Ink composition for ultraviolet-curable aqueous inkjet printing

Abstract

To provide an ultraviolet-curable type aqueous ink composition for inkjet printing, which is excellent in mutual solubility and storage stability, and can form a printed part that does not cause granular feeling and is excellent in curability and water resistance, by performing temporary curing after printing and then performing main curing; and a printing method.SOLUTION: An ultraviolet-curable type aqueous ink composition for inkjet printing includes: 20.0-70.0 mass% of a water-soluble acrylamide monomer, 5.0-60.0 mass% of a water-soluble hydroxyl group-containing monofunctional monomer, and 8.0-35.0 mass% of a water-insoluble polymerizable compound, with respect to total mass of all polymerizable components, respectively; further 3.0-10.0 parts by mass of a photoinitiator and / or a sensitizer, with respect to 100 parts by mass of the total mass of all the polymerizable components; and pigment and water. A 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 0.3-10.0. The ultraviolet-curable aqueous ink composition is used for printing having a process of temporarily curing by irradiation with the UV-LED which has a peak at a wavelength of 365-405 nm and an integrated light quantity of 100 mJ / cm2 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an ink composition for ultraviolet curable aqueous inkjet printing and a printing method.

Background Art

[0002] Patent Document 1 describes an ink composition for ultraviolet curable aqueous inkjet printing containing a water-soluble resin or an emulsion resin and an ultraviolet curable compound, and performing temporary drying by heating and secondary drying after printing, and then performing ultraviolet irradiation to obtain a final printed matter. Patent Document 2 describes an ink for ultraviolet curable aqueous inkjet recording that can contain a monomer component selected from n-butyl acrylate, t-butylacrylamide, 2-hydroxyethyl acrylate, etc., and can be cured by a single ultraviolet irradiation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the inventions described in the above patent documents, although it is possible to print as an inkjet ink composition, the improvement in compatibility and storage stability as an ink composition for ultraviolet curable aqueous inkjet printing is not considered, and the elimination of the granular feeling in the printed part is not considered either. The problem to be solved by the present invention is to obtain an ink composition for ultraviolet curable aqueous inkjet printing and a printing method that are excellent in compatibility and storage stability, and further, by performing final curing after temporary curing after printing, a printed part without a granular feeling can be formed, and the printed part is excellent in curability and water resistance.

Means for Solving the Problems

[0005] As a result of intensive research to solve the above problems, the present inventors have found that the above problems can be solved by using a specific composition and a specific printing method, and have completed the present invention. 1. With respect to the total mass of all polymerizable components, a water-soluble acrylamide-based monomer is 20.0 to 70.0% by mass, a water-soluble hydroxyl group-containing monofunctional monomer is 5.0 to 60.0% by mass, a water-insoluble polymerizable compound is 8.0 to 35.0% by mass, each containing, furthermore, with respect to 100 parts by mass of the total mass of all polymerizable components, 3.0 to 10.0 parts by mass of a photopolymerization initiator and / or a sensitizer is contained, a pigment, and water, the ratio of the mass of the water-soluble acrylamide-based monomer to the water-soluble hydroxyl group-containing monofunctional monomer (acrylamide-based monomer / hydroxyl group-containing monofunctional monomer) is 0.3 to 10.0, a printing ultraviolet-curable aqueous inkjet printing ink composition having a step of being temporarily cured by irradiation with a UV-LED having a peak at a wavelength of 365 to 405 nm and an integrated light amount of 100 mJ / cm 2 or less. 2. The ultraviolet-curable aqueous inkjet printing ink composition according to 1, wherein the water-soluble acrylamide-based monomer contains acryloylmorpholine. 3. The ultraviolet-curable aqueous inkjet printing ink composition according to 1 or 2, wherein the water-soluble hydroxyl group-containing monofunctional monomer contains 4-hydroxybutyl acrylate. 4. The ultraviolet-curable aqueous inkjet printing ink composition according to any one of 1 to 3, wherein the water content is 10.0 to 40.0% by mass with respect to the entire ink composition. 5. The ultraviolet-curable aqueous inkjet printing ink composition according to any one of 1 to 4, containing a pigment dispersant having a maleimide structure and / or a pigment dispersant having a pyridine ring. 6. With respect to the total mass of the completely polymerizable components, it contains 20.0 to 70.0% by mass of a water-soluble acrylamide-based monomer, 5.0 to 60.0% by mass of a water-soluble hydroxyl group-containing monofunctional monomer, 8.0 to 35.0% by mass of a water-insoluble polymerizable compound, and each contains, furthermore, with respect to 100 parts by mass of the total mass of the completely polymerizable components, it contains 3.0 to 10.0 parts by mass of a photopolymerization initiator and / or a sensitizer, a pigment, and water, wherein the mass ratio of the water-soluble acrylamide-based monomer to the water-soluble hydroxyl group-containing monofunctional monomer (acrylamide-based monomer / hydroxyl group-containing monofunctional monomer) is 0.3 to 10.0, it is temporarily cured by irradiation with a UV-LED having a peak at a wavelength of 365 to 405 nm and an integrated light amount of 100 mJ / cm 2 or less, and subsequently, it has a step of being irradiated with ultraviolet rays for final curing A printing method using an ultraviolet-curable aqueous inkjet printing ink composition. 7. The printing method using the ultraviolet-curable aqueous inkjet printing ink composition according to claim 6, wherein the ink composition contains acryloylmorpholine as the water-soluble acrylamide-based monomer. 8. The printing method using the ultraviolet-curable aqueous inkjet printing ink composition according to claim 6 or 7, wherein the water-soluble hydroxyl group-containing monofunctional monomer contains 4-hydroxybutyl acrylate. 9. The printing method using the ultraviolet-curable aqueous inkjet printing ink composition according to any one of claims 6 to 8, wherein the water content is 10.0 to 40.0% by mass with respect to the entire ink composition. 10. The printing method using the ultraviolet-curable aqueous inkjet printing ink composition according to any one of claims 6 to 9, which contains a pigment dispersant having a maleimide structure and / or a pigment dispersant having a pyridine ring.

