example 16, when the content of the N-group-containing monomer approaches 70% by mass, there is little room for blending VEEA. As a result, the curability of the color ink decreases due to a shortage of VEEA, and interlayer peeling tends to occur easily between the primer layer 6 and the color layer 7 (cellophane tape adhesion "△").

[0186] In contrast, in Examples 1 and 14 to 15, the N-group-containing monomer, which imparts scratch resistance to the coating film, and VEEA, which imparts hardening properties to the ink, are well balanced, and it is believed that this has enabled the achievement of both excellent adhesion to the glass substrate 2 and excellent scratch resistance (both cellophane tape adhesion and scratch tests were rated "Good").

[0187] [Overcoat ink 1~8] The components were mixed to obtain the composition (mass %) shown in Table 6 and stirred until fully dissolved. After that, the mixture was filtered using a 5 μm membrane filter to prepare clear overcoat inks 1 to 8.

[0188] The information on the ingredients used in Table 6 is as follows:

[0189] VEEA is manufactured by Nippon Shokubai Co., Ltd. under the trade name "VEEA-AI."

[0190] The monomer having an isocyanurate structure is Tris(2-hydroxyethyl)isocyanurate triacrylate (manufactured by Sartomer Corporation, product name "SR368NS"), Isocyanuric acid EO-modified diacrylate (manufactured by Toagosei Co., Ltd., product name "M-215").

[0191] Other monomers include Phenoxyethyl acrylate (manufactured by Sartomer Corporation, product name "SR339A"), Lauryl acrylate (manufactured by Sartomer Corporation, product name "SR335").

[0192] 1,6-Hexanediol diacrylate (manufactured by Sartomer Corporation, product name "SR238").

[0193] The polymerization initiator was 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by Lambson, trade name "A-TPO").

[0194] The sensitizer is 2-isopropylthioxanthone (Lambson, trade name "2-ITX").

[0195] The polymerization inhibitor is manufactured by Kromachem under the trade name "Florstab UV-5".

[0196] The surfactant is a silicone-based surfactant (manufactured by BYK Japan Co., Ltd., product name "BYK-UV3510").

[0197] The silane coupling agent was manufactured by Shin-Etsu Chemical Co., Ltd. under the trade name "KBM903."

[0198] [Table 6]

[0199] [Examples 17 to 26 and Comparative Examples 7 to 8] The ink sets according to the examples and comparative examples were prepared in the combinations shown in Table 7, and were set in a piezo inkjet printer equipped with a piezo head. Next, a primer layer 6 and a colored layer 7 were formed on a glass substrate 2 by the same method as in Examples 1 to 16 and Comparative Examples 1 to 6. Next, at room temperature and normal pressure, an overcoat ink was ejected in a solid pattern onto the glass substrate 2 on which the primer layer 6 and the colored layer 7 were formed, and an overcoat precursor layer 11 was printed so as to cover the colored layer 7. The printing conditions were a printing speed of 50 m / min, a resolution of 600×600, and a number of passes of 4. Thereafter, the glass substrate 2 on which the overcoat precursor layer 11 was formed was transferred to an ultraviolet irradiation device, and a curing process was performed by irradiating ultraviolet light to cure the overcoat ink, thereby forming an overcoat layer 8. The ultraviolet light irradiation conditions were a wavelength of 350 nm to 420 nm, and a conveying speed of 25 m / min.

[0200] As a result, an evaluation sample was prepared in which an A4 solid pattern sample image consisting of a laminate (printed layer 3) of a primer layer 6, a colored layer 7, and an overcoat layer 8 was recorded on a glass substrate 2. The obtained evaluation sample was then evaluated as follows. (1) Cellophane tape adhesion evaluation Each evaluation sample was prepared according to the Japanese Industrial Standard JIS K5600-5-6 :1999 The cross-cut test described in "General Test Methods for Paints - Part 5: Mechanical Properties of Coating Films - Section 6: Adhesion (Cross-cut Method)" was carried out. The test was carried out both before and after each evaluation sample was immersed in 70°C warm water for 30 minutes. The evaluation criteria for adhesion are as follows. The evaluation results are shown in Table 7. "Good": Classification was 0 to 2. "△": Classification was 3 to 4. "X": Classification was 5. (2) Pencil hardness test Each evaluation sample was prepared according to the Japanese Industrial Standard JIS K5600-5-4 :1999A pencil scratch test was conducted as described in "General Test Methods for Paints - Part 5: Mechanical Properties of Coatings - Section 4: Scratch Hardness (Pencil Method)". The test was conducted both before and after each evaluation sample was immersed in 70°C warm water for 30 minutes. The test results are shown in Table 7. Table 7 lists the hardness scale when a scratch of 3mm or more was produced on the test area. However, a test result of "6H" indicates that even when a pencil with a hardness scale of "6H" was used, a scratch of 3mm or more was not produced on the test area.

