Radiation-curable inkjet composition

Abstract

To provide a radiation-curable ink jet composition having low viscosity and excellent coating film adhesion.SOLUTION: A radiation-curable ink jet composition includes a polyfunctional monomer containing a predetermined acrylic compound, and a monofunctional monomer containing vinyl methyl oxazolidinone.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a radiation-curable ink jet composition. [Background technology]

[0002] Inkjet recording methods are capable of recording high-resolution images using relatively simple equipment and have been rapidly developing in various fields. In particular, various studies have been conducted on the curability of coating films of inkjet compositions that are cured by irradiation with radiation. For example, Patent Document 1 discloses an inkjet curable composition containing an allyloxymethyl group-containing acrylate, with the aim of providing an inkjet curable composition that has low viscosity, excellent dischargeability, and excellent resistance properties such as heat resistance and plating resistance, as well as a cured product thereof and an electronic circuit board using the same. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2013-091788 Summary of the Invention [Problem to be solved by the invention]

[0004] As described in Patent Document 1, acrylic compounds having an allyloxymethyl group have advantages such as low viscosity and excellent resistance, etc. However, it has been found that coating films formed from radiation-curable inkjet compositions containing the above compounds do not have sufficient adhesion. [Means for solving the problem]

[0005] The radiation-curable ink jet composition of the present invention contains a polyfunctional monomer containing an acrylic compound represented by the following formula (1) and a monofunctional monomer containing vinylmethyloxazolidinone. [ka] (In the formula, R 1 represents a hydrogen atom or a monovalent hydrocarbon group which may have an ether bond, and the hydrogen atom of the hydrocarbon group may be substituted with a halogen atom. DETAILED DESCRIPTION OF THE INVENTION

[0006] Below, we will explain in detail the embodiment of the present invention (hereinafter referred to as the ``present embodiment''), but the present invention is not limited to this and various modifications are possible within the scope of the gist of the present invention.

[0007] In this specification, "(meth)acrylate" means at least one of acrylate and its corresponding methacrylate, and "(meth)acrylic" means at least one of acrylic and its corresponding methacrylic.

[0008] 1. Radiation-curable inkjet composition The radiation-curable inkjet composition of this embodiment (hereinafter also simply referred to as "ink composition") contains a polyfunctional monomer including an acrylic compound represented by the following formula (1) and a monofunctional monomer including vinylmethyloxazolidinone: [ka] (In the formula, R 1 represents a hydrogen atom or a monovalent hydrocarbon group which may have an ether bond, and the hydrogen atom of the hydrocarbon group may be substituted with a halogen atom.

[0009] Generally, acrylic compounds such as those represented by the above formula (1) have low viscosity and are easily diluted, allowing them to be mixed with various ink compositions. On the other hand, acrylic compounds such as those represented by the above formula (1) (hereinafter also referred to as "allyloxymethyl group-containing acrylates") can be cyclically polymerized to obtain linear polymers having a ring structure in the main chain, but it has been found that the adhesion of the resulting coating film is insufficient simply by including this monomer.

[0010] In contrast to this, in the present embodiment, by using an allyloxymethyl group-containing acrylate and vinylmethyloxazolidinone in combination, it is possible to achieve both low viscosity and good adhesion.

[0011] The radiation-curable inkjet composition of this embodiment is cured by irradiation with radiation. The radiation is not particularly limited, but examples thereof include ultraviolet light, electron beams, infrared light, visible light, X-rays, and actinic energy rays. As the radiation, ultraviolet light is preferred because radiation sources are readily available and widely used, and materials suitable for curing by ultraviolet radiation are readily available and widely used.

[0012] The radiation-curable inkjet composition of this embodiment is a composition that is used by being ejected from an inkjet head by an inkjet method. Hereinafter, components that can be contained in a radiation-curable ink composition as one embodiment of the radiation-curable inkjet composition and a production method will be described, but the composition according to this embodiment may also be a composition other than an ink composition, for example, a composition used for 3D modeling.

[0013] 1.1. Polymerizable compounds In this embodiment, the polymerizable compound refers to a compound that is cured by irradiation with radiation. The polymerizable compound includes a monofunctional monomer having one polymerizable functional group and a polyfunctional monomer having multiple polymerizable functional groups, and may also include an oligomer having one or multiple polymerizable functional groups as needed. Each polymerizable compound may be used alone or in combination of two or more.

[0014] The ink composition of this embodiment contains, as polymerizable compounds, a polyfunctional monomer containing the allyloxymethyl group-containing acrylate and a monofunctional monomer containing vinylmethyloxazolidinone, and may contain other polymerizable compounds as needed. The other polymerizable compounds are not particularly limited, but examples thereof include monofunctional monomers other than vinylmethyloxazolidinone, polyfunctional monomers other than the allyloxymethyl group-containing acrylate, and oligomers such as urethane oligomers.

[0015] 1.1.1. Monofunctional Monomers The ink composition of this embodiment contains vinylmethyloxazolidinone as a monofunctional monomer, and may contain other monofunctional monomers as needed. Examples of other monofunctional monomers include, but are not limited to, aromatic monofunctional monomers and aliphatic group-containing monofunctional monomers. Furthermore, the ink composition may contain other monofunctional monomers other than those listed above as needed.

