JP2010018702A - Ink composition, inkjet recording method and print recorded by this method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation curable ink composition which exhibits excellent color reproducibility without showing color turbidity, and has a high curing rate, and excellent fretting resistance and blocking resistance by irradiation with ultraviolet components having a wavelength of 300 nm or higher. <P>SOLUTION: The radiation curable ink composition comprises a pigment, a polymerizable compound, a radiation polymerization initiator, and a compound represented by formula (I) (wherein X is O, S or NR; n is 0 or 1; R is hydrogen, an alkyl group or an acyl group; and R<SP>1</SP>to R<SP>8</SP>are each hydrogen or a monovalent substituent) and meets the relationship of 0.1≤(B/A)≤5, when A is taken as an absorbance based on the compound represented by the above formula (I) at a wavelength of 365 nm and B is taken as an absorbance based on a component other than the compound of the above formula (I) at a wavelength of 365 nm. An inkjet recording method uses the above ink composition and a print is made by this method. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink composition, and preferably relates to a radiation curable ink composition, an ink jet recording method, and a printed matter recorded by this method.

  As an image recording method for forming an image on a recording medium such as paper based on an image data signal, there are an electrophotographic method, a sublimation type and a melt type thermal transfer method, an ink jet method and the like. The electrophotographic system requires a process of forming an electrostatic latent image on a photosensitive drum by charging and exposure, and there is a problem that the system becomes complicated and consequently the manufacturing cost becomes high. In addition, although the thermal transfer method is inexpensive, there are problems such as high running costs and waste materials due to the use of ink ribbons.

On the other hand, the ink jet method is an inexpensive device and ejects ink only to a required image portion to form an image directly on a recording medium. Therefore, the ink can be used efficiently and the running cost is low. Furthermore, there is little noise and it is excellent as an image recording method.
In recent years, an ink composition (radiation curable ink composition) curable by irradiation with radiation such as ultraviolet rays is drawn by inkjet, and then the ink is cured by irradiation with radiation such as ultraviolet rays. The recording method is attracting attention.

  In general, compared with water-based inks containing water as a diluent and solvent-based inks containing an organic solvent as a diluent, inkjet recording methods using radiation-curable inks are non-absorbable recording materials such as glass, metal, and plastic recording media. It is possible to draw on the medium, the applicable range of the recording medium is wide, the scratch and solvent resistance of the drawn image is excellent, the sensitivity is high, the productivity is excellent, and the volatile solvent is not included. It has the merit that the load on is small.

  The radiation curable ink composition is mainly composed of a colorant (pigment), a polymerizable compound, and a photopolymerization initiator. Conventionally, the photopolymerization initiator is 254 nm emitted from a light source such as a high-pressure mercury lamp or a metal halide lamp. In order to generate a polymerization initiating species by a strong emission line in the vicinity, a compound having absorption in a wavelength region of 254 nm has been used. However, in the wavelength region of 254 nm, there is a large absorption of components constituting other ink compositions, particularly pigments, so that the initiation of polymerization of the photopolymerization initiator is inhibited, so that a sufficient curing rate cannot be obtained. There was a drawback.

  In order to overcome such drawbacks, an attempt is made to improve the curing speed by using a photosensitizer having absorption near 365 nm, such as thioxanthone, in order to generate a polymerization initiating species using an emission line near 365 nm. Has been done. However, since such a compound has absorption up to a visible light region of 400 nm or more, if it is added for the purpose of increasing the curing speed, the ink composition itself becomes yellowish and causes ink turbidity. was there.

  Patent Documents 1 to 3 disclose actinic ray inkjet ink compositions containing a specific polycyclic aromatic compound, carbazole compound or thioxanthone with respect to a photoacid generator and a cationic polymerizable compound.

JP 2004-43634 A JP 2005-139275 A JP 2007-2097 A

  The problem to be solved by the present invention is that it exhibits excellent color reproducibility without showing color turbidity, and has a high curing rate and excellent scratch resistance by irradiation with an ultraviolet component of 300 nm or more, particularly an ultraviolet component near 365 nm. It is to provide a radiation curable ink composition having blocking resistance.

The above object of the present invention has been achieved by the following means (1), (7) and (8). It lists together with preferable embodiment (2)-(6).
(1) It contains a pigment, a polymerizable compound, a radiation polymerization initiator, and a compound represented by the following formula (I), and the absorbance based on the compound represented by the above formula (I) at a wavelength of 365 nm is defined as A. Radiation curable ink composition characterized by satisfying a relational expression of 0.1 ≦ (B / A) ≦ 5, where B is an absorbance based on components other than the formula (I) at 365 nm. ,

式（Ｉ）中、ＸはＯ、Ｓ、又は、ＮＲを表し、ｎは０又は１の整数を表し、Ｒは水素原子、アルキル基、又はアシル基を表し、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷、及びＲ⁸は、それぞれ独立に、水素原子、又は、一価の置換基を表し、Ｒ¹、Ｒ²、Ｒ³、及び、Ｒ⁴は、それぞれ隣接する２つが互いに連結して環を形成していてもよく、Ｒ⁵又はＲ⁶と、Ｒ⁷又はＲ⁸は、互いに連結して脂肪族環を形成してもよいが、芳香族環を形成することはない。
（２）前記重合性化合物がエチレン性不飽和化合物である（１）に記載の放射線硬化性インク組成物、
（３）単官能エチレン性不飽和化合物及び多官能エチレン性不飽和化合物を含有する（２）に記載の放射線硬化性インク組成物、
（４）前記放射線重合開始剤が、アシルホスフィンオキサイド化合物及び／又はα−アミノアセトフェノン化合物である（１）〜（３）いずれか１つに記載の放射線硬化性インク組成物、
（５）前記顔料が、Ｃ．Ｉ．ピグメントイエロー１２０、Ｃ．Ｉ．ピグメントイエロー１５０、Ｃ．Ｉ．ピグメントイエロー１５５、Ｃ．Ｉ．ピグメントイエロー１８０、Ｃ．Ｉ．ピグメントレッド２０２、Ｃ．Ｉ．ピグメントブルー１５：３、Ｃ．Ｉ．ピグメントブルー１５：４、Ｃ．Ｉ．ピグメントブルー１５：６、Ｃ．Ｉ．ピグメントバイオレット１９、Ｃ．Ｉ．ピグメントバイオレット２３、Ｃ．Ｉ．ピグメントオレンジ３６、及び、Ｃ．Ｉ．ピグメントグリーン７よりなる群から選ばれた少なくとも１種である、（１）〜（４）いずれか１つに記載の放射線硬化性インク組成物、
（６）分散剤をさらに含有する（１）〜（５）いずれか１つに記載のインク組成物、
（７）被記録媒体上に、（１）〜（６）いずれか１つに記載の活性放射線硬化性インク組成物を吐出する工程、及び、吐出された活性放射線硬化性インク組成物に活性放射線を照射することにより前記活性放射線硬化性インクジェット記録用インク組成物を硬化する工程、を含むことを特徴とするインクジェット記録方法、
（８）（７）に記載のインクジェット記録方法によって記録された印刷物。

In the formula (I), X represents O, S, or NR, n represents an integer of 0 or 1, R represents a hydrogen atom, an alkyl group, or an acyl group, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represents a hydrogen atom or a monovalent substituent, and R ¹ , R ² , R ³ , and R ⁴ are Two adjacent to each other may be connected to each other to form a ring, and R ⁵ or R ⁶ and R ⁷ or R ⁸ may be connected to each other to form an aliphatic ring. Will not form.
(2) The radiation curable ink composition according to (1), wherein the polymerizable compound is an ethylenically unsaturated compound,
(3) The radiation-curable ink composition according to (2), which contains a monofunctional ethylenically unsaturated compound and a polyfunctional ethylenically unsaturated compound,
(4) The radiation curable ink composition according to any one of (1) to (3), wherein the radiation polymerization initiator is an acylphosphine oxide compound and / or an α-aminoacetophenone compound.
(5) The pigment is C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. Pigment red 202, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15: 6, C.I. I. Pigment violet 19, C.I. I. Pigment violet 23, C.I. I. Pigment orange 36 and C.I. I. The radiation curable ink composition according to any one of (1) to (4), which is at least one selected from the group consisting of CI Pigment Green 7;
(6) The ink composition according to any one of (1) to (5), further containing a dispersant;
(7) A step of ejecting the actinic radiation curable ink composition according to any one of (1) to (6) onto a recording medium, and actinic radiation to the ejected actinic radiation curable ink composition Curing the actinic radiation curable ink composition for ink jet recording by irradiating the ink composition, and an ink jet recording method comprising:
(8) Printed matter recorded by the ink jet recording method described in (7).

  According to the present invention, a radiation curable ink composition having a high curing speed, excellent scratch resistance and blocking resistance, and excellent color reproducibility without color turbidity was obtained.

The present invention will be described in detail below.
(1) Radiation curable ink composition The radiation curable ink composition of the present invention comprises (A) a pigment, (B) a polymerizable compound, (C) a radiation polymerization initiator, and (D) the following formula (I): When the absorbance based on the compound represented by the formula (I) at a wavelength of 365 nm is A and the absorbance based on a component other than the formula (I) at a wavelength of 365 nm is B, The relational expression 0.1 ≦ (B / A) ≦ 5 is satisfied.

The absorbances A and B are the absorbance based on the compound represented by the formula (I) and the absorbance based on components other than the compound represented by the formula (I) in the radiation curable ink composition, respectively. means. Therefore, the value of (B / A) is a relative ratio of absorbance based on components other than the compound represented by formula (I) to absorbance based on the compound represented by formula (I). Further, when the ink composition contains a plurality of compounds represented by the formula (I), the absorbance A means the sum of the absorbances based on all the compounds represented by the formula (I). Further, when the ink composition contains a plurality of components other than the formula (I) that absorbs 365 nm, the absorbance B means the sum of the absorbances of all these components.
Although depending on the specific composition of the ink composition, in many cases, the absorbance based on components other than the compound represented by the formula (I) has a high ratio of the absorbance of the pigment. Here, when a plurality of pigments are included, the absorbance based on all the pigments affects.

  The values of absorbance A and B can be obtained by actual measurement from the absorbance of the ink composition. Specifically, the radiation curable ink composition and the radiation curable ink composition not containing the compound represented by the formula (I) are mixed with a solvent (for example, 1-methoxy-2) that does not cause precipitation of the pigment. -Propanol) is diluted to an appropriate concentration (for example, 10,000 times) and measured using a spectrophotometer. When the obtained absorbances are X and Y, respectively, A = (XY), B = Y is assigned, and the value of (B / A) is obtained as Y / (XY). . When the absorbance at 365 nm is substantially negligible for components other than the compound represented by formula (I) and the pigment, the value of (B / A) is represented by formula (I) at the same wavelength. It can be understood as the ratio of the absorbance of the pigment to the absorbance of the compound.

  In the relational expression of 0.1 ≦ (B / A) ≦ 5, the smaller the value of (B / A), the smaller the internal absorption based on the pigment, which is preferable in terms of curing speed, but has a certain degree of coloring in the visible region. In order to obtain the value, it is necessary to have a practically preferable size value, preferably 0.2 ≦ (B / A) ≦ 4, and 0.5 ≦ (B / A) ≦ 3. More preferably, 1 ≦ (B / A) ≦ 2 is particularly preferable.

(A) Pigment The radiation curable ink composition of the present invention contains a pigment as the component (A). Hereinafter, for convenience of explanation, the “radiation curable ink composition” is also simply referred to as “ink composition”.
The pigment has a smaller molecular extinction coefficient at a wavelength of 365 nm than the compound represented by the formula (I), and satisfies the relational expression of 0.1 ≦ (B / A) ≦ 5 And blending amounts can be used.
Specific examples include known organic pigments and inorganic pigments, resin particles dyed with dyes, commercially available pigment dispersions and surface-treated pigments (for example, water or liquid using a pigment as a dispersion medium) Examples thereof include those dispersed in an organic compound or an insoluble resin, and those obtained by treating the pigment surface with a resin or a pigment derivative. Examples of the pigment include, for example, “Spirit of Pigments” edited by Seijiro Ito (2000, published by Asakura Shoten Co., Ltd.), Isao Hashimoto, “Organic Pigment Handbook” (2006, published by Color Office); Herbst, K.M. Hunger, “Industrial Organic Pigments” (1992, issued by Wiley-VHC), JP 2002-12607 A, JP 2002-188025 A, JP 2003-26978 A, JP 2003-342503 A Can be mentioned.

  Examples of the organic pigment and the inorganic pigment include a yellow pigment, a red pigment, a magenta pigment, a blue pigment, a cyan pigment, a green pigment, an orange pigment, a purple pigment, a brown pigment, a black pigment, and a white pigment.

  Examples of the yellow pigment include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 10, 65, 73, 74, 75, 97, 98, 111, 116, 130, 167, 205 and other monoazo pigments, 61, 62, 100, 168, 169, Monoazo lake pigments such as 183, 191, 206, 209, 212, 12, 13, 14, 16, 17, 55, 63, 77, 81, 83, 106, 124, 126, 127, 152, 155, 170, 172, Disazo pigments such as 174, 176, 214 and 219, anthraquinone pigments such as 24, 99, 108, 193 and 199, monoazopyrazolone pigments such as 60, condensed azo pigments such as 93, 95, 128 and 166, 109, 110, 139, 173, 185 and other isoindoline pigments, 120, 151, 154, 175, 180, 181, 194 and other benz Midazoron pigments, azomethine metal complex pigments such as 117,129,150,153, quinophthalone pigments such as 138, quinoxaline pigments 213 are preferred. In terms of inkjet discharge properties, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 155, and C.I. I. Pigment Yellow 180 is particularly preferable.

  Examples of the red or magenta pigment include C.I. I. Pigment Red 193 and other monoazo lake pigments, 38 and other disazo pigments, 2, 5, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 22, 23, 31, 32, 112, 114, Naphthol AS pigments such as 146, 147, 150, 170, 184, 187, 188, 210, 213, 238, 245, 253, 256, 258, 266, 268, 269, etc. β-naphthol pigments such as 3, 4, 6, etc. 49, 53, 68 etc. β-naphthol lake pigments, 237, 239, 247 etc. naphthol AS lake pigments, 41 etc. pyrazolone pigments, 48, 52, 57, 58, 63, 64: 1, 200 etc. BONA lakes Pigment, xanthene lake pigment such as 81: 1, 169, 172, thioindigo pigment such as 88, 181, 279, 123, 149, 17 Perylene pigments such as 179, 190 and 224, condensed azo pigments such as 144, 166, 214, 220, 221, 242, and 262, anthraquinone pigments such as 168, 177, 182, 226, and 263, and anthraquinone lake pigments such as 83 Benzimidazolone pigments such as 171, 175, 176, 185, 208, etc., quinacridone pigments such as 122, 202 (including mixtures with CI Pigment Violet 19), 207, 209, 254, 255, 264, 270 Preferred are diketopyrrolopyrrole pigments such as 272 and azomethine metal complex pigments such as 257 and 271. In terms of inkjet discharge properties, C.I. I. Pigment Red 202 is particularly preferable.

