JP2020204000A - Radiation-curable inkjet ink composition - Google Patents

Abstract

To provide a radiation-curable inkjet ink composition that is excellent in curability, storage stability and viscosity as well as stretchability, adhesion and scratch resistance of a cured product thereof in a balanced manner.SOLUTION: A radiation-curable inkjet ink composition contains a polymerization initiator, (i) a compound represented by general formula (I), (ii) a (meth) acrylate having an alicyclic skeleton, (iii) a polymerizable monomer containing a nitrogen atom in a cyclic skeleton, and (iv) a compound represented by general formula (II), wherein the content of (i) is 10.0 mass% or more and 40.0 mass% or less, the content of (ii) is 10.0 mass% or more and 40.0 mass% or less, the content of (iii) is 5.0 mass% or more and 30.0 mass% or less, and the content of (iv) is 5.0 mass% or more and 30.0 mass% or less. H2C=CR1-CO-O-R2-O-CH=CH-R3 (I), H2C=CR4-CO-O-(R5-O-(CO)-(NH))n-R6 (II).SELECTED DRAWING: None

Description

The present invention relates to a radiation curable inkjet ink composition.

The inkjet recording method is a method in which small droplets of ink are ejected from a fine nozzle and adhered to a recording medium for recording. This method is characterized in that high-resolution and high-quality images can be recorded at high speed with a relatively inexpensive device.

The inkjet recording method has been widely studied in order to perform higher quality recording such as the configuration of the recording device, the control method of the recording device, and the ink used for recording. Ink is also being actively developed according to the application, and for example, radiation-curable ink for packaging and sign applications is also being developed. For example, Patent Document 1 discloses an active energy ray-curable inkjet recording ink composition containing a monofunctional monomer, a polyfunctional monomer, or the like as a polymerizable compound in a specific compounding range, and has curability, adhesiveness, and resistance. There is a description that the solvent property is improved.

International Publication No. 2012/172974

However, the curable inkjet ink may need to have various performances at the same time. For example, it is required to achieve both seemingly contradictory performances such as curability and storage stability. Further, it is also required to simultaneously improve the flexibility related to the stretchability of the cured product and the adhesion to the medium, and the surface hardness related to the abrasion resistance. Furthermore, it is also required that the viscosity is such that it can be used by the inkjet method.

All of these performances are intricately correlated with each other, and it is not even clear whether or not all of the performances can be satisfied by the ink components and their compounding ratios. Moreover, when trying to satisfy one of the performances, it is often the case that the other performance cannot be satisfied. In addition, there are a wide range of choices for ink components and blending amounts. For example, the composition described in Patent Document 1 may have insufficient performance other than the performance intended to be improved. That is, it is required to improve the curability, storage stability and viscosity of the radiation-curable inkjet ink composition, and the stretchability, adhesion and abrasion resistance of the cured product in a well-balanced manner.

One aspect of the radiation-curable inkjet ink composition according to the present invention is
Polymerization initiator and
(I) The compound represented by the following general formula (I) and
H ₂ C = CR ^1- CO-O-R ^2- O-CH = CH-R ³
... (I)
(In the formula (I), R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 or more and 20 or less carbon atoms, and R ³ is a hydrogen atom or 1 or more and 11 or less carbon atoms. It is a monovalent organic residue.)
(Ii) (meth) acrylate having an alicyclic skeleton and
(Iii) A polymerizable monomer containing a nitrogen atom in the cyclic skeleton,
(Iv) The compound represented by the following general formula (II) and
H ₂ C = CR ^4- CO-O- (R ^5- O- (CO)-(NH)) _n- R ⁶
... (II)
(In formula (II), R ⁴ is a hydrogen atom or a methyl group, R ⁵ is a divalent organic residue, and R ⁶ is an alkyl group having 1 or more and 10 or less carbon atoms, or 1 or more and 10 carbon atoms. The following hydroxyalkyl groups. In addition, n is an integer of 1 or more.)
Including
When the total amount is 100% by mass,
The above (i) is 10.0% by mass or more and 40.0% by mass or less.
The above (ii) is 10.0% by mass or more and 40.0% by mass or less.
The above (iii) is 5.0% by mass or more and 30.0% by mass or less.
The above (iv) is 5.0% by mass or more and 30.0% by mass or less.
Including.

In the embodiment of the radiation curable inkjet ink composition,
The (i) may be 2- (2-vinyloxyethoxy) ethyl acrylate.

In any aspect of the radiation curable inkjet ink composition,
The (ii) may be an isobornyl acrylate.

In any aspect of the radiation curable inkjet ink composition,
The (iii) may be one or more selected from N-acryloylmorpholine and N-vinylcaprolactam.

In any aspect of the radiation curable inkjet ink composition,
It may further contain a diacrylate monomer.

In any aspect of the radiation curable inkjet ink composition,
As the diacrylate monomer, one or more selected from tripropylene glycol diacrylate and PO-modified neopentyl glycol diacrylate may be further contained.

An embodiment of the present invention will be described below. The embodiments described below describe examples of the present invention. The present invention is not limited to the following embodiments, and includes various modifications implemented without changing the gist of the present invention. It should be noted that not all of the configurations described below are essential configurations of the present invention.

1. 1. Radiation Curable Ink Composition The radiation curable inkjet ink composition according to this embodiment is
Polymerization initiator and
(I) The compound represented by the following general formula (I) and
H ₂ C = CR ^1- CO-O-R ^2- O-CH = CH-R ³
... (I)
(In the formula (I), R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 or more and 20 or less carbon atoms, and R ³ is a hydrogen atom or 1 or more and 11 or less carbon atoms. It is a monovalent organic residue.)
(Ii) (meth) acrylate having an alicyclic skeleton and
(Iii) A polymerizable monomer containing a nitrogen atom in the cyclic skeleton,
(Iv) The compound represented by the following general formula (II) and
H ₂ C = CR ^4- CO-O- (R ^5- O- (CO)-(NH)) _n- R ⁶
... (II)
(In formula (II), R ⁴ is a hydrogen atom or a methyl group, R ⁵ is a divalent organic residue, and R ⁶ is an alkyl group having 1 or more and 10 or less carbon atoms, or 1 or more and 10 carbon atoms. The following hydroxyalkyl groups. In addition, n is an integer of 1 or more.)
including.

And when the total amount is 100% by mass,
(I) is 10.0% by mass or more and 40.0% by mass or less,
(Ii) is 10.0% by mass or more and 40.0% by mass or less,
(Iii) is 5.0% by mass or more and 30.0% by mass or less,
(Iv) is 5.0% by mass or more and 30.0% by mass or less,
Including.

