JP5812399B2 - Pigment composition, photocurable ink composition for ink jet recording, and ink jet recording method - Google Patents

Description

  The present invention relates to a pigment composition, a photocurable ink composition for inkjet recording, and an inkjet recording method.

  Conventionally, color images formed by an ink jet method or the like have excellent reproducibility of high-quality color images, optical properties such as hue, transparency, coloring power, weather resistance, heat resistance, Durability such as solvent resistance is required. It is also required to be safe. Therefore, as a coloring material used in a composition for forming a color image, a pigment is often preferable to a dye from the viewpoint of durability.

  Color index (hereinafter abbreviated as “CI”) pigment yellow (hereinafter also referred to as “PY”) 74, 128 as a pigment for yellow among the basic colors (yellow, magenta, cyan) of colors. Etc. are widely used. However, these yellow pigments have room for improvement because none of them has both yellow color development and weather resistance.

  Therefore, many compositions for forming a yellow image, particularly inks, having sufficient properties as described above have been proposed.

  For example, Patent Document 1 discloses a Pigment Yellow 155 dispersion, an alicyclic epoxy compound, an epoxy compound, an oxetane compound, a cationic polymerizable compound represented as exemplary compound 1-H, and a surfactant. Ink composition comprising a photoacid generator and an anthracene derivative, and a dispersion of Pigment Yellow 213, an alicyclic epoxy compound, an epoxy compound, an oxetane compound, and an exemplary compound 1-G An ink composition comprising a cationically polymerizable compound, a surfactant, a photoacid generator, and an anthracene derivative is disclosed (Ink Nos. Y-6 and Y-7 in Table 2 of Patent Document 1). ).

  For example, Patent Document 2 includes (1) C.I. I. Pigment yellow 213, (2) C.I. I. Pigment yellow 213 and C.I. I. Pigment yellow 110, or (3) C.I. I. Pigment yellow 213 and C.I. I. Disclosed is an oil-based ink composition for ink jet recording comprising any one of Pigment Yellow 139 pigment dispersion, diethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, γ-butyrolactone, and an acrylic resin as a binder resin. (Examples 1 to 3 of [0042] to [0045] of Patent Document 2).

  For example, Patent Document 3 discloses C.I. I. PY150, a dispersant, a bifunctional oxetane, a monofunctional oxetane, a monofunctional oxetane alcohol, and a predetermined alicyclic epoxide as a cationic polymerizable compound, and propylene carbonate 50 of triallylsulfonium salt as a photoacid generator A cationically polymerizable inkjet ink composition comprising a% solution and a polyether-modified silicone at both ends as a surfactant is disclosed (ink No. 1 in Table 5 of Patent Document 3).

  For example, Patent Document 4 discloses a photocurable ink composition comprising 2- (vinyloxyethoxy) ethyl acrylate, a hyperbranched polymer, a polymerization initiator, and a dispersion of Pigment Yellow-155. (Example 4 in Table 1 of Patent Document 4).

JP 2010-260281 A JP 2009-1691 A JP 2010-13557 A JP 2009-57548 A

  However, the ink composition disclosed in Patent Document 1 has a problem that it may be inferior in storage stability and color developability in addition to increasing the viscosity. The oil-based ink composition for ink jet recording disclosed in Patent Document 2 has a VOC (volatile organic compound) problem peculiar to oil-based inks (solvent-based inks), and also has a high viscosity and color developability. The problem of inferiority arises. The cationically polymerizable inkjet ink composition disclosed in Patent Document 3 is a C.I. I. Since PY150 is a pigment containing nickel, in addition to being inferior in safety, there is a problem that the viscosity is increased and storage stability and color developability are also inferior. The photocurable ink composition disclosed in Patent Document 4 has a problem of poor storage stability.

  Therefore, an object of the present invention is to provide a pigment composition that can be reduced in viscosity and is excellent in all of safety, storage stability, color development, and weather resistance.

  The present inventors have intensively studied to solve the above problems. As a result, vinyl ether group-containing (meth) acrylic acid esters having a predetermined structure; I. Pigment yellow 155 and C.I. I. It has been found that the above problems can be solved by using a pigment composition containing Pigment Yellow 213, in particular, a photocurable ink composition for inkjet recording (hereinafter also simply referred to as “ink composition”). Completed the invention.

That is, the present invention is as follows.
[1]
The following general formula (I):
_{^{CH 2 = CR 1 -COOR 2 -O}} -CH = CH-R 3 ··· (I)
Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 to 20 carbon atoms, and R ³ is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. Group.)
A vinyl ether group-containing (meth) acrylic acid ester represented by:
C. I. Pigment yellow 155 and C.I. I. A pigment composition containing a pigment containing CI Pigment Yellow 213, or a pigment dispersion used for preparing the photocurable ink jet recording ink composition.
[2]
The pigment composition according to claim 1, wherein the pigment composition is a photocurable ink composition for inkjet recording, which satisfies both the following formulas (II) and (III).
0.1 ≦ B / A ≦ 0.7 (II)
2% by mass ≦ A + B ≦ 6% by mass (III)
(Wherein A represents the content of CI Pigment Yellow 155 relative to the total mass of the pigment composition, and B represents the content of CI Pigment Yellow 213 relative to the total mass of the pigment composition. Represents.)
[3]
The pigment composition according to claim 1 or 2, wherein the vinyl ether group-containing (meth) acrylic acid ester is 2- (vinyloxyethoxy) ethyl (meth) acrylate.
[4]
The C.I. relative to the total mass of the pigment composition. I. Pigment Yellow 155 and the C.I. I. The value obtained by dividing the total content of Pigment Yellow 213 by the total content of pigments contained in the pigment composition with respect to the total mass of the pigment composition is 0.8 or more. 2. The pigment composition according to item 1.
[5]
The pigment composition according to any one of claims 1 to 4, wherein the content of the vinyl ether group-containing (meth) acrylic acid ester is 10 to 65% by mass relative to the total mass of the pigment composition. .
[6]
The pigment composition according to claim 5, wherein the content of the vinyl ether group-containing (meth) acrylic acid ester is 10 to 40% by mass relative to the total mass of the pigment composition.
[7]
The pigment composition according to any one of claims 1 to 6, which is a photocurable ink composition for inkjet recording, further comprising a photopolymerization initiator.
[8]
The pigment composition according to claim 7, wherein the photopolymerization initiator includes an acyl phosphine oxide compound.
[9]
A discharge step of discharging the pigment composition according to claim 7 or 8 onto a recording medium;
A curing step of irradiating the photocurable ink jet recording ink composition ejected in the ejection step with ultraviolet rays to cure the photocurable ink jet recording ink composition;
An ink jet recording method comprising:

  Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not restrict | limited to the following embodiment, A various deformation | transformation can be implemented within the range of the summary.