  Examples of the blue or cyan pigment include C.I. I. Naphthol AS pigments such as CI Pigment Blue 25 and 26, phthalocyanine pigments such as 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17: 1, 75, and 79 Dye lake pigments such as 1:56, 61, 62, anthraquinone pigments such as 60, indigo pigments such as 63, and dioxazine pigments such as 80 are preferable. In terms of inkjet discharge properties, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4 and C.I. I. Pigment Blue 15: 6 is more preferable, and C.I. I. Pigment Blue 15: 4 is particularly preferable.

  Examples of the green pigment include C.I. I. Dye lake pigments such as CI Pigment Green 1 and 4, phthalocyanine pigments such as 7 and 36, and azomethine metal complex pigments such as 8 are preferable. In terms of inkjet discharge properties, C.I. I. Pigment Green 7 is particularly preferable.

  Examples of the orange pigment include C.I. I. Monoazo pigments such as CI Pigment Orange 1, β-naphthol pigments such as 2, 3, 5 and the like, naphthol AS pigments such as 4, 24, 38 and 74, pyrazolone pigments such as 13, 34, 36, 60, 62, 64 and 72 Benzimidazolone pigments such as 15 and 16, disazo pigments such as 15 and 16, β-naphthol lake pigments such as 17 and 46, naphthalene sulfonic acid lake pigments such as 19; perinone pigments such as 43, quinacridone pigments such as 48 and 49, 51 Anthraquinone pigments such as 61, isoindolinone pigments such as 61, isoindoline pigments such as 66, azomethine metal complex pigments such as 68, and diketopyrrolopyrrole pigments such as 71, 73 and 81 are preferred. In terms of inkjet discharge properties, C.I. I. Pigment Orange 36 is particularly preferable.

Examples of the brown pigment include C.I. I. BONA lake pigments such as CI Pigment Brown 5, condensed azo pigments such as 23, 41 and 42, and benzimidazolone pigments such as 25 and 32 are preferred.
Examples of the purple pigment include C.I. I. Pigment violet 1, 2, 3, 27 etc. dyed lake pigments, 13, 17, 25, 50 etc. naphthol AS pigments, 5: 1 etc. anthraquinone lake pigments, 19 etc. quinacridone pigments, 23, 37 etc. dioxazine pigments A perylene pigment such as No. 29, benzimidazolone pigment such as No. 32, and a thioindigo pigment such as No. 38 are preferred. In terms of inkjet discharge properties, C.I. I. Pigment violet 19 and C.I. I. Pigment Violet 23 is particularly preferable.

  Examples of the black pigment include C.I. I. Indazine pigments such as CI pigment black 1, carbon black as 7, graphite as 10, magnetite as 11, anthraquinone pigment as 20 and perylene pigment as 31 and 32 are preferable.

Examples of the white pigment include C.I. I. Pigment White 4 Zinc oxide, 6 Titanium oxide, 7 Zinc sulfide, 12 Zirconium oxide (zirconium white), 18 Calcium carbonate, 19 Aluminum oxide / silicon oxide (Kaolin clay), 21 Or the barium sulfate which is 22, the aluminum hydroxide (alumina white) which is 23, the silicon oxide which is 27, and the calcium silicate which is 28 are preferable.
The inorganic particles used in the white pigment may be simple substances, or may be oxides such as silicon, aluminum, zirconium, and titanium, organometallic compounds, and composite particles with organic compounds.
Among these, the titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, a large hiding power and coloring power, and is excellent in durability against acids, alkalis and other environments. used. In addition to the titanium oxide, another white pigment (may be other than the white pigment described above) may be used in combination.

  In the present invention, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. Pigment red 202, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15: 6, C.I. I. Pigment violet 19, C.I. I. Pigment violet 23, C.I. I. Pigment orange 36 and C.I. I. It is preferable to use at least one selected from the group consisting of CI Pigment Green 7.

  Further, examples of the pigment include C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. Pigment red 202, C.I. I. Pigment blue 15: 4, C.I. I. Pigment violet 19, C.I. I. Pigment violet 23, C.I. I. Pigment orange 36 and C.I. I. It is more preferable to use at least one selected from the group consisting of CI Pigment Green 7.

  In the present invention, in order to use for multicolor recording, it is preferable to use a combination of a plurality of ink compositions having different hues. Typically, pigments colored in yellow, magenta, cyan and black are used. The ink composition is used as an ink set.

  In this case, as the yellow ink composition, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 155, and C.I. I. It is preferable to use at least one pigment selected from the group consisting of CI Pigment Yellow 180.

  Further, as the magenta ink composition, Pigment Red 202, and C.I. I. It is preferable to use at least one pigment selected from the group consisting of CI Pigment Violet 19.

  Pigment Blue 15: 3, C.I. I. Pigment blue 15: 4, and C.I. I. It is preferable to use at least one pigment selected from the group consisting of CI Pigment Blue 15: 6.

  Further, as the black ink composition, it is preferable to use an ink composition using the above black pigment.

In addition, it is also preferable to use an ink composition having a violet, orange, or green hue for extending the color gamut. As this special color ink composition, C.I. I. Pigment violet 19, C.I. I. Pigment violet 23, C.I. I. Pigment orange 36 and C.I. I. At least one selected from the group consisting of CI Pigment Green 7 can be used.
Further, it is also preferable to use a white ink composition using the above white pigment in combination with the color ink composition.

  In the ink composition of the present invention, the average particle size of the pigment particles is preferably 0.005 to 0.5 μm, more preferably 0.01 to 0.45 μm, and still more preferably 0.015 to 0.4 μm. It is preferable to set the pigment, dispersant, medium selection, dispersion conditions, and filtration conditions. When the average particle size is in the above range, clogging of the head nozzle can be suppressed, and the storage stability, transparency, and curing speed of the ink composition can be maintained.

In the ink composition of the present invention, pigments having the same hue may be used alone or in combination of two or more.
The pigment content in the ink composition can be selected as appropriate depending on the physical properties of the pigment (specific gravity, coloring power, color, etc.), and how many colors of the ink composition are combined to produce a printed matter. From the viewpoint of strength and coloring power, it is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, and more preferably 1 to 10% by weight with respect to the total weight of the ink composition. It is particularly preferred that

(Dispersant)
In the ink composition of the present invention, a dispersant is preferably used for dispersing the pigment, and the pigment is preferably dispersed using a polymer dispersant.
The “polymer dispersant” in the present invention means a dispersant having a weight average molecular weight of 1,000 or more.
The main chain skeleton of the polymer dispersant is not particularly limited, and examples thereof include a polyurethane skeleton, a polyacryl skeleton, a polyester skeleton, a polyamide skeleton, a polyimide skeleton, a polyurea skeleton, and the like, in terms of storage stability of the ink composition, A polyurethane skeleton, a polyacryl skeleton, and a polyester skeleton are preferable. The structure of the polymer dispersant is not particularly limited, and examples thereof include a random structure, a block structure, a comb structure, and a star structure. Similarly, in terms of storage stability, a block structure or a comb structure is used. preferable.

  As the polymer dispersant, wetting dispersant DISPER BYK series 101, 102, 103, 106, 108, 109, 110, 111, 112, 116, 130, 140, 142, 145, 161 marketed by Big Chemie. 162, 163, 164, 166, 167, 168, 170, 171, 174, 108, 182, 183, 184, 185, 2000, 2001, 2020, 2050, 2070, 2096, 2150, from Ciba Specialty Chemicals Commercially available EFKA series 4008, 4009, 4010, 4015, 4020, 4046, 4047, 4050, 4055, 4060, 4080, 4300, 4330, 4340, 4400, 4401, 4402, 4403, 4406, 4800, 010, 5044, 5054, 5055, 5063, 5064, 5065, 5066, 5070, 5244, Solsperse series 3000, 5000, 11200, 13240, 13650, 13940, 16000, 17000, 18000, 20000, commercially available from Lubrizol. 21000, 24000SC, 24000GR, 26000, 28000, 31845, 32000, 32500, 32550, 32600, 33000, 34750, 35100, 35200, 36000, 36600, 37500, 38500, 39000, 53095, 54000, 55000, 56000, 71000 DISPAR LON series 1210, 1220, 1831, 1 available from Kasei Corporation 50, 1860, 2100, 2150, 2200, 7004, KS-260, KS-273N, KS-860, KS-873N, PW-36, DN-900, DA-234, DA-325, DA-375, DA- 550, DA-1200, DA-1401, DA-7301, Ajispur Fine Techno Co., Ltd. commercially available PB-711, PB-821, PB-822, PN-411, PA-111, Air Surfynol series 104A, 104C, 104E, 104H, 104S, 104BC, 104DPM, 104PA, 104PG-50, 420, 440, DF110D, DF110L, DF37, DF58, DF75, DF210, CT111, CT121 commercially available from Products , CT13 , CT136, GA, TG, TGE, Olfin series STG, E1004, commercially available from Nissin Chemical Industry Co., Ltd., SN Sparse Series 70, 2120, 2190, Sannopco Co., Ltd., commercially available from ADEKA Corporation. Adeka Coal and Adekator Series, Sannonic Series, Naroacty CL Series, Emalmin Series, New Pole PE Series, Ionette M Series, Ionette D Series, Ionette S Series, which are available from Sanyo Chemical Industries, Ltd. Examples include the Ionette T series and the Sansepara 100.

  Further, at the time of dispersion, in addition to the dispersant, a dispersion aid generally called synergist (for example, Solsperse series 5000, 12000, 22000, commercially available from Lubrizol, EFKA 6745, commercially available from Ciba Specialty Chemicals, Inc.) Etc.), various surfactants and antifoaming agents are also added to improve the dispersibility and wettability of the pigment.

  The preferred addition amount of the polymer dispersant in the ink composition is that the weight ratio (D / P) where P is the weight of the pigment in the ink composition and D is the weight of the polymer dispersant in the ink composition. ) Is preferably 0.01 ≦ D / P ≦ 1.5, more preferably 0.03 ≦ D / P ≦ 1.0, and 0.05 ≦ D / P ≦ 0.6. More preferably it is. Within the above range, pigment aggregation / sedimentation and ink viscosity increase do not occur, and an ink composition having excellent storage stability can be obtained, and an ink composition having low ink viscosity and excellent ejection stability can be obtained.

  In the present invention, the pigment and the polymer dispersant may be blended by directly adding together with the respective components when preparing the ink composition, but a general-purpose organic solvent (such as methyl ethyl ketone, toluene, butanol, butyl acetate, etc.) A pigment dispersion (also referred to as a mill base) can be added to a liquid medium such as a polymerizable compound used in the invention and dispersed to be blended. In order to avoid the problem of the solvent resistance deterioration when the medium remains in the cured image and the problem of the remaining VOC (Volatile Organic Compound), the pigment, the polymer dispersant, and the dispersion aid are polymerizable. It is preferable to disperse and mix in the compound in advance. In consideration of workability at the time of blending, it is more preferable to select a polymerizable compound having the lowest viscosity as the medium to be used.

In the present invention, when preparing a pigment dispersion, it is preferable to mix the dispersant with the polymerizable compound, and finally add and disperse the pigment.
For the dispersion, for example, a dispersion device such as a ball mill, a bead mill, a sand mill, a salt mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, or a paint shaker can be used. Among these, a bead mill dispersing device is preferable because of its excellent dispersibility. By using beads having a mean diameter of 0.01 to 3.0 mm, preferably 0.05 to 1.5 mm, more preferably 0.1 to 1.0 mm, when using beads mill dispersion, A pigment dispersion having excellent stability can be obtained.

(B) Polymerizable compound The ink composition of the present invention contains (B) a polymerizable compound. As the polymerizable compound, an addition polymerizable compound is preferable, and is roughly classified into an ethylenically unsaturated compound and a cyclic ether compound. Cyclic ether compounds include epoxy compounds, alicyclic epoxy compounds, and oxetane compounds.
The ink composition of the present invention preferably contains an ethylenically unsaturated compound.
An ethylenically unsaturated compound is a radically polymerizable compound and is a compound having at least one ethylenically unsaturated bond capable of radical polymerization in one molecule. Ethylenically unsaturated compounds include those having chemical forms such as monomers, oligomers, polymers, etc., depending on their molecular weight. Only one type of radically polymerizable compound may be used, or two or more types may be used in combination at any ratio in order to improve the desired properties, and two or more types of monomers and / or oligomers are used in combination. It is preferable to control the reactivity and the quality of the printed matter.
Ethylenically unsaturated compounds are broadly classified into monofunctional compounds and polyfunctional compounds, and it is preferable to use both in combination.
The ink composition of the present invention comprises a monofunctional aromatic ethylenically unsaturated compound, a monofunctional ethylenically unsaturated compound having an aliphatic cyclic structure, a monofunctional N-vinyl lactam compound, and a polyfunctional ethylenically unsaturated compound. More preferably, it contains at least one compound selected from the group consisting of:
Hereinafter, these ethylenically unsaturated compounds will be described in detail.

<Monofunctional aromatic ethylenically unsaturated compound and monofunctional ethylenically unsaturated compound having an aliphatic cyclic structure>
The “monofunctional ethylenically unsaturated compound” refers to a compound having only one radical polymerizable ethylenically unsaturated group in one molecule. The “polyfunctional ethylenically unsaturated compound” refers to a compound having two or more radically polymerizable ethylenically unsaturated groups in one molecule. Preferable examples of the radical polymerizable ethylenically unsaturated group in the monofunctional and polyfunctional ethylenically unsaturated compound include acryloyloxy group, methacryloyloxy group, acrylamide group, methacrylamide group, vinyl group and vinyloxy group.
The monofunctional aromatic ethylenically unsaturated compound refers to a monofunctional ethylenically unsaturated compound having an aromatic group.
The monofunctional ethylenically unsaturated compound having an aliphatic cyclic structure refers to a monofunctional ethylenically unsaturated compound having an alicyclic hydrocarbon group which may contain a hetero atom.
In the present invention, the monofunctional ethylenically unsaturated compound having an aliphatic cyclic structure has only one radical polymerizable ethylenically unsaturated group in addition to the aliphatic cyclic group. The ethylenically unsaturated bond contained therein does not correspond to a polymerizable ethylenically unsaturated group.

  The monofunctional aromatic ethylenically unsaturated compound and the monofunctional ethylenically unsaturated compound having an aliphatic cyclic structure are preferably monofunctional ethylenically unsaturated compounds represented by the following formula (D1).