[0016] The content of the monofunctional monomer is not particularly limited, but is, for example, 1% by mass or more and 80% by mass or less relative to the total amount of the ink composition. From the viewpoint of more effectively and reliably achieving the effects of the present invention, the content of the monofunctional monomer is preferably 5% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 60% by mass or less, even more preferably 15% by mass or more and 50% by mass or less, and even more preferably 25% by mass or more and 45% by mass or less, relative to the total amount of the ink composition.

[0017] 1.1.1.1. Vinylmethyloxazolidinone By including vinylmethyloxazolidinone in the ink composition, the viscosity of the ink composition tends to decrease, and the adhesion of the ink coating tends to be improved. Because vinylmethyloxazolidinone has a lower viscosity than other N-vinyl compounds, it is thought that it is less likely to increase the viscosity of the ink composition and improve the adhesion of the coating.

[0018] In this embodiment, vinylmethyloxazolidinone refers to a compound represented by the following chemical formula: [ka]

[0019] The content of vinylmethyloxazolidinone is not particularly limited, but is, for example, 1% by mass to 60% by mass relative to the total amount of the ink composition. From the viewpoint of further improving the adhesion of the ink coating while reducing the viscosity of the ink composition, the content of vinylmethyloxazolidinone is preferably 2% by mass to 55% by mass relative to the total amount of the ink composition, more preferably 3% by mass to 50% by mass, even more preferably 5% by mass to 40% by mass, and even more preferably 10% by mass to 30% by mass.

[0020] 1.1.1.2. Other monofunctional monomers The monofunctional monomer other than vinylmethyloxazolidinone is not particularly limited, but examples thereof include aromatic monofunctional monomers, monofunctional monomers having a polycyclic hydrocarbon group, etc. Use of such monomers tends to further improve the curability of the ink composition and the abrasion resistance and stretchability of the coating film.

[0021] 1.1.1.2.1. Aromatic monofunctional monomers The aromatic monofunctional monomer is not particularly limited, but examples thereof include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, alkoxylated 2-phenoxyethyl (meth)acrylate, ethoxylated nonylphenyl (meth)acrylate, alkoxylated nonylphenyl (meth)acrylate, p-cumylphenol EO-modified (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate.

[0022] In the ink composition of this embodiment, the monofunctional monomer preferably includes a monofunctional (meth)acrylate having an aromatic ring structure. By including a monofunctional (meth)acrylate having an aromatic ring structure, the solubility of the photopolymerization initiator is improved, and the curability of the ink composition tends to be further improved.

[0023] Among the aromatic monofunctional monomers, phenoxyethyl (meth)acrylate (PEA) and benzyl (meth)acrylate (BZA) are preferred. The use of such aromatic monofunctional monomers tends to improve the solubility of the photopolymerization initiator and further improve the curability of the ink composition.

[0024] The content of the aromatic monofunctional monomer is not particularly limited, but is, for example, 1% by mass or more and 30% by mass or less relative to the total amount of the ink composition. From the viewpoint of further improving the curability of the ink composition, the content of the aromatic monofunctional monomer is preferably 2% by mass or more and 25% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and even more preferably 5% by mass or more and 15% by mass or less relative to the total amount of the ink composition.

[0025] 1.1.1.2.2. Aliphatic group-containing monofunctional monomers The aliphatic group-containing monofunctional monomer is not particularly limited, and examples thereof include alicyclic group-containing (meth)acrylates such as 3,3,5-trimethylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tert-butylcyclohexanol (meth)acrylate, and 2-(meth)acrylic acid-1,4-dioxaspiro[4,5]dec-2-ylmethyl; isoamyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, and octyl (meth)acrylate. linear or branched aliphatic group-containing (meth)acrylates such as decyl (meth)acrylate, isodecyl (meth)acrylate, isomyristyl (meth)acrylate, isostearyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, butoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate; and lactone-modified flexible (meth)acrylates.

[0026] Among the above-mentioned aliphatic group-containing monofunctional monomers, isobornyl acrylate (IBXA) is preferred. By using such an aliphatic group-containing monofunctional monomer, the curability and abrasion resistance of the ink composition tend to be further improved.

[0027] The content of the aliphatic group-containing monofunctional monomer is not particularly limited, but is, for example, 1% by mass or more and 40% by mass or less relative to the total amount of the ink composition. From the viewpoint of further improving the curability and abrasion resistance of the ink composition, the content of the aliphatic group-containing monofunctional monomer is preferably 3% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 20% by mass or less, and even more preferably 8% by mass or more and 15% by mass or less.

[0028] 1.1.2. Polyfunctional Monomers The ink composition of this embodiment contains an allyloxymethyl group-containing acrylate as a polyfunctional monomer, and may contain other polyfunctional monomers as needed. The other polyfunctional monomers are not particularly limited, but examples thereof include vinyl ether group-containing (meth)acrylates and bifunctional (meth)acrylates.

[0029] The content of the polyfunctional monomer relative to the total amount of the ink composition is preferably 15% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 75% by mass or less, more preferably 25% by mass or more and 70% by mass or less, even more preferably 30% by mass or more and 65% by mass or less, and even more preferably 35% by mass or more and 60% by mass or less.