  In this specification, “storage stability” refers to a property that the viscosity before and after storage is not easily changed when a pigment composition such as an ink composition is stored at 60 ° C. for 1 week. “Color development” refers to the property indicated by the numerical value representing the amount of color that can be printed by a pigment composition such as an ink composition in terms of the volume of color reproduction, and the higher this value, the range over which the color can be reproduced. Excellent in color development due to widening. “Weather resistance” refers to a property that, when a printed matter on which an image is formed is posted outdoors, the image has excellent storage stability, that is, the image is not easily faded or discolored.

  In this specification, “curing” means that when a pigment composition such as an ink composition containing a polymerizable compound is irradiated with radiation, the polymerizable compound is polymerized and the pigment composition is solidified. “Curable” refers to the property of curing in response to light. “Ejection stability” refers to the property of ejecting droplets of a pigment composition such as an ink composition that is always stable without clogging of the nozzle from the nozzle.

  In this specification, “(meth) acrylate” means at least one of acrylate and its corresponding methacrylate, and “(meth) acryl” means at least one of acryl and its corresponding methacryl.

  In this specification, “recorded material” refers to a material in which ink is recorded on a recording medium to form a cured product. In addition, the hardened | cured material in this specification means the hardened | cured substance containing the cured film and coating film of an ink.

[Pigment composition]
A pigment composition according to an embodiment of the present invention has the following general formula (I):
_{^{CH 2 = CR 1 -COOR 2 -O}} -CH = CH-R 3 ··· (I)
Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 to 20 carbon atoms, and R ³ is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. Group.)
A vinyl ether group-containing (meth) acrylic acid ester represented by C.I. I. Pigment yellow 155 and C.I. I. Pigments including CI Pigment Yellow 213. Here, the “pigment composition” in the present specification is a composition containing at least a pigment and a dispersion medium in which the pigment is dispersed, and the property thereof is any of liquid, solid, and semi-solid. Although it is possible, it is often a liquid. Although the said pigment composition is not limited below, For example, it can be set as the pigment dispersion liquid which consists of a dispersion medium with which the ink and the coating material, the coating agent, and the pigment and the said pigment are disperse | distributed. Among these, an ink is particularly preferable, a photocurable ink is more preferable, and a photocurable inkjet recording ink described below is further preferable.
In addition, if the pigment composition of this embodiment is a composition containing at least a pigment and a dispersion medium in which the pigment is dispersed, the effect of this embodiment can be obtained, and the ink is used. It is not limited to that.
Hereinafter, additives (components) that are or can be included in the pigment composition of the present embodiment will be described.

[Color material]
The pigment composition of this embodiment has at least C.I. I. Pigment yellow 155 and C.I. I. Pigment Yellow 213 is included.

C. I. Pigment Yellow 155 is classified as a condensed azo pigment and has a chemical name of 2,2 ′-[1,4-phenylene-bis [imino (1-acetyl-2-oxoethane-2,1-diyl) azo]] bis ( Dimethyl terephthalate) and the molecular formula is C ₃₄ H ₃₂ N ₆ O ₁₂ . The pigment composition is C.I. I. By including Pigment Yellow 155, the pigment composition is excellent in weather resistance and is excellent in safety and color development.

On the other hand, C.I. I. Pigment Yellow 213 is classified as a quinoxaline pigment and has a chemical name of 2- [2- [2-[(1,2,3,4-tetrahydro-7-hydroxy-2,3-dioxoquinoxalin-6-yl) amino. ] -2-oxo-1-carboxylate ethylidene] hydrazino] terephthalic acid 1,4-dimethyl, chemical formula is _{C 21 H 17 N 5 O 10} . The pigment composition is C.I. I. By including both Pigment Yellow 213, the pigment composition is excellent in weather resistance, and is excellent in safety and storage stability.

  Further, the pigment composition is C.I. I. Pigment yellow 155 and C.I. I. By including both of Pigment Yellow 213, it is excellent in all of safety, storage stability, color developability, and weather resistance.

Moreover, since the said pigment composition becomes further excellent in each balance of a weather resistance, storage stability, and color development property, it is preferable to satisfy | fill both following numerical formula (II) and (III).
0.1 ≦ B / A ≦ 0.7 (II)
2% by mass ≦ A + B ≦ 6% by mass (III)
In the above formula, A is C.I. relative to the total mass (100% by mass) of the pigment composition. I. The content (unit: mass%) of Pigment Yellow 155 is represented. B represents C.I. relative to the total mass (100% by mass) of the pigment composition. I. The content (unit: mass%) of Pigment Yellow 213 is represented.

  Moreover, in the total mass (100 mass%) of the said pigment composition, C.I. I. Pigment yellow 155 and C.I. I. The value obtained by dividing the total content of Pigment Yellow 213 by the total content of pigments is preferably 0.8 or more, and more preferably 0.85 or more. When the value obtained by the division is within the above range, the storage stability and the weather resistance are particularly improved.

  Moreover, said pigment composition may contain another coloring material, and at least one is mentioned among a pigment and dye as the said other coloring material.

(Pigment)
In this embodiment, the light resistance of the pigment composition can be improved by using a pigment as the color material. Of these, yellow pigments (excluding CI PY 155, 213) are not limited to the following, but include, for example, C.I. I. Pigment Yellow (PY) 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.