In the above formula (D1), R ¹ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, and X ¹ represents a single bond, an ether bond (—O—), an ester bond (—C (O) O- or -OC (O)-), amide bond (-C (O) NH- or -NHC (O)-), carbonyl bond (-C (O)-), branched An alkylene group having 20 or less carbon atoms which may be present, or a second divalent linking group obtained by combining these may be bonded, and only the first divalent linking group or the second divalent linking group may be bonded. When it has a group, those having an ether bond, an ester bond and an alkylene group having 20 or less carbon atoms are preferred.

  Y is an aromatic group or alicyclic hydrocarbon group containing a monocyclic aromatic group and a polycyclic aromatic group, and the aromatic group and alicyclic hydrocarbon group are a halogen atom, a hydroxy group, an amino group, It may have a siloxane group, a substituent having 30 or less carbon atoms, and the cyclic structure of the aromatic group or alicyclic hydrocarbon group may contain a heteroatom such as O, N, or S. .

In the above formula (D1), R ¹ is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom.
X ¹ preferably has an ester bond.
In the present invention, the monofunctional aromatic ethylenically unsaturated compound and the monofunctional ethylenically unsaturated compound having an aliphatic cyclic structure may be acrylate or methacrylate (hereinafter also referred to as “(meth) acrylate”). preferable.

[Monofunctional aromatic ethylenically unsaturated compound]
The monofunctional aromatic ethylenically unsaturated compound is preferably a compound represented by the following formula (D2).

In Formula (D2), R ¹ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, X ¹ represents a divalent linking group, R ⁵ represents a substituent, and u represents Represents an integer of 0 to 5, and u R ⁵ may be the same or different, and a plurality of R ⁵ may be bonded to each other to form a ring. May be an aromatic ring.

In formula (D2), R ¹ is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and still more preferably a hydrogen atom.
X ¹ has the same meaning as X ¹ in Formula (D1). The end bonded to the vinyl group of X ¹ in Formula (D2) is preferably a carboxylic acid ester group or an amide group in which the carbonyl carbon of X ¹ and the vinyl group are bonded, and more preferably a carboxylic acid ester group. is there. In particular, it is preferable to have a structure of H ₂ C═C (R ¹ ) —C (O) O—. In that case, the other part of X ¹ bonded to the aromatic ring may be a single bond or may be arbitrarily selected from the aforementioned groups.

The vinyl moiety containing R ¹ and X ¹ (H ₂ C═C (R ¹ ) —X ¹ —) can be attached at any position of the aromatic ring. In addition, from the viewpoint of improving the affinity with (A) the pigment, the end bonded to the aromatic ring of X ¹ in Formula (D2) is preferably an oxygen atom, and is preferably an etheric oxygen atom. More preferably, X ¹ in the formula (D2) is more preferably —C (O) O (CH ₂ CH ₂ O) _p — (p represents 1 or 2).
Each of u ⁵ R ⁵ may be independently a monovalent or polyvalent substituent, and a monovalent substituent may be a hydrogen atom, a hydroxy group, a substituted or unsubstituted amino group, a thiol group, or a siloxane group. Or a hydrocarbon group or heterocyclic group having 30 or less total carbon atoms, which may further have a substituent.

In formula (D2), when a plurality of R ⁵ are bonded to each other to form a ring, it is preferable that an aromatic ring is formed.
That is, in the formula (D2), preferred as the aromatic group is a group obtained by removing one or more hydrogens from benzene which is a monocyclic aromatic group (phenyl group, phenylene group, etc.), as well as 2 to 4 rings. It is the polycyclic aromatic group which has, and is not limited. Specifically, naphthalene, anthracene, 1H-indene, 9H-fluorene, 1H-phenalene, phenanthrene, triphenylene, pyrene, naphthacene, tetraphenylene, biphenylene, as-indacene, s-indacene, acenaphthylene, fluoranthene, acephenanthrylene , Groups obtained by removing one or more hydrogen atoms from, for example, aceanthrylene, chrysene, and preaden.

  These aromatic groups may be aromatic heterocyclic groups containing heteroatoms such as O, N, and S. Specifically, furan, thiophene, 1H-pyrrole, 2H-pyrrole, 1H-pyrazole, 1H-imidazole, isoxazole, isothiazole, 2H-pyran, 2H-thiopyran, pyridine, pyridazine, pyrimidine, pyrazine, 1,2 Group obtained by removing at least one hydrogen atom from a monocyclic aromatic heterocyclic compound such as 1,3-triazole or 1,2,4-triazole.

  Thianthrene, isobenzofuran, isochromene, 4H-chromene, xanthene, phenoxathiin, indolizine, isoindole, indole, indazole, purine, 4H-quinolidine, isoquinoline, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine , Carbazole, β-carboline, phenanthridine, acridine, perimidine, phenanthroline, phenazine, phenothiazine, phenoxazine, pyrrolidine, and the like, a group obtained by removing at least one hydrogen atom.

  The aromatic group may have one or more halogen atoms, hydroxy groups, amino groups, thiol groups, siloxane groups, and substituents having 30 or less carbon atoms. For example, you may form the cyclic structure containing hetero atoms, such as O, N, and S, by two or more substituents which an aromatic group has like phthalic anhydride and phthalimide anhydride.

  In the present invention, the polycyclic aromatic group is more preferably a polycyclic aromatic group having 2 to 3 rings, and particularly preferably a naphthyl group.

  Specific examples of the aromatic monofunctional ethylenically unsaturated compound include [L-1] to [L-62], but are not limited to the following.

[Monofunctional ethylenically unsaturated compound having an alicyclic hydrocarbon group]
The monofunctional ethylenically unsaturated compound having an aliphatic hydrocarbon is more preferably a compound having an alicyclic hydrocarbon group represented by the following formula (D3).

In formula (D3), R ¹ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, X ¹ represents a divalent linking group, an ether group (—O—), an ester group (—C (O) O— or —OC (O) —), an amide group (—C (O) NR′—), a carbonyl group (—C (O) —), a nitrogen atom (—NR′—), It is preferable that it is a C1-C15 alkylene group which may have a substituent, or a bivalent group which combined these 2 or more. R ′ represents a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. R ² represents a substituent, r represents an integer of 0 to 5, q represents a cyclic hydrocarbon structure, and the cyclic hydrocarbon structure includes a carbonyl bond (—C (O) —) and / or a hydrocarbon bond in addition to the hydrocarbon bond. Alternatively, an ester bond (—C (O) O—) may be contained, and r ² R ^{2 s} may be the same or different from each other, and one carbon atom in the norbornane skeleton is substituted with an ether. A bond (—O—) and / or an ester bond (—C (O) O—) may be substituted.
In formula (D3), R ¹ is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group.

The end bonded to the vinyl group of X ¹ in the formula (D3) is preferably an ester group or an amide group in which the carbonyl carbon of X ¹ and the vinyl group are bonded, and more preferably an ester bond. In particular, it is preferable to have a structure of H ₂ C═C (R ¹ ) —C (O) O—. In that case, the other part of X ¹ bonded to the norbornane skeleton may be a single bond or may be arbitrarily selected from the above-mentioned groups.
The vinyl moiety containing R ¹ and X ¹ (H ₂ C═C (R ¹ ) —X ¹ —) can be attached at any position on the alicyclic hydrocarbon structure. In addition, "on each alicyclic hydrocarbon structure" refers to the norbornane structure and the cyclic hydrocarbon structure containing q in Formula (D3).

Further, from the viewpoint of improving the affinity with (A) the pigment, the end bonded to the alicyclic hydrocarbon structure of X ¹ in formula (D3) is preferably an oxygen atom, and an etheric oxygen atom It is more preferable that X ¹ in formula (D3) is —C (O) O (CH ₂ CH ₂ O) _p — (p represents 1 or 2).

R ² in formula (D3) independently represents a substituent, and can be bonded at any position on the alicyclic hydrocarbon structure. Also, r R ^{2 s} may be the same or different.
The R ² R ² may be each independently a monovalent or polyvalent substituent, and as a monovalent substituent, a hydrogen atom, a hydroxy group, a substituted or unsubstituted amino group, a thiol group, a siloxane group Further, a hydrocarbon group or heterocyclic group having 30 or less total carbon atoms which may have a substituent, or an oxy group (═O) as a divalent substituent is preferable.
The substitution number r of R ² represents an integer of 0 to 5.

  Q in the formula (D3) represents a cyclic hydrocarbon structure, and both ends thereof may be substituted at any position of the norbornene skeleton, and may be a monocyclic structure or a polycyclic structure; In addition to the hydrocarbon bond, the cyclic hydrocarbon structure may contain a carbonyl bond (—C (O) —) and / or an ester bond (—C (O) O—).

  The ethylenically unsaturated compound represented by the formula (D3) is preferably an ethylenically unsaturated compound represented by the formula (D4) or the formula (D5). Note that the unsaturated bond in the cyclic hydrocarbon structure in the formula (D5) has low radical polymerizability, and in the present invention, the compound represented by the formula (D5) is a monofunctional ethylenically unsaturated compound.

In Formula (D4) and Formula (D5), R ¹ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, X ¹ represents a divalent linking group, R ³ and R ⁴ Each independently represents a substituent, s and t each independently represent an integer of 0 to 5, and s R ³ and t R ⁴ are the same or different. Also good.

R ¹ and X ¹ in Formula (D4) or formula (D5) has the same meaning as R ¹ and X ¹ in Formula (D3), and preferred ranges are also the same.
The vinyl moiety containing R ¹ and X ¹ in formula (D4) or formula (D5) is bonded at any position on each alicyclic hydrocarbon structure shown below in formula (D4) or formula (D5). Can do.

R ³ and R ⁴ in Formula (D4) or Formula (D5) each independently represent a substituent, and are bonded at any position on each alicyclic hydrocarbon structure in Formula (D4) or Formula (D5). be able to. The substituent in R ³ and R ⁴ has the same meaning as the substituent in R ² of formula (D4), and the preferred range is also the same.
In formula (D4) or formula (D5), s and t each independently represents an integer of 0 to 5, and s R ³ and t R ⁴ are the same or different. May be.

As the ethylenically unsaturated compound represented by the formula (D3), preferred specific examples of monofunctional acrylates are shown below.
In some of the following exemplary compounds, the hydrocarbon chain is described by a simplified structural formula in which symbols of carbon (C) and hydrogen (H) are omitted.

  As the ethylenically unsaturated compound represented by the formula (D3), preferred specific examples of monofunctional methacrylate are shown below.

  Monofunctional acrylamide is preferable as the compound represented by the formula (D3), and the following specific examples are included.

<N-vinyl lactams>
In the present invention, N-vinyl lactams can be used as the polymerizable compound. Preferable examples of N-vinyl lactams that can be used in the present invention include compounds represented by the following formula (D6).

  In formula (D6), m represents an integer of 1 to 5, and m is 2 to 4 from the viewpoints of flexibility after the ink composition is cured, adhesion to a recording medium, and availability of raw materials. It is preferable that m is 2 or 4, and m is 4, that is, N-vinylcaprolactam is particularly preferable. N-vinylcaprolactam is preferable because it is excellent in safety, is generally available and can be obtained at a relatively low price, and provides particularly good ink curability and adhesion of a cured film to a support.

  The N-vinyl lactams may have a substituent such as an alkyl group or an aryl group on the lactam ring, and may be linked with a saturated or unsaturated ring structure. The N-vinyl lactams may be included in the ink composition alone or in a plurality of types.

<Polyfunctional ethylenically unsaturated compound>
A polyfunctional ethylenically unsaturated compound can be used in the ink composition of the present invention. Although a polyfunctional ethylenically unsaturated compound can be used without a monofunctional ethylenically unsaturated compound, it is preferably used in combination with a monofunctional ethylenically unsaturated compound. The radically polymerizable ethylenically unsaturated group is selected from the group consisting of an acrylate group, a methacrylate group, an acrylamide group, a methacrylamide group, a vinyloxy group, and an N-vinyl group even in a polyfunctional ethylenically unsaturated compound. Groups are preferred and may have different ethylenically unsaturated groups in one compound. When the ink composition contains a polyfunctional ethylenically unsaturated compound, an image having high cured film strength can be provided.

  Specific examples of the polyfunctional ethylenically unsaturated compound include bis (4-acryloxypolyethoxyphenyl) propane, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9- Nonanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, di Propylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, pentae Thritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methane tetra (meth) acrylate, tetramethylol methane tri (meth) acrylate, Dimethylol tricyclodecane di (meth) acrylate, modified glycerin tri (meth) acrylate, modified bisphenol A di (meth) acrylate, PO adduct di (meth) acrylate of bisphenol A, EO adduct di (meth) of bisphenol A Examples include acrylate, dipentaerythritol hexa (meth) acrylate, and caprolactone-modified dipentaerythritol hexa (meth) acrylate. Among these, an acyclic polyfunctional ethylenically unsaturated compound having no cyclic structure is preferable.

  The total amount of the polymerizable compound, preferably the ethylenically unsaturated compound, in the ink composition of the present invention is preferably 40 to 95% by weight, more preferably 50 to 90% by weight, and 60 to 85% by weight. More preferably. It is preferable for it to be in the above range since the curability is excellent and the viscosity is moderate.

  In the ink composition of the present invention, when the monofunctional aromatic ethylenically unsaturated compound is contained as the polymerizable compound, the content of the monofunctional aromatic ethylenically unsaturated compound is 80% by weight of the total ink composition. It is preferable that it is below, More preferably, it is 5-70 weight%, More preferably, it is 10-50 weight%. It is preferable for it to be within the above numerical value range because it can be adjusted to an appropriate viscosity and is excellent in ink jet discharge properties.

  In the ink composition of the present invention, when N-vinyl lactams are used, it is preferable to contain only 50% by weight or less of the total ink composition, more preferably 5 to 45% by weight, and still more preferably 10%. -40% by weight. Within the above range, an ink composition exhibiting good copolymerizability with other radical polymerizable compounds and excellent curability is obtained, which is preferable.

  Further, in the ink composition of the present invention, when a monofunctional ethylenically unsaturated compound having an aliphatic cyclic structure is used, it is preferable to contain only 50% by weight or less of the total ink composition, and 5 to 45% by weight. % Content is more preferable, and 10 to 40% by weight is more preferable. In the above range, an ink composition having excellent curability and scratch resistance is obtained, which is preferable.

  From the viewpoint of maintaining the adhesion of the base material (recording medium) of the cured film, the ratio of the polyfunctional ethylenically unsaturated compound to the entire ink composition is preferably 70% by weight or less, and 0 to 60% by weight. It is more preferable that In order to obtain a particularly flexible cured film, the content is preferably 0 to 40% by weight, and more preferably 1 to 30% by weight.

<Other polymerizable compounds>
As the polymerizable compound, the following acyclic monofunctional ethylenically unsaturated compounds can also be used. The acyclic monofunctional ethylenically unsaturated compound has a relatively low viscosity, and can be preferably used, for example, for the purpose of reducing the viscosity of the ink composition. However, from the viewpoint of suppressing the stickiness of the cured film and giving a high film strength that does not cause scratches during molding processing, the proportion of the following acyclic monofunctional ethylenically unsaturated compound in the entire ink composition is 20% by weight. % Or less, and more preferably 15% by weight or less.