1.1. Polymerization Initiator The radiation-curable inkjet ink composition of the present embodiment contains a polymerization initiator. The polymerization initiator has an action of curing ink by polymerization by irradiation with radiation such as ultraviolet rays and visible light. By using ultraviolet rays (UV), safety is excellent and the cost of the light source lamp can be suppressed. The polymerization initiator is not limited as long as it generates active species such as radicals and cations by the energy of radiation and initiates the polymerization of the monomer, but a radical polymerization initiator or a cationic polymerization initiator is used. It is possible, and it is preferable to use a radical polymerization initiator.

Examples of the radical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), and hexaarylbiimidazole compounds. , Ketooxime ester compound, borate compound, azinium compound, metallocene compound, active ester compound, compound having carbon halogen bond, and alkylamine compound.

Among these, at least one of an acylphosphine oxide-based compound and an α-aminoalkylphenone-based compound is preferable because the curability of the radiation-curable inkjet ink composition can be improved, and the acylphosphine oxide is preferable. It is more preferable to use both a system compound and an α-aminoalkylphenone system compound.

Specific examples of the radical polymerization initiator include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, etc. 3-Methylacetophenone, 4-Chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, Michler ketone, benzoin propyl ether, benzoin ethyl ether, benzyl dimethyl ketal, 1- (4-isopropylphenyl) -2 -Hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4- (Methylthio) phenyl] -2-morpholino-propan-1-one, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide , 2,4-Diethylthioxanthone, and bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide.

Of these, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and 2,4-diethylthioxanthone are preferably used, 2 , 4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide are preferably used in combination.

Commercially available products of the radical polymerization initiator include, for example, IRGACURE 651 (2,2-dimethoxy-1,2-diphenylethane-1-one), IRGACURE 184 (1-hydroxy-cyclohexyl-phenyl-ketone), and DAROCUR 1173 ( 2-Hydroxy-2-methyl-1-phenyl-propane-1-one), IRGACURE 2959 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1) -On), IRGACURE 127 (2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one}, IRGACURE 907 ( 2-Methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one), IRGACURE 369 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1) , IRGACURE 379 (2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone), DAROCUR TPO (2,4,6- Trimethylbenzoyl-diphenyl-phosphine oxide), IRGACURE 819 (bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide), IRGACURE TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide), IRGACURE 784 (Bis (η5-2,4-cyclopentadiene-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole-1-yl) -phenyl) titanium), IRGACURE OXE 01 (1,2-) Octandione, 1- [4- (Phenylthio)-, 2- (O-benzoyloxime)]), IRGACURE OXE 02 (Etanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole- 3-Il]-, 1- (O-acetyloxime)), IRGACURE 754 (oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2- (2-hydroxyethoxy) ) Ethyl ester mixture) (above, trade name manufactured by BASF), KAYACURE DETX-S (2,4-diethylthioxanthone) (Nippon Kayaku Co., Ltd. , Ltd. ), Lucirin TPO, LR8883, LR8970 (above, BASF product name), Yubekrill P36 (UCB product name) and the like.

The above-mentioned polymerization initiator may be used alone or in combination of two or more.

The content of the polymerization initiator is the radiation-curable inkjet ink composition in order to improve the curability of the radiation-curable inkjet ink composition and to avoid undissolved residue of the polymerization initiator and coloring derived from the polymerization initiator. With respect to the total mass (100% by mass) of the product, preferably 1.0% by mass or more and 20.0% by mass or less, more preferably 3.0% by mass or more and 10.0% by mass or less, still more preferably 5.0% by mass. It is preferably% or more and 8.0% by mass or less. The polymerization initiator contributes to the curability of the radiation-curable inkjet ink composition, but does not necessarily contribute alone, and radiation depends on the combination with the polymerizable compound, the polymerization inhibitor, the polymerization accelerator, and the like. The curability of the curable inkjet ink composition varies.

1.2. Polymerizable Compound The radiation-curable inkjet ink composition of the present embodiment is, as a polymerizable compound, at least (i) a compound represented by the general formula (I) and (ii) a (meth) acrylate having an alicyclic skeleton. And, including.

1.2.1. Compound represented by general formula (I) The compound represented by the following general formula (I) is a bifunctional vinyl ether group having a (meth) acrylic group double bond and a vinyl ether group double bond. Contains (meth) acrylate. The radiation-curable inkjet ink composition of the present embodiment contains 10.0% by mass or more and 40.0% by mass or less of the compound represented by the general formula (I).
H ₂ C = CR ^1- CO-O-R ^2- O-CH = CH-R ³
... (I)
(In the formula (I), R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 or more and 20 or less carbon atoms, and R ³ is a hydrogen atom or 1 or more and 11 or less carbon atoms. It is a monovalent organic residue.)

Hereinafter, the vinyl ether group-containing (meth) acrylate represented by the general formula (I) may be simply referred to as "a compound of the formula (I)".

When the radiation-curable inkjet ink composition according to the present embodiment contains the compound of the formula (I), the curability of the radiation-curable inkjet ink composition can be further improved. Further, by containing the compound of the formula (I), it is easy to keep the viscosity of the composition low. Furthermore, it is better to use the compound of formula (I) having a vinyl ether group and a (meth) acrylic group in one molecule than to use the compound having a vinyl ether group and the compound having a (meth) acrylic group separately. It is more preferable for improving the curability of the radiation-curable inkjet ink composition. Furthermore, by containing the compound of the formula (I), the abrasion resistance and stretchability of the cured product can be improved.

In the general formula (I), the divalent organic residue of 2 to 20 carbon atoms represented by R ^2, the number 2 to 20 linear carbon atoms, optionally substituted branched or cyclic It may be substituted with an alkylene group having an oxygen atom due to an ether bond and / or an ester bond in the structure, an alkylene group having 2 or more and 20 or less carbon atoms, and 6 or more and 11 or less carbon atoms. A divalent aromatic group is preferred. Among these, an alkylene group having 2 or more and 6 or less carbon atoms such as an ethylene group, an n-propylene group, an isopropylene group, and a butylene group, an oxyethylene group, an oxyn-propylene group, an oxyisopropylene group, and an oxybutylene group. An alkylene group having 2 to 9 carbon atoms and having an oxygen atom due to an ether bond in the structure such as is preferably used. Further, from the viewpoint of further lowering the viscosity of the radiation-curable inkjet ink composition and further improving the curability, R ² contains an oxyethylene group, an oxyn-propylene group, an oxyisopropylene group, and an oxy. A compound having a glycol ether chain, which is an alkylene group having 2 to 9 carbon atoms and having an oxygen atom due to an ether bond in a structure such as a butylene group, is more preferable.

In the general formula (I), examples of the monovalent organic residue having 1 to 11 carbon atoms represented by R ^3, the number 1 to 10 linear carbon atoms, optionally substituted branched or cyclic Alkyl groups may be preferred, and aromatic groups which may be substituted with 6 to 11 carbon atoms are preferable. Among these, an alkyl group having 1 to 2 carbon atoms, which is a methyl group or an ethyl group, and an aromatic group having 6 to 8 carbon atoms such as a phenyl group and a benzyl group are preferably used.