[0030] 1.1.2.1. Allyloxymethyl group-containing acrylates As shown in the following formula (1), allyloxymethyl group-containing acrylate is a polyfunctional monomer in terms of its chemical formula, but as mentioned above, it can be obtained by cyclopolymerization to give a linear polymer having a ring structure in the main chain. Therefore, allyloxymethyl group-containing acrylate can be said to be a type of monofunctional monomer that gives a linear polymer after polymerization.

[0031] [ka] (In the formula, R 1 represents a hydrogen atom or a monovalent hydrocarbon group which may have an ether bond, and the hydrogen atom of the hydrocarbon group may be substituted with a halogen atom.

[0032] In formula (1), the hydrocarbon group is not particularly limited, but examples include chain saturated hydrocarbon groups having 1 or more carbon atoms, chain unsaturated hydrocarbon groups having 3 or more carbon atoms, alicyclic hydrocarbon groups having 3 or more carbon atoms, and aromatic hydrocarbon groups having 6 or more carbon atoms. Of these, chain saturated hydrocarbon groups having 1 to 30 carbon atoms, chain unsaturated hydrocarbon groups having 3 to 30 carbon atoms, alicyclic hydrocarbon groups having 4 to 30 carbon atoms, and aromatic hydrocarbon groups having 6 to 30 carbon atoms are preferred.

[0033] The halogen atom is not particularly limited, but examples thereof include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0034] The chain saturated hydrocarbon group is not particularly limited, but examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-amyl group, a sec-amyl group, a tert-amyl group, a neopentyl group, an n-hexyl group, a sec-hexyl group, an n-heptyl group, an n-octyl group, a sec-octyl group, a tert-octyl group, a 2-ethylhexyl group, a capryl group, a nonyl group, a decyl group, an undecyl group, a lauryl group, a tridecyl group, a myristyl group, a pentadecyl group, a cetyl group, a heptadecyl group, a stearyl group, a nonadecyl group, an eicosyl group, a seryl group, and a melissyl group.

[0035] The chain unsaturated hydrocarbon group is not particularly limited, but examples thereof include a crotyl group, a 1,1-dimethyl-2-propenyl group, a 2-methyl-butenyl group, a 3-methyl-2-butenyl group, a 3-methyl-3-butenyl group, a 2-methyl-3-butenyl group, an oleyl group, a linole group, and a linolene group.

[0036] The alicyclic hydrocarbon group is not particularly limited, but examples thereof include a cyclopentyl group, a cyclopentylmethyl group, a cyclohexyl group, a cyclohexylmethyl group, a 4-methylcyclohexyl group, a 4-tert-butylcyclohexyl group, a tricyclodecanyl group, an isobornyl group, an adamantyl group, a dicyclopentanyl group, and a dicyclopentenyl group.

[0037] The aromatic hydrocarbon group is not particularly limited, but examples thereof include a phenyl group, a methylphenyl group, a dimethylphenyl group, a trimethylphenyl group, a 4-tert-butylphenyl group, a benzyl group, a diphenylmethyl group, a diphenylethyl group, a triphenylmethyl group, a cinnamyl group, a naphthyl group, and an anthranyl group.

[0038] The hydrocarbon group having an ether bond is not particularly limited, and examples thereof include chain ether groups such as a methoxyethyl group, a methoxyethoxyethyl group, a methoxyethoxyethoxyethyl group, a 3-methoxybutyl group, an ethoxyethyl group, and an ethoxyethoxyethyl group; and groups having both an alicyclic hydrocarbon group and a chain ether group, such as a cyclopentoxyethyl group, a cyclohexyloxyethyl group, a cyclopentoxyethoxyethyl group, a cyclohexyloxyethoxyethyl group, and a dicyclopentenyloxyethyl group. groups having both an aromatic hydrocarbon group and a chain ether group, such as a phenoxyethyl group or a phenoxyethoxyethyl group; and cyclic ether groups, such as a glycidyl group, a β-methylglycidyl group, a β-ethylglycidyl group, a 3,4-epoxycyclohexylmethyl group, a 2-oxetanemethyl group, a 3-methyl-3-oxetanemethyl group, a 3-ethyl-3-oxetanemethyl group, a tetrahydrofuranyl group, a tetrahydrofurfuryl group, a tetrahydropyranyl group, a dioxazolanyl group, or a dioxanyl group.

[0039] Examples of the acrylic compound include methyl allyloxymethylacrylate, ethyl allyloxymethylacrylate, methoxyethyl allyloxymethylacrylate, methoxyethoxyethyl allyloxymethylacrylate, vinyl allyloxymethylacrylate, fluoroethyl allyloxymethylacrylate, and chloroethyl allyloxymethylacrylate.

[0040] In this embodiment, the content of the allyloxymethyl group-containing acrylate is not particularly limited, but is, for example, 3% by mass or more and 70% by mass or less relative to the total amount of the ink composition. From the viewpoint of achieving a better balance between viscosity and adhesion in the ink composition, the content of the allyloxymethyl group-containing acrylate is preferably 5% by mass or more and 65% by mass or less, more preferably 10% by mass or more and 60% by mass or less, even more preferably 20% by mass or more and 55% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less.