  The said yellow pigment may be used individually by 1 type, and may use 2 or more types together.

(dye)
In the present embodiment, a dye can be used as the color material. Of these, examples of yellow dyes include, but are not limited to, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Direct yellow 1,12,24,33,50,55,58,86,132,142,144,173 can be mentioned.

  The said yellow dye may be used individually by 1 type, and may use 2 or more types together.

  The content of the color material has good color developability and can reduce the inhibition of curing of the coating film due to light absorption of the color material itself. -5.0 mass% is preferable.

[Dispersant]
The pigment composition of this embodiment may contain a dispersant in order to make the pigment dispersibility better. Although it does not specifically limit as the said dispersing agent, For example, the dispersing agent currently used for preparing pigment dispersion liquids, such as a polymer dispersing agent, is mentioned. Specific examples 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. The thing which has 1 or more types of resin as a main component is mentioned. Commercially available polymer dispersants include Ajinomoto Fine Techno Co., Ltd. Ajisper series (trade name), Solspers series available from Avecia Co. (Solsperse 32000, 36000, etc. [trade name]), BYK Chemie, etc. Disparvic series (trade name) made by the company and Disparon series (trade name) made by Enomoto Kasei.

  A dispersing agent may be used individually by 1 type, and may be used in combination of 2 or more type. The content of the dispersant is not particularly limited, and a preferable amount may be added as appropriate.

(Polymerizable compound)
The pigment composition of this embodiment contains the vinyl ether group containing (meth) acrylic acid ester represented by the said general formula (I) as a polymeric compound. When the pigment composition contains the vinyl ether group-containing (meth) acrylic acid esters, the effect of reducing the viscosity is particularly great and the curability is excellent. Here, the “polymerizable compound” in the present specification can also be a dispersion medium for dispersing the pigment in the pigment composition.

  The polymerizable compound can cure the printed image by polymerization. Here, by using a photopolymerizable compound that polymerizes upon light irradiation as the polymerizable compound, it is possible to cure a printed image without adding a photopolymerization initiator. However, when a photopolymerization initiator is used, the start of polymerization can be easily adjusted. Therefore, when the pigment composition itself is used for printing for image formation, the pigment composition preferably further contains a photopolymerization initiator.

  The vinyl ether group-containing (meth) acrylic acid esters will be described in detail in the embodiments of the photocurable ink composition for ink jet recording described later.

  As described above, according to this embodiment, it is possible to provide a pigment composition that can be reduced in viscosity and is excellent in all of safety, storage stability, color developability, and weather resistance. The product may be used as it is, or may be used as a raw material or a semi-finished product such as a paint, an adhesive, a pressure-sensitive adhesive, a surface modifying material, and a molding material.

[Photocurable ink composition for inkjet recording]
The photocurable ink composition for inkjet recording according to an embodiment of the present invention is a kind of the pigment composition of the above-described embodiment, and preferably further includes a photopolymerization initiator.

  Hereinafter, additives (components) that are or can be included in the ink composition of the present embodiment will be described.

(Polymerizable compound)
The polymerizable compound contained in the ink composition of the present embodiment can be polymerized at the time of ultraviolet irradiation by the action of a photopolymerization initiator described later, and the printed ink can be cured.

(Vinyl ether group-containing (meth) acrylic acid esters)
The vinyl ether group-containing (meth) acrylic acid ester, which is an essential polymerizable compound in the present embodiment, is represented by the general formula (I) as described above.

  When the ink composition contains the vinyl ether group-containing (meth) acrylic acid esters, the ink curability can be improved, and the viscosity of the ink can be lowered. In addition, it is better to use a compound having both a vinyl ether group and a (meth) acryl group in one molecule than to use a compound having a vinyl ether group and a compound having a (meth) acryl group separately. It is preferable for improving curability.

In the above general formula (I), the divalent organic residue having 2 to 20 carbon atoms represented by R ² is a linear, branched or cyclic substituted having 2 to 20 carbon atoms. May be an alkylene group, an optionally substituted alkylene group having an oxygen atom by an ether bond and / or an ester bond in the structure, and an optionally substituted divalent alkylene group having 6 to 11 carbon atoms. Aromatic groups are preferred. Among these, C2-C6 alkylene groups such as ethylene group, n-propylene group, isopropylene group, and butylene group, oxyethylene group, oxy n-propylene group, oxyisopropylene group, and oxybutylene group An alkylene group having 2 to 9 carbon atoms having an oxygen atom due to an ether bond in the structure is preferably used.

In the general formula (I), the monovalent organic residue having 1 to 11 carbon atoms represented by R ³ is a linear, branched or cyclic substituted group having 1 to 10 carbon atoms. Suitable alkyl groups and optionally substituted aromatic groups having 6 to 11 carbon atoms are preferred. Among these, C6-C2 aromatic groups, such as a C1-C2 alkyl group which is a methyl group or an ethyl group, a phenyl group, and a benzyl group, are used suitably.