Specific examples of the compound of the formula (I) are not particularly limited, but for example, 2-vinyloxyethyl (meth) acrylate, 3-vinyloxypropyl (meth) acrylate, 1-methyl-2-methyl-2-methyl (meth) acrylate. Vinyloxyethyl, 2-vinyloxypropyl (meth) acrylate, 4-vinyloxybutyl (meth) acrylate, 1-methyl-3-vinyloxypropyl (meth) acrylate, 1-vinyloxymethylpropyl (meth) acrylate, ( 2-Methyl-3-binyloxypropyl (meth) acrylate, 1,1-dimethyl-2-vinyloxyethyl (meth) acrylate, 3-vinyloxybutyl (meth) acrylate, 1-methyl-2-bini (meth) acrylate Propylpropyl, 2-vinyloxybutyl (meth) acrylate, 4-vinyloxycyclohexyl (meth) acrylate, 6-vinyloxyhexyl (meth) acrylate, 4-vinyloxymethylcyclohexylmethyl (meth) acrylate, (meth) 3-Vinyloxymethylcyclohexylmethyl acrylate, 2-vinyloxymethylcyclohexylmethyl (meth) acrylate, p-vinyloxymethylphenylmethyl (meth) acrylate, m-vinyloxymethylphenylmethyl (meth) acrylate, ( Meta) O-vinyloxymethylphenylmethyl acrylate, 2- (2-vinyloxyethoxy) ethyl methacrylic acid, 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA), 2-(meth) acrylate Vinyloxyisopropoxy) ethyl, (meth) acrylate 2- (vinyloxyethoxy) propyl, (meth) acrylate 2- (vinyloxyethoxy) isopropyl, (meth) acrylate 2- (vinyloxyisopropoxy) propyl, 2- (Vinyloxyisopropoxy) isopropyl (meth) acrylate, 2- (vinyloxyethoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyisopropoxy) ethyl (meth) acrylate, (meth) acrylic 2- (Vinyloxyisopropoxyethoxy) ethyl acid, 2- (meth) acrylic acid 2- (vinyloxyisopropoxyisopropoxy) ethyl, 2- (meth) acrylate 2- (vinyloxyethoxyethoxy) propyl, (meth) acrylic acid 2 -(Vinyloxyethoxyisopropoxy) propyl, (meth) acrylate 2- (vinyloxyisopropoxyethoxy) propyl, (meth) acrylate 2- (vinyloxyisopropoxyisopropoxy) propyl, 2- (Meta) acrylate 2- (vinyloxyethoxyethoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyethoxyisopropoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyisopropoxyethoxy) isopropyl, (meth) 2- (Vinyloxyisopropoxyisopropoxy) isopropyl acrylate, 2- (vinyloxyethoxyethoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyethoxyethoxy) ethyl (meth) acrylate, (meth) 2- (Isopropenoxyethoxy) ethyl acrylate, 2- (isopropenoxyethoxyethoxy) ethyl (meth) acrylate, 2- (isopropenoxyethoxyethoxy) ethyl (meth) acrylate, (meth) acrylic acid Examples thereof include 2- (isopropenoxyethoxyethoxyethoxyethoxy) ethyl, polyethylene glycol monovinyl ether (meth) acrylate, and polypropylene glycol monovinyl ether (meth) acrylate. Among these specific examples, VEEA: 2- (2-vinyloxyethoxy) ethyl acrylate is particularly preferable because the curability and viscosity of the composition can be easily balanced.

The compound represented by the general formula (I) may be used alone or in combination of two or more.

The content of the compound of the formula (I) is 10.0% by mass or more and 40.0% by mass or less with respect to the total mass (100% by mass) of the radiation-curable inkjet ink composition, but more preferably 15. It is 0.0% by mass or more and 35.0% by mass or less, more preferably 20.0% by mass or more and 30.0% by mass or less. When the content of the compound of the formula (I) is 40.0% by mass or less, the stretchability of the cured product of the radiation-curable inkjet ink composition can be sufficiently ensured. Further, when the content of the compound of the formula (I) is 10.0% by mass or more, the curability of the radiation-curable inkjet ink composition can be made sufficient and the viscosity can be suppressed to be low.

In the present embodiment, the content of the compound of the formula (I) is set to 10.0% by mass or more and 40.0% by mass or less in consideration of the combination with other components, whereby the radiation-curable inkjet ink composition is formed. It balances the curability and viscosity of the product and the stretchability of the cured product. The compound represented by the general formula (I) has a strong property of contributing to the curability and viscosity of the radiation-curable inkjet ink composition and the stretchability of the cured product, but it does not necessarily contribute by itself. However, the characteristics of the radiation-curable inkjet ink composition and its cured product change depending on the combination with other polymerizable compounds.

In the present specification, "(meth) acrylate" means either or both of acrylate and methacrylate, and "(meth) acrylic" means either or both of acrylic and methacrylic.

1.2.2. (Meta) acrylate having an alicyclic skeleton A (meth) acrylate having an alicyclic skeleton is a compound having a double bond of a (meth) acrylic group and containing an alicyclic skeleton such as norbornene and norbornadiene. The radiation-curable inkjet ink composition of the present embodiment contains 10.0% by mass or more and 40.0% by mass or less of (meth) acrylate having an alicyclic skeleton.

The alicyclic skeleton is selected from a saturated alicyclic skeleton and an unsaturated alicyclic skeleton. The alicyclic skeleton has, for example, a structure of polycyclic hydrocarbon groups. The (meth) acrylate having an alicyclic skeleton may have two or more kinds of alicyclic skeletons. By having the alicyclic skeleton, the glass transition temperature of the cured product of the radiation-curable inkjet ink composition can be adjusted. The lower the glass transition temperature, the more flexible the cured product.

Specific examples of the (meth) acrylate having an alicyclic skeleton include dicyclopentenyloxyethyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and isobornyl acrylate (IBXA). Isobornyl methacrylate, trimethylolpropaneformal mono (meth) acrylate, adamantyl (meth) acrylate, oxetane (meth) acrylate, 3,3,5-trimethylcyclohexane (meth) acrylate, t-butylcyclohexyl (meth) acrylate, etc. Can be mentioned. Among these, isobornyl (meth) acrylate is preferable, and isobornyl acrylate (IBXA) is more preferable.

The (meth) acrylate having an alicyclic skeleton may be used alone or in combination of two or more.

The content of the (meth) acrylate having an alicyclic skeleton is 10.0% by mass or more and 40.0% by mass or less with respect to the total mass (100% by mass) of the radiation-curable inkjet ink composition, but more. It is preferably 15.0% by mass or more and 35.0% by mass or less, more preferably 20.0% by mass or more and 30.0% by mass or less, and particularly preferably 23.0% by mass or more and 28.0% by mass or less. When the content of the (meth) acrylate having an alicyclic skeleton is 40.0% by mass or less, the curability of the radiation-curable inkjet ink composition can be sufficiently ensured. Further, when the content of the (meth) acrylate having an alicyclic skeleton is 10.0% by mass or more, the abrasion resistance and stretchability of the cured product of the radiation-curable inkjet ink composition can be made sufficient. ..