[0201] [Table 7]

[0202] [Evaluation Results] First, referring to Table 7, the results of Examples 17 to 26 and Comparative Examples 7 to 8 show that even if the colored layer 7 is covered and protected with the overcoat layer 8, it is not possible to achieve both excellent adhesion to the glass substrate 2 and excellent scratch resistance unless the primer ink contains (A) acryloyl morpholine and (B) a monofunctional monomer containing a hydroxyl group, the mass ratio (A / B) of (A) acryloyl morpholine to 100 mass parts of the monofunctional monomer containing a hydroxyl group (B) is 10 mass parts to 50 mass parts, and the colored ink contains at least one type of N-group-containing monomer selected from urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide.

[0203] For example, in Comparative Examples 7 and 8, since there was no acryloylmorpholine, which is responsible for the hardness of the primer ink, the pencil hardness before immersion in hot and cold water remained at "2H" even though the overcoat layer 8 was formed. Furthermore, these pencil hardnesses were reduced by one rank to "H" after immersion in hot and cold water.

[0204] In Comparative Example 7, the diethylacrylamide in the primer ink contains an N group, and therefore has a high affinity with monomers containing an N group, such as diethylacrylamide, in the colored ink, and the cellophane tape adhesion was "good" before immersion in hot and cold water. However, the resistance to hot and cold water was not high, and the cellophane tape adhesion after immersion in hot and cold water was "good". On the other hand, in Comparative Example 8, the phenoxyethyl acrylate in the primer ink does not contain an N group, and therefore the cellophane tape adhesion remained "good" even before immersion in hot and cold water, and after immersion in hot and cold water, the cellophane tape adhesion became "bad".

[0205] Furthermore, a comparison of Examples 17 to 19 shows that the overcoat ink preferably contains a monomer having an isocyanurate structure (Examples 17 and 18), and more preferably contains a monomer having a trifunctional isocyanurate structure. In Example 17, which contains a monomer having a trifunctional isocyanurate structure, the cellophane tape adhesion was rated as "good" regardless of whether the ink was immersed in hot or cold water, and a pencil hardness of "6H" was achieved.

[0206] On the other hand, in Example 18, which contains an isocyanurate structure but has two functionalities, the pencil hardness before and after immersion in hot and cold water was "5H", which was slightly inferior to Example 17. In addition, in Example 19, which has an overcoat ink layer made of a monomer that does not contain an isocyanurate structure, the overcoat ink layer was formed to achieve a practically sufficient pencil hardness of "4H", but the results were inferior to those of Examples 17 and 18. In addition, the evaluation of cellophane tape adhesion in Example 19 also showed results inferior to those of Examples 17 and 18. This is thought to be due to the fact that interlayer peeling is more likely to occur between the overcoat layer 8 and the colored layer 7 due to the absence of an N group in the overcoat layer 8.

[0207] Furthermore, a comparison between Examples 17 and 20 revealed that the overcoat ink preferably contains phenoxyethyl (meth)acrylate. In Example 20, which does not contain phenoxyethyl (meth)acrylate, the pencil hardness before and after immersion in hot and cold water was "4H", a result slightly inferior to that of Example 17. In Example 17, it is believed that phenoxyethyl (meth)acrylate, which is highly flexible and scratch-resistant, contributed to the improvement in pencil hardness.