[0041] In this embodiment, the content of the polyfunctional monomer other than the allyloxymethyl group-containing acrylate is preferably 25% by mass or less, based on the total amount of the polyfunctional monomer. The content of the allyloxymethyl group-containing acrylate is more preferably 3% by mass or more and 20% by mass or less, and even more preferably 5% by mass or more and 15% by mass or less, based on the total amount of the polyfunctional monomer. By having the content of the polyfunctional monomer other than the allyloxymethyl group-containing acrylate within the above range, the viscosity of the ink composition can be further reduced.

[0042] In this embodiment, the total content of the allyloxymethyl group-containing acrylate and vinylmethyloxazolidinone is preferably 40% by mass or more relative to the total amount of the ink composition. From the viewpoint of further reducing the viscosity of the ink composition and further improving adhesion, the total content of the allyloxymethyl group-containing acrylate and vinylmethyloxazolidinone is more preferably 45% by mass or more and 85% by mass or less, even more preferably 50% by mass or more and 75% by mass or less, and even more preferably 50% by mass or more and 65% by mass or less, relative to the total amount of the ink composition.

[0043] 1.1.2.2. Vinyl ether group-containing (meth)acrylate The vinyl ether group-containing (meth)acrylate that can be contained in the ink composition of this embodiment is not particularly limited, and examples thereof include compounds represented by the following formula (2): By including such a vinyl ether group-containing (meth)acrylate, the viscosity of the ink composition tends to decrease, and the ejection stability tends to be further improved. Furthermore, the curability of the ink composition is improved, and therefore the adhesion and abrasion resistance of the coating film tend to be further improved. H2C=CR 2 -CO-OR 3 -O-CH=CH-R 4 (2) (In the formula, R 2 is a hydrogen atom or a methyl group, and R 3 is a divalent organic residue having 2 to 20 carbon atoms, and R 4 is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms.

[0044] In the above formula (2), R 2 Examples of the divalent organic residue having 2 to 20 carbon atoms represented by the formula (I) include a linear, branched, or cyclic alkylene group having 2 to 20 carbon atoms, which may be substituted; an alkylene group having 2 to 20 carbon atoms and having an oxygen atom via an ether bond and / or an ester bond in its structure, which may be substituted; and a divalent aromatic group having 6 to 11 carbon atoms, which may be substituted. Among these, alkylene groups having 2 to 6 carbon atoms, such as an ethylene group, an n-propylene group, an isopropylene group, and a butylene group, and alkylene groups having 2 to 9 carbon atoms and having an oxygen atom via an ether bond in its structure, such as an oxyethylene group, an oxy-n-propylene group, an oxyisopropylene group, and an oxybutylene group, are preferred. Furthermore, from the viewpoint of further reducing the viscosity of the ink composition and further improving the curability of the ink composition, R 2 is an alkylene group having 2 to 9 carbon atoms and having an oxygen atom by an ether bond in the structure, such as an oxyethylene group, an oxy-n-propylene group, an oxyisopropylene group, or an oxybutylene group, and more preferred are compounds having a glycol ether chain.

[0045] In the above formula (2), R 3 Suitable monovalent organic residues having 1 to 11 carbon atoms and represented by the formula (I) are linear, branched, or cyclic alkyl groups having 1 to 10 carbon atoms, which may be substituted, and aromatic groups having 6 to 11 carbon atoms, which may be substituted. Among these, alkyl groups having 1 to 2 carbon atoms, such as methyl or ethyl groups, and aromatic groups having 6 to 8 carbon atoms, such as phenyl and benzyl groups, are preferably used.

[0046] When each of the above organic residues is a group that may be substituted, the substituent is divided into a group containing carbon atoms and a group not containing carbon atoms. First, when the above substituent is a group containing carbon atoms, the carbon atom is counted in the number of carbon atoms of the organic residue. Examples of the group containing carbon atoms include, but are not limited to, a carboxyl group and an alkoxy group. Next, examples of the group not containing carbon atoms include, but are not limited to, a hydroxyl group and a halo group.

[0047] Specific examples of the compound of formula (2) include, but are not limited to, 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA), 1-methyl-2-vinyloxypropyl (meth)acrylate, 2-vinyloxybutyl (meth)acrylate, 4-vinyloxycyclohexyl (meth)acrylate, 6-vinyloxyhexyl (meth)acrylate, 4-vinyloxymethylcyclohexylmethyl (meth)acrylate, 3-vinyloxymethylcyclohexylmethyl ... Examples of suitable acrylates include 2-vinyloxymethylcyclohexylmethyl (meth)acrylate, p-vinyloxymethylphenylmethyl (meth)acrylate, m-vinyloxymethylphenylmethyl (meth)acrylate, o-vinyloxymethylphenylmethyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl methacrylate, 2-(vinyloxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxy)propyl (meth)acrylate, and 2-(vinyloxyethoxy)isopropyl (meth)acrylate. Among these specific examples, 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA) is preferred from the viewpoint of easily achieving a balance between the curability and viscosity of the ink composition and the abrasion resistance of the coating film.

[0048] The content of the vinyl ether group-containing (meth)acrylate is not particularly limited, but is, for example, 0% by mass or more and 60% by mass or less relative to the total amount of the ink composition. From the viewpoint of easily achieving a balance between the curability and viscosity of the ink composition and the abrasion resistance of the coating film, the content of the vinyl ether group-containing (meth)acrylate is preferably 1% by mass or more and 40% by mass or less, more preferably 3% by mass or more and 30% by mass or less, and even more preferably 5% by mass or more and 25% by mass or less relative to the total amount of the ink composition.