In the present embodiment, the content of the (meth) acrylate having an alicyclic skeleton is set to 10.0% by mass or more and 40.0% by mass or less in consideration of the combination with other components, thereby making the radiation-curable type. The curability of the inkjet ink composition and the stretchability and scratch resistance of the cured product are balanced. The (meth) acrylate having an alicyclic skeleton contributes to the abrasion resistance, stretchability, and curability of the cured product of the radiation-curable inkjet ink composition, but does not necessarily contribute to the curability of the composition alone. , The characteristics of the radiation-curable inkjet ink composition and its cured product change depending on the combination with other polymerizable compounds.

1.2.3. Polymerizable Monomer Containing Nitrogen Atoms in Cyclic Frame The radiation-curable inkjet ink composition of the present embodiment contains 5.0% by mass or more and 30.0% by mass or less of a polymerizable monomer containing nitrogen atoms in the cyclic skeleton. ..

The polymerizable monomer containing a nitrogen atom in the cyclic skeleton is not particularly limited, and examples thereof include nitrogen-containing monofunctional vinyl monomers such as N-vinylcaprolactam, N-vinylcarbazole, and N-vinylpyrrolidone, and acryloylmorpholine. Examples include nitrogen-containing monofunctional acrylate monomers.

Among these, it is preferable to contain either a nitrogen-containing monofunctional vinyl monomer or a nitrogen-containing monofunctional acrylate monomer, and N-vinylcaprolactam (n-VC), N-vinylcarbazole, N-vinylpyrrolidone, or acryloylmorpho. Monomers having a nitrogen-containing heterocyclic structure such as phosphorus (ACMO) are more preferable, and one or more selected from N-vinylcaprolactam and acryloylmorpholine are further preferable.

By using a polymerizable monomer containing a nitrogen atom in the cyclic skeleton, the adhesion of the cured product of the radiation-curable inkjet ink composition to the recording medium tends to be further improved. Further, when a polymerizable monomer containing a nitrogen atom in the cyclic skeleton is used, the storage stability of the radiation-curable inkjet ink composition tends to be improved.

The polymerizable monomer containing a nitrogen atom in the cyclic skeleton may be used alone or in combination of two or more.

The content of the polymerizable monomer containing a nitrogen atom in the cyclic skeleton is 5.0% by mass or more and 30.0% by mass or less with respect to the total mass (100% by mass) of the radiation-curable inkjet ink composition. , More preferably 5.0% by mass or more and 20.0% by mass or less, still more preferably 8.0% by mass or more and 15.0% by mass or less. When the content of the polymerizable monomer containing a nitrogen atom in the cyclic skeleton is 30.0% by mass or less, the storage stability of the radiation-curable inkjet ink composition can be sufficiently ensured. Further, when the content of the polymerizable monomer containing a nitrogen atom in the cyclic skeleton is 5.0% by mass or more, the adhesion of the cured product of the radiation-curable inkjet ink composition to the recording medium is sufficient. Can be done.

In the present embodiment, the content of the polymerizable monomer containing a nitrogen atom in the cyclic skeleton is set to 5.0% by mass or more and 30.0% by mass or less in consideration of the combination with other components and the like, thereby causing radiation. The storage stability of the curable inkjet ink composition and the adhesion of the cured product to the recording medium are balanced. The polymerizable monomer containing a nitrogen atom in the cyclic skeleton has a strong property of contributing to the storage stability of the composition and the adhesion of the cured product to the recording medium, but does not necessarily contribute alone. The characteristics of the radiation-curable inkjet ink composition and its cured product change depending on the combination with other polymerizable compounds.

1.2.4. Compound represented by general formula (II) The compound represented by the following general formula (II) is a monofunctional urethane (meth) acrylate containing a double bond of a (meth) acrylic group and at least one urethane bond. is there. The compound of formula (II) can also be referred to as a urethane bond-containing mono (meth) acrylate. The radiation-curable inkjet ink composition of the present embodiment contains 5.0% by mass or more and 30.0% by mass or less of the compound represented by the general formula (II).
H ₂ C = CR ^4- CO-O- (R ^5- O- (CO)-(NH)) _n- R ⁶
... (II)
(In formula (II), R ⁴ is a hydrogen atom or a methyl group, R ⁵ is a divalent organic residue, and R ⁶ is an alkyl group having 1 or more and 10 or less carbon atoms, or 1 or more and 10 carbon atoms. The following hydroxyalkyl groups. In addition, n is an integer of 1 or more.)

Hereinafter, the monofunctional urethane (meth) acrylate represented by the general formula (II) may be simply referred to as "a compound of the formula (II)".

By containing the compound of the formula (II) in the radiation-curable inkjet ink composition according to the present embodiment, the adhesion of the cured product of the radiation-curable inkjet ink composition to the recording medium is further improved. Can be done. Further, by containing the compound of the formula (II), the viscosity of the composition can be kept low and the storage stability can be improved.

In the general formula (II), 2-valent organic residue represented by R ⁵ is an ethylene group, n- propylene group, preferably an alkylene group having 2 to 4 carbon atoms, such as isopropylene group and butylene group, The alkyl group having 1 to 10 carbon atoms or the hydroxyalkyl group having 1 to 10 carbon atoms represented by R ⁶ is an alkyl group having 1 to 6 carbon atoms or 1 to 6 carbon atoms. The following hydroxyalkyl groups are more preferable, and n is more preferably 1 or more and 5 or less.

Further, in the compound represented by the general formula (II), when R ⁶ is an alkyl group having 1 or more and 10 or less carbon atoms, the group is linear, branched or linear or having 10 or less carbon atoms. It is a cyclic alkyl group. When R ⁶ is a hydroxyalkyl group having 1 or more and 10 or less carbon atoms, the group has 1 or 2 or more carbon atoms of a linear, branched or cyclic alkyl group having 1 or more and 10 or less carbon atoms. A group in which hydrogen bonded to an atom is substituted by one or two or more by a hydroxyl group.

Examples of R ⁶ are methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group, butyl group, pentyl group, pentyl group, hexyl group, hexyl group, heptyl group, octyl group. Examples thereof include a group, a nonyl group, a decyl group, a group having a structural isomerism thereof, and a group containing a cyclo ring, a bicyclo ring, and / or a spiro ring thereof. Further, as an example of R ⁶ , a group in which hydrogen bonded to one or more carbon atoms of these groups is substituted by one or two or more by a hydroxyl group can be mentioned.