Advantages of the Invention

[0006] The ink composition for ultraviolet-curable aqueous inkjet printing of the present invention is excellent in compatibility and storage stability. Furthermore, after temporarily curing by irradiating the printed portion with ultraviolet rays after printing, and then irradiating with ultraviolet rays again for final curing, it is possible to form a printed portion that has no granular feeling and is excellent in curability and water resistance.

Embodiments for Carrying Out the Invention

[0007] The ink composition for ultraviolet-curable aqueous inkjet printing of the present invention and its printing method will be described below. In addition, each water-soluble compound in the present invention, when the compound is liquid at room temperature, the compound and water are mixed at a mass ratio of 1:9, and even after standing for a sufficient time, the compound and water do not separate and are in a dissolved state. When the compound is solid at room temperature, the compound and water are mixed under heating conditions so as to reach a sufficient temperature at a mass ratio of 1:9, and then, even after standing at room temperature for a sufficient time, the compound and water do not separate and are in a dissolved state. A compound that does not show such behavior is not a water-soluble compound in the present invention and is regarded as water-insoluble.

[0008] (Water-soluble acrylamide) Examples of the water-soluble acrylamide used in the present invention include acrylamides such as (meth)acrylamide, acryloylmorpholine, N-methoxymethylacrylamide, diacetoneacrylamide, N,N-dimethylacrylamide, and diethylacrylamide. In addition to these, N-alkylol (C1-5) (meth)acrylamides such as hydroxymethyl (meth)acryldiamide, di(2-hydroxyethyl) (meth)acrylamide, di(3-hydroxypropyl) (meth)acrylamide, and di(4-hydroxybutyl) (meth)acrylamide, and 1-3 mole adducts of ethylene oxide or propylene oxide of these N-alkylol (C1-5) (meth)acrylamides can also be used. In the total polymerizable components in the ultraviolet-curable aqueous inkjet printing ink composition of the present invention, 20.0 to 70.0% by mass of water-soluble acrylamide is contained. And it is preferably contained in an amount of 25.0% by mass or more, more preferably 30.0% by mass or more, still more preferably 35.0% by mass or more, and most preferably 40.0% by mass or more. Also, in the total polymerizable components, it is preferably contained in an amount of 65.0% by mass or less of water-soluble acrylamide, more preferably 60.0% by mass or less, still more preferably 55.0% by mass or less, and most preferably 50.0% by mass or less.

[0009] (Water-soluble hydroxyl group-containing monofunctional monomer) As the water-soluble hydroxyl group-containing monofunctional monomer used in the present invention, hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate can be employed. In addition, as for the water-soluble hydroxyl group-containing monofunctional monomer, a compound included in the monomer corresponding to the above acrylamide compound is considered as the content of the above water-soluble acrylamide when determining the content in the composition of the present invention, and is not regarded as a water-soluble hydroxyl group-containing monofunctional monomer. In the total polymerizable components in the ultraviolet-curable aqueous inkjet printing ink composition of the present invention, 5.0 to 60.0% by mass of a water-soluble hydroxyl group-containing monofunctional monomer is contained. And it is preferably contained in an amount of 10.0% by mass or more, more preferably 15.0% by mass or more, still more preferably 20.0% by mass or more, and most preferably 25.0% by mass or more. Also, in the total polymerizable components, it is preferably contained in an amount of 55.0% by mass or less of the water-soluble hydroxyl group-containing monofunctional monomer, more preferably 50.0% by mass or less, still more preferably 45.0% by mass or less, and most preferably 40.0% by mass or less.

[0010] (Other water-soluble monofunctional monomers) Other water-soluble monofunctional monomers that may be contained in the present invention include (meth)acrylic acid, (ethylene glycol)methyl ether acrylate, (ethylene glycol)methyl ether methacrylate, vinyl pyrrolidone, vinyl 4-methylpyrrolidone, vinyl 4-phenylpyrrolidone, vinyl imidazole, vinyl 4-methylimidazole, vinyl 4-phenylimidazole, and the like.