[0049] In this embodiment, the total content of the allyloxymethyl group-containing acrylate, vinylmethyloxazolidinone, and vinyl ether group-containing (meth)acrylate is preferably 50% by mass or more relative to the total amount of the ink composition. From the viewpoint of further reducing the viscosity of the ink composition, further improving the ejection stability, and further improving the adhesion, the total content is more preferably 55% by mass or more and 90% by mass or less, even more preferably 65% ​​by mass or more and 85% by mass or less, and even more preferably 70% by mass or more and 85% by mass or less.

[0050] 1.1.2.3. Difunctional (meth)acrylates In this embodiment, the ink composition may contain a bifunctional (meth)acrylate. The bifunctional (meth)acrylate is not particularly limited, but examples thereof include dipropylene glycol diacrylate (DPGDA), diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol dimethacrylate, tripropylene glycol di(meth)acrylate (TPGDA), polypropylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate. Examples of the di(meth)acrylates include 1,6-hexanediol di(meth)acrylate (HDDA), 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, EO (ethylene oxide) adduct di(meth)acrylate of bisphenol A, PO (propylene oxide) adduct di(meth)acrylate of bisphenol A, hydroxypivalic acid neopentyl glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate.

[0051] Among these, it is preferable to include dipropylene glycol diacrylate (DPGDA) and / or tripropylene glycol di(meth)acrylate (TPGDA) as the bifunctional (meth)acrylate.

[0052] The content of the bifunctional (meth)acrylate is not particularly limited, but is, for example, from 0% to 20% by mass, preferably from 2% to 15% by mass, and more preferably from 3% to 10% by mass, relative to the total amount of the ink composition.

[0053] 1.1.2.4. Other polyfunctional monomers The ink composition of this embodiment may contain a polyfunctional monomer other than the allyloxymethyl group-containing acrylate and bifunctional (meth)acrylate. Examples of such polyfunctional monomers include trifunctional or higher polyfunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxy tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, pentaerythritol ethoxy tetra(meth)acrylate, and caprolactam-modified dipentaerythritol hexa(meth)acrylate.

[0054] Oligomers The ink composition of this embodiment may contain an oligomer. An oligomer is a polymer containing a polymerizable compound as a constituent component, and refers to a compound having one or more polymerizable functional groups. Note that the polymerizable compound referred to here is not limited to the monofunctional monomers and polyfunctional monomers described above. In this embodiment, an oligomer is defined as a compound having a molecular weight of 1000 or more, and a monomer is defined as a compound having a molecular weight of 1000 or less.

[0055] Such oligomers are not particularly limited, but examples thereof include urethane acrylate oligomers in which the repeating unit is a urethane, polyester acrylate oligomers in which the repeating unit is an ester, and epoxy acrylate oligomers in which the repeating unit is an epoxy.

[0056] Among these, urethane acrylate oligomers are preferred, aliphatic urethane acrylate oligomers and aromatic urethane acrylate oligomers are more preferred, and aliphatic urethane acrylate oligomers are even more preferred. Furthermore, the urethane acrylate oligomer is preferably a tetrafunctional or less urethane acrylate oligomer, and more preferably a difunctional or less urethane acrylate oligomer. By using such an oligomer, the viscosity tends to be further reduced, and curability and adhesion tend to be further improved.

[0057] The content of the oligomer relative to the total amount of the ink composition is preferably 1.0 to 15% by mass, more preferably 1.0 to 10% by mass, and even more preferably 2.0 to 7.0% by mass. When the content of the oligomer relative to the total amount of the ink composition is within the above range, the viscosity tends to be further reduced, and the curability and adhesion tend to be further improved.

[0058] 1.2. Photopolymerization initiator The photopolymerization initiator that may be contained in the ink composition of this embodiment is not particularly limited as long as it generates an active species upon irradiation with radiation, and examples thereof include known photopolymerization initiators such as acylphosphine oxide-based photopolymerization initiators, alkylphenone-based polymerization initiators, and titanocene-based polymerization initiators. Among these, acylphosphine oxide-based photopolymerization initiators are preferred. Use of such photopolymerization initiators tends to further improve the curability of the ink composition, particularly the curability in a curing process using UV-LED light. Note that the photopolymerization initiators may be used alone or in combination of two or more.

[0059] The acylphosphine oxide photopolymerization initiator is not particularly limited, but examples thereof include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

[0060] Examples of commercially available acylphosphine oxide photopolymerization initiators include, by trade name, Omnirad 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide), Omnirad TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide), Omnirad TPO-L (ethyl 2,4,6-trimethylbenzoylphenylphosphineate), IRGACURE 1800 (a mixture of bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 1-hydroxycyclohexylphenyl ketone in a mass ratio of 25:75), and IRGACURE TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide).

[0061] The content of the photopolymerization initiator is preferably 3.0 to 20% by mass, more preferably 5.0 to 18% by mass, and even more preferably 8.0 to 15% by mass, relative to the total amount of the ink composition. When the content of the photopolymerization initiator is within the above range, the curability of the ink composition and the solubility of the photopolymerization initiator tend to be further improved.