R ⁶ includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a direct group from the viewpoint of further improving the flexibility of the cured product and the adhesion to the recording medium, and from the viewpoint of easy availability or production. To a chain or branched butyl group, butyl group, butyl group, pentyl group, pentyl group, hexyl group, hexyl group, heptyl group, octyl group, nonyl group, and decyl group, and the carbon atom at the end of these groups. A group in which the hydrogen to be bonded is substituted with a hydroxyl group can be mentioned.

The compound represented by the general formula (II) is not limited to the following, and for example, a compound obtained by reacting a hydroxyalkyl (meth) acrylate with an alkyl monoisocyanate, a hydroxyalkyl (meth) acrylate and a hydroxyalkyl monoisocyanate. It can be obtained by the reaction of. As specific examples, 2- (butylcarbamoyloxy) ethyl acrylate, 2- (butylcarbamoyloxy) ethyl methacrylate, 2- (hexylcarbamoyloxy) ethyl (meth) acrylate, 2- (butylcarbamoyloxy) propyl (meth) acrylate , 2- (2- (Butylcarbamoyloxy) ethyl) carbamoyloxy) ethyl (meth) acrylate and the like. Of these, 2- (butylcarbamoyloxy) ethyl acrylate is particularly preferable because it is easy to balance the viscosity of the composition, the storage stability, and the adhesion of the cured product.

The compound represented by the general formula (II) may be used alone or in combination of two or more.

The content of the compound of the formula (II) is 5.0% by mass or more and 30.0% by mass or less with respect to the total mass (100% by mass) of the radiation-curable inkjet ink composition, but more preferably 5. It is 0.0% by mass or more and 25.0% by mass or less, more preferably 5.0% by mass or more and 20.0% by mass or less, and particularly preferably 8.0% by mass or more and 15.0% by mass or less. When the content of the compound of the formula (II) is 30.0% by mass or less, the storage stability of the radiation-curable inkjet ink composition can be sufficiently ensured, and the viscosity can be kept low. Further, when the content of the compound of the formula (II) is 5.0% by mass or more, the adhesion of the cured product of the radiation-curable inkjet ink composition can be sufficiently sufficient.

In the present embodiment, the content of the compound of the formula (II) is set to 5.0% by mass or more and 30.0% by mass or less in consideration of the combination with other components, whereby the radiation-curable inkjet ink composition is formed. The storage stability and viscosity of the product and the adhesion of the cured product are balanced. The compound represented by the general formula (II) contributes to the storage stability and viscosity of the radiation-curable inkjet ink composition and the adhesion of the cured product to the recording medium, but does not necessarily contribute to the cured product alone. However, the characteristics of the radiation-curable inkjet ink composition and its cured product change depending on the combination with other polymerizable compounds.

1.2.5. Other Polymerizable Compounds The radiation-curable inkjet ink composition of the present embodiment has the above-mentioned (i) compound represented by the general formula (I), (ii) (meth) acrylate having an alicyclic skeleton, and (iii). A polymerizable monomer other than the polymerizable monomer containing a nitrogen atom in the cyclic skeleton and the compound represented by (iv) general formula (II) may be contained. Other polymerizable compounds are used as long as the above-mentioned performance balance of the radiation-curable inkjet ink composition can be maintained. Hereinafter, examples of such polymerizable compounds include monofunctional monomers, bifunctional monomers, and trifunctional or higher functional monomers.

1.2.5.1. Monofunctional Monomer The radiation-curable inkjet ink composition of the present embodiment may contain a monofunctional monomer. The monofunctional monomers exemplified below can be used if necessary, but are used within a range in which the above-mentioned performance balance of the radiation-curable inkjet ink composition can be maintained.

The monofunctional monomer is not particularly limited, and is, for example, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, alkoxylated 2-phenoxyethyl (meth) acrylate, ethoxylated nonylphenyl (meth) acrylate, and alkoxylated nonylphenyl. (Meta) acrylate, p-cumylphenol EO modified (meth) acrylate, and 2-hydroxy-3-phenoxypropyl (meth) acrylate, tertbutylcyclohexanol acrylate (TBCHA), 2- (meth) acrylic acid-1, 4-Dioxaspiro [4,5] deci-2-ylmethyl, isoamyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, 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, etc. Be done.

1.25.2. Bifunctional Monomer The radiation-curable inkjet ink composition of the present embodiment may contain a bifunctional monomer. Examples of the bifunctional monomer include bifunctional (meth) acrylate. As will be demonstrated in the examples described later, the bifunctional (meth) acrylate can maintain a good balance of performance of the radiation-curable inkjet ink composition even if it is contained in an amount of about 35% by mass. Further, since the bifunctional (meth) acrylate has a relatively low odor and low viscosity, it is easy to use in a radiation-curable inkjet ink composition.

The bifunctional (meth) acrylate is not particularly limited, and is, for example, tripropylene glycol diacrylate (TPGDA), tripropylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and dipropylene glycol diacrylate (DPGDA). ), Diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol dimethacrylate, polypropylene glycol di (meth) acrylate, 1,4-butanediol di (meth). ) Acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol diacrylate (NPGDA) and its PO modified product (NPGDA (PO)), neopentyl glycol Dimethacrylate, dimethylol-tricyclodecanedi (meth) acrylate, EO (ethylene oxide) adduct of bisphenol A di (meth) acrylate, PO (propylene oxide) adduct of bisphenol A di (meth) acrylate, hydroxypivalic acid Examples thereof include neopentyl glycol di (meth) acrylate and polytetramethylene glycol di (meth) acrylate.

As the bifunctional (meth) acrylate, one kind or two or more kinds may be used. When bifunctional (meth) acrylate is used, the content is 1.0% by mass or more and 35.0% by mass or less, more preferably 5 with respect to the total mass (100% by mass) of the radiation-curable inkjet ink composition. It is 0.0% by mass or more and 25.0% by mass or less.

Further, as the bifunctional monomer, bifunctional urethane (meth) acrylate may be used. The bifunctional urethane (meth) acrylate can be added as long as the above-mentioned performance balance of the radiation-curable inkjet ink composition can be maintained. The bifunctional urethane (meth) acrylate tends to increase the viscosity of the composition, as will be demonstrated in Examples described later, and it is preferable to use a relatively small amount in order to maintain a good balance of physical properties.

As the bifunctional urethane (meth) acrylate, for example, CN9893 (urethane-based monomer manufactured by Sartmer) can be exemplified.

1.2.5.3. Trifunctional or higher-functional monomers The radiation-curable inkjet ink composition of the present embodiment may contain trifunctional or higher-functionalized monomers. The trifunctional or higher-functional monomers exemplified below can be used as needed, but are used within a range in which the above-mentioned performance balance of the radiation-curable inkjet ink composition can be maintained.

The trifunctional or higher functional polyfunctional (meth) acrylate is not particularly limited, and is, for example, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and pentaerythritol. Tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, glycerin propoxytri (meth) acrylate, caprolactone-modified trimethylolpropane tri (meth) acrylate, pentaerythritol ethoxytetra (meth) Examples thereof include acrylates and caprolactam-modified dipentaerythritol hexa (meth) acrylates.