[0011] (Water-insoluble polymerizable compounds) The water-insoluble polymerizable compounds used in the present invention include monofunctional monomers, polyfunctional monomers, oligomers, etc., and contain one or more of these. The water-insoluble polymerizable compound is contained in an amount of 8.0 to 35.0% by mass in the total polymerizable components in the ultraviolet curable aqueous inkjet printing ink composition of the present invention. And it is preferable that the water-insoluble polymerizable compound is contained in an amount of 10.0% by mass or more, more preferably 13.0% by mass or more, still more preferably 15.0% by mass or more, and most preferably 17.0% by mass or more in the total polymerizable components. Also, it is preferable that the water-insoluble polymerizable compound is contained in an amount of 30.0% by mass or less, more preferably 27.0% by mass or less, still more preferably 25.0% by mass or less, and most preferably 23.0% by mass or less in the total polymerizable components.

[0012] Examples of the monofunctional monomer include alkyl (meth)acrylates such as ethyl (meth)acrylate, methyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, aromatic (meth)acrylates such as benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, ethoxylated phenyl (meth)acrylate, and the like.

[0013] Examples of the polyfunctional monomer include dipropylene glycol diacrylate, 1,6 - hexanediol diacrylate, tripropylene glycol diacrylate, PO - modified neopentyl glycol diacrylate, modified bisphenol A diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane tri(meth)acrylate, EO - modified trimethylolpropane tri(meth)acrylate, PO - modified trimethylolpropane tri(meth)acrylate, EO - modified glycerin tri(meth)acrylate, PO - modified glycerin tri(meth)acrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, and the like.

[0014] Examples of the oligomer include one or more selected from amine - modified (meth)acrylate oligomers and epoxy (meth)acrylate oligomers. These polymerizable oligomers are preferably contained in an amount of 5.0 mass% or more, more preferably 10.0 mass% or more, based on the total polymerizable components of the ink. Also, they are preferably contained in an amount of 25.0 mass% or less, more preferably 20.0 mass% or less. The amine - modified (meth)acrylate oligomer is not particularly limited as long as it has at least one amino group and at least one (meth)acryloyl group in the molecule. On the other hand, the number of (meth)acryloyl groups in the amine - modified (meth)acrylate oligomer is not particularly limited as long as it is one or more, but is preferably one or more and six or less, more preferably two or more and four or less. When the number of (meth)acryloyl groups is within the above range, the amine - modified (meth)acrylate oligomer is likely to react with the polymerizable compound, and the viscosity of the ink composition is likely to be in an appropriate range.

[0015] The amine-modified (meth)acrylate oligomer may be a synthetic product obtained by polymerizing a desired monomer or a commercially available product. Examples of commercially available amine-modified (meth)acrylate oligomers include product names such as "GENOMER5161", "GENOMER5275" (RAHN); product names such as "CN371", "CN373", "CN383", "CN384", "CN386", "CN501", "CN550", "CN551" ( Sartomer); product names such as "EBECRYL7100", "EBECRYL80", "EBECRYL81", "EBECRYL83", "EBECRYL84", "EBECRYLP115" (Daicel-Cytec); product names such as "Laromer PO77F (LR8946)", "Laromer LR8956", "Laromer LR8996", "Laromer PO94F (LR8894)" (BASF); product names such as "Photomer4771", "Photomer4775", "Photomer4967", "Photomer5096", "Photomer5662", "Photomer5930" (Cognis); product names such as "DoublecureEPD", "DoublecureOPD", "Doublecure115", "Doublecure225", "Doublecure645", "PolyQ222", "PolyQ226", "PolyQ224", "PolyQ101" (DoubleBondChemicals).

[0016] The epoxy (meth)acrylate oligomer may be a synthetic product obtained by polymerizing a desired monomer or a commercially available product. Examples of commercially available epoxy (meth)acrylate oligomers include product names such as "EBECRYL3708", "EBECRYL1606" (Daicel-Cytec), "CN116", "CN120B60", "CN120M50", "CN131B", "CN132", "CN137", "CN152", "CN153", "CN2102E", "CN2003" (Sartomer).

[0017] (Photoinitiator) The ink composition for ultraviolet curable aqueous inkjet printing of the present invention contains a photoinitiator. The photoinitiator is not particularly limited as long as it can initiate photopolymerization, and a photoinitiator used in an ink composition for photocurable inkjet printing can be used. Examples of the photoinitiator include benzoin ether-based photoinitiators, acetophenone-based photoinitiators, α-ketol-based photoinitiators, aromatic sulfonyl chloride-based photoinitiators, photoactive oxime-based photoinitiators, benzoin-based photoinitiators, benzyl-based photoinitiators, benzophenone-based photoinitiators, ketal-based photoinitiators, thioxanthone-based photoinitiators, triazine-based photoinitiators, acylphosphine oxide-based photoinitiators, and the like. Among these, from the viewpoint of good curability with respect to light-emitting diode (LED) light, triazine-based photoinitiators and acylphosphine oxide-based photoinitiators are preferred. The photoinitiator can be used alone or in combination of two or more.