[0062] 1.3.Sensitizers The ink composition of this embodiment may contain a sensitizer in addition to the photopolymerization initiator described above. The sensitizer that may be contained is not particularly limited, but examples thereof include compounds containing a thioxanthone skeleton, and more specifically, diesters of carboxymethoxythioxanthone and polytetramethylene glycol. When the ink composition contains a sensitizer, the curability tends to be further improved.

[0063] Examples of commercially available sensitizers include Speedcure DETX (2,4-diethylthioxanthone), Omnipol TX (a diester of carboxymethoxythioxanthone and polytetramethylene glycol), and SpeedCure 7010 (a thioxanthone-based sensitizer).

[0064] The content of the sensitizer is not particularly limited, but is, for example, 1.0% by mass to 10% by mass of the total amount of the ink composition. From the viewpoint of further improving the curability of the ink composition, the content is preferably 1.5% by mass to 5.0% by mass, and more preferably 2.0% by mass to 3.0% by mass.

[0065] 1.4.Fluorescent whitening agents The fluorescent brightening agent that can be contained in the ink composition of this embodiment is not particularly limited, but for example, it absorbs light with a wavelength of about 300 to 450 nm and emits light with a wavelength of about 400 to 500 nm. Examples of such fluorescent brightening agents include, but are not particularly limited to, naphthalene benzoxazolyl derivatives, thiophene benzoxazolyl derivatives, stilbene benzoxazolyl derivatives, coumarin derivatives, styrene biphenyl derivatives, pyrazolone derivatives, stilbene derivatives, styryl derivatives of benzene and biphenyl, and bis(benzazol-2-yl) derivatives. These may be used alone or in combination of two or more.

[0066] Commercially available fluorescent whitening agents include, for example, TELALUX KCB and TELALUX OB.

[0067] The content of the fluorescent brightening agent is not particularly limited, but is, for example, 0.1 to 1 mass % relative to the total amount of the ink composition. From the viewpoint of further improving the curability of the ink composition, the content of the fluorescent brightening agent is preferably 0.1 to 0.5 mass %.

[0068] 1.5. Polymerization inhibitors The polymerization inhibitor that can be contained in the ink composition of this embodiment is not particularly limited, but examples include p-methoxyphenol, hydroquinone monomethyl ether (MEHQ), 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (LA-7RD), hindered amine compounds, 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) hydroquinone, cresol, t-butylcatechol, 3,5-di-t-butyl-4-hydroxytoluene, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), and derivatives thereof. Among these, p-methoxyphenol, hydroquinone monomethyl ether (MEHQ), 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (LA-7RD), or derivatives thereof are preferred as the polymerization inhibitor. By including such a polymerization inhibitor, the storage stability of the ink composition at room temperature and low temperatures tends to be further improved.

[0069] Although not particularly limited, it is, for example, 0.1 to 0.5% by mass. From the viewpoint of further improving the storage stability of the ink composition, the content of the polymerization inhibitor is preferably 0.1 to 0.3% by mass.

[0070] 1.6.Surfactants The ink composition may further contain a surfactant. The surfactant is not particularly limited, but examples thereof include acetylene glycol surfactants, fluorine-based surfactants, and silicone-based surfactants.

[0071] The acetylene glycol surfactant is not particularly limited, but examples thereof include alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and alkylene oxide adducts of 2,4-dimethyl-5-decyne-4-ol and 2,4-dimethyl-5-decyne-4-ol.

[0072] The fluorine-based surfactant is not particularly limited, but examples thereof include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, and perfluoroalkyl amine oxide compounds.

[0073] Examples of silicone surfactants include polysiloxane compounds, polyester-modified silicones, and polyether-modified organosiloxanes. Examples of polyester-modified silicones include BYK-347, 348, BYK-UV3500, 3510, and 3530 (all manufactured by BYK Additives & Instruments). Examples of polyether-modified silicones include BYK-3570 (manufactured by BYK Additives & Instruments).

[0074] The content of the surfactant is preferably 0.1 to 1 mass %, more preferably 0.2 to 0.8 mass %, relative to the total mass of the composition. When the content of the surfactant is within the above range, the wettability of the composition tends to be further improved.

[0075] 1.7.Colorants The ink composition may further contain a coloring material, which may be at least one of a pigment and a dye.

[0076] The total content of the coloring materials is preferably 0.2 to 20% by mass, more preferably 0.5 to 15% by mass, and even more preferably 1 to 10% by mass, relative to the total amount of the ink composition.

[0077] As the pigment, either an inorganic pigment or an organic pigment can be used. The pigment may be used alone or in combination of two or more kinds.

[0078] As inorganic pigments, carbon blacks (CI (Colour Index Generic Name) Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, iron oxide, and titanium oxide can be used.

[0079] Examples of organic pigments include azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye chelates (for example, basic dye chelates, acid dye chelates, etc.); dye lakes (basic dye lakes, acid dye lakes), nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments.

[0080] The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. The dyes may be used alone or in combination of two or more.

[0081] 1.8.Other Ingredients The radiation-curable ink jet composition of this embodiment may further contain additives such as a dispersant, if necessary.