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

  Examples of the vinyl ether group-containing (meth) acrylic acid esters include, but are not limited to, for example, 2-vinyloxyethyl (meth) acrylate, 3-vinyloxypropyl (meth) acrylate, and 1-methyl (meth) acrylate. 2-vinyloxyethyl, 2-vinyloxypropyl (meth) acrylate, 4-vinyloxybutyl (meth) acrylate, 1-methyl-3-vinyloxypropyl (meth) acrylate, 1-vinyloxymethyl (meth) acrylate Propyl, 2-methyl-3-vinyloxypropyl (meth) acrylate, 1,1-dimethyl-2-vinyloxyethyl (meth) acrylate, 3-vinyloxybutyl (meth) acrylate, 1-methyl- (meth) acrylate 2-vinyloxypropyl, 2-vinyloxybutyl (meth) acrylate, (meth) a 4-vinyloxycyclohexyl silylate, 6-vinyloxyhexyl (meth) acrylate, 4-vinyloxymethylcyclohexylmethyl (meth) acrylate, 3-vinyloxymethylcyclohexylmethyl (meth) acrylate, (meth) acrylic acid 2-vinyloxymethylcyclohexylmethyl, p-vinyloxymethylphenylmethyl (meth) acrylate, m-vinyloxymethylphenylmethyl (meth) acrylate, o-vinyloxymethylphenylmethyl (meth) acrylate, (meth) 2- (vinyloxyethoxy) ethyl acrylate, 2- (vinyloxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxy) propyl (meth) acrylate, 2- (vinyloxy) (meth) acrylate Ethoxy) isopropyl, (meth) acrylic acid 2- Vinyloxyisopropoxy) propyl, 2- (vinyloxyisopropoxy) isopropyl (meth) acrylate, 2- (vinyloxyethoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyisopropoxy) (meth) acrylate ) Ethyl, 2- (vinyloxyisopropoxyethoxy) ethyl (meth) acrylate, 2- (vinyloxyisopropoxyisopropoxy) ethyl (meth) acrylate, 2- (vinyloxyethoxyethoxy) propyl (meth) acrylate 2- (vinyloxyethoxyisopropoxy) propyl (meth) acrylate, 2- (vinyloxyisopropoxyethoxy) propyl (meth) acrylate, 2- (vinyloxyisopropoxyisopropoxy) propyl (meth) acrylate, (Meth) acrylic acid 2- (vinylo) Xylethoxyethoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyethoxyisopropoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyisopropoxyethoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyisopropoxy) Isopropoxy) isopropyl, (meth) acrylic acid 2- (vinyloxyethoxyethoxyethoxyethoxy) ethyl, (meth) acrylic acid 2- (vinyloxyethoxyethoxyethoxyethoxy) ethyl, (meth) acrylic acid 2- (isopropenoxyethoxy) ) Ethyl, (meth) acrylic acid 2- (isopropenoxyethoxyethoxyethoxy) ethyl, (meth) acrylic acid 2- (isopropenoxyethoxyethoxyethoxy) ethyl, (meth) acrylic acid 2- (isopropenoxyethoxyethoxyethoxy) D ) Ethyl, and (meth) Polyethylene glycol monovinyl ether acrylate, and (meth) acrylic acid polypropylene glycol monovinyl ether.

  Among these, since the viscosity of the ink can be further reduced, the flash point is high, and the curability of the ink is excellent, 2- (vinyloxyethoxy) ethyl (meth) acrylate, that is, 2- (vinyloxy) acrylate At least one of ethoxy) ethyl and 2- (vinyloxyethoxy) ethyl methacrylate is preferable, and 2- (vinyloxyethoxy) ethyl acrylate is more preferable. In particular, since 2- (vinyloxyethoxy) ethyl acrylate and 2- (vinyloxyethoxy) ethyl methacrylate have a simple structure and a small molecular weight, the viscosity of the ink can be significantly reduced. Examples of 2- (vinyloxyethoxy) ethyl (meth) acrylate include 2- (2-vinyloxyethoxy) ethyl (meth) acrylate and 2- (1-vinyloxyethoxy) ethyl (meth) acrylate. Examples of 2- (vinyloxyethoxy) ethyl acrylate include 2- (2-vinyloxyethoxy) ethyl acrylate and 2- (1-vinyloxyethoxy) ethyl acrylate. Incidentally, 2- (vinyloxyethoxy) ethyl acrylate is superior in terms of curability compared to 2- (vinyloxyethoxy) ethyl methacrylate.

  A vinyl ether group containing (meth) acrylic acid ester may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the vinyl ether group-containing (meth) acrylic acid esters is preferably 10 to 65% by mass and preferably 10 to 40% by mass with respect to the total mass (100% by mass) of the ink composition. More preferred. When the content is 10% by mass or more, the viscosity of the ink can be further lowered and the curability of the ink can be improved. On the other hand, when the content is 65% by mass or less, and further 40% by mass or less, the storage stability of the ink can be further improved, and the curability of the ink should be excellent. Can do.

  The method for producing the vinyl ether group-containing (meth) acrylic acid esters is not limited to the following, but is a method of esterifying (meth) acrylic acid and a hydroxyl group-containing vinyl ether (Production Method B), (meth) acrylic acid halide. And esterification of (meth) acrylic anhydride and hydroxyl group-containing vinyl ether (production method D), esterification of (meth) acrylic acid ester and hydroxyl group-containing vinyl ether Method of exchange (Production method E), Method of esterifying (meth) acrylic acid and halogen-containing vinyl ether (Method of production F), Method of esterifying alkali (earth) metal salt of (meth) acrylic acid and halogen-containing vinyl ether (Production G), hydroxyl group-containing (meth) acrylic acid ester and carboxylic acid vinyl ester How to vinyl exchange and Le (Procedure H), hydroxyl group-containing (meth) How to ether exchange and acrylic acid ester and an alkyl vinyl ether (Process I).

  Among these, since the desired effect can be further exhibited in this embodiment, the production method E is preferable.

(Monofunctional (meth) acrylate)
The ink composition of this embodiment may further contain a monofunctional (meth) acrylate as a polymerizable compound. Examples of the monofunctional (meth) acrylate include, but are not limited to, isoamyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, and isomyristyl. (Meth) acrylate, isostearyl (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (Meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate , Phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) ) Acrylate, lactone-modified flexible (meth) acrylate, t-butylcyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and benzyl (meth) acrylate. .

  Among these, phenoxyethyl (meth) has good compatibility with additives such as a photopolymerization initiator, can further reduce viscosity and odor, and can improve ink curability. Acrylates are preferred, and phenoxyethyl acrylate is more preferred.

  A monofunctional (meth) acrylate may be used individually by 1 type, and may be used in combination of 2 or more type.

  10-40 mass% is preferable with respect to the total mass (100 mass%) of an ink composition, and, as for content of monofunctional (meth) acrylate, especially phenoxyethyl (meth) acrylate, 12-37 mass% is more preferable. When the content is within the above range, the solubility of the photopolymerization initiator and the curability of the ink can be improved.