[0018] Examples of the triazine-based photoinitiator include 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine, 2-piperenyl-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxy-naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, 2,4-trichloromethyl(4'-methoxystyryl)-6-triazine, and the like. Examples of commercially available products include the product name "TAZ-204" (Midori Chemical Co., Ltd.).

[0019] Examples of the acylphosphine oxide-based photoinitiator include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (trade name "TPO", manufactured by Lamberti), (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide (TPO-L), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name "Omnirad819", manufactured by IGM Resins B.V.), and the like.

[0020] (Sensitizer) From the viewpoint of improving curability, the ultraviolet curable aqueous inkjet printing ink composition of the present invention may contain a sensitizer. The sensitizer can be used alone or in combination of two or more kinds.

[0021] Examples of the sensitizer include anthracene-based sensitizers such as 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-bis(2-ethylhexyloxy)anthracene; thioxanthone-based sensitizers such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, and the like. Among these, thioxanthone-based sensitizers are preferred. Examples of commercially available products of the sensitizer include, for anthracene-based sensitizers, trade names "DBA", "DEA" (both manufactured by Kawasaki Kasei Kogyo Co., Ltd.), and for thioxanthone-based sensitizers, trade names "DETX", "ITX" (manufactured by Lambson), and the like.

[0022] In the ink composition, the proportion of the sensitizer is preferably 5% by mass or less from the viewpoint of preventing excessive addition. When a thioxanthone-based sensitizer is used as the sensitizer, since the ultraviolet curable inkjet printing ink composition tends to change color to yellow, it is preferable to appropriately determine the content of the thioxanthone-based sensitizer for each hue. For example, in the white ink composition and the clear ink composition that are easily affected by the change in color tone, it is preferable not to contain a thioxanthone-based sensitizer as the sensitizer. In addition, in the magenta ink composition and the cyan ink composition, since the change in hue becomes a problem, it is preferable to use them within a range where no problem occurs in the hue. In addition, since the black ink composition and the yellow ink composition are not affected by the hue even if there is discoloration and have less photopolymerizability than other hues, it is preferable to use a thioxanthone-based sensitizer as the sensitizer. In the present invention, 3.0 to 10.0 parts by mass of a photopolymerization initiator and / or a sensitizer is contained with respect to 100 parts by mass of the total mass of all the polymerizable components of the ink composition. Here, when a photopolymerization initiator and a sensitizer are contained, this ratio is the ratio of the total amount of these, and when only one of them is contained, it is the ratio of each alone.

[0023] (Pigment) The ultraviolet curable aqueous inkjet printing ink composition of the present invention contains a pigment. The pigment can be used alone or in combination of two or more.

[0024] The above-mentioned pigments can be used without particular limitation, such as organic pigments and inorganic pigments used in inkjet ink compositions. As the organic pigments, for example, dye lake pigments, azo pigments, benzimidazolone pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, perylene pigments, perinone pigments, diketopyrrolopyrrole pigments, isoindolinone pigments, nitro pigments, nitroso pigments, anthraquinone pigments, flavanthrone pigments, quinophthalone pigments, pyranthrone pigments, indanthrone pigments, etc. can be mentioned. Further, as the inorganic pigments, for example, carbon black, titanium oxide, zinc white, red iron oxide, graphite, iron black, chromium oxide green, aluminum hydroxide, etc. can be mentioned. The pigments may be those surface-treated with a known surface treatment agent.

[0025] Specific examples for each typical hue of the above-mentioned pigments are as follows. As yellow pigments, for example, C.I.Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 42, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 108, 109, 114, 120, 128, 129, 138, 139, 150, 151, 155, 166, 180, 184, 185, 213, etc. can be mentioned.

[0026] As magenta pigments, for example, C.I.Pigment Red 5, 7, 12, 22, 38, 48:1, 48:2, 48:4, 49:1, 53:1, 57, 57:1, 63:1, 101, 102, 112, 122, 123, 144, 146, 149, 168, 177, 178, 179, 180, 184, 185, 190, 202, 209, 224, 242, 254, 255, 270, C.I.Pigment Violet 19, etc. can be mentioned.

[0027] Examples of the cyan pigment include C.I.Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 18, 22, 27, 29, 60, etc.

[0028] Examples of the black pigment include carbon black (C.I.Pigment Black 7), etc.

[0029] Examples of the white pigment include titanium oxide, aluminum oxide, etc., and they may be surface-treated with various materials such as alumina and silica.

[0030] In the ink composition, from the viewpoint of improving the printing density of the printed matter, the proportion of the pigment is preferably 1.0% by mass or more, more preferably 1.2% by mass or more, and from the viewpoint of improving the ejection stability, it is preferably 5.0% by mass or less, more preferably 4.0% by mass or less. However, when the pigment is a white pigment, in the ink composition, the proportion of the white pigment is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, and preferably 15.0% by mass or less, more preferably 10.0% by mass or less.