[0082] 2. Method for producing ink composition The radiation-curable ink jet composition is manufactured (prepared) by mixing the components and stirring them to ensure a sufficiently uniform mixture. In this embodiment, the ink composition is preferably prepared by subjecting a mixture of a polymerization initiator and at least a portion of the monomers to at least one of ultrasonic treatment and heating treatment. This reduces the amount of dissolved oxygen in the prepared ink composition, resulting in an ink composition with excellent ejection stability and storage stability. The mixture may contain at least the components described above, and may further contain other components, or may contain all of the components that can be contained in the ink composition. The monomers contained in the mixture may be at least a portion of the monomers that can be contained in the ink composition.

[0083] 3. Recorded materials The recorded matter of this embodiment is obtained by adhering the radiation-curable inkjet composition to a recording medium and curing it. The ink composition has good viscosity, adhesion, and extensibility, which can prevent cracking or chipping of the coating film when post-processing such as cutting or bending is performed. Therefore, the recorded matter of this embodiment can be suitably used for signage and the like.

[0084] The material of the recording medium is not particularly limited, but examples include plastics such as polyvinyl chloride, polyethylene terephthalate, polypropylene, polyethylene, polycarbonate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, and polyvinyl acetal, as well as plastics whose surfaces have been treated, glass, paper, metal, and wood. [Example]

[0085] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0086] 1. Preparation of Radiation-Curable Inkjet Composition First, the colorant, dispersant, and a portion of each monomer were weighed and placed in a pigment dispersion tank. A 1 mm diameter ceramic bead mill was then placed in the tank and stirred to obtain a pigment dispersion in which the colorant was dispersed in the monomer. Next, the remaining monomers, polymerization initiator, and polymerization inhibitor were placed in a stainless steel mixing tank so as to obtain the composition shown in Table 1, and mixed and stirred to completely dissolve. After that, the pigment dispersion obtained above was added, and the mixture was further mixed and stirred at room temperature for an hour, and then filtered through a 5 μm membrane filter to obtain the radiation-curable inkjet composition of each example. Note that the numerical values ​​for each component shown in each example in the table represent mass %.

[0087] The abbreviations and product ingredients used in Table 1 are as follows: <Monofunctional monomer> VMOX (vinylmethyloxazolidinone, manufactured by BASF) PEA (phenoxyethyl acrylate, manufactured by Osaka Organic Chemical Industry Ltd.) BZA (benzyl acrylate, manufactured by Osaka Organic Chemical Industry Ltd.) IBXA (isobornyl acrylate, manufactured by Osaka Organic Chemical Industry Ltd.) LA (Lauryl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.) <Polyfunctional Monomer> AOMA (2-allyloxymethyl methyl acrylate, manufactured by Nippon Shokubai Co., Ltd.) VEEA (2-(2-vinyloxyethoxy)ethyl acrylate, manufactured by Nippon Shokubai Co., Ltd.) DPGDA (dipropylene glycol diacrylate, manufactured by Sartomer Corporation) TPGDA (tripropylene glycol diacrylate, manufactured by Osaka Organic Chemical Industry Ltd.) <Oligomer> EC6081 (manufactured by Choko Materials Industry Co., Ltd., product name "ETERCURE6081", aliphatic urethane acrylate oligomer, functional group number 1) CN9893 (Sartomer, polyester-based aliphatic urethane acrylate oligomer, functional group number 2) <Photopolymerization initiator> Omnirad 819 (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, manufactured by IGM Resins BV) Omnirad TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by IGM Resins BV) Omnirad TPO-L (2,4,6-trimethylbenzoylphenylphosphinate, manufactured by IGM Resins BV) <Sensitizer> DETX (2,4-diethylthioxanthen-9-one, manufactured by Lambson) <Fluorescent whitening agents> TELALUX KCB (1,4-bis(2-benzoxazolyl)naphthalene, manufactured by Clariant Japan) <Surfactant> BYK-UV3500 (polyether-modified polydimethylsiloxane with acryloyl groups, manufactured by BYK Additives & Instruments) <Polymerization inhibitor> LA-7RD (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, manufactured by ADEKA Corporation) MEHQ (hydroquinone monomethyl ether, manufactured by Kanto Chemical Co., Ltd.) <Colorant> Pigment Blue 15:3 (Phthalocyanine Blue, manufactured by DIC) <Dispersant> Solsperse 36000 (polymeric dispersant, manufactured by Lubrizol)

[0088] 2. Evaluation Method 2.1. Viscosity evaluation The viscosity of each radiation-curable inkjet composition was measured using a rotational viscometer (product name "Rheometer MCR-301", manufactured by Anton Paar) in an environment of 20° C. The evaluation criteria were as follows. (Evaluation criteria) A: Viscosity less than 5.0 mPa·s B: Viscosity is 5.0 mPa·smPa·s or more and less than 10 mPa·s C: Viscosity is 10 mPa·s or more and less than 15 mPa·s D: Viscosity is 15 mPa·s or more

[0089] 2.2.Evaluation of adhesion A cured coating film was prepared on a polyvinyl chloride film in the same manner as in the evaluation of stretchability described above, and the resulting coating film was evaluated by a cross-cut test in accordance with JIS K5600-5-6.