[0208] In addition, from the comparison of Examples 21 to 24, it was found that the content of the monomer having an isocyanurate structure is preferably 15% by mass to 30% by mass, and particularly preferably 20% by mass to 25% by mass, based on the total mass of the monomers contained in the overcoat ink. For example, as in Example 21, when the content of the monomer having an isocyanurate structure approaches 15% by mass, it is considered that the interlayer peeling due to the affinity with the monomer containing an N group contained in the colored ink cannot be sufficiently suppressed, and the adhesion is reduced (cellophane tape adhesion before and after immersion in hot and cold water "△"). On the other hand, as in Example 24, when the content of the monomer having an isocyanurate structure approaches 30% by mass, it is considered that the cured product of the overcoat ink (overcoat layer 8) itself becomes too hard, and marks made by a pencil or the like are easily left (pencil hardness before and after immersion in hot and cold water "4H").

[0209] In contrast, in Examples 22 and 23, the blending ratio of monomer having an isocyanurate structure was good, and it is believed that both excellent adhesion to the glass substrate 2 and excellent scratch resistance were achieved (cellophane tape adhesion before and after immersion in hot and cold water: "Good", pencil hardness before and after immersion in hot and cold water: "6H").

[0210] In addition, a comparison between Example 17 and Example 25 revealed that when the monofunctional monomer containing a hydroxyl group combined with acryloylmorpholine was 4HBA, not only was adhesion and pencil hardness before immersion in hot and cold water excellent, but resistance to hot and cold water was also high. For example, in Example 25, in which 2HEA was used, the cellophane tape adhesion before and after immersion in hot and cold water was "△", and the pencil hardness before and after immersion in hot and cold water was "5H", whereas in Example 17, in which 4HBA was used, the cellophane tape adhesion before and after immersion in hot and cold water was "◯", and the pencil hardness before and after immersion in hot and cold water was "6H".

[0211] In addition, a comparison of Example 17 and Example 26 revealed that if the primer ink contains a silane coupling agent, the hot water resistance can be improved. For example, in Example 26, where the primer ink does not contain a silane coupling agent, the cellophane tape adhesion decreased from "good" to "△" and the pencil hardness decreased from "5H" to "3H" before and after immersion in hot water. In contrast, in Example 17, where the primer ink contains a silane coupling agent, the cellophane tape adhesion and pencil hardness ratings were able to be maintained before and after immersion in hot water. [Explanation of symbols]

[0212] 1 Printed matter 2 Base material 3 printing layer 4 Print side 5 Back side 6 Primer layer 7 Colored layer 8 Overcoat Layer 9. Primer Precursor Layer 10 Colored precursor layer 11 Overcoat precursor layer

Claims

1. An actinic radiation curable inkjet ink set comprising a combination of a clear primer ink and one or more color inks, the primer ink contains (A) acryloylmorpholine and (B) a monofunctional monomer containing a hydroxyl group, in which a mass ratio (A / B) of the acryloylmorpholine (A) to 100 parts by mass of the monofunctional monomer containing a hydroxyl group (B) is 10 parts by mass to 50 parts by mass, The color ink of the ink set includes at least one N-group-containing monomer selected from the group consisting of urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide.

2. 2. The ink set according to claim 1, wherein the monofunctional monomer constituting the primer ink is 4-hydroxybutyl acrylate.

3. The ink set according to claim 2 , wherein the primer ink further contains a silane coupling agent.

4. The ink set according to any one of claims 1 to 3, further comprising an ink containing a monomer having an isocyanurate structure as an overcoat ink printed on the color ink.

5. A method for producing a printed matter using an actinic energy ray curable inkjet ink set comprising a combination of a clear primer ink and one or more colored inks, comprising: A first step of printing the primer ink on a substrate; a second step of printing the one or more colored inks onto the primer ink; the primer ink contains (A) acryloylmorpholine and (B) a monofunctional monomer containing a hydroxyl group, in which a mass ratio (A / B) of the acryloylmorpholine (A) to 100 parts by mass of the monofunctional monomer containing a hydroxyl group (B) is 10 parts by mass to 50 parts by mass, The method for producing a printed matter, wherein the color ink contains at least one N-group-containing monomer selected from the group consisting of urethane (meth)acrylate, amine-modified (meth)acrylate, and acrylamide.

6. A third step of printing an overcoat ink over the color ink, The method for producing a printed matter according to claim 5 , wherein the overcoat ink contains a monomer having an isocyanurate structure.

7. The method for producing a printed matter according to claim 5 or 6, wherein the substrate is a hard substrate.

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