[0031] In the ultraviolet curable aqueous inkjet printing ink composition of the present invention, when using the pigment, it is preferable to use a pigment dispersant. The pigment dispersant is used to improve the dispersibility of the pigment and the storage stability of the ink composition, and those conventionally used can be used without particular limitation. Among them, it is preferable to use a polymer pigment dispersant. The pigment dispersant can be used alone or in combination of two or more.

[0032] Examples of the polymer pigment dispersant include carbodiimide-based dispersants, polyesteramine-based dispersants, fatty acid amine-based dispersants, modified polyacrylate-based dispersants, modified polyurethane-based dispersants, multi-chain polymer nonionic dispersants, polymer ion activators, and the like. Such polymer pigment dispersants are preferably water-soluble, such as BYKJET-9150, BYKJET-9151, BYKJET-9170, DISPERBYK-168, DISPERBYK-190, DISPERBYK-198, DISPERBYK-2010, DISPERBYK-2012, DISPERBYK-2015 manufactured by BYK Chemie; SMA1440, SMA2625, SMA17352, SMA3840, SMA1000, SMA2000, SMA3000 manufactured by Cray Valley; JONCRYL67, JONCRYL678, JONCRYL586, JONCRYL611, JONCRYL680, JONCRYL682, JONCRYL690, JONCRYL819, JONCRYL-JDX5050, EFKA4550, EFKA4560, EFKA4585, EFKA5220, EFKA6230 manufactured by BASF Japan; SOLSPERSE20000, SOLSPERSE27000, SOLSPERSE41000, SOLSPERSE41090, SOLSPERSE43000, SOLSPERSE44000, SOLSPERSE46000, SOLSPERSE47000, SOLSPERSE54000 manufactured by Lubrizol, and the like.

[0033] From the viewpoint of enhancing the dispersibility of the pigment and the storage stability of the ink composition, the content of the pigment dispersant is preferably 1.0 part by mass or more, more preferably 5.0 parts by mass or more, and preferably 100 parts by mass or less, more preferably 60.0 parts by mass or less, based on 100 parts by mass of the pigment.

[0034] (Water) Water is blended as a solvent for dissolving and dispersing a colorant or the like. The water is purified water, ion-exchanged water, or the like. The water content is preferably 10% by mass or more in the ink composition. Further, the water content is preferably 40% by mass or less in the ink composition. When the water content is within the above range, the ink composition has the advantage of good dispersion stability.

[0035] (Optional component) The ink composition of the present invention may optionally contain, as optional components, a surface conditioner, a water-soluble organic solvent, a preservative improver, an ultraviolet absorber, an antioxidant, an antifoaming agent, an antifungal agent, a rust inhibitor, a thickener, a humectant, and various additives such as a pH adjuster.

[0036] ·Surface conditioner The surface conditioner that may be contained in the ink composition of the present invention is not particularly limited. Silicone-based surface conditioners, fluorine-based surface conditioners, acetylene-based surface conditioners, etc. are preferred. Acetylene diol-based surface conditioners include Dynol 607, Dynol 609, EXP-4001, EXP-4300, Orfin E1010 (Nissin Chemical Industry Co., Ltd.), etc. Silicone-based surfactants include BYK-307, 333, 347, 348, 349, 345, 378, 3455 (BYK-Chemie GmbH), etc. Fluorine-based surfactants include F-410, 444, 553 (DIC Corporation), FS-65, 34, 35, 31, 30 (E. I. du Pont de Nemours and Company), etc. When a surface conditioner is contained, the content of the surface conditioner is not particularly limited, and it is preferably a content such that the surface tension of the ink composition becomes 25 to 40 mN / m, and more preferably 0.1 to 1.5% by mass in the ink composition.

[0037] ·Water-soluble organic solvent The ink composition of the present invention may contain a water-soluble organic solvent in order to adjust storage stability, ejection stability, ink flying property, etc. The water-soluble organic solvent is not particularly limited, and alcohols, polyhydric alcohols, lower alkyl ethers of polyhydric alcohols, ketones, ethers, esters, nitrogen-containing compounds, amides, etc. are preferred. Also, the content of the water-soluble organic solvent is not particularly limited.

[0038] The alcohols are methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonyl alcohol, n-decanol, or their isomers, cyclopentanol, cyclohexanol, etc.

[0039] The polyhydric alcohols are glycerin, ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,2-pentanediol, 4-methyl-1,2-pentanediol, 3,3-dimethyl-1,2-butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-hexanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,3-butanediol, 5-methyl-1,2-hexanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-butanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,5-dimethyl-2,5-hexanediol, 1,2-octanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, pentaerythritol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol, thiodiglycol, etc.

[0040] Lower alkyl ethers of polyhydric alcohols include ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol monopropyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, ethylene glycol isobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, and the like.

[0041] Ketones include acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diisopropyl ketone, cyclopentanone, cyclohexanone, and the like.

[0042] Ethers include diethyl ether, isopropyl ether, n-butyl ether, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, and the like.