[0090] More specifically, a cutter blade was placed perpendicular to the coating film, and squares were cut with 1 mm spacing between each square to create a 10 x 10 grid. A piece of transparent adhesive tape (25 mm wide) approximately 75 mm long was attached to the grid, and the tape was rubbed thoroughly with a finger so that the cured film was visible through it. Next, within 5 minutes of application, the tape was firmly peeled off the cured film at an angle close to 60° in 0.5 to 1.0 seconds, and the condition of the grid was visually observed. The evaluation criteria are as follows: (Evaluation criteria) A: Peeling of the cured film was observed in less than 10% of the lattice. B: Peeling of the cured film was observed in 10% or more but less than 20% of the lattice. C: Peeling of the cured film was observed in 20% or more but less than 35% of the lattice. D: Peeling of the cured film was observed in more than 35% of the lattice.

[0091] 2.3.Evaluation of stretchability Each radiation-curable inkjet composition was applied to a polyvinyl chloride film (JT5829R, manufactured by MACtac) using a bar coater to a thickness of 10 μm. Then, a metal halide lamp (manufactured by iGraphics) was used to apply the inkjet composition to the film at 400 mJ / cm. 2The coating was cured with an energy of 100 sq. m to form a coating film. The release paper was peeled off from the PVC film on which the coating was formed, and test specimens were cut into strips measuring 1 cm wide and 8 cm long. The elongation percentage as an indicator of extensibility was measured for each test specimen using a tensile tester (TENSILON, manufactured by ORIENTEC). The elongation percentage was the value at which a crack occurred when pulled at 5 mm / min. The value was calculated using {(length at crack - length before stretching) / length before stretching x 100}. The evaluation criteria are shown below. (Evaluation criteria) A: 300% or more B: 200% or more but less than 300% C: Less than 200%

[0092] 2.4. Evaluation of abrasion resistance Each radiation-curable inkjet composition was applied to a polyvinyl chloride film (JT5829R, manufactured by MACtac) using a bar coater to a thickness of 10 μm. Then, a metal halide lamp (manufactured by iGraphics) was used to apply the inkjet composition to the film at 400 mJ / cm. 2 The coating was cured with an energy of 100 sq. ft. to form a coating film. Subsequently, abrasion resistance was evaluated using a Gakushin-type rub fastness tester (manufactured by TESTER SANGYO CO., LTD.) in accordance with JIS K5701 (ISO 11628) (specifying methods for testing inks, drawn samples, and printed matter used in lithographic printing). Specifically, a metal cloth was placed on the surface of the coating film, and rubbed 50 times with a load of 500 g. After rubbing, the cured surface of the printed matter was visually inspected for peeling. The evaluation criteria are as follows: (Evaluation criteria) A: There was no dirt on the gold foil. There was no peeling or scratches on the image surface. B: Dirt on the gold foil was observed. There was no peeling or scratches on the image surface. C: Dirt on the gold foil was observed. Peeling or scratches on the image surface were observed.

[0093] [Table 1]

[0094] [Table 2]

[0095] [Table 3]

[0096] 3. Evaluation Results It can be seen that Examples 1 to 20 in Tables 1 and 2, which are radiation-curable inkjet compositions containing a polyfunctional monomer including an acrylic compound represented by the above formula (1) and a monofunctional monomer including vinylmethyloxazolidinone, have overall higher evaluations of viscosity, adhesion, stretchability, and abrasion resistance than Comparative Examples 1 to 5, which do not contain such a monomer. [Industrial Applicability]

[0097] The present invention has industrial applicability as a radiation-curable ink composition.

Claims

1. a polyfunctional monomer containing an acrylic compound represented by the following formula (1); 【Chemical 1】 (In the formula, R 1 represents a hydrogen atom or a monovalent hydrocarbon group which may have an ether bond, and the hydrocarbon group includes a chain saturated hydrocarbon group having 1 or more carbon atoms, a chain unsaturated hydrocarbon group having 3 or more carbon atoms, or an aromatic hydrocarbon group having 6 or more carbon atoms, and the hydrogen atoms of the hydrocarbon group may be substituted with halogen atoms. a monofunctional monomer including vinylmethyloxazolidinone; Radiation-curable inkjet compositions.

2. the content of the polyfunctional monomer other than the acrylic compound is 25% by mass or less relative to the total amount of the radiation-curable inkjet composition; The radiation-curable ink jet composition according to claim 1 .

3. the total content of the acrylic compound and the vinylmethyloxazolidinone is 40% by mass or more relative to the total amount of the radiation-curable inkjet composition; The radiation-curable ink jet composition according to claim 1 or 2.

4. The polyfunctional monomer includes a vinyl ether group-containing (meth)acrylate represented by the following formula (2): H 2 C=CR 2 -CO-OR 3 -O-CH=CH-R 4 ・・・ (2) (In the formula, R 2 is a hydrogen atom or a methyl group, and R 3 is a divalent organic residue having 2 to 20 carbon atoms, and R 4 is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. The radiation-curable ink jet composition according to any one of claims 1 to 3.

5. the total content of the acrylic compound, the vinylmethyloxazolidinone, and the vinyl ether group-containing (meth)acrylate is 50% by mass or more with respect to the total amount of the radiation-curable inkjet composition; The radiation-curable ink jet composition according to claim 4.

6. the monofunctional monomer includes a monofunctional (meth)acrylate having an aromatic ring structure; The radiation-curable ink jet composition according to any one of claims 1 to 5.

Images