1.3. Other Ingredients The radiation-curable inkjet composition according to the present embodiment may further contain additives such as a coloring material, a dispersant, a polymerization inhibitor, a slip agent, a photosensitizer, and a polymerization inhibitor, if necessary. Good.

13.1. Coloring Material The radiation-curable inkjet composition according to the present embodiment may further contain a coloring material. When the radiation-curable inkjet composition according to the present embodiment contains a coloring material, it can be used as a colored radiation-curable inkjet composition. As the coloring material, at least one of a pigment and a dye can be used.

The total content of the coloring material is preferably 0.1% by mass or more and 10.0% by mass or less, and more preferably 0.5% by mass or more and 5.0% by mass or less with respect to the total amount of the composition. is there. The radiation-curable inkjet composition according to the present embodiment does not contain a coloring material or contains a coloring material to the extent that it is not intended to be colored (for example, 0.1% by mass or less) as a clear ink. May be good.

1.3.1.1. When a pigment is used as the pigment coloring material, the weather resistance of the radiation-curable ink may be improved. As the pigment, either an inorganic pigment or an organic pigment can be used.

As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, and channel black, iron oxide, and titanium oxide can be used.

Examples of organic pigments include azo pigments such as insoluble azo pigments, condensed azo pigments, azolakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments and quinophthalone pigments. Polycyclic pigments, dye chelate (for example, basic dye type chelate, acidic dye type chelate, etc.), dyeing rake (basic dye type rake, acidic dye type rake), nitro pigment, nitroso pigment, carbon black, aniline black , Daylight fluorescent pigments.

As the black pigment, No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, No. 2200B, etc. (above, trade name manufactured by Mitsubishi Chemical Corporation (Mitsubishi Chemical Corporation)), Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. (above, Columbia Carbon (Carbon Col)) 400R, Rega1 330R, Rega1 660R, Mogul L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. (above, Cabot Corporation) Name), Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color B1ackS150, Color BlackExEx, Color Black Special Black 5, Special Black 4A, Special Black 4 and the like (these are trade names manufactured by Degussa) can be mentioned.

As a white pigment, C.I. I. Examples thereof include metal compounds such as Pigment White 6, 18, 21, metal oxides, barium sulfate, and calcium carbonate. Examples of the metal oxide include titanium dioxide, zinc oxide, silica, alumina, magnesium oxide and the like.

Examples of the yellow pigment include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7,
10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138, 139, 147, 151, 153, 154, 167, 172, 180.

Examples of magenta pigments include C.I. I. Pigment Red 1,2,3,4,5,6,7,8,9,10,11,12,14,15,16,17,18,19,21,22,23,30,31,32, 37, 38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144, 146, 149, 150, 166, 168 , 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, and C.I. I. Pigment Violet 19, 23, 32, 33, 36, 38, 43, 50.

Examples of the cyan pigment include C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16, 18, 22, 25, 60, 65, 66, and C.I. I. Bat blue 4, 60 can be mentioned.

Examples of color pigments other than magenta, cyan and yellow include C.I. I. Pigment Green 7, 10, and C.I. I. Pigment Brown 3, 5, 25, 26, and C.I. I. Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63.

The pigment may be used alone or in combination of two or more.

1.3.1.2. A dye can be used as the dye coloring material. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. One type of dye may be used alone, or two or more types may be used in combination.

The dye is not particularly limited, but for example, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9, 45, 249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Hood Black 1, 2, C.I. I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C.I. I. Direct Red 1, 4, 9, 80, 81, 225, 227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Direct Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive Black 3, 4, 35 can be mentioned.

1.3.2. Dispersant When the radiation-curable inkjet composition contains a pigment, it may further contain a dispersant in order to improve the pigment dispersibility. The dispersant may be used alone or in combination of two or more.

The dispersant is not particularly limited, and examples thereof include dispersants commonly used for preparing a pigment dispersion such as a polymer dispersant. Specific examples thereof include polyoxyalkylene polyalkylene polyamines, vinyl polymers and copolymers, acrylic polymers and copolymers, polyesters, polyamides, polyimides, polyurethanes, amino polymers, silicon-containing polymers, sulfur-containing polymers, fluorine-containing polymers, and epoxies. Examples thereof include resins containing one or more of the main components.

Commercially available polymer dispersants include Ajinomoto Fine-Techno's Ajisper series, Avecia and Noveon's Solspers series (Solsperse36000, etc.), and BYK Adaptives & Instruments' Disperbic series. , Kusumoto Kasei Co., Ltd.'s Disparon series can be mentioned.

The content of the dispersant is preferably 0.01% by mass or more and 1.0% by mass or less, and more preferably 0.1% by mass or more and 0.5% by mass or less, based on the total amount of the composition.

1.3.3. Polymerization Inhibitor The radiation-curable inkjet composition according to the present embodiment may further contain a polymerization inhibitor. The polymerization inhibitor may be used alone or in combination of two or more.

Polymerization inhibitors include, but are not limited to, p-methoxyphenol, hydroquinone monomethyl ether (MEHQ), 4-hydroxy-2,2,6,6-tetramethylpiperidin-N-oxyl, hydroquinone, cresol, and the like. 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), hindered amine compounds and the like.

Commercially available products of the polymerization inhibitor include Adecastab LA-7RD (2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl), LA-52, LA-57, LA-62, LA. -63P, LA-68LD, LA-77Y, LA-77G, LA-81, LA-82 (1,2,2,6,6-pentamethyl-4-piperidylmethacrylate), LA-87 (all manufactured by ADEKA) Trade name), IRGASTAB UV 10 (4,4'-[1,10-dioxo-1,10-decandyl) bis (oxy)] bis [2,2,6,6-tetramethyl] -1-piperidinyl Oxy) (CAS.2516-92-9), TINUVIN 123 (4-hydroxy-2,2,6,6, -tetramethylpiperidin-N-oxyl), TINUVIN 111FDL, TINUVIN 144, TINUVIN 152, TINUVIN 292, TINUVIN 765, TINUVIN 770DF, TINUVIN 5100, SANOL LS-2626, CHIMASORB 119FL, CHIMASORB 2020 FDL, CHIMASSORB 944 FDL, TINUVIN 622 LD (above, BASF 2, 712HM , 6-Tetramethylpiperidinyl methacrylate, trade name manufactured by Hitachi Kasei Kogyo Co., Ltd.) and the like.

The content of the polymerization inhibitor is preferably 0.01% by mass or more and 1.0% by mass or less, and more preferably 0.1% by mass or more and 0.5% by mass or less, based on the total amount of the composition. ..

1.3.4. Slip Agent The radiation-curable inkjet composition according to this embodiment may further contain a slip agent. The slip agent may be used alone or in combination of two or more.