[0043] Esters include ethyl acetate, propylene carbonate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, amyl acetate, lactate ester, butyrate ester, dibutyl phthalate, dioctyl phthalate, and cyclic esters such as ε-caprolactone and ε-caprolactam.

[0044] Nitrogen-containing compounds include 2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, N-methyloxazolidinone, N-ethyloxazolidinone, and the like.

[0045] Amides include β-alkoxypropionamide and the like.

[0046] ·Preservation improver As a preservative improver, hindered amines such as N-CH3 type, N-H type, and N-OR type can be used.

[0047] · UV absorber UV absorbers include benzophenone-based UV absorbers, benzotriazole-based UV absorbers, salicylate-based UV absorbers, hydroxyphenyltriazine-based UV absorbers, cyanoacrylate-based UV absorbers, nickel complex salt-based UV absorbers, and the like.

[0048] · Antioxidant Antioxidants include phenolic antioxidants, amine-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.

[0049] · Defoamer Defoamers include silicone-based defoamers, pluronic-based defoamers, and the like.

[0050] The ink composition for ultraviolet curable aqueous inkjet printing of the present invention preferably has a viscosity at 25°C of 100 mPa·s or less, and more preferably 30 mPa·s or less. If necessary, a viscosity modifier or the like is blended into the ink composition. The viscosity described in the specification of the present application is a value measured at 25°C using an E-type viscometer (RE100L type viscometer, manufactured by Toki Sangyo Co., Ltd.).

[0051] <Method for preparing ink composition> The method for preparing the ink composition for ultraviolet curable aqueous inkjet printing of the present invention is not particularly limited. For example, the ink composition can be prepared by mixing the contained materials using a bead mill, a three-roll mill, or the like. The pigment may be prepared by mixing the pigment with the above-mentioned pigment dispersant and the above-mentioned photopolymerizable monomer in advance to obtain a base ink composition, and then adding the remaining portions of the above-mentioned components to have a desired composition.

[0052] <Printing method> A printing method using the ink composition for ultraviolet curable aqueous inkjet printing of the present invention will be described. The inkjet printing apparatus to be used is not particularly limited as long as it can print an ultraviolet-curable ink composition. Also, the substrate to be printed is not particularly limited, and as the substrate, various resin substrates, paper, capsules, gels, metal foils, glass, wood, cloth, etc. can be adopted.

[0053] The printed portion of the ultraviolet-curable aqueous inkjet printing ink composition of the present invention obtained by discharging onto the substrate surface is irradiated with ultraviolet rays for temporary curing (pinning), and then irradiated with ultraviolet rays for final curing to cure the ink composition in the printed portion. Here, the temporary curing (pinning) means curing the ink composition discharged onto the substrate surface to such an extent that it loses fluidity, and the ink composition after pinning contains uncured components and a solvent. In this temporary curing (pinning), on the surface of the printed portion, irradiation is performed with a UV-LED having a peak at a wavelength of 365 to 405 nm so that the integrated light amount is 100 mJ / cm 2 as follows. The final curing step after the temporary curing is a step of irradiating ultraviolet rays so that the integrated light amount becomes such that the ink composition can be completely cured. Only in this final curing step, it is preferable to irradiate ultraviolet rays so that the integrated light amount becomes 100 to 300 mJ / cm 2

Examples

[0054] Ink compositions 1 to 14 described in Table 1 below were prepared and pinned under the conditions of Table 2. EO-modified TMPTA: Trimethylolpropane EO-modified triacrylate CN131B: Epoxy (meth) acrylate oligomer (trade name "Sartomer CN131B", Sartomer Co., Ltd.) CN371: Amine-modified (meth) acrylate oligomer (trade name "Sartomer CN371", Sartomer Co., Ltd.) TPO-L: (2,4,6-Trimethylbenzoyl) ethoxyphenylphosphine oxide BYK-333: Silicone-based surface conditioner (Big Chemie) ​PB15:4: Pigment Blue 15:4 PR122: Pigment Red 122 PY138: Pigment Yellow 138 P.Bk.7: Carbon black BYKJET-9151: Water-soluble polymer dispersant (BYK)

[0055] Evaluation method (compatibility) Each ink was placed in a brown bottle and allowed to stand at room temperature for 24 hours, after which the presence or absence of separation was visually confirmed. ○: No separation ×: Separated into two layers

[0056] The following evaluations were made on the basis of compatibility ratings other than "x". (Storage stability) Each ink was placed in a brown bottle, sealed, and stored at 60°C for 2 weeks. After that, the viscosity was measured at a temperature of 25°C and a rotor rotation speed of 20 rpm using an E-type viscometer (product name: RE100L type viscometer, Toki Sangyo Co., Ltd.). The viscosity increase rate was calculated using formula (1) and evaluated according to the following evaluation criteria. Formula (1) ((Viscosity after 2 weeks at 60°C - Viscosity before storage) / Viscosity before storage) x 100 〇: Viscosity increase rate is less than 10% ×: Viscosity increase rate is 10% or more