  Specific examples of the acyclic monofunctional ethylenically unsaturated compound include octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) ) Acrylate, hexadecyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, carbitol (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, polyethylene glycol (meth) acrylate monomethyl Examples include ether, polypropylene glycol (meth) acrylate monomethyl ether, and polybutylene glycol (meth) acrylate monomethyl ether.

Examples of the radically polymerizable ethylenically unsaturated compound include the monofunctional aromatic ethylenically unsaturated compound, a monofunctional ethylenically unsaturated compound having an aliphatic cyclic structure, a monofunctional N-vinyl lactam compound, In addition to acyclic monofunctional ethylenically unsaturated compounds, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid and their salts, and anhydrides having an ethylenically unsaturated group , Acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, unsaturated urethane (meth) acrylic monomers or prepolymers, epoxy monomers or prepolymers, urethane monomers or prepolymers, etc. (Meth) acrylic acid esters are also preferably used
Specific examples include (poly) ethylene glycol mono (meth) acrylate, (poly) ethylene glycol (meth) acrylate methyl ether, (poly) ethylene glycol (meth) acrylate ethyl ether, (poly) ethylene glycol (meth) acrylate phenyl Ether, (poly) propylene glycol mono (meth) acrylate, (poly) propylene glycol mono (meth) acrylate phenyl ether, (poly) propylene glycol (meth) acrylate methyl ether, (poly) propylene glycol (meth) acrylate ethyl ether, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, n-decyl (meth) acrylate, isooctyl (meth) Acrylate, n-lauryl (meth) acrylate, n-tridecyl (meth) acrylate, n-cetyl (meth) acrylate, n-stearyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, Tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, caprolactone-modified hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, diacetone (meth) acrylamide, epoxy (meth) acrylate, methyl (meth) acrylate, n -(Meth) acryl derivatives such as butyl (meth) acrylate, allyl (meth) acrylate, glycidyl (meth) acrylate, dimethylaminomethyl (meth) acrylate; Derivatives of allyl compounds such as sidyl ether, diallyl phthalate, triallyl trimellitate; 2-ethylhexyl-diglycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl phthalic acid , Tetramethylol methane triacrylate, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, ethoxylated phenyl acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, lactone modified flexible Acrylate, butoxyethyl acrylate, 2-hydroxyethyl acrylate, methoxydipropylene glycol acrylate, and more specifically, Yamashita Shinzo, “Crosslinking agent handbook” (1981, Taiseisha); edited by Kiyotsugu Kato, “UV / EB Curing Handbook (raw material)” (1985, Polymer Publishing Society); Radtech Study Group, “Application and Market of UV / EB Curing Technology” 79 Page (1989, CMC); commercially available products described in “Polyester resin handbook” by Eiichiro Takiyama (1988, Nikkan Kogyo Shimbun), etc., or radically polymerizable or crosslinkable monomers, oligomers and polymers known in the industry. Can be used.

Furthermore, it is also preferable to use a vinyl ether compound as the radical polymerizable compound. Suitable vinyl ether compounds include, for example, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, and cyclohexanedimethanol. Di- or trivinyl ether compounds such as divinyl ether, hydroxyethyl monovinyl ether, trimethylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, Monovinyl ether compounds such as chlorohexane dimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl vinyl ether, dodecyl vinyl ether, ethylene glycol monovinyl ether, triethylene glycol monovinyl ether, hydroxynonyl monovinyl ether, diethylene glycol monovinyl ether, octadecyl vinyl ether, etc. Is mentioned.
Of these vinyl ether compounds, divinyl ether compounds and trivinyl ether compounds are preferable from the viewpoints of curability, adhesion, and surface hardness, and divinyl ether compounds are particularly preferable. A vinyl ether compound may be used individually by 1 type, and may be used in combination of 2 or more type as appropriate. In the present invention, the vinyl ether compound is particularly preferably used for the purpose of lowering the viscosity. However, when the addition amount is increased, the curability may be deteriorated or the surface of the cured film may be sticky. It is preferably 20% by weight or less, more preferably 10% by weight or less, based on the whole.

(C) Radiation polymerization initiator The radiation curable ink composition of the present invention contains (C) a radiation polymerization initiator (hereinafter also simply referred to as “polymerization initiator”). The “radiation polymerization initiator” refers to a compound that can generate a polymerization initiating species upon irradiation with actinic radiation and initiate addition polymerization of a polymerizable compound.
This radiation polymerization initiator is preferably a compound that generates radical polymerization initiating species of an ethylenically unsaturated compound. Here, examples of the actinic radiation include γ rays, β rays, electron beams, ultraviolet rays, visible rays, and infrared rays. However, from the viewpoint of device cost and operational safety, ultraviolet rays or visible rays are preferable, and the wavelength is 365 nm. The ultraviolet ray containing is more preferable.
“Radiation polymerization initiators” are known, and it is preferable to use compounds known as photoradical polymerization initiators. The radiation polymerization initiator that can be used in the present invention may be used alone or in combination of two or more.

  Specific radiation polymerization initiators known to those skilled in the art can be used without limitation, and specifically, for example, Bruce M. et al. Monroe et al., Chemical Review, 93, 435 (1993); S. By Davidson, Journal of Photochemistry and Biology A: Chemistry, 73. 81 (1993); P. Faussier, Photoinitiated Polymerization-Theory and Applications: Rapra Review vol. 9, Report, Rapra Technology (1998); Tsunooka et al. , Prog. Polym. Sci. , 21, 1 (1996). In addition, “Organic Materials for Imaging” (edited by Organic Electronics Materials Research Group, Bunshin Publishing (1993), pages 187 to 192) describes many chemical amplification type photoresists and compounds used for cationic photopolymerization. Yes. Further, F.I. D. Saeva, Topics in Current Chemistry, 156, 59 (1990); G. Maslak, Topics in Current Chemistry, 168, 1 (1993); B. Shuster et al, JACS, 112, 6329 (1990); D. F. Also known is a group of compounds that undergo oxidative or reductive bond cleavage through interaction with the electronically excited state of a sensitizer as described in Eaton et al, JACS, 102, 3298 (1980), etc. It is done.

  In the present invention, the radiation polymerization initiator preferably contains an acylphosphine oxide compound and / or an α-aminoacetophenone compound. It is preferable to use the above compound as a radical polymerization initiator because it can be cured with particularly high sensitivity. Acylphosphine oxide compounds and α-aminoacetophenone compounds that can be preferably used are as follows.

<Acylphosphine oxide compound>
The acylphosphine oxide compound is preferably a compound represented by the following formula (E1) or the following formula (E2).

R ¹ and R ² in the formula (E1) each independently represent an aliphatic group, an aromatic group, an aliphatic oxy group, an aromatic oxy group, or a heterocyclic group, and R ³ represents an aliphatic group or an aromatic group. Represents a group or heterocyclic group. R ¹ and R ² may combine to form a 5- to 9-membered ring. The ring structure may be a heterocyclic ring having an oxygen atom, a nitrogen atom, a sulfur atom or the like in the ring structure.
Examples of the aliphatic group represented by R ¹ , R ² or R ³ include an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group, a substituted alkynyl group, an aralkyl group, and a substituted aralkyl group. Among them, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aralkyl group, or a substituted aralkyl group is preferable, and an alkyl group and a substituted alkyl group are more preferable. The aliphatic group may be a cyclic aliphatic group or a chain aliphatic group. Moreover, the chain aliphatic group may have a branch.
Examples of the alkyl group include linear, branched, and cyclic alkyl groups, and the number of carbon atoms of the alkyl group is preferably 1 to 30, and more preferably 1 to 20. The preferred range of the number of carbon atoms in the alkyl part of the substituted alkyl group is the same as in the case of the alkyl group. Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, cyclohexyl group, cyclopentyl group, neopentyl group, An isopropyl group, an isobutyl group, etc. are mentioned.

Examples of the substituent of the substituted alkyl group include —COOH (carboxy group), —SO ₃ H (sulfo group), —CN (cyano group), halogen atom (for example, fluorine atom, chlorine atom, bromine atom), —OH (Hydroxy group), alkoxycarbonyl group having 30 or less carbon atoms (for example, methoxycarbonyl group, ethoxycarbonyl group, benzyloxycarbonyl group), alkylsulfonylaminocarbonyl group having 30 or less carbon atoms, arylsulfonylaminocarbonyl group, alkyl Sulfonyl group, arylsulfonyl group, acylaminosulfonyl group having 30 or less carbon atoms, alkoxy group having 30 or less carbon atoms (for example, methoxy group, ethoxy group, benzyloxy group, phenoxyethoxy group, phenethyloxy group, etc.), carbon An alkylthio group having 30 or less atoms ( For example, methylthio group, ethylthio group, methylthioethylthioethyl group, etc.), aryloxy group having 30 or less carbon atoms (eg, phenoxy group, p-tolyloxy group, 1-naphthoxy group, 2-naphthoxy group, etc.), nitro group , Alkoxycarbonyloxy group, aryloxycarbonyloxy group, acyloxy group having 30 or less carbon atoms (for example, acetyloxy group, propionyloxy group, etc.), acyl group having 30 or less carbon atoms (for example, acetyl group, propionyl group, Benzoyl group etc.), carbamoyl group (eg carbamoyl group, N, N-dimethylcarbamoyl group, morpholinocarbonyl group, piperidinocarbonyl group etc.), sulfamoyl group (eg sulfamoyl group, N, N-dimethylsulfamoyl group) , Morpholinosulfonyl group, pipette Dinosulfonyl group, etc.), aryl groups having 30 or less carbon atoms (eg, phenyl group, 4-chlorophenyl group, 4-methylphenyl group, α-naphthyl group, etc.), substituted amino groups (eg, amino group, alkylamino group) , Dialkylamino group, arylamino group, diarylamino group, acylamino group, etc.), substituted ureido group, substituted phosphono group, heterocyclic group and the like. Here, the carboxy group, the sulfo group, the hydroxy group, and the phosphono group may be in a salt state. In this case, the cation that forms a salt is a group that can form a cation, and is an organic cationic compound, a transition metal coordination complex cation (such as the compound described in Japanese Patent No. 2791143) or a metal cation (for example, Na ⁺ , K ⁺ , Li ⁺ , Ag ⁺ , Fe ²⁺ , Fe ³⁺ , Cu ⁺ , Cu ²⁺ , Zn ²⁺ , Al ^3+, etc.) are preferred.

Examples of the alkenyl group include linear, branched, and cyclic alkenyl groups, and the number of carbon atoms of the alkenyl group is preferably 2 to 30, and more preferably 2 to 20. The alkenyl group may be a substituted alkenyl group having a substituent or an unsubstituted alkenyl group, and the preferred range of the number of carbon atoms in the alkenyl part of the substituted alkenyl group is the same as that of the alkenyl group. . Examples of the substituent of the substituted alkenyl group include the same substituents as those of the substituted alkyl group.
Examples of the alkynyl group include linear, branched, and cyclic alkynyl groups, and the number of carbon atoms of the alkynyl group is preferably 2 to 30, and more preferably 2 to 20. The alkynyl group may be a substituted alkynyl group having a substituent or an unsubstituted alkynyl group, and the preferred range of the number of carbon atoms in the alkynyl part of the substituted alkynyl group is the same as in the case of the alkynyl group. . Examples of the substituent for the substituted alkynyl group include the same substituents as those for the substituted alkyl group.
Examples of the aralkyl group include aralkyl groups having a linear, branched, or cyclic alkyl side chain. The number of carbon atoms in the aralkyl group is preferably 7 to 35, more preferably 7 to 25. . The aralkyl group may be a substituted aralkyl group having a substituent or an unsubstituted aralkyl group, and the preferred range of the number of carbon atoms in the aralkyl part of the substituted aralkyl group is the same as in the case of the aralkyl group. . Examples of the substituent for the substituted aralkyl group include the same substituents as those for the substituted alkyl group. In addition, the aryl part of the aralkyl group may have a substituent, and the substituent is the same as that of the alkyl group and a linear, branched or cyclic alkyl having 30 or less carbon atoms. Examples are groups.

Examples of the aromatic group represented by R ¹ , R ² or R ³ include an aryl group and a substituted aryl group. As a carbon atom number of an aryl group, 6-30 pieces are preferable and 6-20 pieces are more preferable. The preferable range of the number of carbon atoms in the aryl part of the substituted aryl group is the same as that of the aryl group. Examples of the aryl group include a phenyl group, an α-naphthyl group, a β-naphthyl group, and the like. Examples of the substituent of the substituted aryl group include the same substituents as those in the case of the substituted alkyl group and linear, branched or cyclic alkyl groups having 30 or less carbon atoms.
As the aliphatic oxy group represented by R ¹ or R ² , an alkoxy group having 1 to 30 carbon atoms is preferable, and examples thereof include a methoxy group, an ethoxy group, a butoxy group, an octyloxy group, and a phenoxyethoxy group. Can be mentioned. However, it is not limited to these.
The aromatic oxy group represented by R ¹ or R ² is preferably an aryloxy group having 6 to 30 carbon atoms, such as a phenoxy group, a methylphenyloxy group, a chlorophenyloxy group, a methoxyphenyloxy group, An octyloxyphenyloxy group etc. are mentioned. However, it is not limited to these.
The heterocyclic group represented by R ¹ , R ² or R ³ is preferably a heterocyclic group containing an N, O or S atom, for example, a pyridyl group, a furyl group, a thienyl group, an imidazolyl group, a pyrrolyl group or the like. Is mentioned.

R ⁴ and R ⁶ in the formula (E2) each independently represent an alkyl group, an aryl group, or a heterocyclic group, and R ⁵ represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, or a heterocyclic group. To express.
The alkyl group, aryl group, heterocyclic group, alkoxy group and aryloxy group represented by R ⁴ , R ⁵ or R ⁶ may have a substituent. The same substituents as in (E1) can be mentioned.
The alkyl group, aryl group, heterocyclic group, alkoxy group and aryloxy group in the formula (E2) have the same meaning as in the formula (E1).

  The compound represented by the formula (E1) is more preferably a compound represented by the following formula (E3).

In the formula (E3), R ⁷ and R ⁸ each independently represent a phenyl group, a methoxy group, or an isopropoxy group, and R ⁹ represents a 2,4,6-trimethylphenyl group or a 2,4-dimethylphenyl group. , 2-methylphenyl group (o-toluyl group), isobutyl group, or t-butyl group.

  The compound represented by the formula (E2) is more preferably a compound represented by the following formula (E4).

In formula (E4), R ¹⁰ and R ¹² each independently represents a 2,4,6-trimethylphenyl group, a 2,6-dimethylphenyl group, or a 2,6-dimethoxyphenyl group, and R ¹¹ represents phenyl. Represents a group or a 2,4,4-trimethylpentyl group.

Examples of the acylphosphine oxide compound represented by the formula (E1) or (E2) include, for example, JP-B 63-40799, JP-B 5-29234, JP-A-10-95788, JP-A-10- Examples include compounds described in Japanese Patent No. 29997.
Specific examples of the acylphosphine oxide compound include the following compounds (exemplary compounds (P-1) to (P-26)), but the present invention is not limited to these.

  As the acylphosphine oxide compound, a monoacylphosphine oxide compound, a bisacylphosphine oxide compound, or the like can be used. As the monoacylphosphine oxide compound, a known monoacylphosphine oxide compound can be used. Examples thereof include monoacylphosphine oxide compounds described in Japanese Patent Publication No. 60-8047 and Japanese Patent Publication No. 63-40799. Specific examples include isobutyryl-methylphosphinic acid methyl ester, isobutyryl-phenylphosphinic acid methyl ester, pivaloyl-phenylphosphinic acid methyl ester, 2-ethylhexanoyl-phenylphosphinic acid methyl ester, pivaloyl-phenylphosphinic acid isopropyl ester, p. -Toluyl-phenylphosphinic acid methyl ester, o-toluyl-phenylphosphinic acid methyl ester, 2,4-dimethylbenzoyl-phenylphosphinic acid methyl ester, p-tert-butylbenzoyl-phenylphosphinic acid isopropyl ester, acryloyl-phenylphosphinic acid Methyl ester, isobutyryl-diphenylphosphine oxide, 2-ethylhexanoyl-diphenylphosphine oxide, -Toluyl-diphenylphosphine oxide, p-tert-butylbenzoyl-diphenylphosphine oxide, 3-pyridylcarbonyl-diphenylphosphine oxide, acryloyl-diphenylphosphine oxide, benzoyl-diphenylphosphine oxide, pivaloyl-phenylphosphinic acid vinyl ester, adipoyl-bis -Diphenylphosphine oxide, pivaloyl-diphenylphosphine oxide, p-toluyl-diphenylphosphine oxide, 4- (tert-butyl) -benzoyl-diphenylphosphine oxide, 2-methylbenzoyl-diphenylphosphine oxide, 2-methyl-2-ethylhexa Noyl-diphenylphosphine oxide, 1-methyl-cyclohexanoyl Diphenyl phosphine oxide, pivaloyl - phenyl phosphinic acid methyl ester and pivaloyl - phenyl phosphinic acid isopropyl ester.

  A known bisacylphosphine oxide compound can be used as the bisacylphosphine oxide compound. Examples thereof include bisacylphosphine oxide compounds described in JP-A-3-101686, JP-A-5-345790, and JP-A-6-298818. Specific examples include bis (2,6-dichlorobenzoyl) -phenylphosphine oxide, bis (2,6-dichlorobenzoyl) -2,5-dimethylphenylphosphine oxide, bis (2,6-dichlorobenzoyl). -4-ethoxyphenylphosphine oxide, bis (2,6-dichlorobenzoyl) -4-propylphenylphosphine oxide, bis (2,6-dichlorobenzoyl) -2-naphthylphosphine oxide, bis (2,6-di Chlorobenzoyl) -1-naphthylphosphine oxide, bis (2,6-dichlorobenzoyl) -4-chlorophenylphosphine oxide, bis (2,6-dichlorobenzoyl) -2,4-dimethoxyphenylphosphine oxide, bis ( 2,6-dichlorobenzoyl) -decylphos Zinc oxide, bis (2,6-dichlorobenzoyl) -4-octylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5 -Dimethylphenylphosphine oxide, bis (2,6-dichloro-3,4,5-trimethoxybenzoyl) -2,5-dimethylphenylphosphine oxide, bis (2,6-dichloro-3,4,5-trimethoxy Benzoyl) -4-ethoxyphenylphosphine oxide, bis (2-methyl-1-naphthoyl) -2,5-dimethylphenylphosphine oxide, bis (2-methyl-1-naphthoyl) -4-ethoxyphenylphosphine oxide, bis ( 2-Methyl-1-naphthoyl) -2- Butylphosphine oxide, bis (2-methyl-1-naphthoyl) -4-propylphenylphosphine oxide, bis (2-methyl-1-naphthoyl) -2,5-dimethylphenylphosphine oxide, bis (2-methoxy-1) -Naphthoyl) -4-ethoxyphenylphosphine oxide, bis (2-chloro-1-naphthoyl) -2,5-dimethylphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine Examples include oxides.

  Among these, in the present invention, as the acylphosphine oxide compound, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (IRGACURE 819: manufactured by Ciba Specialty Chemicals), bis (2,6-dimethoxy) Benzoyl) -2,4,4-trimethyl-pentylphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (DAROCUR TPO: Ciba Specialty Chemicals, Lucirin TPO: BASF) preferable.

<Α-Aminoacetophenone compound>
The α-aminoacetophenone compound may be used alone or in combination of two or more.
As the α-aminoacetophenone compound, a compound represented by the following formula (E5) can be preferably used.

In the formula, X ¹ represents a group represented by the following (a), (b) or (c).

式中ｐは０又は１である。

In the formula, p is 0 or 1.

式中ｑは０〜３の整数であり、ｒは０又は１である。

In the formula, q is an integer of 0 to 3, and r is 0 or 1.

In the formula, Y represents a hydrogen atom, a halogen atom, an OH group, or an alkyl group having 1 to 12 carbon atoms (note that unless otherwise specified, an alkyl group means a linear or branched alkyl group. The same applies to the invention.), An alkoxy group having 1 to 12 carbon atoms, an aromatic ring group, or a heterocyclic group. A preferable example of the aromatic ring group is a phenyl group or a naphthyl group. Moreover, as said heterocyclic group, a furyl group, a thienyl group, or a pyridyl group can be illustrated preferably.
The alkyl group, alkoxy group, aromatic ring group, and heterocyclic group in Y may have a substituent.

Examples of the substituent that the alkyl group in Y may have include an OH group, a halogen atom, -N (X ¹⁰ ) ₂ (X ¹⁰ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and 3 or more carbon atoms. Represents an alkenyl group having 5 or less, a phenylalkyl group having 7 to 9 carbon atoms, a hydroxyalkyl group having 1 to 4 carbon atoms, or a phenyl group.), An alkoxy group having 1 to 12 carbon atoms, -COOR (R Represents an alkyl group having 1 to 18 carbon atoms.), —CO (OCH ₂ OCH ₂ ) _n OCH ₃ (n represents an integer of 1 to 20), or —OCOR (R represents 1 carbon atom). Represents an alkyl group of 4 or less.).
As the substituent that the alkoxy group in Y may have, —COOR (R represents an alkyl group having 1 to 18 carbon atoms) or —CO (OCH ₂ CH ₂ ) _n OCH ₃ (n Represents an integer of 1 or more and 20 or less.
As the substituent that the aromatic ring group or heterocyclic group in Y may have, — (OCH ₂ CH ₂ ) _n OH (n represents an integer of 1 or more and 20 or less), — (OCH ₂ CH ₂ ) _N OCH ₃ (n represents an integer of 1 to 20), an alkylthio group having 1 to 8 carbon atoms, a phenoxy group, and —COOR (R represents an alkyl group having 1 to 18 carbon atoms), _{-CO (OCH 2 CH 2) n} OCH 3 (n represents an integer of 1 to 20.), a phenyl group, or, benzyl groups.
If possible, these substituents may have two or more, and if possible, the substituents may be further substituted.

In the formula, X ¹² represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. X ¹³ , X ¹⁴ and X ¹⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. X ¹³ and X ¹⁴ may be cross-linked to form an alkylene group having 3 to 7 carbon atoms.

In the formula, X ² represents the same group as X ¹ , a cycloalkyl group having 5 or 6 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or a phenyl group.
The alkyl group and phenyl group in X ² may have a substituent.
Examples of the substituent that the alkyl group in X ² may have include an alkoxy group having 1 to 4 carbon atoms, a phenoxy group, a halogen atom, and a phenyl group.
Examples of the substituent that the phenyl group in X ² may have include a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.
If possible, these substituents may have two or more, and if possible, the substituents may be further substituted.
In the formula, X ¹ and X ² may be cross-linked to form a group represented by the following formula.

In the formula, X ³ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 3 to 5 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, or a phenylalkyl having 7 to 9 carbon atoms. Represents a group.
The alkyl group, alkenyl group, cycloalkyl group, and phenylalkyl group in X ³ may have a substituent, such as an OH group, an alkoxy group having 1 to 4 carbon atoms,- CN or -COOR (R represents an alkyl group having 1 to 4 carbon atoms).
In the formula, X ⁴ is an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 3 to 5 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, a phenylalkyl group having 7 to 9 carbon atoms, or phenyl Represents a group.
The alkyl group, alkenyl group, cycloalkyl group, phenylalkyl group, and phenyl group in X ⁴ may have a substituent.
Examples of the substituent that the alkyl group, alkenyl group, cycloalkyl group, and phenylalkyl group in X ⁴ may have include an OH group, an alkoxyl group having 1 to 4 carbon atoms, -CN, or -COOR. (R represents an alkyl group having 1 to 4 carbon atoms). When the alkyl group denoted by X ⁴ has a substituent, the number of carbon atoms in the alkyl group that is substituted is preferably 2 to 4.
Examples of the substituent that the phenyl group in X ⁴ may have include a halogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or —COOR (where R is 1 carbon atom). Represents an alkyl group of 4 or less.).

Here, X ² and X ⁴ are crosslinked to form an alkylene group having 1 to 7 carbon atoms, a phenylalkylene group having 7 to 10 carbon atoms, an o-xylylene group, a 2-butenylene group, or 2 or 3 oxa- or aza-alkylene groups may be formed.
X ³ and X ⁴ may be crosslinked to form an alkylene group having 3 to 7 carbon atoms.
The alkylene group formed by crosslinking X ³ and X ⁴ is, as a substituent, an OH group, an alkoxy group having 1 to 4 carbon atoms, or —COOR (R represents an alkyl having 1 to 4 carbon atoms). .), And —O—, —S—, —CO—, or —N (X ¹⁶ ) — (X ¹⁶ is a hydrogen atom, having 1 to 12 carbon atoms) in the bond. An alkyl group, or an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 3 to 5 carbon atoms, or a phenylalkyl having 7 to 9 carbon atoms, with one or more —O— interposed in the bond chain Group, a hydroxyalkyl group having 1 to 4 carbon atoms, —CH ₂ CH ₂ CN, —CH ₂ CH ₂ COOR (where R represents an alkyl group having 1 to 4 carbon atoms), 2 to 8 carbon atoms. 1 or more carbon atoms with an alkanoyl group or benzoyl group interposed Represents an an alkyl group.) May be interposed.
In the formula, X ⁵ , X ⁶ , X ⁷ , X ⁸ and X ⁹ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 or 6 carbon atoms, a phenyl group, benzyl group, a benzoyl group, -OX ¹⁷ group, -SX ¹⁸ group, -SO-X ¹⁸ group, -SO ₂ -X ^{18 group, -N (X 19) (X} 20) group, -NH-SO ₂ -X ²¹ group, or a group represented by the following formula.

Wherein, Z is -O -, - S -, - N (X 10) -X 11 -N (X 10) - or a group represented by the following formula. X ¹ , X ² , X ³ and X ⁴ have the same meanings as in the formula (1).

In the formula, X ¹⁰ is the same as described above, X ¹¹ is a linear or branched alkylene group having 2 to 16 carbon atoms, or one or more —O—, —S—, or —N in these chains. (X ¹⁰ ) — represents a linear or branched alkylene group having 2 to 16 carbon atoms (X ¹⁰ is the same as described above).

X ¹⁷ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, — (CH ₂ CH ₂ O) _n H (n is an integer of 2 to 20), an alkanoyl group having 2 to 8 carbon atoms, and 3 carbon atoms. An alkenyl group having 12 or less, a cyclohexyl group, a hydroxycyclohexyl group, a phenyl group, a phenylalkyl group having 7 to 9 carbon atoms, or —Si (R ⁴ ) _r (R ⁵ ) _3-r (R ⁴ is the number of carbon atoms) 1 to 8 alkyl groups, R ⁵ represents a phenyl group, and r represents 1, 2 or 3).
The alkyl group and phenyl group in X ¹⁷ may have a substituent.
As the substituent that the alkyl group for X ¹⁷ may have, —CN, —OH, an alkoxy group having 1 to 4 carbon atoms, an alkenyloxy group having 3 to 6 carbon atoms, —OCH ₂ CH ₂ CN , —CH ₂ CH ₂ COOR (R represents an alkyl group having 1 to 4 carbon atoms), —COOH, or —COOR (R represents an alkyl group having 1 to 4 carbon atoms). . When the alkyl group denoted by X ¹⁷ has a substituent, the carbon number of the alkyl group is substituted is preferably 1 or more and 6 or less.
Examples of the substituent that the phenyl group in X ¹⁷ may have include a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.

X ¹⁸ represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 3 to 12 carbon atoms, a cyclohexyl group, a phenyl group, or a phenylalkyl group having 7 to 9 carbon atoms.
The alkyl group and phenyl group in X ¹⁸ may have a substituent.
The substituent which the alkyl group in X ¹⁸ may have is —SH, —OH, —CN, —COOR (R represents an alkyl group having 1 to 4 carbon atoms), 1 to 4 carbon atoms. Or an —OCH ₂ CH ₂ CN or —OCH ₂ CH ₂ COOR (wherein R represents an alkyl having 1 to 4 carbon atoms).
Examples of the substituent that may have a phenyl group in X ^18, a halogen atom, 1 or more than 12 carbons in the alkyl group, or, an alkoxy group having 1 to 4 carbon atoms.

X ¹⁹ and X ²⁰ are each independently a hydrogen atom; an alkyl group having 1 to 12 carbon atoms; a hydroxyalkyl group having 2 to 4 carbon atoms; an alkoxyalkyl group having 2 to 10 carbon atoms; The following alkenyl groups; a cycloalkyl group having 5 to 12 carbon atoms; a phenylalkyl group having 7 to 9 carbon atoms; a phenyl group; a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkyl group having 1 to 4 carbon atoms. A phenyl group substituted by an alkoxy group; or an alkanoyl group having 2 or 3 carbon atoms; or a benzoyl group. X ¹⁹ and X ²⁰ are cross-linked to form an alkylene group having 2 to 8 carbon atoms, or an OH group, an alkoxy group having 1 to 4 carbon atoms, or —COOR (R is an alkyl group having 1 to 4 carbon atoms. ) An alkylene group having 2 to 8 carbon atoms substituted by a group; an alkylene group having 2 to 8 carbon atoms in which —O—, —S— or —N (X ¹⁶ ) — is interposed in the bond chain (X ¹⁶ may be the same as described above.

X ²¹ is an alkyl group having 1 to 18 carbon atoms; a phenyl group; a naphthyl group; a halogen atom, or a phenyl group substituted by an alkyl group or an alkoxy group having 1 to 8 carbon atoms of 1 to 12 carbon atoms Represents a naphthyl group.

  It is more preferable that the formula (1) is represented by the formula (d).

In formula (d), X ¹ and X ² each independently represent a methyl group, an ethyl group, or a benzyl group, —NX ³ X ⁴ represents a dimethylamino group, a diethylamino group, or a morpholino group, and X ⁵ Represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkylthio group having 1 to 8 carbon atoms, a dimethylamino group, or a morpholino group. -NX ³ X ⁴ is a dimethylamino group Among these, or, more preferably morpholino group.

Furthermore, an acid adduct salt of the compound represented by the above formula (1) can also be used as the α-aminoacetophenone compound.
As commercially available α-aminoacetophenone compounds, polymerization initiators available from Ciba Specialty Chemicals under the trade names Irgacure 907 (IRGACURE 907), Irgacure 369 (IRGACURE 369), and Irgacure 379 (IRGACURE 379) are available. It can be illustrated.

Specific examples of the α-aminoacetophenone compound include the following compounds.
For example, 2-dimethylamino-2-methyl-1-phenylpropan-1-one, 2-diethylamino-2-methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino-1-phenylpropane- 1-one, 2-dimethylamino-2-methyl-1- (4-methylphenyl) propan-1-one, 2-dimethylamino-1- (4-ethylphenyl) -2-methylpropan-1-one, 2-dimethylamino-1- (4-isopropylphenyl) -2-methylpropan-1-one, 1- (4-butylphenyl) -2-dimethylamino-2-methylpropan-1-one, 2-dimethylamino -1- (4-methoxyphenyl) -2-methylpropan-1-one, 2-dimethylamino-2-methyl-1- (4-methylthiophenyl) propane- -One, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (IRGACURE 907), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane -1-one (IRGACURE 369), 2-benzyl-2-dimethylamino-1- (4-dimethylaminophenyl) -butan-1-one, 2-dimethylamino-2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone (IRGACURE 379).

(D) Compound Represented by Formula (I) The radiation-curable ink composition of the present invention comprises (D) a compound represented by the following formula (I) (hereinafter also simply referred to as “compound (I)”). Containing.

式（Ｉ）中、ＸはＯ、Ｓ、又は、ＮＲを表し、ｎは０又は１の整数を表し、Ｒは水素原子、アルキル基、又はアシル基を表し、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷、及びＲ⁸は、それぞれ独立に、水素原子、又は、一価の置換基を表し、Ｒ¹、Ｒ²、Ｒ³、及び、Ｒ⁴は、それぞれ隣接する２つが互いに連結して環を形成していてもよく、Ｒ⁵又はＲ⁶と、Ｒ⁷又はＲ⁸は、互いに連結して脂肪族環を形成してもよいが、芳香族環を形成することはない。

In the formula (I), X represents O, S, or NR, n represents an integer of 0 or 1, R represents a hydrogen atom, an alkyl group, or an acyl group, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represents a hydrogen atom or a monovalent substituent, and R ¹ , R ² , R ³ , and R ⁴ are Two adjacent to each other may be connected to each other to form a ring, and R ⁵ or R ⁶ and R ⁷ or R ⁸ may be connected to each other to form an aliphatic ring. Will not form.

In the formula (I), X represents O, S, or NR, where R represents a hydrogen atom, an alkyl group, or an acyl group. n represents 0 or 1.
X is preferably O or S, and more preferably S.

n represents 0 or 1. Here, when n is 0, there is no carbon atom bonded to R ⁷ and R ^8, and X containing a hetero atom and a carbon atom bonded to R ⁵ and R ⁶ are directly bonded to form X A 5-membered heterocycle containing

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represents a hydrogen atom or a monovalent substituent.
When R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent a monovalent substituent, examples of the monovalent substituent include a halogen atom and an aliphatic group (for example, An acyclic group or a cyclic hydrocarbon group such as an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group or a cycloalkenyl group) an aromatic group, a heterocyclic group, a cyano group, a hydroxyl group, a nitro group, an amino group, an alkylamino group , Dialkylamino group, alkoxy group, aryloxy group, amide group, arylamino group, ureido group, sulfamoylamino group, alkylthio group, arylthio group, alkoxycarbonylamino group, sulfonamide group, carbamoyl group, sulfamoyl group, sulfonyl Group, alkoxycarbonyl group, heterocyclic oxy group, azo group, acyloxy group, carbamoyloxy group, silyloxy group, aryl Examples include a ruoxycarbonyl group, an aryloxycarbonylamino group, an imide group, a heterocyclic thio group, a sulfinyl group, a phosphonyl group, an acyl group, a carboxy group, and a sulfo group. Among them, an alkoxy group, an alkyl group, and a halogen are preferable. An atom, and more preferably an alkyl group and a halogen atom.
These monovalent substituents may be further substituted with the above substituents. For example, the alkyl group may be a haloalkyl group substituted with a halogen atom, a carboxyalkyl group substituted with a carboxy group, or the like.

In the formula (I), when R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent a monovalent substituent, the alkyl group may be a methyl group or an ethyl group. , A propyl group, an n-butyl group, a sec-butyl group, and a t-butyl group, preferably having 1 to 4 carbon atoms.
Similarly, alkoxy groups include those having 1 to 4 carbon atoms such as methoxy, ethoxy, hydroxyethoxy, propoxy, n-butoxy, isobutoxy, sec-butoxy, and t-butoxy. Preferably mentioned.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  The compound (I) is preferably a compound represented by the following formula (IA).

In the formula (IA), X represents O or S. n represents 0 or 1. R ^1A , R ^2A , R ^3A , R ^4A , R ^5A , R ^6A , R ^7A and R ^8A are each independently a hydrogen atom, halogen atom, alkyl group, hydroxyl group, cyano group, nitro group, amino group, alkylamino Represents a group, dialkylamino group, alkylthio group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxyl group or sulfo group.
These monovalent substituents may be further substituted with the above substituents. For example, the alkyl group may be a haloalkyl group substituted with a halogen atom, a carboxyalkyl group substituted with a carboxy group, or the like.

  Examples of compound (I) that can be used more suitably include compounds represented by the following formula (IB).

In the formula (IB), X represents O or S. R ^1B , R ^2B , R ^3B , R ^4B , R ^5B , R ^6B , R ^7B and R ^8B are each independently a hydrogen atom, halogen atom, alkyl group, hydroxyl group, cyano group, nitro group, amino group, alkylamino Represents a group, dialkylamino group, alkylthio group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxyl group or sulfo group.
These monovalent substituents may be further substituted with the above substituents. For example, the alkyl group may be a haloalkyl group substituted with a halogen atom, a carboxyalkyl group substituted with a carboxy group, or the like.

  The compound (I) that can be used more suitably includes a compound represented by the following formula (IC).

In the formula ( ^IC ), R ^1C , R ^2C , R ^3C , R ^4C , R ^5C , R ^6C , R ^7C and R ^8C are each independently a hydrogen atom, a halogen atom, an alkyl group, a hydroxyl group, or a cyano group. Nitro group, amino group, alkylthio group, alkylamino group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxyl group or sulfo group.
These monovalent substituents may be further substituted with the above substituents. For example, the alkyl group may be a haloalkyl group substituted with a halogen atom, a carboxyalkyl group substituted with a carboxy group, or the like.

Specific examples of the compound represented by formula (I) [Exemplary compounds (I-1) to (I-96)] that can be suitably used in the present invention are shown below, but the present invention is not limited thereto. It is not something. In the present invention, a part of the structural formula is described by a simplified structural formula in which the hydrocarbon chain is omitted from the symbols of carbon (C) and hydrogen (H). Also, Me means a methyl group, Bu ^t is tert- butyl group, Pr ⁱ isopropyl group.

  The compounds represented by the above formula (I) include, for example, Japanese Patent Application Laid-Open No. 2004-189695, Tetrahedron, vol. 49, p. 939 to 1993, Journal of Organic Chemistry, p. 893 to 1945, and , Journal of Organic Chemistry, p.4939-, 1965, and the like.

  Compared with thioxanthone compounds, the compound represented by the above formula (I) has less unnecessary absorption in the visible region, so there is no color turbidity when used as an ink composition, and excellent color reproduction. Give sex.

By using the ink composition containing the compound represented by the formula (I), ultraviolet light (250 nm to 400 nm), particularly an ultraviolet light component around 365 nm, which is contained in a generally used exposure light source. On the other hand, it is possible to form a cured film and a cured product having high sensitivity and little discoloration and bleeding of non-cured components. In the radiation curable ink composition of the present invention, polymerization of the polymerizable compound is initiated by irradiation with actinic radiation, and thereby cured.
In the present invention, “a to b” is also referred to as “ab”. That is, for example, “40 to 98 wt%” is also described as “40 to 98 wt%” or “40 to 98 wt%”.

  The ink composition of the present invention contains at least a compound represented by the formula (I) (hereinafter, a compound represented by the formula (I) is also referred to as a compound (I)). This compound (I) may be used individually by 1 type, and may use 2 or more types together. The addition concentration of the compound (I) contained in the ink composition is preferably 0.1 to 15.0% by weight, more preferably 0.5 to 0.5%, based on the total weight of the ink composition. 12.0% by weight, more preferably 1.0-10.0% by weight. It is preferable for the amount added to be in the above range since good curability can be obtained.

The ink composition of the present invention preferably contains, as a radiation polymerization initiator, at least one compound selected from the group consisting of an acylphosphine oxide compound and an α-hydroxyacetophenone compound. It is presumed that the compound (I) acts as a photosensitizer and causes polymerization initiation action by the acylphosphine oxide compound and the α-hydroxyacetophenone compound by energy transfer.
The ink composition may contain one of an acylphosphine oxide compound and an α-hydroxyacetophenone compound, or both may be used in combination.
The addition concentration of at least one compound selected from the group consisting of an acylphosphine oxide compound and an α-hydroxyacetophenone compound contained in the ink composition is 0.1 to 20% relative to the total weight of the ink composition. The content is preferably 0% by weight, more preferably 0.5 to 18.0% by weight, and still more preferably 1.0 to 15.0% by weight. It is preferable for the amount added to be in the above range since good curability can be obtained.

The ink composition of the present invention preferably contains a co-sensitizer (synonymous with supersensitizer).
Such co-sensitizers include amine compounds such as M.I. R. Sander et al., “Journal of Polymer Society”, Vol. 10, 3173 (1972), Japanese Patent Publication No. 44-20189, Japanese Patent Publication No. 51-82102, Japanese Patent Publication No. 52-134692, Japanese Patent Publication No. 59-138205. No. 60, No. 60-84305, No. 62-18537, No. 64-33104, Research Disclosure 33825, and the like. Examples include ethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like.

  Other co-sensitizers include thiol and sulfide compounds, for example, thiol compounds described in JP-A-53-702, JP-B-55-500806, JP-A-5-142772, and JP-A-56- And the like, and more specifically, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercapto, and the like. And naphthalene.

Still other co-sensitizers include, for example, amino acid compounds (eg, N-phenylglycine), organometallic compounds described in Japanese Patent Publication No. 48-42965 (eg, tributyltin acetate), Japanese Patent Publication No. 55-. No. 34414, a hydrogen donor described in JP-A-6-308727 (eg, trithiane), a phosphorus compound described in JP-A-6-250387 (eg diethylphosphite), Examples include Si-H and Ge-H compounds described in Japanese Patent No. 191605.
Among such co-sensitizers, an amine compound is preferably contained, and a tertiary amine compound is more preferably contained.

  The addition concentration of the co-sensitizer is preferably 0.1 to 10.0% by weight, more preferably 0.2 to 5.0% by weight, and still more preferably based on the total weight of the ink composition. Is 0.3 to 3.0% by weight. It is preferable that the addition amount of the co-sensitizer is in the above range because it is excellent in curability, is suitable from the viewpoint of reducing surface stickiness and preventing discoloration of the cured film.

In the ink composition of the present invention, various additives can be used in combination according to the purpose. For example, an antioxidant and a polymerization inhibitor can be added to improve the stability of the ink composition.
The ink composition of the present invention further includes various organic and metal complex anti-fading agents, potassium thiocyanate, lithium nitrate, ammonium thiocyanate, dimethylamine hydrochloride, etc. for the purpose of controlling ejection properties. In order to improve the adhesion between the conductive salt and the recording medium, a trace amount of organic solvent can be added.

In addition, various polymer compounds can be added to the ink composition of the present invention in order to adjust film physical properties.
In addition, a nonionic surfactant, a cationic surfactant, an organic fluoro compound, or the like can be added to the ink composition of the present invention in order to adjust liquid properties.
In addition to the above, the ink composition of the present invention can be applied to recording media such as leveling additives, matting agents, waxes for adjusting film physical properties, polyolefins, PET, etc., if necessary. In order to improve adhesion, a tackifier or the like that does not inhibit polymerization can be contained.
Below, each additive is described.

<Surfactant>
A surfactant may be added to the ink composition of the present invention in order to impart stable ejection properties for a long time.
Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers and silicone oils, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.
The content of the surfactant in the ink composition is appropriately adjusted so as to match the surface tension suitable for ejection of the inkjet head, but is preferably 0 to 6% by weight, more preferably 0 to 4% by weight, Preferably it is the range of 0-2 weight%.

<Polymerization inhibitor>
A polymerization inhibitor may be added from the viewpoint of enhancing the storage stability. In addition, when the ink composition of the present invention is used as an ink composition for ink jet recording, it is preferably heated at a temperature in the range of 40 to 80 ° C. and discharged at a low viscosity, in order to prevent head clogging due to thermal polymerization. However, it is preferable to add a polymerization inhibitor. The polymerization inhibitor is preferably added in an amount of 200 to 20,000 ppm based on the total amount of the ink composition of the present invention. Examples of the radical polymerization inhibitor include hydroquinone, benzoquinone, p-methoxyphenol, TEMPO, TEMPOL, cuperon Al, tris (N-nitroso-N-phenylhydroxylamine) aluminum salt, and the like.

<Antioxidant>
An antioxidant can be added to improve the stability of the ink composition. Examples of the antioxidant include European Published Patent Nos. 223739, 309401, 309402, 310551, 310552, 457416, and German Patent No. 3435443. JP-A-54-48535, JP-A-62-262047, JP-A-63-113536, JP-A-63-163351, JP-A-2-262654, JP-A-2-71262, and JP-A-3 No. 112449, JP-A-5-61166, JP-A-5-119449, US Pat. No. 4,814,262, US Pat. No. 4,980,275, and the like.
The addition amount is appropriately selected according to the purpose, but is preferably 0.1 to 8% by weight based on the total amount of the ink composition.

<Anti-fading agent>
In the ink composition of the present invention, various organic and metal complex anti-fading agents can be used. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocycles. Examples of the metal complex-based antifading agent include nickel complexes and zinc complexes. No. 17643, No. VII, I to J, i. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of representative compounds described in JP-A-62-215272, pages 127 to 137 can be used. .
The addition amount is appropriately selected according to the purpose, but is preferably 0.1 to 8% by weight based on the total amount of the ink composition.

<Conductive salts>
Conductive salts such as potassium thiocyanate, lithium nitrate, ammonium thiocyanate, and dimethylamine hydrochloride can be added to the ink composition of the present invention for the purpose of controlling ejection properties.

<Solvent>
In order to improve the adhesion to the recording medium, it is also effective to add a very small amount of an organic solvent to the ink composition of the present invention.
Examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone, and diethyl ketone, alcohol solvents such as methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, and tert-butanol, and chlorine such as chloroform and methylene chloride. Solvents, aromatic solvents such as benzene and toluene, ester solvents such as ethyl acetate, butyl acetate and isopropyl acetate, ether solvents such as diethyl ether, tetrahydrofuran and dioxane, glycols such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether Examples include ether solvents.
In this case, it is effective to add the solvent within the range that does not cause the problem of solvent resistance and VOC, and the amount is preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight based on the whole ink composition. % Range.

<Polymer compound>
Various polymer compounds can be added to the ink composition of the present invention in order to adjust film physical properties. High molecular compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination. Of these, vinyl copolymer obtained by copolymerization of acrylic monomers is preferred. Furthermore, as a copolymer composition of the polymer compound, a copolymer containing “carboxyl group-containing monomer”, “alkyl methacrylate ester” or “alkyl acrylate ester” as a structural unit is also preferably used.

<Basic compound>
The basic compound is preferably added from the viewpoint of improving the storage stability of the ink composition. As the basic compound that can be used in the present invention, known basic compounds can be used. For example, basic inorganic compounds such as inorganic salts, and basic organic compounds such as amines can be preferably used. .

In addition to this, if necessary, for example, leveling additives, matting agents, waxes for adjusting film physical properties, polymerization to inhibit the adhesion to recording media such as polyolefin and PET, and the like, The tackifier which does not do can be contained.
Specifically, the tackifier is a high molecular weight adhesive polymer (for example, (meth) acrylic acid and alkyl having 1 to 20 carbon atoms) described in JP-A-2001-49200, pages 5-6. An ester of an alcohol having a group, an ester of (meth) acrylic acid and an alicyclic alcohol having 3 to 14 carbon atoms, and an ester of (meth) acrylic acid and an aromatic alcohol having 6 to 14 carbon atoms. Copolymer) and low molecular weight tackifying resins having a polymerizable unsaturated bond.

  The ink composition of the present invention is particularly preferably used as an ink composition for inkjet recording and an ink composition for ultraviolet curable printing. The ink composition of the present invention is particularly suitable as an ink composition for ink jet recording.

The ink composition of the present invention may be liquid at room temperature, but from the viewpoint of ink jetting suitability, the viscosity at 25 ° C. is preferably 100 mPa · s or less, or the viscosity at 60 ° C. is preferably 30 mPa · s or less. More preferably, the viscosity at 25 ° C. is 60 mPa · s or less or the viscosity at 60 ° C. is 20 mPa · s or less, and the viscosity at 25 ° C. is 40 mPa · s or less or the viscosity at 60 ° C. is 15 mPa · s or less. Particularly preferred.
Similarly, the surface tension at 25 ° C. of the ink composition is preferably 18 mN / m or more and 40 mN / m or less, more preferably 20 mN / m or more and 35 mN / m or less, and more preferably 22 mN / m or more and 32 mN from the viewpoint of ink droplet ejection suitability. / M or less is more preferable.
The “viscosity” here is a viscosity determined using a RE80 viscometer manufactured by Toki Sangyo Co., Ltd. The RE80 type viscometer is a conical rotor / plate type viscometer corresponding to the E type. Measurement is performed at a rotation speed of 10 rpm using the first rotor. However, for those having a viscosity higher than 60 mPa · s, measurement is performed by changing the number of revolutions to 5 rpm, 2.5 rpm, 1 rpm, 0.5 rpm, or the like as necessary.
Here, the surface tension is measured at a liquid temperature of 25 ° C. by the Wilhelmy method using a generally used surface tension meter (for example, surface tension meter CBVP-Z manufactured by Kyowa Interface Science Co., Ltd.). It is a measured value.

  The ink jet recording apparatus described in detail below can be used for the ink composition ejection step in the ink jet recording method of the present invention.

[Inkjet recording device]
There is no restriction | limiting in particular as an inkjet recording device used for the inkjet recording method of this invention, The well-known inkjet recording device which can achieve the target resolution can be selected arbitrarily and can be used. That is, any known ink jet recording apparatus including a commercially available product can eject ink onto a recording medium in the ink composition ejecting step of the ink jet recording method of the present invention.
Examples of the ink jet recording apparatus that can be used in the present invention include an apparatus including an ink supply system, a temperature sensor, and an actinic radiation source.
The ink supply system includes, for example, an original tank containing the ink composition of the present invention, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head. The piezo-type inkjet head preferably has a multi-size dot of 1 to 100 pl, more preferably 8 to 30 pl, preferably 320 × 320 to 4,000 × 4,000 dpi, more preferably 400 × 400 to 1,600 ×. It can be driven so that it can discharge at a resolution of 1,600 dpi, more preferably 720 × 720 dpi. In the present invention, dpi represents the number of dots per 2.54 cm.

  As described above, since it is desirable that the radiation-curable ink, like the ink composition of the present invention, has a constant temperature for the ink to be ejected, heat insulation and heating are performed from the ink supply tank to the inkjet head portion. It can be carried out. The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors at each piping site and perform heating control according to the ink flow rate and the environmental temperature. The temperature sensor can be provided near the ink supply tank and the nozzle of the inkjet head. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

Using the above inkjet recording apparatus, the ink composition of the present invention is ejected by heating the ink composition to preferably 25 to 80 ° C., more preferably 25 to 50 ° C. Preferably it is performed after lowering to 3 to 15 mPa · s, more preferably 3 to 13 mPa · s. In particular, it is preferable to use an ink composition having an ink viscosity at 25 ° C. of 50 mPa · s or less as the ink composition of the present invention, since it can be discharged satisfactorily. By using this method, high ejection stability can be realized.
A radiation curable ink composition such as the ink composition of the present invention generally has a higher viscosity than a water-based ink usually used in ink jet recording inks, and therefore has a large viscosity fluctuation due to temperature fluctuations during ejection. The ink viscosity fluctuation has a great influence on the change of the droplet size and the change of the droplet discharge speed, and causes the image quality deterioration. Therefore, it is necessary to keep the temperature of the ink at the time of ejection as constant as possible. Therefore, in the present invention, the control range of the ink temperature is preferably set to ± 5 ° C. of the set temperature, more preferably ± 2 ° C. of the set temperature, and further preferably set to ± 1 ° C.

Next, the step of irradiating the ejected ink composition with actinic radiation to cure the ink composition will be described.
The ink composition ejected on the recording medium is cured by irradiation with actinic radiation. This is because the polymerization initiator contained in the ink composition of the present invention is decomposed by irradiation with actinic radiation to generate radicals, acids, bases, and other starting species, and the function of the starting species is polymerization of a radical polymerizable compound. This is because the reaction occurs and is accelerated. At this time, if a sensitizer is present together with the polymerization initiator in the ink composition, the sensitizer in the system absorbs actinic radiation to be in an excited state, and promotes decomposition of the polymerization initiator by contacting with the polymerization initiator. And a more sensitive curing reaction can be achieved.

  Here, α rays, γ rays, electron beams, X rays, ultraviolet rays, visible light, infrared rays, or the like can be used as the active radiation used. Although the peak wavelength of actinic radiation is based also on the absorption characteristic of a sensitizer, it is preferable that it is 200-600 nm, for example, it is more preferable that it is 300-450 nm, and it is further more preferable that it is 350-420 nm.

In addition, the polymerization initiation system of the ink composition of the present invention has sufficient sensitivity even with a low output actinic radiation. Therefore, it is appropriate that the exposure surface illuminance is preferably 10 to 4,000 mW / cm ² , more preferably 20 to 2,500 mW / cm ² .

Mercury lamps and gas / solid lasers are mainly used as actinic radiation sources, and mercury lamps and metal halide lamps are widely known as light sources used for curing UV photocurable ink jet recording inks. Yes. However, from the viewpoint of environmental protection, mercury-free is strongly desired, and replacement with a GaN-based semiconductor ultraviolet light-emitting device is very useful industrially and environmentally. Furthermore, LED (UV-LED) and LD (UV-LD) are small, have a long lifetime, high efficiency, and low cost, and are expected as light sources for photo-curable ink jets.
Further, a light emitting diode (LED) and a laser diode (LD) can be used as the active radiation source. In particular, when an ultraviolet light source is required, an ultraviolet LED and an ultraviolet LD can be used. For example, Nichia Corporation has introduced a purple LED whose main emission spectrum has a wavelength between 365 nm and 420 nm. When even shorter wavelengths are required, US Pat. No. 6,084,250 discloses an LED that can emit actinic radiation centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands. The actinic radiation source particularly preferred in the present invention is a UV-LED, particularly preferably a UV-LED having a peak wavelength at 350 to 420 nm.
Incidentally, it is preferable that maximum illumination intensity of the LED on a recording medium is 10 to 2,000 mW / cm ^2, more preferably 20 to 1,000 mW / cm ^2, is 50 to 800 mW / cm ² It is particularly preferred.

The ink composition of the present invention is appropriately irradiated with such actinic radiation for 0.01 to 120 seconds, more preferably for 0.1 to 90 seconds.
Actinic radiation irradiation conditions and a basic irradiation method are disclosed in JP-A-60-132767. Specifically, the light source is provided on both sides of the head unit including the ink ejection device, and the head unit and the light source are scanned by a so-called shuttle method. Irradiation with actinic radiation takes a certain period of time (preferably 0.01 to 0.5 seconds, more preferably 0.01 to 0.3 seconds, still more preferably 0.01 to 0.15 seconds) after ink landing. Will be done. In this way, by controlling the time from ink landing to irradiation to an extremely short time, it is possible to prevent the ink that has landed on the recording medium from spreading before curing. In addition, since it can be exposed to the porous recording medium before the ink penetrates to a deep part where the light source does not reach, it is preferable because residual unreacted monomer can be suppressed.
Further, the curing may be completed by another light source that is not driven. International Publication No. 99/54415 pamphlet discloses a method using an optical fiber or a method of irradiating a recording unit with UV light by applying a collimated light source to a mirror surface provided on the side of the head unit as an irradiation method. Such a curing method can also be applied to the ink jet recording method of the present invention.

By adopting the ink jet recording method as described above, the dot diameter of the landed ink can be kept constant even on various recording media having different surface wettability, and the image quality is improved. In addition, in order to obtain a color image, it is preferable to superimpose in order from the color with the lowest brightness. By superimposing the inks in the order of low lightness, it becomes easier for the irradiation line to reach the lower ink, and good curing sensitivity, reduction of residual monomers, and improvement in adhesion can be expected. In addition, irradiation can be performed by discharging all colors and collectively exposing, but exposure for each color is preferable from the viewpoint of promoting curing.
Thus, the ink composition of the present invention can form an image on the surface of a recording medium by being cured with high sensitivity by irradiation with actinic radiation.

  In the ink jet recording method of the present invention, the ink set of the present invention can be suitably used. The order of the colored ink compositions to be ejected is not particularly limited, but it is preferably applied to the recording medium from the colored ink composition having a low brightness, and the ink composition of the present invention and yellow, cyan, magenta When black is used, it is preferably applied on the recording medium in the order of the ink composition of the present invention → yellow → cyan → magenta → black. When white is used in addition to this, it is preferably applied on the recording medium in the order of white → the ink composition of the present invention → yellow → cyan → magenta → black. Further, the present invention is not limited to this, and includes at least eight colors of the ink composition of the present invention of light cyan, light magenta, and light black and the dark ink composition of cyan, magenta, gray, black, white, and yellow. The ink set of the present invention can be preferably used, and in this case, it is preferably applied on the recording medium in the order of white → light cyan → light magenta → light black → yellow → cyan → magenta → black.

  In the present invention, the recording medium is not particularly limited, and a known recording medium can be used as a support or a recording material. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. In addition, as the recording medium in the present invention, a non-absorbable recording medium can be preferably used.

(Ink set)
The ink set of the present invention may be an ink set having at least one ink composition of the present invention and having two or more ink compositions in combination with the ink composition of the present invention or an ink composition other than the present invention. For example, although there is no particular limitation, it is preferable to include at least one ink composition of the present invention having a color selected from the group consisting of light magenta, light cyan, and light black (gray), and light magenta and light cyan. It is more preferable to include at least one ink composition of the present invention having a color selected from the group consisting of, and it is even more preferable to include the light magenta and light cyan ink compositions of the present invention.
The ink set of the present invention can be suitably used for the ink jet recording method of the present invention.
In order to obtain a full-color image using the ink composition of the present invention, the ink set of the present invention includes a dark ink composition of four colors consisting of yellow, cyan, magenta, and black and the ink composition of the present invention. It is preferable that the ink set is a combination of at least one, and the ink set is a combination of at least one of the dark ink composition of five colors consisting of yellow, cyan, magenta, black and white and the ink composition of the present invention. More preferably, the ink set is a combination of five color ink compositions consisting of yellow, cyan, magenta, black and white and three ink compositions of the present invention consisting of light cyan, light magenta and light black. Is more preferable.
The “dark ink composition” in the present invention means an ink composition in which the content of the colorant exceeds 1% by weight of the entire ink composition. There is no restriction | limiting in particular as said coloring agent, A well-known coloring agent can be used, A pigment and oil-soluble dye can be illustrated.
Needless to say, the ink set of the present invention may contain an ink composition not containing the compound represented by the formula (I).

  The ink set of the present invention includes at least one dark color ink composition and the ink composition of the present invention, and the dark color ink composition and the ink composition of the present invention use a colorant having a similar color. The ratio of the colorant concentration between the dark color ink composition and the ink composition of the present invention is preferably dark color ink composition: light color ink composition = 15: 1 to 4: 1, : 1 to 4: 1 is more preferable, and 10: 1 to 4.5: 1 is still more preferable. Within the above range, a vivid full-color image with little graininess can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples. In the following description, “parts” means “parts by weight” unless otherwise specified.

(Material used)
The materials used for the preparation of the ink composition are as shown below.
・ NOVOPERM YELLOW H2G (CI Pigment Yellow 120, manufactured by Clariant)
・ NOVOPERM YELLOW 4G01 (CI Pigment Yellow 155, manufactured by Clariant)
NOVOPERM YELLOW P-HG (CI Pigment Yellow 180, manufactured by Clariant)
-BAYFAST YELLOW Y-5688 (CI Pigment Yellow 150, manufactured by LANXESS)
・ KENALAKE ORANGE HP-RLO (CI Pigment Orange 36, manufactured by Albion Colors)
CINQUASIA MAGENTA RT-335 D (a mixture of CI Pigment Red 202 and CI Pigment Violet 19, manufactured by Ciba Specialty Chemicals)
・ HOSTAPERM INKJET E5B02 (CI Pigment Violet 19, Clariant)
HOSTAPERM VIOLET RL-NF (CI Pigment Violet 23, manufactured by Clariant)
・ IRGALITE BLUE GLVO (CI Pigment Blue 15: 4, manufactured by Ciba Specialty Chemicals)
・ HEUCO GREEN 6000070K (CI Pigment Green 7, manufactured by Heubach GmbH)
DISPERBYK-168 (pigment dispersant, solid content 30%, manufactured by BYK Chemie)
AJISPER PB-822 (pigment dispersant, manufactured by Ajinomoto Fine Techno Co., Ltd.)
TEGO DISPERSE 685 (pigment dispersant, manufactured by Tego Chemie Service)
SOLPERSE 5000 (pigment dispersant, manufactured by Lubrizol)
SOLPERSE 22000 (pigment dispersant, manufactured by Lubrizol)
SOLPERSE 32000 (pigment dispersant, manufactured by Lubrizol)
・ RAPI-CURE DVE-3 (triethylene glycol divinyl ether, manufactured by ISP)
-FA-512AS (dicyclopentenyloxyethyl acrylate, manufactured by Hitachi Chemical Co., Ltd.)
SR339A (2-phenoxyethyl acrylate, manufactured by SARTOMER)
SR238F (1,6-hexanediol diacrylate, manufactured by SARTOMER)
SR508 (dipropylene glycol diacrylate, manufactured by SARTOMER)
SR9003 (propoxylated (2) neopentyl glycol diacrylate (compound obtained by diacrylate conversion of neopentyl glycol propylene oxide 2-mol adduct), manufactured by SARTOMER)
SR351S (trimethylolpropane triacrylate, manufactured by SARTOMER)
・ KAYARAD DPCA-60 (Caprolactone-modified dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd.)
・ EBECRYL 657 (aliphatic urethane acrylate, manufactured by Daicel-Cytec)
CN964A85 (aliphatic urethane acrylate oligomer, manufactured by SARTOMER)
・ N-vinyl-ε-caprolactam (NVC, manufactured by BASF)
・ Lucirin TPO (radical polymerization initiator, manufactured by BASF)
IRGACURE 184 (radical polymerization initiator, manufactured by Ciba Specialty Chemicals; 1-hydroxycyclohexyl phenyl ketone)
IRGACURE 819 (radical polymerization initiator, manufactured by Ciba Specialty Chemicals; bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide)
IRGACURE 369 (radical polymerization initiator, manufactured by Ciba Specialty Chemicals)
DAROCUR EBD (Ethyl-4-dimethylaminobenzoate, manufactured by Ciba Specialty Chemicals)
・ Benzophenone (radical polymerization initiator, manufactured by Wako Pure Chemical Industries, Ltd.)
FIRSTCURE ST-1 (polymerization inhibitor, manufactured by Chem First)
・ P-methoxyphenol (polymerization inhibitor, manufactured by Wako Pure Chemical Industries, Ltd.)
・ BYK-307 (silicone surfactant, manufactured by BYK Chemie)
・ TEGORAD 2100 (silicone acrylate, manufactured by TEGO)
・ KF-353 (silicone surfactant, manufactured by Shin-Etsu Chemical Co., Ltd.)

(Pigment dispersion)
[Preparation of pigment dispersion (mill base)]
The components listed in Table 1 were mixed and stirred for 10 minutes at 3,000 rpm using a mixer (Silverson L4R). Then, it is put into a bead mill disperser DISPERMAT SL (manufactured by VMA-GETZMANN GmbH), and zirconia beads having a diameter of 0.65 mm (YTZ ball, manufactured by Nikkato Co., Ltd.) are used. Dispersion was performed for 6 hours, and mill bases 1 to 10 were produced.

Example 1
The following components were stirred at 2,500 rpm for 15 minutes using a mixer (Silverson L4R) to obtain a yellow ink composition.
The viscosity at 25 ° C. measured using TVE-22LT manufactured by Toki Sangyo Co., Ltd. was 18.5 mPa · s. The surface tension at 25 ° C. measured using a fully automatic surface tension meter CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. was 27.6 mN / m.

Millbase 1 13.0 parts N-vinyl-ε-caprolactam 24.7 parts FA-512AS 38.0 parts SR339A 5.3 parts KAYARAD DPCA-60 1.9 parts FIRSTCURE ST-1 0.3 Part ・ P-methoxyphenol 1.5 part ・ Lucirin TPO 9.0 part ・ Benzophenone 2.0 part ・ IRGACURE 184 1.2 part ・ KF-353 0.1 part ・ Compound A 3.0 part Chemical structure of Compound A Is shown below.

  When this ink was diluted 10,000 times (volume) with 1-methoxy-2-propanol and measured using a 1 cm long quartz cell, the absorbance at a wavelength of 365 nm was 0.2174. On the other hand, the absorbance of the ink to which compound A was not added at a wavelength of 365 nm was 0.1809. Therefore, the absorbance at a wavelength of 365 nm derived from the compound A in the ink could be attributed to 0.0365, and the absorbance at a wavelength of 365 nm derived from components other than the compound A could be attributed to 0.1809.

(Evaluation of ink composition)
<Curing speed>
The ink composition was applied to the surface of a polyvinyl chloride sheet (thickness 220 μm) as a recording medium using a K hand coater (bar No. 2) so as to have a wet film thickness of 12 μm. Next, inside the UV conveyor device CSOT (manufactured by GS Yuasa Lighting) equipped with an ozone-less metal halide lamp MAN125L and set at a conveyor speed of 6 m / min and an exposure intensity of 1,800 W / cm ² until the adhesiveness of the coating surface disappears Repeated passage and radiation curing. The curing rate was evaluated according to the following criteria. The results are shown in Table 2.

A: Tack-free after one pass. The curing rate is extremely fast.
○: Tack-free after 2 passes. Cure speed is fast.
Δ: Tack-free after 3 passes. Curing time is somewhat slow.
X: It became tack-free when the number of passes was 4 or more. Curing time is slow.

<Abrasion resistance>
The ink composition was applied to the surface of a polyvinyl chloride sheet (thickness 220 μm) as a recording medium using a K hand coater (bar No. 2) so as to have a wet film thickness of 12 μm. Next, the inside of UV conveyor device CSOT (manufactured by GS Yuasa Lighting Co., Ltd.) equipped with an ozone-less metal halide lamp MAN125L and set at a conveyor speed of 6 m / min and an exposure intensity of 1,800 W / cm ² was used. It was repeatedly passed through until it disappeared, and was cured by radiation. The strength was evaluated according to the following criteria by ISO 15184 (scratch hardness-pencil method) using this cured coating film. The results are shown in Table 2.

A: 4H or more, scratch resistance is very good.
○: F or more and 3H or less, good scratch resistance.
(Triangle | delta): 3B or more and HB or less, and abrasion resistance are a little bad.
X: 4B or less, scratch resistance is poor.

<Blocking resistance>
The ink composition was applied to the surface of a polyvinyl chloride sheet (thickness 220 μm) as a recording medium using a K hand coater (bar No. 2) so as to have a wet film thickness of 12 μm. Next, the inside of UV conveyor device CSOT (manufactured by GS Yuasa Lighting Co., Ltd.) equipped with an ozone-less metal halide lamp MAN125L and set at a conveyor speed of 6 m / min and an exposure intensity of 1,800 W / cm ² was used. It was repeatedly passed through until it disappeared, and was cured by radiation. An uncoated recording medium was superimposed on the coated surface of this recording medium, and a uniform load of 25 g / cm ² was applied to the entire recording medium, and stored at 25 ° C. for 24 hours. The blocking was evaluated based on the following criteria on the degree of coating film breakage and transfer to an uncoated recording medium when the uncoated recording medium was peeled off from the coated recording medium. The results are shown in Table 2.

A: No blocking of coating film or transfer to uncoated recording medium, blocking resistance is very good.
○: The coated film is not broken, but a slight transfer to an uncoated recording medium was observed (10% or less of the coated area), but the blocking resistance is good.
Δ: The coated film was not broken, but transfer to an uncoated recording medium was observed (from 10% to 50% of the coated area), and the blocking resistance was poor.
X: The coated film was broken, severe transfer to an uncoated recording medium was observed (50% or more of the coated area), and the blocking resistance was extremely poor.

<Dischargeability>
JetLyser (manufactured by Mimaki Engineering Co., Ltd.) equipped with an inkjet print head CA3 (manufactured by TOSHIBA TEC CO., LTD.) Is set to discharge voltage 22V, discharge drop number 7 drop, and the ink composition is continuously discharged at 45 ° C. for 60 minutes. The evaluation was based on the following criteria. The results are shown in Table 2.

(Double-circle): It was sprayed normally. Inkjet ejection is very good.
○: Slight mist generation was observed. Inkjet ejection is good.
Δ: Generation of mist was observed. Inkjet ejection properties are somewhat poor.
X: Severe mist generation was observed. Inkjet ejection properties are poor.

(Examples 2-7 and Comparative Examples 1-2)
An ink composition was prepared and evaluated in the same manner as in Example 1 except that the amounts of Millbase 1, FA-512AS and Compound A were changed as shown in Table 1. The results are shown in Table 2.

(Example 8)
An ink composition was prepared and evaluated in the same manner as in Example 1 using the following components. The results are shown in Table 4. The viscosity of this ink composition at 25 ° C. measured using TVE-22LT manufactured by Toki Sangyo Co., Ltd. was 22.0 mPa · s. The surface tension at 25 ° C. measured using a fully automatic surface tension meter CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. was 28.5 mN / m.

-Millbase 3 7.0 parts-SR238F 30.0 parts-SR508 31.7 parts-RAPI-CURE DVE-3 8.7 parts-FIRSTCURE ST-1 0.3 parts-Lucirin TPO 5.0 parts-IRGACURE 819 4 0.0 parts IRGACURE 369 2.0 parts EBECRYL 657 9.3 parts TEGORAD 2100 0.5 parts Compound B 1.5 parts The chemical structure of Compound B is shown below.

(Examples 9-14 and Comparative Examples 3-4)
An ink composition was prepared and evaluated in the same manner as in Example 8 except that the amounts of Millbase 3, SR508 and Compound B were changed as shown in Table 3. The results are shown in Table 4.

(Examples 15 to 22)
An ink composition was prepared and evaluated in the same manner as in Example 1 except that the amounts of mill base, FA-512AS and compound A were changed as shown in Table 5. The results are shown in Table 6.

(Examples 23 to 26)
Example compound (I-17), (I-34), (I-56) and (I-84) of formula (I) were used in place of compound A in the same manner as in Example 1, except that the same amount was used. Thus, four types of radiation curable ink compositions were prepared. In all cases, the same results as in Example 1 were obtained.

(Comparative Examples 5 and 6)
An ink composition of Comparative Example 5 was prepared in exactly the same manner as in Example 21 except that the same amount of FIRSTCURE ITX was used instead of Compound A. Further, an ink composition of Comparative Example 6 was prepared in exactly the same manner except that Compound A was not used in Example 21.
These ink compositions were applied to the surface of a polyvinyl chloride sheet (thickness 220 μm) as a recording medium using a K hand coater (bar No. 2) so as to have a wet film thickness of 12 μm. Next, the inside of UV conveyor device CSOT (manufactured by GS Yuasa Lighting Co., Ltd.) equipped with an ozone-less metal halide lamp MAN125L and set at a conveyor speed of 6 m / min and an exposure intensity of 1,800 W / cm ² was used. It was repeatedly passed through until it disappeared, and was cured by radiation. This cured coating film was evaluated in the same manner as in Example 21, and using a spectrocolorimeter CM-2600d manufactured by Konica Minolta Sensing Co., Ltd. under the conditions of a viewing angle of 2 °, a light source D65, and SCE (regular reflection light removal). , A ^* and b ^* values were measured, and the results shown in Table 8 were obtained.

As is apparent from Table 8, when the compound A was used (Example 21), improvements were observed in the curing rate, scratch resistance and blocking resistance as compared with the case where it was not used (Comparative Example 6). There was no change in color. On the other hand, when FIRSTCURE ITX was used (Comparative Example 5), improvements in the curing rate, scratch resistance and blocking resistance were observed as in Compound (A), but the a ^* and b ^* values changed. Obviously, the original cyan color was changed to greenish even by visual observation.

  The chemical structure of FIRSTCURE ITX (isopropylthioxanthone, manufactured by Chem First) is shown below.

Claims (8)

Pigments,
Polymerizable compounds,
A radiation polymerization initiator, and a compound represented by the following formula (I):
0.1 ≦ (B / A) where A is the absorbance based on the compound represented by the formula (I) at a wavelength of 365 nm and B is the absorbance based on a component other than the formula (I) at a wavelength of 365 nm. Satisfying the relational expression ≦ 5,
Radiation curable ink composition.

In the formula (I), X represents O, S, or NR, n represents an integer of 0 or 1, R represents a hydrogen atom, an alkyl group, or an acyl group, R ¹ , R ² , R ^{3 , R 4, R 5, R} 6, R 7, and R ⁸ each independently represent a hydrogen atom, or represents a monovalent ^{substituent, R 1, R 2, R} 3 and,, R ⁴ is two respectively adjacent but may form a ring together with R ⁵ or R ^6, R ⁷ or R ⁸ may or may form an aliphatic ring by combining to each other, an aromatic ring Will not form.   The radiation curable ink composition according to claim 1, wherein the polymerizable compound is an ethylenically unsaturated compound.   The radiation-curable ink composition according to claim 2, comprising a monofunctional ethylenically unsaturated compound and a polyfunctional ethylenically unsaturated compound.   The radiation curable ink composition according to claim 1, wherein the radiation polymerization initiator is an acylphosphine oxide compound and / or an α-aminoacetophenone compound.   The pigment is C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. Pigment red 202, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15: 6, C.I. I. Pigment violet 19, C.I. I. Pigment violet 23, C.I. I. Pigment orange 36 and C.I. I. The radiation curable ink composition according to any one of claims 1 to 4, which is at least one selected from the group consisting of CI Pigment Green 7.   The ink composition according to claim 1, further comprising a dispersant.   A step of ejecting the actinic radiation curable ink composition according to any one of claims 1 to 6 onto a recording medium, and irradiating the ejected actinic radiation curable ink composition with actinic radiation. A step of curing the actinic radiation curable ink composition for ink jet recording.   A printed matter recorded by the inkjet recording method according to claim 7.