(Multifunctional (meth) acrylate)
The ink composition of this embodiment may further contain polyfunctional (meth) acrylate as a polymerizable compound. Among the polyfunctional (meth) acrylates, bifunctional (meth) acrylates (excluding the above-mentioned predetermined vinyl ether group-containing (meth) acrylic acid esters) are not limited to the following, for example, triethylene glycol Di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, 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 di (meth) acrylate, dimethylol trisi Rhodecane di (meth) acrylate, EO (ethylene oxide) adduct di (meth) acrylate of bisphenol A, PO (propylene oxide) adduct di (meth) acrylate of bisphenol A, neopentyl glycol di (meth) acrylate hydroxypivalate, And polytetramethylene glycol di (meth) acrylate. Among these, at least one of dipropylene glycol diacrylate and tripropylene glycol diacrylate is preferable because both viscosity reduction and excellent curability can be achieved.

  Among polyfunctional (meth) acrylates, trifunctional or higher (meth) acrylates are not limited to the following, but include, for example, 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 propoxytri (meth) acrylate, cowprolactone modified trimethylolpropane tri (meth) ) Acrylate, pentaerythritol ethoxytetra (meth) acrylate, and caprolactam-modified dipentaerythritol hexa (meth) acrylate.

  A polyfunctional (meth) acrylate may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the polyfunctional (meth) acrylate is preferably 2 to 30% by mass and is preferably 3 to 25% by mass because the effect of improving the curability is small when the content is small and the viscosity of the ink is greatly increased. More preferred.

(Polymerizable compounds other than the above)
In addition to the above-mentioned vinyl ether group-containing (meth) acrylic acid esters, monofunctional (meth) acrylates, and polyfunctional (meth) acrylates, various conventionally known monofunctional and polyfunctional monomers and oligomers are also used. It is possible (hereinafter referred to as “other polymerizable compounds”). Examples of the monomer include unsaturated carboxylic acids such as itaconic acid, crotonic acid, isocrotonic acid and maleic acid, salts or esters thereof, urethanes, amides and anhydrides thereof, acrylonitrile, styrene, various unsaturated polyesters, unsaturated monomers. Examples include saturated polyethers, unsaturated polyamides, and unsaturated urethanes. Moreover, as said oligomer, the oligomer formed from said monomer is mentioned, for example.

  Another polymeric compound may be used individually by 1 type, and may be used in combination of 2 or more type. The content of the other polymerizable compound may be 20% by mass or less with respect to the total mass (100% by mass) of the ink composition.

(Photopolymerization initiator)
The photopolymerization initiator contained in the ink composition of the present embodiment is used to form a print by curing the ink present on the surface of the recording medium by photopolymerization by ultraviolet irradiation. By using ultraviolet rays (UV) among the radiation, the safety is excellent and the cost of the light source lamp can be suppressed. There is no limitation as long as it generates active species such as radicals and cations by the energy of light (ultraviolet rays) and initiates the polymerization of the polymerizable compound. However, a photo radical polymerization initiator or a photo cationic polymerization initiator may be used. Among them, it is preferable to use a radical photopolymerization initiator.

  Examples of the photo radical polymerization initiator include aromatic ketones, acyl phosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiphenyls, and the like. Examples include imidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon halogen bond, and alkylamine compounds.

  Among these, since it is possible to further improve the curability of the ink, it is preferable to use at least one of an acyl phosphine oxide compound and a thioxanthone compound, and it is more preferable to use an acyl phosphine oxide compound. More preferably, an acylphosphine oxide compound and a thioxanthone compound are used in combination.

  Specific examples of the photo radical polymerization initiator include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine. , Carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1- (4-isopropylphenyl) ) -2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthio Xanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, bis (2,4,6-trimethylbenzoyl) -phenyl Phosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4-diethylthioxanthone, and bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide Can be mentioned.

  Examples of commercially available photo radical polymerization initiators include IRGACURE 651 (2,2-dimethoxy-1,2-diphenylethane-1-one), IRGACURE 184 (1-hydroxy-cyclohexyl-phenyl-ketone), DAROCUR 1173. (2-hydroxy-2-methyl-1-phenyl-propan-1-one), IRGACURE 2959 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane- 1-one), 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-morphol Linopropan-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 784 (bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole-1-) Yl) -phenyl) titanium), IRGACURE OXE 01 (1.2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)]), IRGACURE OXE 02 (ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime)), IRGACURE 754 (oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2- (Mixture of (2-hydroxyethoxy) ethyl ester) (manufactured by BASF), KAYACURE DETX-S (2,4-diethylthioxanthone) (manufactured by Nippon Kayaku Co., Ltd.), Lucirin TPO LR8883, LR8970 (manufactured by BASF), Ubekrill P36 (UCB), and the like.

  A photoinitiator may be used individually by 1 type and may be used in combination of 2 or more type.

  The content of the photopolymerization initiator can improve the ultraviolet curing rate and have excellent curability, and in order to avoid undissolved photopolymerization initiator and coloring derived from the photopolymerization initiator, The content is preferably 8 to 20% by mass with respect to the total mass (100% by mass) of the ink composition.

  In particular, when the photopolymerization initiator includes an acyl phosphine oxide compound and a thioxanthone compound, the curability is further improved because a sufficient curing rate is obtained particularly when curing with an LED (preferable emission peak wavelength: 350 nm to 420 nm). Therefore, the content of the acylphosphine oxide compound is preferably 7 to 15% by mass with respect to the total mass (100% by mass) of the ink composition. Moreover, it is preferable that content of a thioxanthone compound is 1-5 mass% with respect to the total mass (100 mass%) of an ink composition.

[Slip agent]
The ink composition of the present embodiment may further include a slip agent (surfactant). The slip agent is not particularly limited. For example, polyester-modified silicone or polyether-modified silicone can be used as a silicone-based surfactant, and polyether-modified polydimethylsiloxane or polyester-modified polydimethylsiloxane is particularly used. preferable. Specific examples include BYK-347, BYK-348, BYK-UV3500, 3510, 3530, and 3570 (above, manufactured by BYK).

  A slip agent may be used individually by 1 type, and may be used in combination of 2 or more type. The content of the slip agent is not particularly limited, and a preferable amount may be added as appropriate.