[0057] (graininess) Each ink was printed on OK topcoat paper (Oji Paper Co., Ltd.) using an inkjet evaluation machine, and pinned by irradiating it with a UV-LED with the pinning cumulative light amount shown in Table 2. After pinning, the cumulative light amount was 200 mJ / cm 2 The resulting cured coating film was visually observed and evaluated according to the following criteria. 〇: No graininess △: Slight graininess is observed ×: Graininess is evident

[0058] (curable) Each ink was printed on OK topcoat paper (Oji Paper Co., Ltd.) using an inkjet evaluation machine, pinned by irradiating with a UV-LED having a pinning integrated light amount shown in Table 2, and then cured by irradiating with ultraviolet rays of an integrated light amount of 200 mJ / cm 2 The resulting cured coating film was rubbed with a cotton swab and evaluated according to the following evaluation criteria. 〇: No trace remains after rubbing with a cotton swab △: A slight rubbing trace remains ×: The coating film is picked up by a cotton swab

[0059] (Water resistance) Each ink was printed on OK topcoat paper (Oji Paper Co., Ltd.) using an inkjet evaluation machine, pinned by irradiating with a UV-LED having a pinning integrated light amount shown in Table 2, and then cured by irradiating with ultraviolet rays of an integrated light amount of 200 mJ / cm 2 The resulting cured coating film was rubbed with a cotton swab moistened with water and evaluated according to the following evaluation criteria. 〇: Not picked up even after 40 reciprocations △: Picked up in 11 to 39 reciprocations ×: Picked up in 10 reciprocations or less

[0060]

Table 1

[0061]

Table 2

[0062] As shown in Table 1, according to Ink Compositions 1 to 8 which are examples of the ultraviolet curable aqueous inkjet printing ink composition according to the present invention, they are excellent in compatibility and storage stability. However, in terms of components other than water in the ultraviolet curable aqueous inkjet printing ink composition, according to Ink Compositions 10 to 12 and 14 not included in the present invention, without even evaluating the storage stability, they were inferior in compatibility. Furthermore, in Table 2, according to Examples 1 to 10 using Ink Compositions 1 to 8, the cured printed portions had no granular feeling and were excellent in curability and water resistance. On the other hand, according to Comparative Example 1 where pinning was not performed, Comparative Example 2 where the integrated light amount of ultraviolet rays during pinning was too large, and Comparative Example 3 using Ink 9 that does not contain water, all were inferior in granular feeling. According to Comparative Example 7 using Ink Composition 13 with a low content of the water-insoluble polymerizable compound, the water resistance was inferior.

Claims

1. Based on the total mass of all polymerizable components, the water-soluble acrylamide-based monomer is 20.0 to 70.0% by mass, the water-soluble hydroxyl group-containing monofunctional monomer is 5.0 to 60.0% by mass, the water-insoluble polymerizable compound containing an oligomer is 8.0 to 35.0% by mass, each containing, furthermore, based on 100 parts by mass of the total mass of all polymerizable components, 3.0 to 10.0 parts by mass of a photoinitiator and / or a sensitizer is contained, a pigment, and water, the mass ratio of the water-soluble acrylamide-based monomer to the water-soluble hydroxyl group-containing monofunctional monomer (acrylamide-based monomer / hydroxyl group-containing monofunctional monomer) is 0.3 to 10.0, An ink composition for ultraviolet curable aqueous inkjet printing for printing, which has a step of being temporarily cured by irradiation with a UV-LED having a peak at a wavelength of 365 to 405 nm and an integrated light quantity of 100 mJ / cm ２ 2 (however, except for the case of containing a polysilane compound having a phenyl group).

2. The ultraviolet-curable aqueous inkjet printing ink composition according to claim 1, wherein the water-soluble acrylamide-based monomer contains acryloylmorpholine.

3. Based on the total mass of all polymerizable components, the water-soluble acrylamide-based monomer is 20.0 to 70.0% by mass, the water-soluble hydroxyl group-containing monofunctional monomer is 5.0 to 60.0% by mass, the water-insoluble polymerizable compound is 8.0 to 35.0% by mass, each containing, furthermore, based on 100 parts by mass of the total mass of all polymerizable components, 3.0 to 10.0 parts by mass of a photoinitiator and / or a sensitizer is contained, a pigment, and water, the mass ratio of the water-soluble acrylamide-based monomer to the water-soluble hydroxyl group-containing monofunctional monomer (acrylamide-based monomer / hydroxyl group-containing monofunctional monomer) is 0.3 to 10.0, An ink composition for ultraviolet curable aqueous inkjet printing for printing, which has a step of being temporarily cured by irradiation with a UV-LED having a peak at a wavelength of 365 to 405 nm and an integrated light amount of 100 mJ / cm ２ wherein the irradiation is as follows The ultraviolet-curable aqueous inkjet printing ink composition, wherein the water-soluble hydroxyl group-containing monofunctional monomer contains 4-hydroxybutyl acrylate.

4. The ultraviolet-curable aqueous inkjet printing ink composition according to any one of claims 1 to 3, wherein the water content is 10.0 to 40.0% by mass based on the entire ink composition.

5. Based on the total mass of all polymerizable components, the water-soluble acrylamide-based monomer is 20.0 to 70.0% by mass, the water-soluble hydroxyl group-containing monofunctional monomer is 5.0 to 60.0% by mass, the water-insoluble polymerizable compound is 8.0 to 35.0% by mass, each containing, furthermore, based on 100 parts by mass of the total mass of all polymerizable components, 3.0 to 10.0 parts by mass of a photoinitiator and / or a sensitizer is contained, a pigment, and water, the mass ratio of the water-soluble acrylamide-based monomer to the water-soluble hydroxyl group-containing monofunctional monomer (acrylamide-based monomer / hydroxyl group-containing monofunctional monomer) is 0.3 to 10.0, An ink composition for ultraviolet-curable aqueous inkjet printing for printing, which has a step of being temporarily cured by irradiation with a UV-LED having a peak at a wavelength of 365 to 405 nm and an integrated light amount of 100 mJ / cm ２ or less. An ink composition for ultraviolet-curable aqueous inkjet printing, further comprising a pigment dispersant having a maleimide structure and / or a pigment dispersant having a pyridine ring.

6. Based on the total mass of all polymerizable components, 20.0 to 70.0% by mass of a water-soluble acrylamide-based monomer, 5.0 to 60.0% by mass of a water-soluble hydroxyl group-containing monofunctional monomer, 8.0 to 35.0% by mass of a water-insoluble polymerizable compound, each containing, furthermore, based on 100 parts by mass of the total mass of all polymerizable components, 3.0 to 10.0 parts by mass of a photopolymerization initiator and / or a sensitizer are contained, a pigment, and water, A printing method using an ink composition for ultraviolet-curable aqueous inkjet printing, wherein the mass ratio of the water-soluble acrylamide-based monomer to the water-soluble hydroxyl group-containing monofunctional monomer (acrylamide-based monomer / hydroxyl group-containing monofunctional monomer) is 0.3 to 10.0 (however, except when containing a polysilane compound having a phenyl group), A step of performing temporary curing by irradiation with a UV-LED having a peak at a wavelength of 365 to 405 nm and an integrated light quantity of 100 mJ / cm ２ is performed, where the integrated light quantity is 100 mJ / cm or less having a step of then irradiating with ultraviolet rays for final curing.

7. A printing method using the ink composition for ultraviolet-curable aqueous inkjet printing according to claim 6, wherein the ink composition contains acryloylmorpholine as the water-soluble acrylamide-based monomer.

8. Based on the total mass of all polymerizable components, 20.0 to 70.0% by mass of a water-soluble acrylamide-based monomer, 5.0 to 60.0% by mass of a water-soluble hydroxyl group-containing monofunctional monomer, 8.0 to 35.0% by mass of a water-insoluble polymerizable compound, each containing, furthermore, based on 100 parts by mass of the total mass of all polymerizable components, 3.0 to 10.0 parts by mass of a photopolymerization initiator and / or a sensitizer are contained, a pigment, and water, A printing method using an ink composition for ultraviolet-curable aqueous inkjet printing, wherein the mass ratio of the water-soluble acrylamide-based monomer to the water-soluble hydroxyl group-containing monofunctional monomer (acrylamide-based monomer / hydroxyl group-containing monofunctional monomer) is 0.3 to 10.0, A step of performing temporary curing by irradiation having an integrated light amount of 100 mJ / cm ２ or less is carried out by irradiation having a peak at a wavelength of 365 to 405 nm, having a step of then irradiating with ultraviolet rays for final curing, in which the water-soluble hydroxyl group-containing monofunctional monomer contains 4-hydroxybutyl acrylate.

9. A printing method using the ink composition for ultraviolet-curable aqueous inkjet printing according to any one of claims 6 to 8, wherein the content of the water is 10.0 to 40.0% by mass based on the entire ink composition.

10. Based on the total mass of all polymerizable components, 20.0 to 70.0% by mass of a water-soluble acrylamide-based monomer, 5.0 to 60.0% by mass of a water-soluble hydroxyl group-containing monofunctional monomer, 8.0 to 35.0% by mass of a water-insoluble polymerizable compound, each containing, further, with respect to 100 parts by mass of the total mass of all polymerizable components, 3.0 to 10.0 parts by mass of a photopolymerization initiator and / or a sensitizer is contained, a pigment, and water, A printing method using an ultraviolet-curable aqueous inkjet printing ink composition in which the mass ratio of the water-soluble acrylamide-based monomer to the water-soluble hydroxyl group-containing monofunctional monomer (acrylamide-based monomer / hydroxyl group-containing monofunctional monomer) is 0.3 to 10.0, A step of performing temporary curing by irradiation with a UV-LED having a peak at a wavelength of 365 to 405 nm and an integrated light amount of 100 mJ / cm ２ is carried out by irradiation as described below, subsequently having a step of irradiating with ultraviolet rays for final curing, in the printing method, The ultraviolet-curable aqueous inkjet printing ink composition further contains a pigment dispersant having a maleimide structure and / or a pigment dispersant having a pyridine ring.

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