As the slip agent, a silicone-based surfactant is preferable, and a polyester-modified silicone or a polyether-modified silicone is more preferable. Examples of the polyether-modified silicone include BYK-378, 3455, BYK-UV3500, 3510, 3530 (all manufactured by BYK Ads & Instruments) and the like, and examples of the polyester-modified silicone include BYK-3570 (manufactured by BYK Ads & Instruments). Can be mentioned.

The content of the slip agent is preferably 0.1% by mass or more and 1.0% by mass or less, and more preferably 0.3% by mass or more and 0.8% by mass or less with respect to the total amount of the composition.

1.3.5. Photosensitizer The radiation-curable inkjet composition according to this embodiment may further contain a photosensitizer. Examples of the photosensitizer include amine compounds (aliphatic amines, amines containing aromatic groups, piperidine, reaction products of epoxy resins and amines, triethanolamine triacrylates, etc.), urea compounds (allylthiourea, o-tolylthiourea, etc.). , Etc.), sulfur compounds (sodium diethyldithiophosphate, soluble salts of aromatic sulfinic acid, etc.), nitrile compounds (N, N-diethyl-p-aminobenzonitrile, etc.), phosphorus compounds (tri-n-butylphosphine, etc.) , Sodium diethyldithiophosphide, etc.), nitrogen compounds (Michler ketone, N-nitrisohydroxylamine derivatives, oxazolidine compounds, tetrahydro-1,3-oxazine compounds, formaldehyde or condensates of acetaldehyde and diamine, etc.), chlorine compounds (tetrachloride) Carbon, hexachloroethane, etc.) and the like.

1.4. Physical Properties The viscosity of the radiation-curable inkjet composition according to this embodiment at 20 ° C. is preferably 25 mPa · s or less, and more preferably 5 mPa · s or more and 25 mPa · s or less. When the viscosity of the composition at 20 ° C. is within the above range, an appropriate amount of the composition is ejected from the nozzle, and flight bending and scattering of the composition can be further reduced. Therefore, the composition is suitably used for an inkjet recording device. Can be done. The viscosity is measured by increasing the Shear Rate to 10 to 1000 in an environment of 20 ° C. using a viscoelasticity tester MCR-300 (manufactured by Pysica) and reading the viscosity at Shear Rate 200. Can be measured.

The surface tension of the radiation-curable inkjet composition according to this embodiment at 20 ° C. is preferably 20 mN / m or more and 40 mN / m or less. When the surface tension of the radiation-curable inkjet composition at 20 ° C. is in this range, the composition is less likely to get wet with the liquid-repellent nozzle surface. As a result, the composition is discharged normally and in an appropriate amount from the nozzle, and the flight bending and scattering of the composition can be further reduced, so that the composition can be suitably used for an inkjet recording device. To measure the surface tension, use an automatic surface tension meter CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) to check the surface tension when the platinum plate is wetted with a radiation-curable inkjet composition in an environment of 20 ° C. It can be measured by doing so.

2. 2. Examples and Comparative Examples Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples. Hereinafter, "%" is based on mass unless otherwise specified.

2.1. Preparation of Inks The inks of each example were mixed so as to have the compositions (unit: mass%) shown in Tables 1 and 2, and this was prepared by stirring with a high-speed water-cooled stirrer. The pigment (CI Pigment Blue 15: 3) was previously blended with a dispersion in which 50% by mass of Solspece 36000 (trade name manufactured by LUBRIZOL) was added to the pigment as a dispersant.

In Tables 1 and 2, each component is as follows.
VEEA: 2- (2-vinyloxyethoxy) ethyl acrylate "(i) Compound represented by general formula (I)"
IBXA: Isobornyl acrylate "(ii) (meth) acrylate with an alicyclic skeleton"
ACMO: Trade name, manufactured by KJ Chemicals Co., Ltd., acryloylmorpholin "(iii) polymerizable monomer containing nitrogen atom in cyclic skeleton"
n-VC: N-vinylcaprolactam "(iii) Polymerizable monomer containing nitrogen atom in cyclic skeleton"
819: Product name "IRGACURE 819" manufactured by BASF, acylphosphine oxide-based polymerization initiator 369: Product name "IRGACURE 369" manufactured by BASF, α-aminoalkylphenone-based polymerization initiator 6101: Product name "EM2080 (oligomer 6101)" ) (Manufactured by Changxing Materials Industry Co., Ltd.) "(2- (Butylcarbamoyloxy) ethyl acrylate)," (iv) Compound represented by general formula (II) "
CN9893: Trade name, manufactured by Tomoe Engineering Co., Ltd. "(iv) Not a compound represented by the general formula (II)"
TPGDA: Tripropylene glycol diacrylate NPGDA (PO): PO modified product of neopentyl glycol diacrylate (NPGDA) LA-7RD: Trade name "ADEKA STAB LA-7RD", manufactured by ADEKA, polymerization inhibitor MEHQ: hydroquinone monomethyl ether, Polymerization inhibitor BYK-UV3500: Slip agent C.I., manufactured by BYK Adaptives & Instruments. I. Pigment Blue 15: 3: Pigment Dispersant: Solsperse36000 (trade name, manufactured by Lubrizol, polymer dispersant)

2.2. Evaluation of inkjet ink composition and cured product 2.2.1. With a stretchable bar coater, each radiation-curable inkjet composition was applied onto a vinyl chloride film (JT5829R, manufactured by MACtac) to a thickness of 10 μm. Then, using a metal halide lamp (manufactured by Eye Graphics), the coating film was formed by curing with an energy of 400 mJ / cm ² . The release paper of the vinyl chloride film on which the coating film was formed was peeled off and cut into strips having a width of 1 cm and a length of 8 cm to prepare test pieces. For each test piece, the elongation rate as stretchability was measured using a tensile tester (TENSILON, manufactured by ORIENTEC). The elongation rate was set to the value at the time when cracks occurred when pulled at 5 mm / min. The value was calculated from {(length at crack-length before stretching) / length before stretching x 100}. The evaluation criteria were as follows, and the results are shown in Tables 1 and 2.

(Evaluation criteria)
A: 200% or more B: 100% or more and less than 200% C: less than 100%

2.2.2. Adhesion A cured coating film was produced on each film in the same manner as in the above evaluation of stretchability, except that a polypropylene board (manufactured by Corplast) was used as the recording medium. The cross-cut test was evaluated on the obtained coating film.

More specifically, with a cutter, the blade of the cutting tool was applied so as to be perpendicular to the coating film, and squares with a distance of 1 mm between the cuts were inserted to form a grid of 6 × 6 squares. A transparent adhesive tape (width 25 mm) having a length of about 75 mm was attached to the lattice, and the tape was sufficiently rubbed with a finger so that the cured film could be seen through. Next, within 5 minutes after the tape was applied, the tape was surely peeled off from the cured film at an angle close to 60 ° in 0.5 to 1.0 seconds, and the state of the lattice was visually observed. The evaluation criteria were as follows, and the results are shown in Tables 1 and 2.

(Evaluation criteria)
A: No peeling of the cured film was observed, or the lattice where peeling was observed was 5% or less.
B: Peeling of the cured film was observed in more than 5% and 35% or less of the lattice.
C: Peeling of the cured film was observed in more than 35% of the lattice.

2.2.3. Abrasion resistance A microscratch test was evaluated for the cured coating film prepared in the above stretchability evaluation according to JIS R3255. For the measurement, an ultra-thin scratch tester (CSR-5000, manufactured by Nanotech) was used to measure the load capacity as scratch resistance. The withstand load was the load when the stylus reached the media surface by microscratching while applying the load. The larger the load capacity, the better the abrasion resistance. The measurement was performed with a stylus diameter of 15 μm, an amplitude of 100 μm, and a scratch speed of 10 μm / sec. The evaluation criteria were as follows, and the results are shown in Tables 1 and 2.

(Evaluation criteria)
A: 30mN / cm ² or more B: 20mN / cm ² or more and less than 30mN / cm ² C: 20mN / cm less than ²

2.2.4. The curability cotton swab weighted tackiness was evaluated. Specifically, the ink composition was applied to a PET film (PET50A PL thin [trade name], manufactured by Lintec Corporation) with a bar coater, and ultraviolet rays were irradiated at a predetermined irradiation intensity at a rate of 0.04 sec / cm. At that time, as a light source, an LED having a peak wavelength of 395 nm was used. The thickness of the obtained cured coating film was 8 μm. Then, the surface of the coating film was rubbed 10 times with a weight of 100 g using a cotton swab, and the curing energy (irradiation energy) was determined based on the irradiation intensity at which the cotton swab was not colored. The irradiation energy [mJ / cm ² ] was obtained by measuring the irradiation intensity [mW / cm ² ] on the irradiated surface irradiated from the light source and multiplying this by the irradiation duration [sec]. The irradiation intensity was measured using an ultraviolet intensity meter UM-10 and a light receiving unit UM-400 (both manufactured by Konica Minolta SENSING, INC.). The evaluation criteria were as follows, and the results are shown in Tables 1 and 2.

(Evaluation criteria)
A: 200mJ / cm ² or less B: Over 200 300mJ / cm ² or less C: 300mJ / cm Over ²

2.2.5. Preservability 24 mL of each of the radiation-curable inks of each example was placed in a 30 mL glass bottle, and the ink was left at 70 ° C. for 8 days in the dark. By measuring the ink viscosity after standing with respect to the ink viscosity before leaving, the rate of increase in ink viscosity before and after leaving was calculated, and the storage stability of the ink was evaluated. The evaluation criteria are as follows, and the evaluation results are shown in Tables 1 and 2.

(Evaluation criteria)
A: Viscosity increase rate is less than 5%.
B: Viscosity increase rate of 5% or more and less than 10%.
C: Viscosity increase rate of 10% or more.

2.2.6. Viscosity The viscosity (mPa · s) of the radiation-curable ink of each example was measured at 20 ° C. using a rheometer (MCR-300, manufactured by Anton Pearl). Evaluation was made according to the following criteria, and the evaluation results are shown in Tables 1 and 2.

(Evaluation criteria)
A: Less than 25 mPa ・ s B: More than 25 mPa ・ s More than 30 mPa ・ s C: More than 30 mPa ・ s

2.3. Evaluation Results From the examples and comparative examples, the following was found.
A polymerization initiator, (i) a compound represented by the general formula (I), (ii) a (meth) acrylate having an alicyclic skeleton, (iii) a polymerizable monomer containing a nitrogen atom in a cyclic skeleton, and (iv). ) Containing the compound represented by the general formula (II), (i) is 10.0% by mass or more and 40.0% by mass or less, (ii) is 10.0% by mass or more and 40.0% by mass or less, (iiii). The radiation-curable inkjet ink composition of each example containing 5.0% by mass or more and 30.0% by mass or less of (iv) and 5.0% by mass or more and 30.0% by mass or less of (iv) is curable and preserved. Good results were obtained in terms of stability and viscosity, as well as stretchability, adhesion and abrasion resistance of the cured product.

On the other hand, in the radiation-curable inkjet ink composition of each comparative example in which any of the components deviates from the above range, one or more of stretchability, adhesion, abrasion resistance, curability, storage stability, and viscosity are obtained. The result was inadequate.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the present invention includes a configuration substantially the same as the configuration described in the embodiment, for example, a configuration having the same function, method and result, or a configuration having the same purpose and effect. The present invention also includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. The present invention also includes a configuration that exhibits the same effects as the configuration described in the embodiment or a configuration that can achieve the same object. The present invention also includes a configuration in which a known technique is added to the configuration described in the embodiment.

Claims (6)

Polymerization initiator and
(I) The compound represented by the following general formula (I) and
H ₂ C = CR ^1- CO-O-R ^2- O-CH = CH-R ³
... (I)
(In the formula (I), R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 or more and 20 or less carbon atoms, and R ³ is a hydrogen atom or 1 or more and 11 or less carbon atoms. It is a monovalent organic residue.)
(Ii) (meth) acrylate having an alicyclic skeleton and
(Iii) A polymerizable monomer containing a nitrogen atom in the cyclic skeleton,
(Iv) The compound represented by the following general formula (II) and
H ₂ C = CR ^4- CO-O- (R ^5- O- (CO)-(NH)) _n- R ⁶
... (II)
(In formula (II), R ⁴ is a hydrogen atom or a methyl group, R ⁵ is a divalent organic residue, and R ⁶ is an alkyl group having 1 or more and 10 or less carbon atoms, or 1 or more and 10 carbon atoms. The following hydroxyalkyl groups. In addition, n is an integer of 1 or more.)
Including
When the total amount is 100% by mass,
The above (i) is 10.0% by mass or more and 40.0% by mass or less.
The above (ii) is 10.0% by mass or more and 40.0% by mass or less.
The above (iii) is 5.0% by mass or more and 30.0% by mass or less.
The above (iv) is 5.0% by mass or more and 30.0% by mass or less.
A radiation curable inkjet ink composition, including. In claim 1,
The above (i) is a radiation-curable inkjet ink composition which is 2- (2-vinyloxyethoxy) ethyl acrylate. In claim 1 or 2,
The (ii) is a radiation-curable inkjet ink composition which is an isobornyl acrylate. In any one of claims 1 to 3,
The (iii) is a radiation-curable inkjet ink composition which is one or more selected from N-acryloylmorpholine and N-vinylcaprolactam. In any one of claims 1 to 4,
A radiation curable inkjet ink composition further comprising a diacrylate monomer. In claim 5,
A radiation-curable inkjet ink composition further comprising one or more selected from tripropylene glycol diacrylate and PO-modified neopentyl glycol diacrylate as the diacrylate monomer.