[Polymerization inhibitor]
The ink composition of this embodiment may further contain a polymerization inhibitor. When the ink composition contains a polymerization inhibitor, the polymerization reaction of the polymerizable compound before curing can be prevented.

  Although it does not restrict | limit especially as a polymerization inhibitor, For example, a phenol type polymerization inhibitor is mentioned. Examples of the phenol-based polymerization inhibitor include, but are not limited to, for example, p-methoxyphenol, cresol, t-butylcatechol, di-t-butylparacresol, hydroquinone monomethyl ether, α-naphthol, 3,5-di- t-butyl-4-hydroxytoluene, 2,6-di-t-butyl-4-methylphenol, 2,2'-methylene-bis (4-methyl-6-t-butylphenol), 2,2'-methylene -Bis (4-ethyl-6-butylphenol) and 4,4'-thio-bis (3-methyl-6-tert-butylphenol).

  Examples of commercially available phenolic polymerization inhibitors include p-methoxyphenol (trade name, p-methoxyphenol, manufactured by Tokyo Chemical Industry Co., Ltd.), non-flex MBP (Seiko Chemical Co., Ltd. ( Seiko Chemical Co., Ltd., trade name, 2,2′-methylene-bis (4-methyl-6-tert-butylphenol)), BHT Swanox (trade name, 2,6-di-t, manufactured by Seiko Chemical Co., Ltd.) -Butyl-4-methylphenol).

  A polymerization inhibitor may be used individually by 1 type, and may be used in combination of 2 or more type. The content of the polymerization inhibitor is not particularly limited, and a preferable amount may be added as appropriate.

[Other additives]
The ink composition of the present embodiment may include additives (components) other than the additives listed above. Such components are not particularly limited, and may include, for example, conventionally known polymerization accelerators, penetration enhancers, wetting agents (humectants), and other additives. Examples of the other additives include conventionally known fixing agents, antifungal agents, preservatives, antioxidants, ultraviolet absorbers, chelating agents, pH adjusting agents, and thickeners.

[Characteristics of Photocurable Inkjet Recording Ink Composition]
The ink composition is preferably cured by irradiation with ultraviolet rays having an emission peak wavelength in the range of 350 to 420 nm. When the ink composition of the present embodiment can be cured at the emission peak wavelength within the above range, it can be cured at a low energy and at a high speed due to the composition of the ink composition. In particular, it is preferable to be able to cure with low energy because a light emitting diode (LED) which has been attracting attention in recent years from the environmental viewpoint can be used as an ultraviolet irradiation source. That is, the ink composition of this embodiment is excellent in curability by the LED.

Further, an ink composition that cures with an irradiation energy of ultraviolet rays of 300 mJ / cm ² or less is preferable, and an ink composition that cures with an irradiation energy of ultraviolet rays of 200 mJ / cm ² or less is more preferable. By using such an ink composition, an image can be formed at low cost. The irradiation energy is calculated by multiplying the irradiation time by the irradiation intensity.

  Thus, according to the present embodiment, a photocurable ink composition for ink jet recording that can be reduced in viscosity and is excellent in all of safety, storage stability, color developability, and weather resistance is provided. Can do.

[Recording medium]
The ink composition of the present embodiment can be recorded by being ejected onto a recording medium by an inkjet recording method described later. Examples of the recording medium include an absorptive or non-absorbable recording medium. The ink jet recording method of the embodiment described below is widely used for recording media having various absorption performances from non-absorbing recording media in which water-based ink penetration is difficult to absorbent recording media in which water-based ink penetration is easy. Applicable. However, when the above ink composition is applied to a non-absorbable recording medium, it may be necessary to provide a drying step after being cured by irradiation with ultraviolet rays.

  The absorbent recording medium is not particularly limited. For example, plain paper such as electrophotographic paper having high water-based ink permeability, ink jet paper (an ink absorbing layer composed of silica particles or alumina particles, or polyvinyl alcohol). Art paper and coats used for general offset printing with relatively low permeability of water-based ink from (PVA) and inkjet pyrrole (PVP) and other ink-absorbing layers composed of hydrophilic polymers such as polyvinylpyrrolidone (PVP). Examples thereof include paper and cast paper.

  The non-absorbable recording medium is not particularly limited. For example, films, sheets and plates of plastics such as polyvinyl chloride (PVC), polyethylene, polypropylene, polyethylene terephthalate (PET), iron, silver, copper, Examples thereof include a metal plate such as aluminum, a metal plate produced by vapor deposition of these various metals, a plastic film, a plate made of an alloy such as stainless steel or brass.

[Inkjet recording method]
One embodiment of the present invention relates to an inkjet recording method. The photocurable ink composition for ink jet recording of the above embodiment can be suitably used for the ink jet recording method of the present embodiment. The inkjet recording method includes a discharge step of discharging the ink composition onto a recording medium, and a curing step of curing the ink composition by irradiating the ink composition discharged in the discharge step with ultraviolet rays. ,including. In this way, an image, that is, an ink coating film (cured film) is formed by the ink composition cured on the recording medium.

[Discharge process]
In the ejection step, the ink composition is ejected onto the recording medium, and the ink composition adheres to the recording medium. The viscosity of the ink composition during ejection is preferably 5 to 20 mPa · s. If the viscosity of the ink composition is as described above with the temperature of the ink composition at room temperature or without heating the ink composition, the temperature of the ink composition is at room temperature or without heating the ink composition. Can be discharged. In that case, it is preferable that the temperature of the ink at the time of discharge is 20-30 degreeC. On the other hand, the ink composition may be discharged to a preferable viscosity by heating to a predetermined temperature. In this way, good discharge stability is realized.

  Since the photocurable ink composition for ink jet recording of the present embodiment has a higher viscosity than a normal aqueous ink composition, the viscosity fluctuation due to temperature fluctuation at the time of ejection is large. Such a variation in the viscosity of the ink has a great influence on the change in the droplet size and the change in the droplet ejection speed, and can cause image quality degradation. Therefore, it is preferable to keep the temperature of the ink during ejection as constant as possible.

[Curing process]
Next, in the curing step, the ink composition ejected and adhered onto the recording medium is cured by irradiation with light (ultraviolet rays). This is because the photopolymerization initiator contained in the ink composition is decomposed by irradiation with ultraviolet rays to generate starting species such as radicals, acids, and bases, and the polymerization reaction of the polymerizable compound depends on the function of the starting species. It is to be promoted. Or it is because the polymerization reaction of a polymeric compound starts by irradiation of an ultraviolet-ray. At this time, if a sensitizing dye is present together with the photopolymerization initiator in the ink composition, the sensitizing dye in the system absorbs ultraviolet rays to be in an excited state and contacts the photopolymerization initiator to decompose the photopolymerization initiator. And a more sensitive curing reaction can be achieved.

  Mercury lamps and gas / solid lasers are mainly used as ultraviolet sources, and mercury lamps and metal halide lamps are widely known as light sources used for curing photocurable ink compositions for inkjet recording. Yes. On the other hand, there is a strong demand for mercury-free from the viewpoint of environmental protection, and replacement with a GaN-based semiconductor ultraviolet light-emitting device is very useful industrially and environmentally. Furthermore, ultraviolet light-emitting diodes (UV-LEDs) and ultraviolet laser diodes (UV-LDs) are small, have a long life, have high efficiency, and are low in cost, and are expected as light sources for photo-curable ink jets. Among these, UV-LED is preferable.

Here, since it is easy to increase the output of the LED, it is preferable to use a UV-LED whose emission peak wavelength is preferably in the range of 350 to 420 nm, and is preferably a photocurable inkjet recording that can be cured with an irradiation energy of 300 mJ / cm ² or less. It is preferable to use the ink composition for ink jet recording. In this case, low cost printing and high printing speed can be realized. Such an ink composition can be obtained by including at least one of a photopolymerization initiator that decomposes upon irradiation with ultraviolet rays in the wavelength range and a polymerizable compound that starts polymerization upon irradiation with ultraviolet rays in the wavelength range.

  As described above, according to the present embodiment, the photocurable ink composition for ink jet recording that can be reduced in viscosity and is excellent in all of safety, storage stability, color developability, and weather resistance is used. A suitable inkjet recording method can be provided.

  Hereinafter, the embodiments of the present invention will be described more specifically by way of examples. However, the embodiments are not limited to these examples.

[Use ingredients]
The components used in the following examples and comparative examples are as follows.
[Pigment]
Novoperm Yellow 4G01 (trade name, CI Pigment Yellow 155, manufactured by Clariant, abbreviated as “PY-155” below)
Hostaper Yellow H5G (trade name, CI Pigment Yellow 213, manufactured by Clariant, abbreviated as “PY-213” below)
[Dispersant]
Solsperse 32000 (trade name manufactured by LUBRIZOL, abbreviated as “SOL32000” below)
[Vinyl ether group-containing (meth) acrylic acid esters]
VEEA (2- (2-vinyloxyethoxy) ethyl acrylate, trade name of Nippon Shokubai Co., Ltd., hereinafter abbreviated as “VEEA”)
In the following tables, vinyl ether group-containing (meth) acrylic acid esters are abbreviated as “acrylic / vinyl-containing monomers”.
[Monofunctional (meth) acrylate]
Biscoat # 192 (phenoxyethyl acrylate, trade name of OSAKA ORGANIC CHEMICAL INDUSTRY LTD., Hereinafter abbreviated as “PEA”)
[Multifunctional (meth) acrylate]
NK ester APG-100 (trade name, dipropylene glycol diacrylate, manufactured by SHIN-NAKAMURA CHEMICAL CO., LTD., Hereinafter abbreviated as “DPGDA”)
NK ester APG-200 (trade name, tripropylene glycol diacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd., abbreviated as “TPGDA” below)
[Polymerization inhibitor]
P-methoxyphenol (trade name, p-methoxyphenol, manufactured by Tokyo Chemical Industry Co., Ltd., abbreviated as “MEHQ” below)
[Slip agent]
BYK-UV3500 (trade name of BYK, silicone-based surface conditioner, hereinafter abbreviated as “UV-3500”)
(Photopolymerization initiator)
IRGACURE 819 (trade name, manufactured by BASF, solid content: 100%, hereinafter abbreviated as “819”)
DAROCUR TPO (trade name, manufactured by BASF, solid content: 100%, hereinafter abbreviated as “TPO”)
KAYACURE DETX-S (trade name, manufactured by Nippon Kayaku Co., Ltd., solid content: 100%, hereinafter abbreviated as “DETX”)

[Examples 1 to 17, Comparative Examples 1 to 8]
First, a pigment dispersion (hereinafter also referred to as “dispersion”) was prepared. In Tables 1 to 3 below, the components described in the “Dispersion” column are added and mixed so as to have the composition (unit: mass%) described in Tables 1 to 3 to prepare dispersions 1 to 4. did.
Next, the dispersion liquids 1 to 4 prepared above were stirred with a high-speed water-cooled stirrer to prepare a yellow photocurable ink jet recording ink composition (a kind of the pigment composition of the present invention). In Comparative Example 8, a colorless photocurable ink composition for ink jet recording was prepared by adding and mixing so that the composition shown in Table 3 was used without using a dispersion.

[Evaluation item]
About the photocurable ink composition for inkjet recording prepared in each Example and each comparative example, the viscosity, storage stability, color development property, and weather resistance were evaluated by the following methods.

(1. Viscosity)
The viscosity of the ink composition of each example and each comparative example was measured using a DVM-E type rotational viscometer (manufactured by TOKYO KEIKI INC) under the conditions of a temperature of 25 ° C. and a rotational speed of 10 rpm. . The evaluation criteria are as follows. The evaluation results are shown in Tables 4 to 6 below.
A: 25 mPa · s or less,
B: more than 25 mPa · s and less than 30 mPa · s,
C: 30 mPa · s or more.

(2. Storage stability)
The ink compositions of each Example and each Comparative Example whose viscosity was measured in the above “1. Viscosity” were placed in a 50 mL glass bottle, sealed, put into a 60 ° C. thermostatic bath and stored for 1 week. Thereafter, the viscosity of each ink composition whose temperature was lowered to room temperature was measured by the same method as in “1. Viscosity” above. The storage stability was evaluated based on the viscosity increase ratio before and after storage (ratio of the viscosity of the ink composition after storage to the viscosity of the ink composition before storage).
The evaluation criteria are as follows. The evaluation results are shown in Tables 4 to 6 below.
A: Less than 5%
B: 5% or more and less than 15%,
C: 15% or more.

(3. Color development)
Using an ink jet recording apparatus provided with a piezo ink jet nozzle, each nozzle row was filled with the ink composition of each example and each comparative example. A solid pattern image (printed material) having a thickness of 10 μm on a PVC sheet (Frontlite Glossy 120 g [trade name], manufactured by Cooley) at room temperature and normal pressure while adjusting the ink discharge amount. A recording resolution of 720 × 720 dpi) was printed. At this time, the dischargeability of each ink composition was good. In addition, the UV-LED in the UV irradiation device mounted on the side of the carriage is irradiated with UV light having an irradiation intensity of 1 W / cm ² and a peak wavelength of 395 nm at an irradiation condition of 200 mJ / cm ² per pass. The solid pattern image was cured by adding the number of passes until tack-free. As described above, a recorded matter in which a solid pattern image was printed on a PVC sheet was produced.
Note that the “solid pattern image” is an image in which dots are recorded for all of the pixels that are the minimum recording unit area defined by the recording resolution. The “number of passes” means the number of times the head moves relative to the recorded matter and the coating film is irradiated with ultraviolet rays from the ultraviolet irradiation device mounted on the head. The irradiation energy [mJ / cm ² ] was obtained from the product of the irradiation intensity [mW / cm ² ] on the irradiated surface irradiated from the light source and the irradiation duration [s]. 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.).
Whether or not it can be said to be tack-free was determined under the following conditions. That is, it is determined whether ink adheres to the swab or whether the ink cured product on the recording medium is scratched. The ink does not adhere to the cotton swab and the ink cured product on the recording medium The case where no scratches were made was considered tack-free. The cotton swab used here was a Johnson swab manufactured by Johnson & Johnson. The number of rubbing was 10 reciprocations and the rubbing strength was 100 g load.
About the recorded matter produced above, it measured using the colorimeter X-Rite (GretagMacbeth (brand name made by GretagMacbeth) company), and evaluated it according to the following evaluation criteria by the obtained OD (Y) value. The evaluation results are shown in Tables 4 to 6 below.
A: 1.7 or more,
B: 1.5 or more and less than 1.7,
C: Less than 1.5.

(4. Weather resistance)
The recorded material prepared in the above “3. Color development” is put into a xenon fade meter SX75 (manufactured by Suga Test Instruments Co., Ltd.), and the integrated value of irradiation energy becomes 100 MJ / m ² . Light was irradiated until The OD value before charging and the OD value after charging were measured, and the residual ratio of OD value represented by the following formula was calculated.
OD value residual ratio = OD value after charging / OD value before charging Evaluation criteria are as follows. The evaluation results are shown in Tables 4 to 6 below.
A: OD value residual rate is 80% or more,
B: OD value residual ratio is 60% or more and less than 80%,
C: OD value residual ratio is less than 60%.

  From the above results, vinyl ether group-containing (meth) acrylic acid esters represented by the above general formula (I), C.I. I. Pigment yellow 155 and C.I. I. The ink composition (each example) containing the pigment yellow pigment 213 has any of viscosity, storage stability, color developability, and weather resistance as compared with the ink composition (each comparative example) that does not. It was also found to be excellent.

Claims (9)

The following general formula (I):
_{^{CH 2 = CR 1 -COOR 2 -O}} -CH = CH-R 3 ··· (I)
Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 to 20 carbon atoms, and R ³ is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. Group.)
A vinyl ether group-containing (meth) acrylic acid ester represented by:
C. I. Pigment yellow 155 and C.I. I. A pigment composition containing a pigment containing CI Pigment Yellow 213, or a pigment dispersion used for preparing the photocurable ink jet recording ink composition . The pigment composition according to claim 1, wherein the pigment composition is a photocurable ink composition for inkjet recording , which satisfies both the following formulas (II) and (III).
0.1 ≦ B / A ≦ 0.7 (II)
2% by mass ≦ A + B ≦ 6% by mass (III)
(Wherein A represents the content of CI Pigment Yellow 155 relative to the total mass of the pigment composition, and B represents the content of CI Pigment Yellow 213 relative to the total mass of the pigment composition. Represents.)   The pigment composition according to claim 1 or 2, wherein the vinyl ether group-containing (meth) acrylic acid ester is 2- (vinyloxyethoxy) ethyl (meth) acrylate. The C.I. relative to the total mass of the pigment composition. I. Pigment Yellow 155 and the C.I. I. The value obtained by dividing the total content of Pigment Yellow 213 by the total content of pigments contained in the pigment composition with respect to the total mass of the pigment composition is 0.8 or more. 2. The pigment composition according to item 1.   The pigment composition according to any one of claims 1 to 4, wherein the content of the vinyl ether group-containing (meth) acrylic acid ester is 10 to 65% by mass relative to the total mass of the pigment composition. .   The pigment composition according to claim 5, wherein the content of the vinyl ether group-containing (meth) acrylic acid ester is 10 to 40% by mass relative to the total mass of the pigment composition.   The pigment composition according to any one of claims 1 to 6, which is a photocurable ink composition for inkjet recording, further comprising a photopolymerization initiator.   The pigment composition according to claim 7, wherein the photopolymerization initiator includes an acyl phosphine oxide compound. A discharge step of discharging the pigment composition according to claim 7 or 8 onto a recording medium;
A curing step of irradiating the photocurable ink jet recording ink composition ejected in the ejection step with ultraviolet rays to cure the photocurable ink jet recording ink composition;
An ink jet recording method comprising: