JP5253015B2 - Pigment dispersion and ink composition using the same - Google Patents

Description

  The present invention relates to a pigment dispersion, an ink composition using the pigment dispersion, and an ink composition for inkjet recording. Specifically, a pigment dispersion excellent in dispersibility and storage stability, and an ink suitable for inkjet printing that can form a high-quality image containing the pigment dispersion and can be cured by irradiation with actinic radiation. It relates to a composition.

  In various colored compositions, when a pigment is used as a colorant, it is important to ensure the dispersibility and dispersion stability of the solid pigment. By using a pigment dispersion excellent in pigment dispersibility and dispersion stability, a curable composition or ink composition having a uniform hue can be obtained. In particular, pigments with excellent light resistance are widely used as colorants in ink compositions. However, when there is a problem in the dispersibility of the pigment, the color tone becomes uneven or the ink composition used in the ink jet recording method. In this case, various problems such as a decrease in dischargeability are caused.

  In recent years, an inkjet recording method has attracted attention as an image recording method for forming an image on a recording medium based on an image data signal. The ink jet recording method has an advantage that a high-definition image can be recorded at a low running cost by ejecting very fine droplets with less noise.

  According to the ink jet recording method, it is possible to print not only on plain paper but also on a non-liquid-absorbing recording medium such as a plastic sheet and a metal plate, in order to realize high speed and high image quality when printing, It is desired to shorten the time required for drying and curing. For this reason, as one of the ink jet methods, there is a recording method using a curable ink composition that can be cured in a short time by irradiation with active energy rays as an ink composition for ink jet recording. According to this method, a sharp image can be formed by irradiating active energy rays immediately after printing and curing the ink droplets. Such an ink composition for ink jet recording is required to have high pigment dispersibility and stability over time in order to form a high-definition image having excellent color developability and to stably eject ink.

  In order to impart a clear color tone and high coloring power to the ink composition, it is essential to make the pigment finer. In particular, in an ink composition used for ink jet recording, since the ejected ink droplets greatly affect the sharpness of the image, the amount of ejected droplets is small, and the ink cured formed from the ink composition. It is essential to use finer particles than the film thickness. As described above, when the pigment particles are further miniaturized in order to obtain a high coloring power, it becomes difficult to disperse the pigment fine particles, and aggregates are easily generated. Further, there is a problem that the viscosity of the pigment dispersion and the ink composition increases due to excessive addition of the dispersant. The occurrence of pigment aggregates and the increase in viscosity of the ink composition both have an adverse effect on the ink ejection properties. Therefore, it is not preferable to use an ink composition in which pigment aggregation or thickening has occurred for inkjet recording.

  Moreover, when using an ink composition for inkjet recording, it must be excellent in heat cycle property. The ink composition is stored in a cartridge and heated to reduce the liquid viscosity during ejection, but the temperature is lowered during non-ejection and storage, and thus undergoes repeated heating-cooling temperature changes. This temperature change also has an adverse effect on the pigment dispersibility, resulting in a problem that the dispersibility of the pigment decreases with time, and the aggregation and thickening of the pigment tend to occur.

As a manufacturing method of an ink composition containing a fine pigment dispersion, a concentrated pigment dispersion (also called a mill base) is prepared in advance, and the obtained mill base is diluted with a desired liquid such as a solvent or a polymerizable compound. There is a method for obtaining an ink composition. Since the mill base is a thick pigment dispersion, the interaction between the pigments is strong, and the viscosity tends to increase during dispersion and storage. An increase in the viscosity of the mill base is not preferable because it not only increases the load on the production machine, but also reduces the production stability due to poor circulation and the redispersibility during ink preparation.
Accordingly, there is a need for a mill base having sufficient fluidity and storage stability, and an inkjet ink composition having sufficient fluidity, a finely divided pigment stably dispersed, and excellent curability. ing.

  Various proposals have been made for dispersants for obtaining stable ink compositions. That is, in order to improve the affinity with the pigment, the dispersant is used for an ink composition using a pigment derivative as a dispersant (see, for example, Patent Documents 1 and 2) and a specific pigment such as phthalocyanine or quinacridone. As an ink composition using a polymer having a basic group as a polymer (see, for example, Patent Document 3), a dispersant such as poly (ethyleneimine) -poly (12-hydroxystearic acid) graft polymer, and the dispersant are dissolved. An ink composition containing a specific monomer and not using an organic solvent (for example, see Patent Document 4) is disclosed.

When these pigment dispersants and ink compositions are used, the pigment can be finely dispersed and the stability of the ink is higher than before, but there is still room for improvement in the stability of the ink. Further, for those having excellent ink stability, it has been desired to improve the stability of the mill base.
JP 2003-119414 A JP 2004-18656 A JP 2003-321628 A JP 2004-131589 A

An object of the present invention is to solve the conventional problems and achieve the following objects.
That is, an object of the present invention is to provide a pigment dispersion having excellent pigment dispersion stability even when the pigment is finely dispersed and stored for a long period of time.
Another object of the present invention is an ink suitable for inkjet recording that has a clear color tone and high coloring power, can form a high-quality image, and can be cured by irradiation with active energy rays. It is to provide a composition.

  As a result of intensive studies, the present inventors have obtained that a pigment dispersion excellent in dispersibility and dispersion stability of the pigment can be obtained by using a specific polymer as a pigment dispersant. By using the dispersion, it was found that an ink composition in which a decrease in dispersion stability was effectively suppressed even after long-term storage or repeated temperature changes was obtained, and the present invention was completed.

That is, the means for solving the above problems are as follows.
<1> A weight average molecular weight of 500 to 20000 having at least (a) a pigment, (b) a repeating unit represented by the following general formula (I), and further a terminal unit having an ethylenically unsaturated double bond as a copolymer unit. A pigment dispersion containing a graft copolymer having a repeating unit derived from a polymerizable oligomer in the range of 1 and a weight average molecular weight in the range of 10,000 to 1,000,000, and (c) a radical polymerizable monomer .

In general formula (I), Q ¹ represents a hydrogen atom or a methyl group. Z ¹ represents —CO—, —COO—, —CONQ ² —, —OCO—, or a phenylene group, and Q ² represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. Z ² represents a single bond or a divalent linking group. Y ¹ represents a resin acid residue.

<2> The pigment dispersion according to <1>, wherein the (b) graft copolymer further includes a repeating unit derived from dialkylaminoalkyl (meth) acrylate or alkylaminoalkyl (meth) acrylate as a copolymerization unit.
<3> The repeating unit derived from the polymerizable oligomer which is a copolymer unit contained in the (b) graft copolymer is a repeating unit derived from the polymerizable oligomer represented by the following general formula (III) <1 > Or <2>.

In general formula (III), Q ⁵ and Q ⁷ each independently represent a hydrogen atom or a methyl group, and Q ⁶ represents an alkylene group having 1 to 12 carbon atoms. Y ² represents a phenyl group, a phenyl group having an alkyl group having 1 to 4 carbon atoms, or —COOQ ⁸ . Q ⁸ represents an alkyl group having 1 to 6 carbon atoms, a phenyl group, or an arylalkyl group having 7 to 10 carbon atoms. q1 represents an integer of 15 to 200.
<4> The pigment dispersion according to any one of <1> to <3>, wherein Y ¹ in the general formula (I) is a residue of a resin acid derivative represented by the following general formula (II): .

In general formula (II), Q ³ and Q ⁴ represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and Z ³ and Z ⁴ represent a single bond or a carbon-carbon double bond. . B is bonded to the carbon to which Z ⁴ is bonded and includes Z ⁴ to form a 6-membered ring such as a cyclohexane ring, a cyclohexene ring, a cyclohexadiene ring, or a benzene ring. The 6-membered ring has one or two alkyl groups having 1 to 3 carbon atoms or alkenyl groups.

< 5 > Residue of the resin acid derivative represented by the general formula (II) is abietic acid, neoabietic acid, parastrinic acid, levopimaric acid, dihydroabietic acid, tetrahydroabietic acid, pimaric acid, isopimaric acid, dehydroabieticin The pigment dispersion according to any one of <1> to <4>, which is a residue of a resin acid derivative selected from acids.

<6> The (b) graft copolymer, either general formula of repeating units represented by (I) 2 to 50 mass% is including graft copolymer of <1> to <5> 2. The pigment dispersion according to item 1.

< 7 > An ink composition comprising the pigment dispersion according to any one of <1> to < 6 >, and (d) a photopolymerization initiator.
<8> The ink composition according to <7>, wherein the viscosity at 25 ° C. is from 0.5 mPa · s to 200 mPa · s.
< 9 > The ink composition according to <7> or <8 >, which is for inkjet use.

According to the present invention, it is possible to provide a pigment dispersion having excellent pigment dispersion stability even when the pigment is finely dispersed and stored for a long period of time.
Furthermore, it is possible to provide an ink composition suitable for inkjet recording, which has a clear color tone and high coloring power, can form a high-quality image, and can be cured by irradiation with active energy rays. .

The pigment dispersion of the present invention comprises at least (a) a pigment, (b) a repeating unit represented by the following general formula (I), and a weight average molecular weight having an ethylenically unsaturated double bond at the terminal as a copolymer unit. there and a repeating unit derived from a polymerizable oligomer is in the range of 500 to 20,000, graft polymer and the weight average molecular weight in the range of 10,000 to 1,000,000 (hereinafter, may be referred to as specific polymer), (C) a radically polymerizable monomer . By using this specific polymer, the pigment is stably dispersed, and the performance is excellent in long-term storage stability. Moreover, when it is set as an ink composition, it is excellent also in the discharge stability at the time of using for an inkjet use.

In general formula (I), Q ¹ represents a hydrogen atom or a methyl group. Z ¹ represents —CO—, —COO—, —CONQ ² —, —OCO—, or a phenylene group, and Q ² represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. Z ² represents a single bond or a divalent linking group. Y ¹ represents a resin acid residue.

  Hereinafter, each component used for the pigment dispersion and ink composition of the present invention will be described in order.

[Pigment dispersion]
The pigment dispersion of the present invention includes at least (a) a pigment, (b) a specific polymer, and (c) a polymerizable compound.

  The pigment dispersion of the present invention has a high dispersibility of the pigment due to the action of the specific polymer even when the pigment is contained at a high concentration, and a small increase in viscosity even when stored for a long period of time. Can be maintained. Furthermore, by selecting a fine pigment as the pigment, a pigment dispersion excellent in color development and colorability can be obtained.

Since the pigment dispersion of the present invention has good dispersibility and dispersion stability of the pigment, it can be diluted and used in various applications. For example, from the viewpoint of improving the productivity of pigment dispersions, liquid properties, colorability, curability, cured film properties, etc. are adjusted by preparing a thick pigment dispersion (mill base) and diluting it. be able to.
Since the ink composition containing the pigment dispersion of the present invention is excellent in dispersion stability even at a low viscosity, the discharge stability when an image is printed using an ink jet printer is excellent.
In addition, when used as an ink composition for ink jet recording, a high quality image can be directly formed on a non-absorbable recording medium based on digital data. Therefore, the ink composition of the present invention has a large area. It is also suitably used for the production of printed materials.

  The pigment dispersion of the present invention is suitably used for an ink composition for ink jet recording. However, in addition to the use of the ink composition for ink jet recording, the pigment dispersion is mixed with a compound imparting desired performance to prepare an ink composition. , Used for normal printing to form sharp images with excellent color developability and obtain high-quality printed materials, as well as various ink compositions, colored curable compositions, resists for color filters, etc. Can be suitably used for manufacturing color filters and optical discs, and is also useful as an optical modeling material. In addition, the pigment dispersion of the present invention is suitably used in a wide range of applications such as applications requiring good color developability and applications requiring a light-resistant colorant, such as nanoimprint compositions and surface coating agents. sell.

  The pigment dispersion of the present invention is suitable as a colored curable composition that can be cured by irradiation with active energy rays or the like by containing (a) a pigment, (b) a specific polymer, and (c) a polymerizable compound. Can be used. Such a colored curable composition is suitable as a curable ink composition that can be cured by irradiation with active energy rays or heating, particularly as an ink composition for inkjet recording.

Hereinafter, each component in the pigment dispersion of this invention is explained in full detail.
[(A) Pigment]
The pigment dispersion of the present invention contains a pigment as an essential component. In the pigment dispersion of the present invention, the pigment is uniformly and stably dispersed in the pigment dispersion by the action of the specific polymer described later, even if the pigment particle has a small particle size.

  The pigment contained in the pigment dispersion of the present invention is not particularly limited, and various known pigments can be appropriately selected and used depending on the purpose. However, the specific polymer of the present invention is a residual resin acid derivative. Due to the action of the group, it is particularly excellent in adsorptivity to organic pigments, and therefore it is preferable to contain organic pigments.

  Since the pigment dispersion of the present invention contains a pigment, it can be suitably used for applications requiring the weather resistance of a colorant, for example, a colored composition such as an ink composition. Moreover, when applying this pigment dispersion as a coloring component of various compositions, a dye may be used in combination for the purpose of adjusting the hue and the like.

  As the pigment contained in the pigment dispersion of the present invention, generally used organic pigments and inorganic pigments can be used. Furthermore, dyes, resin particles dyed with dyes, and the like can be used in combination. Any commercially available pigment can be used. Furthermore, a pigment pretreated with a commercially available pigment dispersion or surface treatment agent, for example, a pigment dispersed in an insoluble resin or the like as a dispersion medium, or a pigment A resin grafted on the surface can be used as long as the effects of the present invention are not impaired.

  Examples of the pigment include, for example, “Encyclopedia of Pigments” edited by Seijiro Ito (2000); Herbst, K.M. Hunger “Industrial Organic Pigments”, JP 2002-12607 A, JP 2002-188025 A, JP 2003-26978 A, JP 2003-342503 A, and the like.

Examples of the organic pigment and the inorganic pigment include the following pigments.
Examples of the pigment exhibiting a yellow color include C.I. I. Pigment Yellow 1 (Fast Yellow G etc.), C.I. I. A monoazo pigment such as C.I. Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow, etc.), C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 155, C.I. I. Disazo pigments such as C.I. Pigment Yellow 219; I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Pigment yellow 95 (condensed azo yellow, etc.), C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. Condensed azo pigments such as C.I. Pigment Yellow 166; I. Acidic dye lake pigments such as C.I. Pigment Yellow 115 (such as quinoline yellow lake); I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake, etc.), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and quinophthalone yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (nickel nitroso yellow, etc.); I. Metal complex salt azomethine pigments such as C.I. Pigment Yellow 117 (copper azomethine yellow, etc.); I. Pigment yellow 120 (benzimidazolone yellow) C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 175, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 181, C.I. I. And acetolone pigments such as CI Pigment Yellow 194.

  Examples of pigments exhibiting red or magenta color include C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Pigment red 1, C.I. I. Pigment red 4, C.I. I. B-naphthol pigments such as C.I. Pigment Red 6; I. Disazo pigments such as C.I. Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Pigment Red 57: 1 (Brilliant Carmine 6B etc.), C.I. I. Pigment red 52: 1, C.I. I. Azo lake pigments such as C.I. Pigment Red 48 (B-oxynaphthoic acid lake, etc.); I. Pigment red 144 (condensed azo red, etc.), C.I. I. Pigment red 166, C.I. I. Pigment red 220, C.I. I. Pigment red 214, C.I. I. Pigment red 221, C.I. I. Condensed azo pigments such as C.I. Pigment Red 242, C.I. I. Pigment Red 174 (Phloxine B lake, etc.), C.I. I. Acidic dye lake pigments such as C.I. Pigment Red 172 (Erythrosin Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Red 81 (Rhodamine 6G 'lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Red 177 (eg, dianthraquinonyl red); I. Thioindigo pigments such as C.I. Pigment Red 88 (Thioindigo Bordeaux, etc.); I. Perinone pigments such as C.I. Pigment Red 194 (perinone red, etc.); I. Pigment red 149 (perylene scarlet, etc.), C.I. I. Pigment red 179, C.I. I. Pigment red 178, C.I. I. Pigment red 190, C.I. I. Pigment red 224, C.I. I. Pigment red 123, C.I. I. Perylene pigments such as C.I. Pigment Red 224; I. Pigment violet 19 (unsubstituted quinacridone), C.I. I. Pigment red 122 (quinacridone magenta, etc.), C.I. I. Pigment red 262, C.I. I. Pigment red 207, C.I. I. Quinacridone pigments such as C.I. Pigment Red 209; I. Isoindolinone pigments such as CI Pigment Red 180 (isoindolinone red 2BLT, etc.); I. Alizarin lake pigments such as C.I. Pigment Red 83 (Madalake, etc.); I. Pigment red 171, C.I. I. Pigment red 175, C.I. I. Pigment red 176, C.I. I. Pigment red 185, C.I. I. Naphtholone pigments such as C.I. Pigment Red 208; I. Naphthol AS lake pigments such as C.I. Pigment Red 247; I. Pigment red 2, C.I. I. Pigment red 5, C.I. I. Pigment red 21, C.I. I. Pigment red 170, C.I. I. Pigment red 187, C.I. I. Pigment red 256, C.I. I. Pigment red 268, C.I. I. Naphthol AS pigments such as C.I. Pigment Red 269; I. Pigment red 254, C.I. I. Pigment red 255, C.I. I. Pigment red 264, C.I. I. And diketopyrrolopyrrole pigments such as CI Pigment Red 27.

  Examples of pigments exhibiting blue or cyan color include C.I. I. Disazo pigments such as C.I. Pigment Blue 25 (Dianisidine Blue, etc.); I. Pigment blue 15, C.I. I. Pigment blue 15: 1, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15: 6, C.I. I. Phthalocyanine pigments such as C.I. Pigment Blue 16 (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (Peacock Blue Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Blue 1 (Viclotia Pure Blue BO Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).

  Examples of the pigment exhibiting green include C.I. I. Pigment green 7 (phthalocyanine green), C.I. I. Phthalocyanine pigments such as C.I. Pigment Green 36 (phthalocyanine green); I. Pigment green 8 (nitroso green), C.I. I. And azo metal complex pigments such as CI Pigment Green 10.

  Examples of orange pigments include C.I. I. An isoindoline pigment such as C.I. Pigment Orange 66 (isoindoline orange); I. Anthraquinone pigments such as C.I. Pigment Orange 51 (dichloropyrantron orange); I. Pigment orange 2, C.I. I. Pigment orange 3, C.I. I. Β-naphthol pigments such as C.I. Pigment Orange 5; I. Pigment orange 4, C.I. I. Pigment orange 22, C.I. I. Pigment orange 24, C.I. I. Pigment orange 38, C.I. I. Naphthol AS pigments such as CI Pigment Orange 74; I. Isoindolinone pigments such as CI Pigment Orange 61; I. Perinone pigments such as C.I. Pigment Orange 43; I. Pigment orange 15, C.I. I. Disazo pigments such as CI Pigment Orange 16; I. Pigment orange 48, C.I. I. Quinacridone pigments such as CI Pigment Orange 49; I. Pigment orange 36, C.I. I. Pigment orange 62, C.I. I. Pigment orange 60, C.I. I. Pigment orange 64, C.I. I. An acetolone pigment such as C.I. Pigment Orange 72; I. Pigment orange 13, C.I. I. And pyrazolone pigments such as CI Pigment Orange 34.

  Examples of the pigment exhibiting brown include C.I. I. Pigment brown 25, C.I. I. And naphthron pigments such as CI Pigment Brown 32.

  Examples of pigments exhibiting black color include carbon black, titanium black, C.I. I. Indazine pigments such as CI Pigment Black 1 (aniline black); I. Pigment black 31, C.I. I. And perylene pigments such as CI Pigment Black 32.

Examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), and titanium. Strontium acid (SrTiO ₃ , so-called titanium strontium white) can be used. The inorganic particles used for the white pigment may be a simple substance or, for example, oxides such as silicon, aluminum, zirconium and titanium, organometallic compounds, and composite particles with organic compounds.

  Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, so that it has a large hiding power and coloring power as a pigment. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the listed white pigments) may be used as necessary.

  Since pigments other than white are more excellent in color developability as the average particle size is smaller, if the pigment dispersion of the present invention is applied to a pigment dispersion other than white, the average particle size of the pigment contained in the pigment dispersion The diameter is preferably about 0.01 μm to 0.4 μm, more preferably 0.02 μm to 0.3 μm. The maximum particle diameter of the pigment is 3 μm or less, preferably 1 μm or less. The particle size of the pigment can be adjusted by selecting a pigment, a dispersant, a dispersion medium, setting dispersion conditions, and filtering conditions. In addition, when the pigment dispersion of the present invention is prepared as a white pigment dispersion that can be applied to a white ink composition or the like, the average particle size of the pigment contained in the pigment dispersion is sufficiently concealed. From the viewpoint of imparting properties, the thickness is preferably about 0.05 μm to 1.0 μm, more preferably about 0.1 μm to 0.4 μm. Also in the case of using a white pigment dispersion, the maximum particle size of the pigment is preferably 3 μm or less, more preferably 1 μm or less.

  By such particle size control, for example, the storage stability of the pigment dispersion, the transparency of the pigment dispersion, and the curing sensitivity can be maintained if the pigment dispersion is applied to the curable composition, Further, even when the pigment dispersion is applied to an ink jet ink composition, clogging of the head nozzle can be suppressed.

  Since the pigment dispersion of the present invention contains a specific polymer excellent in pigment dispersibility and dispersion stability as a pigment dispersant, it is a uniform and stable pigment dispersion even when a fine pigment is used. It becomes.

  The particle diameter of the pigment in the pigment dispersion can be measured by a known measurement method. Specifically, the particle size of the pigment can be measured by a centrifugal sedimentation light transmission method, an X-ray transmission method, a laser diffraction / scattering method, and a dynamic light scattering method.

  The pigment density | concentration in the pigment dispersion of this invention is the range of 2 mass%-50 mass% with respect to the total solid of a pigment dispersion, and the range of 2 mass%-25 mass% is more preferable. In the case of preparing a pigment dispersion as a thick pigment dispersion (mill base), the pigment concentration in the mill base is preferably in the range of 10% by mass to 50% by mass, and 15% by mass to 50%. A range of mass% is more preferred.

  For dispersion of these pigments, for example, ball mill, sand mill, bead mill, attritor, roll mill, jet mill, homogenizer, paint shaker, kneader, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, etc. Any known dispersing device can be used. The specific polymer described later is preferably added when the pigment is dispersed.

[(B) Specific polymer]
The specific polymer (b) which is a characteristic component in the present invention will be described.
In the present invention, (meth) acrylic acid is a generic term for acrylic acid and methacrylic acid, and similarly, (meth) acrylate is a generic term for acrylate and methacrylate.

  The specific polymer (b) in the present invention is preferably used as a pigment dispersant, and is favorably adsorbed to the pigment by the interaction between the pigment surface treatment agent and the component derived from the general formula (1). It is considered a thing. Furthermore, it is possible to disperse and stabilize the pigment even in the non-aqueous organic medium, together with the steric repulsion effect that is considered to be manifested by other components.

  The specific polymer (b) in the present invention is a polymer having a repeating unit represented by the following general formula (I).

In general formula (I), Q ¹ represents a hydrogen atom or a methyl group. Z ¹ is ^{-CO -, - COO -, -} CONQ 2 -, - OCO-, or a phenylene group, and among ^{them, -COO -, - CONQ 2 -} , or a phenylene group is preferable. Q ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

Z ² represents a divalent linking group which may have a single bond or a substituent. The divalent linking group represents alkylene or arylene and may have a substituent. A preferred example of Z ² is an alkylene group having 1 to 6 carbon atoms which is unsubstituted or substituted with a hydroxyl group.

Y ¹ represents a resin acid residue. Here, the resin acid means a carboxylic acid component constituting the natural resin, and in the present invention, a nonvolatile resin acid is preferably used.
As a preferable structure derived from the resin acid used in the present invention, a structure represented by the following general formula (II) is more preferable.

In the general formula (II), Q ³ and Q ⁴ represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and Z ³ and Z ⁴ are a single bond or a carbon-carbon double bond (- CR ^A = CR ^B − where R ^A and R ^B represent a hydrogen atom or a substituent. B is bonded to the carbon to which Z ⁴ is bonded and includes Z ⁴ to form a 6-membered ring such as a cyclohexane ring, a cyclohexene ring, a cyclohexadiene ring, or a benzene ring. The 6-membered ring is preferably substituted with one or two alkyl groups having 1 to 3 carbon atoms or alkenyl groups.

  Specific examples of the resin acid that gives the structure of the general formula (II) include abietic acid, neoabietic acid, parastrinic acid, levopimaric acid, dihydroabietic acid, tetrahydroabietic acid, pimaric acid, isopimaric acid, and dehydroabietic acid. . It is preferable to use the one or more resin acids selected from these groups as a starting material to form a repeating unit that gives the general formula (I) of the present invention to obtain the polymer of the present invention. Although the preferable structure of the repeating unit of general formula (I) is described below, this invention is not limited to these.

  The amount contained in the specific polymer of the repeating unit giving the general formula (I) of the present invention is 2% by mass to 50% by mass, preferably 3% by mass to 40% by mass, and 5% by mass to 30% by mass. % Is more preferable. Within this range, the dispersion stability is good.

  The specific polymer according to the present invention may have a repeating unit other than the repeating units represented by the general formula (I) and the general formula (II), and has an ethylenically unsaturated double bond at the terminal. Particularly preferred is a graft copolymer containing a repeating unit derived from the polymerizable oligomer (hereinafter also simply referred to as “polymerizable oligomer”). Such a polymerizable oligomer having an ethylenically unsaturated double bond at the terminal is also called a macromonomer because it is a compound having a predetermined molecular weight.

  By including the repeating unit derived from the polymerizable oligomer, it is considered that the specific polymer according to the present invention can disperse the pigment more stably due to the high affinity of the polymerizable oligomer to the liquid medium. For this reason, it is preferable that the said polymerizable oligomer has high affinity with respect to a liquid medium. The affinity of the polymerizable oligomer in the liquid medium can be estimated by, for example, the solubility parameter proposed by HOY. (See, for example, “Journal of Paint Technology” 1970, 42, 76-78.)

  When the solubility parameter δt between the solute and the solvent is close, it is considered that the solubility of the solute in the solvent is good. Therefore, the solubility parameter of the polymerizable oligomer is 80% to 120% of the solubility parameter of the liquid medium. Is preferable, and the range of 85% to 115% is more preferable. The preferable range of the solubility parameter of the polymerizable oligomer is the same in the ink composition to which the pigment dispersion of the present invention is applied. If the value of the solubility parameter is within this range, the structure of the polymerizable oligomer is not particularly limited. When the solubility parameter of the polymerizable oligomer is within this range, the dispersion stability of the pigment contained in the pigment dispersion becomes more excellent.

The polymerizable oligomer consists of a polymer chain part and a part of a polymerizable functional group having an ethylenically unsaturated double bond at its terminal. It is preferable from the viewpoint of obtaining a desired graft polymer that such a group having an ethylenically unsaturated double bond is present only at one end of the polymer chain. As the group having an ethylenically unsaturated double bond, a (meth) acryloyl group and a vinyl group are preferable, and a (meth) acryloyl group is particularly preferable.
The polymer chain portion in the polymerizable oligomer is a homopolymer or copolymer formed from at least one monomer selected from the group consisting of alkyl (meth) acrylate, styrene and derivatives thereof, acrylonitrile, vinyl acetate, and butadiene, or Polyethylene oxide, polypropylene oxide, and polycaprolactone are generally used.

  The polymerizable oligomer is preferably a polymerizable oligomer represented by the following general formula (III).

In general formula (III), Q ⁵ and Q ⁷ each independently represent a hydrogen atom or a methyl group, and Q ⁶ represents an alkylene group having 1 to 12 carbon atoms (preferably an alkylene having 2 to 4 carbon atoms). A group which may have a substituent (for example, a hydroxyl group, and may be further linked via an ester bond, an ether bond, an amide bond, or the like).
Y ² represents a phenyl group, a phenyl group having an alkyl group having 1 to 4 carbon atoms, or —COOQ ⁸ . However, ^{Q 8} represents an alkyl group, a phenyl group, or an arylalkyl group having 7 to 10 carbon atoms of 1 to 6 carbon atoms. Y ² is preferably a phenyl group or —COOQ ⁸ in which Q ⁸ is an alkyl group having 1 to 12 carbon atoms.
q1 represents 15 to 200, preferably 20 to 150, and more preferably 20 to 100.

  Preferred examples of the polymerizable oligomer (macromonomer) include polymethyl (meth) acrylate, poly-n-butyl (meth) acrylate and poly-iso-butyl (meth) acrylate, and (meth) acryloyl at one molecular end of polystyrene. Mention may be made of polymers having groups attached thereto. As such polymerizable oligomers available on the market, one-end methacryloylated polystyrene oligomer (Mn = 6000, trade name: AS-6, manufactured by Toagosei Chemical Co., Ltd.), one-end methacryloylated polymethyl methacrylate oligomer ( Mn = 6000, trade name: AA-6, manufactured by Toa Gosei Chemical Co., Ltd.) and one-terminal methacryloylated poly-n-butyl acrylate oligomer (Mn = 6000, trade name: AB-6, Toa Gosei Chemical Co., Ltd.) ) Made).

As the polymerizable oligomer, not only a polymerizable oligomer represented by the general formula (III) but also a polymerizable oligomer represented by the following general formula (IV) is preferable.
When a polymerizable compound is used in combination, the polymerizable oligomer is particularly preferably selected as appropriate according to the polymerizable compound.

In General Formula (IV), Q ¹¹ represents a hydrogen atom or a methyl group, and Q ¹² represents an alkylene group having 1 to 8 carbon atoms. X ³⁰ represents —OQ ¹³ or —OCOQ ¹⁴ . ^{Here, Q 13} and ^{Q 14} represents a hydrogen atom, an alkyl group, or an aryl group. n1 represents 2 to 200.

Q ¹¹ represents a hydrogen atom or a methyl group.
Q ¹² represents an alkylene group having 1 to 8 carbon atoms. Among them, an alkylene group having 1 to 6 carbon atoms is preferable, and an alkylene group having 2 to 3 carbon atoms is more preferable.
When X ³⁰ represents —OQ ¹³ , Q ¹³ is preferably a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, a phenyl group, or a phenyl group substituted with an alkyl group having 1 to 18 carbon atoms. When X ³⁰ represents —OCOQ ¹⁴ , Q ¹⁴ is preferably an alkyl group having 1 to 18 carbon atoms.
n1 represents 2 to 200, preferably 5 to 150, and particularly preferably 10 to 100.

  Examples of the polymerizable oligomer represented by the general formula (IV) include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol polypropylene glycol mono (meth) acrylate, and polytetramethylene glycol monomethacrylate. These may be commercially available products or may be appropriately synthesized.

  The polymerizable monomer represented by the general formula (IV) is also available as a commercial product as described above. Commercially available products include methoxypolyethylene glycol methacrylate, trade names: NK ester M-40G, M-90G, M-230G (manufactured by Shin-Nakamura Chemical Co., Ltd.), Bremmer PME-100, PME-200, PME-400, PME-1000, PME-2000, PME-4000 (above, manufactured by Nippon Oil & Fats Co., Ltd.), polyethylene glycol monomethacrylate Product names: Blemmer PE-90, PE-200, PE-350 (above, manufactured by NOF Corporation) ), Lauryloxypolyethylene glycol acrylate Product name: Blemmer ALE series (manufactured by NOF Corporation), Polypropylene glycol monomethacrylate Product name: BLEMMER PP-500, PP-800, PP-1000 (above, manufactured by NOF Corporation) ), Polyethylene glycol Polypropylene glycol monomethacrylate Product name: Blemmer 70PEP-370B (Nippon Yushi Co., Ltd.), polyethylene glycol polytetramethylene glycol monomethacrylate Product name: Blemmer 55 PET-800 (Nippon Yushi Co., Ltd.), polypropylene glycol polytetramethylene Glycol monomethacrylate Brand name: BLEMMER NHK-5050 (manufactured by NOF Corporation) and the like.

The polymerizable oligomer preferably has a polystyrene-equivalent weight average molecular weight (Mw) in the range of 500 to 20000, and particularly preferably in the range of 2000 to 15000.
The proportion of the repeating unit derived from the polymerizable oligomer contained in the specific polymer is preferably 40% by mass to 96% by mass, more preferably 50% by mass to 90% by mass, and most preferably 55% by mass to 85% by mass. . Since the ratio of the repeating unit derived from the polymerizable oligomer in the specific polymer is within this range, the affinity to the liquid medium is good, and the adsorptivity to the pigment of the specific polymer is excellent. It is possible to effectively suppress the viscosity of the ink composition as an application form.

  Below, the specific example of the polymerizable oligomer preferably used in this invention is shown. Note that the present invention is not limited to this.

  It is also preferable that the specific polymer (b) used in the present invention is a copolymer of a monomer that gives a repeating unit of the general formula (I), a polymerizable oligomer, and another monomer that can be copolymerized. It is. Examples of other copolymerizable monomers include (meth) acrylic acid alkyl esters (eg, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, etc.) ), (Meth) acrylic acid alkyl aryl esters (eg, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, etc.), (meth) acrylic acid substituted alkyl esters (eg, glycidyl (meth) acrylate, 2-hydroxyethyl ( Meth) acrylate, dialkylaminoalkyl (meth) acrylate, alkylaminoalkyl (meth) acrylate, etc.), unsaturated carboxylic acid (eg, (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid and fumaric acid), aromatic Vinyl compounds (eg, styrene, α- Til styrene, vinyl toluene, 2-vinyl pyridine, 4-vinyl pyridine, N-vinyl imidazole, etc.), alkyl (meth) acrylamide (such as tert-butyl acrylamide), substituted (meth) acrylamide (such as methylol acrylamide, dimethylaminopropyl acrylamide) Carboxylic acid vinyl esters (eg, vinyl acetate and vinyl propionate), vinyl cyanides (eg, (meth) acrylonitrile and α-chloroacrylonitrile), vinyl ethers (cyclohexyl vinyl ether, 4-hydroxybutyl vinyl and aliphatic conjugated dienes (eg, 1,3-butadiene and isoprene).

  Among these, (b) in order to enhance the adsorptivity of the polymer to the pigment, unsaturated carboxylic acid, dialkylaminoalkyl (meth) acrylate, alkylaminoalkyl (meth) acrylate, which interacts with the pigment surface and acid-base, Dialkylaminoalkyl (meth) acrylamide and the like are preferable. As these preferable copolymerization components, (meth) acrylic acid, (meth) acryloyloxyethyl succinate, (meth) acryloyloxyethyl phthalate, (meth) acryloyloxyethyl hexahydrophthalate, N, N- Examples thereof include dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, 2-tert-butylaminoethyl methacrylate, and 3-dimethylaminopropyl (meth) acrylamide.

  Moreover, it is also preferable to use (meth) acrylic-acid substituted alkyl ester and (meth) acrylic-acid alkylester (meth) acrylic-acid alkylaryl ester from a viewpoint of improving solvent affinity.

  When (b) the specific polymer of the present invention uses a monomer that gives a repeating unit composed of the above general formula (I) and general formula (II), a polymerizable oligomer, and another monomer that can be copolymerized, It is preferable to have a repeating unit derived from another copolymerizable monomer in the range of 2 to 30% by mass of all repeating units. Within this range, the dispersion stability of the pigment is good.

  The preferred weight average molecular weight (Mw) of the specific polymer (b) of the present invention is preferably in the range of 10,000 to 1,000,000, particularly preferably in the range of 15,000 to 500,000. When the weight average molecular weight is smaller than this range, the dispersion stability tends to decrease, and when the weight average molecular weight is larger than this range, the viscosity of the pigment dispersion tends to increase. Here, the weight average molecular weight is a polystyrene equivalent weight average molecular weight measured by gel permeation chromatography (carrier: N-methylpyrrolidone).

(B) Although the example of the said graft copolymer used suitably for a specific polymer is shown below, this invention is not restrict | limited to these.
C-1) Monomer that gives the exemplified compound B-1 / Copolymer of polymerizable oligomer that gives the exemplified compound N-1 C-2) Monomer that gives the exemplified compound B-1 / the exemplified compound N-5 Polymerizable oligomer copolymer C-3) to give the above exemplified compound B-3 / polymerizable oligomer copolymer C-4 to give the above exemplified compound N-2) Monomer to give the above exemplified compound B-6 / Copolymer of polymerizable oligomers C-5 that gives the exemplified compound N-1) Monomer that gives the exemplified compound B-6 / Copolymer C-6 of the polymerizable oligomer that gives the exemplified compound N-5) Monomer giving exemplary compound B-1 / polymerizable oligomer giving exemplary compound N-1 / copolymer of 3-dimethylaminopropylacrylamide C-7) Monomer that gives Compound B-1 / Polymerizable oligomer that gives Exemplified Compound N-2 / Copolymer of 2-tert-butylaminoethyl methacrylate C-8) Monomer that gives Exemplified Compound B-1 / Exemplified Compound N Polymeric oligomer giving C-4 / copolymer of methacrylic acid C-9) Copolymer of monomer giving the above exemplified compound B-6 / polymerizable oligomer giving the above exemplified compound N-1 / 2-tertbutylaminoethyl methacrylate Compound C-10) Monomer that gives the exemplified compound B-6 / polymerizable oligomer that gives the exemplified compound N-1 / 2-tertbutylaminoethyl methacrylate / copolymer of cyclohexyl methacrylate

<Other pigment dispersants>
In addition to the specific polymer, a known pigment dispersant can be used in combination with the pigment dispersion of the present invention as long as the effect is not impaired. The addition amount is preferably in the range of 5% by mass to 50% by mass with respect to the total mass of the specific polymer. Furthermore, a synergist according to various pigments can be used as a dispersion aid as required. The dispersing aid is preferably added in the range of 1% by mass to 30% by mass with respect to the total mass of the pigment.

[(C) polymerizable compound]
The pigment dispersion and ink composition of the present invention contain (c) a polymerizable compound. The polymerizable compound is not particularly limited as long as it is a compound that causes a polymerization reaction by being imparted with some energy and cures, and can be used regardless of the type of monomer, oligomer, or polymer. Various known polymerizable monomers known as radically polymerizable monomers and cationically polymerizable monomers that cause a polymerization reaction with an initiation species generated from the polymerization initiator are preferred. Among these, a radical polymerizable monomer and a cationic polymerizable monomer containing no oxirane compound are more preferable from the viewpoint of stability.

  One or more polymerizable compounds can be used in combination for the purpose of adjusting the reaction rate, ink physical properties, cured film physical properties, and the like. The polymerizable compound may be a monofunctional compound or a polyfunctional compound. When the proportion of the monofunctional monomer is large, the cured product tends to be flexible, and when the proportion of the polyfunctional monomer is large, the curability tends to be excellent. Therefore, the ratio between the monofunctional monomer and the polyfunctional monomer is arbitrarily determined according to the application.

In the present invention, various known radically polymerizable monomers that cause a polymerization reaction with an initiating species generated from a photoradical initiator can also be used as the polymerizable compound.
Examples of the radical polymerizable monomer include (meth) acrylates, (meth) acrylamides, aromatic vinyls and the like.

Examples of the (meth) acrylates used as the radical polymerizable monomer include monofunctional (meth) acrylate, bifunctional (meth) acrylate, trifunctional (meth) acrylate, tetrafunctional (meth) acrylate, and five Functional (meth) acrylates, hexafunctional (meth) acrylates, and the like can be given.
Examples of the monofunctional (meth) acrylate include hexyl group (meth) acrylate, 2-ethylhexyl (meth) acrylate, tert-octyl (meth) acrylate, isoamyl (meth) acrylate, decyl (meth) acrylate, and isodecyl (meth). Acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-n-butylcyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, 2-ethylhexyl diglycol (meth) acrylate, butoxyethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 4-bromobutyl (meth) acrylate, cyanoe (Meth) acrylate, benzyl (meth) acrylate, butoxymethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, alkoxymethyl (meth) acrylate, alkoxyethyl (meth) acrylate, 2- (2-methoxyethoxy) ethyl (Meth) acrylate, 2- (2-butoxyethoxy) ethyl (meth) acrylate, 2,2,2-tetrafluoroethyl (meth) acrylate, 1H, 1H, 2H, 2H perfluorodecyl (meth) acrylate, 4- Butylphenyl (meth) acrylate, phenyl (meth) acrylate, 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxyethyl (meth) acrylate Glycidyl (meth) acrylate, glycidyloxybutyl (meth) acrylate, glycidyloxyethyl (meth) acrylate, glycidyloxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, hydroxyalkyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate,

  4-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, trimethoxy Silylpropyl (meth) acrylate, trimethylsilylpropyl (meth) acrylate, polyethylene oxide monomethyl ether (meth) acrylate, oligoethylene oxide monomethyl ether (meth) acrylate, polyethylene oxide (meth) acrylate, oligoethylene oxide (meth) acrylate, oligoethylene oxide monoalkyl Ether (meth) acrylate, polyethylene oxide monoalkyl ether ) Acrylate, dipropylene glycol (meth) acrylate, polypropylene oxide monoalkyl ether (meth) acrylate, oligopropylene oxide monoalkyl ether (meth) acrylate, 2-methacryloyloxytyl succinic acid, 2-methacryloyloxyhexahydrophthalic acid 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, butoxydiethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate EO modified phenol (meth) acrylate, EO modified cresol (meth) acrylate, EO modified nonylphenol (meth) acrylate, PO modified Ruphenol (meth) acrylate, EO-modified-2-ethylhexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (3-ethyl- 3-oxetanylmethyl) (meth) acrylate, phenoxyethylene glycol (meth) acrylate are mentioned.

  Examples of the bifunctional (meth) acrylate include 1,6-hexanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and 2,4-dimethyl. -1,5-pentanediol di (meth) acrylate, butylethylpropanediol (meth) acrylate, ethoxylated cyclohexanemethanol di (meth) acrylate, polyethylene glycol di (meth) acrylate, oligoethylene glycol di (meth) acrylate, Ethylene glycol di (meth) acrylate, 2-ethyl-2-butyl-butanediol di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, EO-modified bisphenol A di (meth) acrylate Bisphenol F polyethoxydi (meth) acrylate, polypropylene glycol di (meth) acrylate, oligopropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 2-ethyl-2-butylpropanediol di (Meth) acrylate, 1,9-nonane di (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, tricyclodecane di (meth) acrylate, dipropylene glycol di (meth) acrylate, propoxylated neopentyl glu Examples thereof include cold di (meth) acrylate.

  Examples of the trifunctional (meth) acrylate include trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane alkylene oxide-modified tri (meth) acrylate, and pentaerythritol tri (meth) acrylate. , Dipentaerythritol tri (meth) acrylate, trimethylolpropane tri ((meth) acryloyloxypropyl) ether, isocyanuric acid alkylene oxide modified tri (meth) acrylate, propionate dipentaerythritol tri (meth) acrylate, tri ((meta ) Acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde-modified dimethylolpropane tri (meth) acrylate, sorbitol tri (meth) a Relate, propoxylated trimethylolpropane tri (meth) acrylate, and the like ethoxylated glycerol triacrylate.

  Examples of the tetrafunctional (meth) acrylate include pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate propionate, and ethoxylated penta Examples include erythritol tetra (meth) acrylate.

  Examples of pentafunctional (meth) acrylates include sorbitol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate.

  Examples of hexafunctional (meth) acrylates include dipentaerythritol hexa (meth) acrylate, sorbitol hexa (meth) acrylate, phosphazene alkylene oxide-modified hexa (meth) acrylate, and ε-captolactone-modified dipentaerythritol hexa (meth). ) Acrylate and the like.

  Examples of (meth) acrylamides used as the radical polymerizable monomer include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, and N-n. -Butyl (meth) acrylamide, Nt-butyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) Examples include acrylamide, N, N-diethyl (meth) acrylamide, and (meth) acryloylmorpholine.

  Examples of the aromatic vinyl used as the radical polymerizable monomer include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene. , Bromostyrene, vinyl benzoic acid methyl ester, 3-methylstyrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexyl styrene, 4-hexyl styrene, 3-octyl styrene, 4-octyl styrene, 3- (2-ethylhexyl) styrene, 4- (2-ethylhexyl) styrene, allyl styrene, isoprop Rusuchiren, butenylstyrene, octenyl styrene, 4-t-butoxycarbonyl styrene, 4-methoxystyrene, and a 4-t-butoxystyrene.

  Furthermore, examples of the radical polymerizable monomer in the present invention include vinyl esters [vinyl acetate, vinyl propionate, vinyl versatate, etc.], allyl esters [allyl acetate, etc.], halogen-containing monomers [vinylidene chloride, chloride] Vinyl etc.], vinyl ether [methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxy vinyl ether, 2-ethylhexyl vinyl ether, methoxyethyl vinyl ether, cyclohexyl vinyl ether, chloroethyl vinyl ether, triethylene glycol divinyl ether, etc.], vinyl cyanide [(meth) acrylonitrile Etc.], olefins [ethylene, propylene, etc.], N-vinyl compounds [N-vinylcaprolactam, N-vinylpyrrolidone, N- Sulfonyl imidazole etc.] and the like.

  Among these, as the radically polymerizable monomer in the present invention, (meth) acrylates and (meth) acrylamides are preferable from the viewpoint of curing speed. From the viewpoint of curing speed and viscosity of the ink composition, it is preferable to use the above polyfunctional (meth) acrylate, monofunctional or bifunctional (meth) acrylate, and (meth) acrylamide together.

  In the present invention, a cationic polymerizable monomer can be used as the polymerizable compound. Examples of the cationic polymerizable monomer that can be used in the present invention include Japanese Patent Laid-Open Nos. 6-9714, 2001-31892, 2001-40068, 2001-55507, and 2001-310938. , Epoxy compounds, vinyl ether compounds, oxetane compounds and the like described in each publication such as JP 2001-310937 A and 2001-220526 Gazette. Among these, from the viewpoint of stability, it is preferable to use a vinyl ether compound or oxetane when long-term storage is required.

  Examples of the monofunctional epoxy compound used as the cationic polymerizable monomer include phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, and 1,2-butylene oxide. 1,3-butadiene monooxide, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-methacryloyloxymethylcyclohexene oxide, 3-acryloyloxymethylcyclohexene oxide, Examples include 3-vinylcyclohexene oxide.

Examples of the polyfunctional epoxy compound used as the cationic polymerizable monomer include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, and brominated bisphenol F diester. Glycidyl ether, brominated bisphenol S diglycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ′, 4'-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-di Xanthine, bis (3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexylene oxide, 4-vinylepoxycyclohexane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl -3 ′, 4′-epoxy-6′-methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexylmethyl) ether, ethylene bis (3,4-epoxycyclohexanecarboxylate), dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1,4-butanediol diglycidyl ether, 1,6 -Hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,1,3-tetradecadiene dioxide, limonene dioxide, 1, Examples include 2,7,8-diepoxyoctane and 1,2,5,6-diepoxycyclooctane.
Among these epoxy compounds, aromatic epoxides and alicyclic epoxides are preferable from the viewpoint of excellent curing speed, and alicyclic epoxides are more preferable.

  Examples of the monofunctional vinyl ether compound used as the cationic polymerizable monomer include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, and cyclohexyl. Vinyl ether, cyclohexyl methyl vinyl ether, 4-methyl cyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxy Ethyl vinyl A , Methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, Examples include chlorobutyl vinyl ether, chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxypolyethylene glycol vinyl ether, and the like.

Examples of the polyfunctional vinyl ether compound used as the cationic polymerizable monomer include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, and hexane. Divinyl ethers such as diol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether; trimethylol ethane trivinyl ether, trimethylol propane trivinyl ether, ditrimethylol propane tetravinyl ether, glycerin trivinyl ether, pentaerythritol ether Lavinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexavinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether Polyfunctional vinyl ethers such as ethylene oxide-added pentaerythritol tetravinyl ether, propylene oxide-added pentaerythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, propylene oxide-added dipentaerythritol hexavinyl ether And the like.
Of the polyfunctional vinyl ether compounds described above, di- or trivinyl ether compounds are preferable from the viewpoints of curability, adhesion to a recording medium, surface hardness of the formed image, and the like, and particularly divinyl ether compounds are more preferable.

  The oxetane compound used as the cationic polymerizable monomer refers to a compound having an oxetane ring, and is described in JP-A Nos. 2001-220526, 2001-310937, and 2003-341217. As such, known oxetane compounds can be arbitrarily selected and used. The compound having an oxetane ring is preferably a compound having 1 to 4 oxetane rings in the structure. By using such a compound, it becomes easy to maintain the viscosity of the ink composition in a good handling property range, and it is possible to obtain high adhesion of the cured ink to the recording medium. .

  Examples of the monofunctional oxetane used as the cationic polymerizable monomer include, for example, 3-ethyl-3-hydroxymethyloxetane, 3- (meth) allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanyl). Methoxy) methylbenzene, 4-fluoro- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, 4-methoxy- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, [1- (3-Ethyl-3-oxetanylmethoxy) ethyl] phenyl ether, isobutoxymethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyl (3 -Ethyl-3-oxetanylmethyl) ether, 2-e Ruhexyl (3-ethyl-3-oxetanylmethyl) ether, ethyldiethylene glycol (3-ethyl-3-oxetanylmethyl) ether, dicyclopentadiene (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyloxyethyl (3- Ethyl-3-oxetanylmethyl) ether, dicyclopentenyl (3-ethyl-3-oxetanylmethyl) ether, tetrahydrofurfuryl (3-ethyl-3-oxetanylmethyl) ether, tetrabromophenyl (3-ethyl-3-oxetanyl) Methyl) ether, 2-tetrabromophenoxyethyl (3-ethyl-3-oxetanylmethyl) ether, tribromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tribromophenoxyethyl (3- Til-3-oxetanylmethyl) ether, 2-hydroxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxypropyl (3-ethyl-3-oxetanylmethyl) ether, butoxyethyl (3-ethyl-3- Oxetanylmethyl) ether, pentachlorophenyl (3-ethyl-3-oxetanylmethyl) ether, pentabromophenyl (3-ethyl-3-oxetanylmethyl) ether, bornyl (3-ethyl-3-oxetanylmethyl) ether, and the like. .

  Examples of the polyfunctional oxetane used as the cationic polymerizable monomer include, for example, 3,7-bis (3-oxetanyl) -5-oxa-nonane, 3,3 ′-(1,3- (2-methylenyl) Propanediylbis (oxymethylene)) bis- (3-ethyloxetane), 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 1,2-bis [(3-ethyl-3- Oxetanylmethoxy) methyl] ethane, 1,3-bis [(3-ethyl-3-oxetanylmethoxy) methyl] propane, ethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenylbis (3-ethyl) -3-oxetanylmethyl) ether, triethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether , Tetraethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, tricyclodecanediyldimethylene (3-ethyl-3-oxetanylmethyl) ether, trimethylolpropane tris (3-ethyl-3-oxetanylmethyl) ether 1,4-bis (3-ethyl-3-oxetanylmethoxy) butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, pentaerythritol tris (3-ethyl-3-oxetanylmethyl) ether, Pentaerythritol tetrakis (3-ethyl-3-oxetanylmethyl) ether, polyethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, di Ntaerythritol pentakis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritoltetrakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether , Caprolactone-modified dipentaerythritol pentakis (3-ethyl-3-oxetanylmethyl) ether, ditrimethylolpropane tetrakis (3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ) Ether, PO-modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, EO-modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, PO-modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol F (3-ethyl-3-oxetanylmethyl) ether, bis {[1-ethyl (3-oxetanyl)] methyl} ether Etc.

The compound having such an oxetane ring is described in detail in the aforementioned JP-A No. 2003-341217, paragraph numbers [0021] to [0084], and the compounds described herein can be suitably used in the present invention. .
Among the oxetane compounds as the cationic polymerizable monomer, it is preferable to use a compound having 1 to 2 oxetane rings from the viewpoint of viscosity and adhesiveness of the ink composition.

  In the pigment dispersion and the ink composition of the present invention, only one type of compound may be used as the cationic polymerizable monomer, or two or more types may be used in combination, but the shrinkage during ink curing is effectively suppressed. From such a viewpoint, it is preferable to use at least one oxetane compound in combination with at least one compound selected from an epoxy compound and a vinyl ether compound.

  When the polymerizable compound is used in the pigment dispersion and the ink composition of the present invention, the content of the polymerizable compound is preferably 50 to 95% by mass, more preferably 55 to 92% by mass in the pigment dispersion. The ink composition is preferably 60% to 95% by mass, and more preferably 75% to 92% by mass. In this range, good curability can be obtained.

[Dispersion medium]
In the pigment dispersion of the present invention, a dispersion medium used when dispersing various components such as a pigment can be appropriately selected according to the purpose. For example, a solvent may be used as a dispersion medium, or a polymerizable compound having a low viscosity without a solvent may be used as the dispersion medium.
When a solvent is used as the dispersion medium, a known alcohol solvent, ester solvent, ether solvent, hydrocarbon solvent or the like is preferably used as the solvent. Specifically, alkylene oxide monoalkyl ether, alkylene oxide monoalkyl ether acetate, alkylene glycol diacetate, dicarboxylic acid dialkyl ester and the like are preferable. When a polymerizable compound is used as the dispersion medium, (meth) acrylates, divinyl ethers, oxetanes and the like are preferable as the polymerizable compound.
Moreover, when applying a pigment dispersion to the ink composition for inkjet, it is preferable not to contain a volatile solvent, and it is preferable that it is a high boiling point solvent with a boiling point of 180 degreeC or more, or a non-solvent. In such a case, it is also preferable to use a polymerizable compound as a dispersion medium.

[(D) Photopolymerization initiator]
In the ink composition of the present invention, a polymerization initiator is preferably used in combination from the viewpoint of improving the curing sensitivity.
When a thermal polymerization initiator is included as a polymerization initiator, good curability is exhibited by heating. Moreover, when a photoinitiator is included, the ink composition hardened | cured by irradiation of an active energy ray is obtained. When, for example, an ink composition is prepared using the pigment dispersion of the present invention and used for forming an image, it is preferable to instantaneously cure the ink composition in order to obtain a sharp image. For this reason, after forming an image using the ink composition using a photoinitiator, it is a preferable aspect to make it harden | cure instantly using an active energy ray. Here, the active energy ray is not particularly limited as long as it can impart energy capable of generating a starting species in the ink composition by the irradiation, and is broadly α-ray, γ-ray, X-ray, Including ultraviolet rays, visible rays, electron beams, etc. Among them, ultraviolet rays and electron beams are preferable from the viewpoint of curing sensitivity and availability of the apparatus, and ultraviolet rays are more preferable.

  Accordingly, the pigment dispersion and the ink composition of the present invention are preferably those that can be cured by irradiating ultraviolet rays as radiation. As the ultraviolet light source, a mercury lamp, a metal halide lamp, a light emitting diode (LED), a semiconductor laser, a fluorescent lamp, or the like is used. In the present invention, it is preferable to use a mercury lamp, a metal halide lamp, or a light emitting diode as a light source, and it is more preferable to have an emission wavelength of 300 nm to 400 nm.

The ink composition of the present invention preferably contains a polymerization initiator for radical polymerization, and more preferably contains a photopolymerization initiator.
The photopolymerization initiator in the present invention undergoes a chemical change through the action of light or the interaction with the electronically excited state of the sensitizing dye to generate at least one of radicals, acids and bases. A compound.
The photopolymerization initiator is an actinic ray to be irradiated, for example, an ultraviolet ray having a wavelength of 400 to 200 nm, a far ultraviolet ray, a g ray, an h ray, an i ray, a KrF excimer laser beam, an ArF excimer laser beam, an electron beam, an X ray, Those having sensitivity to a molecular beam or an ion beam can be appropriately selected and used.

  As the photopolymerization initiator, those known to those skilled in the art can be used without limitation. For example, Bruce M. et al. Monroe et al., Chemical Review, 93, 435 (1993). R. S. By Davidson, Journal of Photochemistry and biology A: Chemistry, 73.81 (1993). J. P. Fausier “Photoinitiated Polymerization—Theory and Applications”: Rapra Review vol. 9, Report, Rapra Technology (1998). M. Tsunooka et al. , Prog. Polym. Sci. , 21, 1 (1996). Can be used. In addition, chemical amplification type photoresists and compounds used for photocation polymerization described in “Organic Materials for Imaging” edited by Organic Electronics Materials Research Group, Bunshin Publishing (1993), pages 187-192 are used. can do. Further, F.I. D. Saeva, Topics in Current Chemistry, 156, 59 (1990). G. G. Maslak, Topics in Current Chemistry, 168, 1 (1993). H., et al. B. Shuster et al, JACS, 112, 6329 (1990). I. D. F. Eaton et al, JACS, 102, 3298 (1980). A group of compounds that undergo oxidative or reductive bond cleavage through interaction with the electronically excited state of a sensitizing dye as described in the above.

  Examples of the photopolymerization initiator include (i) aromatic ketones, (ii) aromatic onium salt compounds, (iii) organic peroxides, (iv) hexaarylbiimidazole compounds, (v) ketoxime ester compounds, Vi) a borate compound, (vii) an azinium compound, (viii) a metallocene compound, (ix) an active ester compound, (x) a compound having a carbon halogen bond, and the like are preferable.

  (I) Examples of aromatic ketones include “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY” P. FOUASSIER J.M. F. RABEK (1993), compounds having a benzophenone skeleton or a thioxanthone skeleton described in p77 to 117 are preferable, an α-thiobenzophenone compound described in JP-B-47-6416, a benzoin ether compound described in JP-B-47-3981, and Α-substituted benzoin compound described in 22326, benzoin derivative described in JP-B-47-23664, aroylphosphonic acid ester described in JP-A-57-30704, dialkoxybenzophenone described in JP-B-60-26483, Benzoin ethers described in JP-A-60-26403, JP-A-62-81345, JP-B-1-34242, US Pat. No. 4,318,791, and α-aminobenzophenones described in European Patent 0284561A1, JP No.-211452, p-di (dimethylaminobenzoyl) benzene, thio-substituted aromatic ketone described in JP-A-61-194062, acylphosphine oxide described in JP-A-58-15471, JP-B-2 JP-A-9597, acylphosphine sulfide described in JP-B-2-9596, thioxanthones described in JP-B-63-61950, coumarins described in JP-B-59-42864, etc. Monoacylphosphine oxides described in JP-8047A and JP-B-63-40799, and bisacylphosphine oxides described in JP-A-3-101686, JP-A-5-345790, and JP-A-6-298818 are more preferable. .

  (Ii) Aromatic onium salts include Group V, VI and VII elements of the Periodic Table, specifically N, P, As, Sb, Bi, O, S, Se, Te, or I fragrances Group onium salts are included. For example, iodonium salts described in European Patent No. 104143, US Pat. No. 4,837,124, Japanese Patent Laid-Open No. 2-150848, Japanese Patent Laid-Open No. 2-96514, European Patent Nos. 370693, 233567, and 297443 are disclosed. , 294442, 279210, and 422570, U.S. Pat. Nos. 3,902,144, 4,933,377, 4,760013, 4,734,444, and 2,833,827, sulfonium salts and diazonium salts (Such as benzenediazonium which may have a substituent), diazonium salt resins (formaldehyde resin of diazodiphenylamine, etc.), N-alkoxypyridinium salts, etc. (for example, US Pat. No. 4,743,528, JP 63-1383 No. 5, JP-A-63-142345, JP-A-63-142346, and JP-B-46-42363, specifically 1-methoxy-4-phenylpyridinium tetrafluoro And the compounds described in JP-B Nos. 52-147277, 52-14278, and 52-14279 are preferably used. Generates radicals and acids as active species.

  (Iii) The organic peroxide includes almost all organic compounds having one or more oxygen-oxygen bonds in the molecule. For example, 3,3′4,4′-tetra- (t-butylperoxide Oxycarbonyl) benzophenone, 3,3'4,4'-tetra- (t-amylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (t-hexylperoxycarbonyl) benzophenone, 3,3 '4,4'-tetra- (t-octylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (cumylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (p Peroxyesters such as -isopropylcumylperoxycarbonyl) benzophenone and di-t-butyldiperoxyisophthalate are preferred.

  (Iv) Examples of hexaarylbiimidazoles include lophine dimers described in JP-B-45-37377 and JP-B-44-86516, such as 2,2'-bis (o-chlorophenyl) -4,4 '. , 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-bromophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o, p- Dichlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-chlorophenyl) -4,4', 5,5'-tetra (m-methoxyphenyl) biimidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-nitrophenyl) -4,4', 5 '-Tetraphenylbiimidazole, 2,2'-bis (o-methylphenyl) -4,4', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-trifluorophenyl) -4 4,4 ', 5,5'-tetraphenylbiimidazole and the like.

  (V) Examples of ketoxime esters include 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, 3-propionyloxyiminobutan-2-one, 2-acetoxyiminopentane- 3-one, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3-p-toluenesulfonyloxyiminobutan-2-one, 2- And ethoxycarbonyloxyimino-1-phenylpropan-1-one.

  (Vi) Examples of the borate salt include compounds described in U.S. Pat. Nos. 3,567,453, 4,343,891, European Patents 109,772 and 109,773. Can be mentioned.

  (Vii) Examples of the azinium salt compound include JP-A-63-138345, JP-A-63-142345, JP-A-63-142346, JP-A-63-143537, and JP-B-46- The compound group which has NO bond of 42363 gazette is mentioned.

(Viii) Examples of the metallocene compound include, for example, JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, and JP-A-2-4705. And the iron-arene complexes described in JP-A-1-304453 and JP-A-1-152109.
Examples of the titanocene compound include di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, and di-cyclopentadienyl-Ti-bis-2,3,4. , 5,6-pentafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis -2,4,6-trifluorophen-1-yl, di-cyclopentadienyl-Ti-2,6-difluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4- Difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, di-methylcyclopentadienyl-Ti- -2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl, bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pyridin-1-yl) phenyl) titanium, bis (cyclopentadienyl) bis [2,6-difluoro-3- (methylsulfonamido) phenyl] titanium, bis (cyclopenta And dienyl) bis [2,6-difluoro-3- (N-butylbialoyl-amino) phenyl] titanium.

  Examples of (ix) active ester compounds include, for example, European Patent Nos. 0290750, 046083, 156153, 271851, and 0388343, U.S. Pat. Nos. 3,901,710 and 4,181,531. Nitrobenzester compounds described in the specifications of JP-A-60-198538 and JP-A-53-133022, European Patent Nos. 0199672, 84515, and 199672. Nos. 4,044,115 and 0101122, U.S. Pat. Nos. 4,618,564, 4,371,605 and 4,431,774, JP-A 64-18143, JP-A No. 2-245756 and JP Examples include iminosulfonate compounds described in each publication of JP-A-365048, compounds described in JP-B-62-2623, JP-B63-14340, and JP-A-59-174831. .

  (X) Examples of the compound having a carbon halogen bond include Wakabayashi et al., Bull. Chem. Soc. Examples include compounds described in Japan, 42, 2924 (1969), compounds described in British Patent 1388492, compounds described in JP-A-53-133428, compounds described in German Patent 3333724, and the like.

  Examples of the compound (x) having a carbon halogen bond include F.I. C. J. Schaefer et al. Org. Chem. 29, 1527 (1964), compounds described in JP-A-62-258241, compounds described in JP-A-5-281728, and the like. A compound as described in German Patent No. 2641100, a compound as described in German Patent No. 3333450, a compound group as described in German Patent No. 3021590, or a compound as described in German Patent No. 3021599 Groups, etc.

  At least one of the photopolymerization initiators may be a photopolymerization initiator selected from the group consisting of an α-aminoacetophenone compound, an acylphosphine oxide compound, an α-hydroxyacetophenone compound, and an oxime ester compound. preferable.

<Α-Aminoacetophenone compound>
As the α-aminoacetophenone compound, a compound represented by the following formula (1) can be preferably used.

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

In formula (a), p is 0 or 1. 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 crosslinked to form an alkylene group having 3 to 7 carbon atoms.

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

In formula (c), ^X38 represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. 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 hereinafter. ), 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 ²² ) ₂ (X ²² 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 ⁷¹ ( R ⁷¹ represents an alkyl group having 1 to 18 carbon atoms.), —CO (OCH ₂ OCH ₂ ) naOCH ₃ (na represents an integer of 1 to 20), or —OCOR ⁷² (R ⁷² represents Represents an alkyl group having 1 to 4 carbon atoms.).

As a substituent that the alkoxy group in Y may have, —COOR ⁷³ (R ⁷³ represents an alkyl group having 1 to 18 carbon atoms) or —CO (OCH ₂ CH ₂ ) nbOCH ₃ ( nb 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 ) ncOH (nc represents an integer of 1 or more and 20 or less), — (OCH ₂ CH ₂ ). ndOCH ₃ (nd represents an integer of 1 to 20), an alkylthio group having 1 to 8 carbon atoms, a phenoxy group, —COOR (R represents an alkyl group having 1 to 18 carbon atoms), —CO. (OCH ₂ CH ₂ ) neOCH ₃ (ne represents an integer of 1 or more and 20 or less), a phenyl group, or a benzyl group.
If possible, these substituents may have two or more, and if possible, the substituents may be further substituted.

In formula (1), 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 the 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 Formula (1), 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 7 or more carbon atoms. 9 or less phenylalkyl groups are represented.
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 ⁷⁴ (R ⁷⁴ represents an alkyl group having 1 to 4 carbon atoms) can be mentioned.

In formula (1), X ⁴ represents 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, and a phenylalkyl having 7 to 9 carbon atoms. Represents a group or a phenyl 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. ⁷⁵ (R ⁷⁵ 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.

As the substituent that the phenyl group in X ⁴ may have, a halogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or —COOR ⁷⁶ (where R ⁷⁶ is carbon Represents an alkyl group of 1 to 4).
Here, X ² and X ⁴ are cross-linked to form an alkylene group having 1 to 7 carbon atoms, a phenyl alkylene 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.

Further, X ³ and X ⁴ in the formula (1) may be crosslinked to form an alkylene group having 3 to 7 carbon atoms. An 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 ⁷⁷ (R ⁷⁷ is an alkyl having 1 to 4 carbon atoms). . a representative) may have, also, -O during binding -, - S -, - CO- , ^{or, -N (X 16) - (} X 16 represents a hydrogen atom, 1 or more carbon atoms 12 The following alkyl groups, or 1 or 2 or more —O— in the bond chain, an alkenyl group having 3 to 5 carbon atoms, a phenylalkyl group having 7 to 9 carbon atoms, or a hydroxyalkyl having 1 to 4 carbon atoms Group, —CH ₂ CH ₂ CN, —CH ₂ CH ₂ COOR ⁷⁸ (R ⁷⁸ represents an alkyl group having 1 to 4 carbon atoms), an alkanoyl group or benzoyl group having 2 to 8 carbon atoms. Al having 1 to 12 carbon atoms Represents a kill group).

In formula (1), 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, or a cyclohexane having 5 or 6 carbon atoms. Alkyl group, phenyl group, benzyl group, benzoyl group, -OX ¹⁷ group, -SX ¹⁸ group, -SO-X ¹⁸ group, -SO ₂ -X ¹⁸ group, -N (X ¹⁹ ) (X ²⁰ ) group,- The NH—SO ₂ —X ²¹ group or a group represented by the following formula is represented.

In the above formula (g), ^{Z 5} 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 are as defined in the above formula (1).

In the formula (1), X ¹⁰ is the same as described above, and X ¹¹ is a linear or branched alkylene group having 2 to 16 carbon atoms, or one or more —O— in these chains. , -S-, or -N ^{(X 10)} - alkylene group having a linear or branched 2 to 16 carbon atoms or intervening ^{(X 10} is the same as above) represents a.

Wherein ^{(1), X 5, X} 6, X 7, X 8, and ^{X 9} can take ^{-OX 17} group of ^{X 17} represents a hydrogen atom, 1 to 12 alkyl group carbon atoms, - (CH ₂ CH ₂ O) nfH (nf is an integer of 2 to 20), an alkanoyl group having 2 to 8 carbon atoms, an alkenyl group having 3 to 12 carbon atoms, a cyclohexyl group, a hydrocyclohexyl group, a phenyl group, and 7 or more carbon atoms 9 following phenylalkyl group, _{^{or, -Si (R 4) r (}} R 5) 3-r (R 4 is 1 or more carbon atoms 8 an alkyl group, ^{R 5} is a phenyl group, r is 1, 2 or 3).

The alkyl group and the phenyl group in X ¹⁷ may have a substituent. As the substituent that the alkyl group in 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 ⁷⁹ (R ⁷⁹ represents an alkyl group having 1 to 4 carbon atoms), —COOH, or —COOR ⁸⁰ (R ⁸⁰ 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 the 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 ⁸¹ (R ⁸¹ represents an alkyl group having 1 to 4 carbon atoms), and 1 or more carbon atoms. 4 an alkoxy _group, -OCH 2 _CH 2 _{CN, ^{or, -OCH 2 CH 2 COOR 82 (}} R 82 represents. alkyl of 1 to 4 carbon atoms) are exemplified.
Examples of the substituent that the phenyl group in X ¹⁸ 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 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, an OH group, an alkoxy group having 1 to 4 carbon atoms, or —COOR ⁸³ (R ⁸³ has 1 to 4 carbon atoms). An alkylene group substituted with 2 to 8 carbon atoms; an alkylene group having 2 to 8 carbon atoms with —O—, —S— or —N (X ¹⁶ ) — interposed in the bond chain. ^{(X 16} is the same as above) may be formed.

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

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

In formula (d), X ³³ and X ³⁴ each independently represent a methyl group, an ethyl group, or a benzyl group, —NX ³⁵ X ³⁶ represents a dimethylamino group, a diethylamino group, or a morpholino group, X ³⁷ 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 35 ^{X 36} Among these, dimethylamino group, 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).

[Acylphosphine oxide compound]
The acylphosphine oxide compound is preferably a compound represented by the following formula (2) or the following formula (3).

R ¹ and R ² in the formula (2) 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-membered 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 particularly preferable. The aliphatic group may be a cyclic aliphatic group or a chain aliphatic group. The chain aliphatic group may have a branch.

  Examples of the alkyl group include linear, branched, and cyclic alkyl groups. The number of carbon atoms of the alkyl group is preferably 1 or more and 30 or less, and more preferably 1 or more and 20 or less. 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 (carboxyl group), —SO ₃ H (sulfo group), —CN (cyano group), halogen atom (eg, fluorine atom, chlorine atom, bromine atom), —OH (Hydroxy group), C30 or less alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, benzyloxycarbonyl group), C30 or less alkylsulfonylaminocarbonyl group, arylsulfonylaminocarbonyl group, alkylsulfonyl group An arylsulfonyl group, an acylaminosulfonyl group having 30 or less carbon atoms, an alkoxy group having 30 or less carbon atoms (for example, a methoxy group, an ethoxy group, a benzyloxy group, a phenoxyethoxy group, a phenethyloxy group, etc.), Alkylthio groups (eg methylthio Group, ethylthio group, methylthioethylthioethyl group, etc.), aryloxy group having 30 or less carbon atoms (for example, 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 Groups (for example, carbamoyl group, N, N-dimethylcarbamoyl group, morpholinocarbonyl group, piperidinocarbonyl group, etc.), sulfamoyl groups (for example, sulfamoyl group, N, N-dimethylsulfamoyl group, morpholinosulfonyl group, Peridinosulfonyl group), carbon number 30 or less aryl groups (for example, phenyl group, 4-chlorophenyl group, 4-methylphenyl group, α-naphthyl group, etc.), substituted amino groups (for example, 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 carboxyl group, the sulfo group, the hydroxy group, and the phosphono group may be in a salt state. At that time, a 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 a 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. The number of carbon atoms of the alkenyl group is preferably 2 or more and 30 or less, and more preferably 2 or more and 20 or less. 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, and the number of carbon atoms of the aralkyl group is preferably 7 or more and 35 or less, and more preferably 7 or more and 25 or less. . 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 group having 30 or less carbon atoms. Can be illustrated.

Examples of the aromatic group represented by R ¹ , R ² , or R ³ include an aryl group and a substituted aryl group. The number of carbon atoms of the aryl group is preferably 6 or more and 30 or less, and more preferably 6 or more and 20 or less. 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.
The aliphatic oxy group represented by R ¹ or R ² is preferably an alkoxy group having 1 to 30 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a butoxy group, an octyloxy group, and a phenoxyethoxy group. It is done. 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, for example, phenoxy group, methylphenyloxy group, chlorophenyloxy group, methoxyphenyloxy group, octyl An oxyphenyloxy 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, such as a pyridyl group, a furyl group, a thienyl group, an imidazolyl group, or a pyrrolyl group. Etc.

R ⁴ and R ⁶ in the formula (3) 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. Represent.
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, and as the substituent, The same substituents as in the formula (2) can be mentioned.
The alkyl group, aryl group, heterocyclic group, alkoxy group and aryloxy group in the formula (3) have the same meaning as in the formula (2).

  The compound represented by the formula (2) is more preferably a compound represented by the following formula (4).

In formula (4), 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, 2,4-dimethyl. A phenyl group, a 2-methylphenyl group (o-toluyl group), an isobutyl group, or a t-butyl group is represented.

  The compound represented by the formula (3) is more preferably a compound represented by the following formula (5).

In Formula (5), 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 is Represents a phenyl group or a 2,4,4-trimethylpentyl group.

Examples of the acylphosphine oxide compound represented by the formula (2) or (3) include, for example, JP-B 63-40799, JP-B 5-29234, JP-A-10-95788, JP-A-10 -29997 etc. can mention the compound.
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 JP-B-60-8047 and JP-B-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, o-to Yl-diphenylphosphine oxide, p-tertiary 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- (tertiarybutyl) -benzoyl-diphenylphosphine oxide, 2-methylbenzoyl-diphenylphosphine oxide, 2-methyl-2-ethylhexanoyl -Diphenylphosphine oxide, 1-methyl-cyclohexanoyl-diphenylphosphine Examples thereof include oxide, pivaloyl-phenylphosphinic acid methyl ester, and pivaloyl-phenylphosphinic 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) -decylphosphine 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-trimethoxybenzoyl) -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-naphthylphosphine 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, Examples thereof include bis (2-chloro-1-naphthoyl) -2,5-dimethylphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide.

  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-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (DAROCUR TPO: manufactured by Ciba Specialty Chemicals, LUCIRIN TPO: manufactured by BASF) and the like are preferable.

[Α-hydroxyacetophenone compound]
The α-hydroxyacetophenone compound is preferably a compound represented by the following formula (6).

In Formula (6), R ¹³ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. R ¹⁴ and R ¹⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R ¹⁴ and R ¹⁵ may combine to form a ring having 4 to 8 carbon atoms.
The alkyl group, alkoxy group, alkyl group, and ring having 4 to 8 carbon atoms may have a substituent, and examples of the substituent include the substituents exemplified in Formula (2).

Examples of α-hydroxyacetophenones include 2-hydroxy-2-methyl-1-phenylpropan-1-one (DAROCURE 1173), 2-hydroxy-2-methyl-1-phenylbutan-1-one, 1- (4-methylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-isopropylphenyl) -2-methylpropan-1-one, 1- (4-butylphenyl) -2-hydroxy 2-methylpropan-1-one, 2-hydroxy-2-methyl-1- (4-octylphenyl) propan-1-one, 1- (4-dodecylphenyl) -2-methylpropan-1-one, 1- (4-methoxyphenyl) -2-methylpropan-1-one, 1- (4-methylthiophenyl) -2-methylpropan-1-one, 1 (4-Chlorophenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-bromophenyl) -2-hydroxy-2-methylpropan-1-one, 2-hydroxy-1- (4- Hydroxyphenyl) -2-methylpropan-1-one, 1- (4-dimethylaminophenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-carboethoxyphenyl) -2-hydroxy- 2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184), 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (IRGACURE 2959).
Further, as commercially available α-hydroxyacetophenone compounds, trade names of Irgacure 184 (IRGACURE 184), Darocur 1173 (DARUCUR 1173), Irgacure 127 (IRGACURE 127), and Irgacure 2959 (IRGACURE 2959) manufactured by Ciba Specialty Chemicals. Available polymerization initiators can also be used.

[Oxime ester compound]
The oxime ester compound is preferably a compound represented by the following formula (7).

In the formula (7), Ar ² represents a structure selected from the group consisting of naphthalene structure, anthracene structure, anthraquinone structure, benzophenone structure, thianthrene structure, phenoxathian structure, diphenylthioether structure, thioxanthone structure, and morpholinobenzene structure. . Among these, naphthalene structure, anthraquinone structure, benzophenone structure, diphenylthioether structure, thioxanthone structure, and morpholinobenzene structure are preferable, and thioxanthone structure is particularly preferable. Ar ³ represents a phenyl group. These structures or groups may have a substituent such as an alkyl group such as a methyl group or an ethyl group, a halogen atom, or -CN (cyano group).

  n represents an integer of 1 or 2. When n is 1, M is an alkyl group having 1 to 20 carbon atoms such as methyl group or ethyl group, a cycloalkyl group having 5 to 8 carbon atoms such as cyclopropane group or cyclohexane group, acetyloxy group, propylene. A divalent group in which an alkanoyl group having 2 to 20 carbon atoms such as noyloxy, an alkoxycarbonyl group having 2 to 12 carbon atoms such as propyloxycarbonyl group and butyloxycarbonyl, and a plurality of polymethylene groups are connected by an ether bond. A monovalent group in which an alkoxy group is linked to one bond of the above, phenyl group, benzoyl group, benzoyloxy group, phenoxycarbonyl group, aralkylcarbonyloxy group having 7 to 13 carbon atoms, 7 to 13 carbon atoms An aralkyloxycarbonyl group or an alkylthio group having 1 to 6 carbon atoms is represented. Among these, M is preferably an alkyl group having 1 to 20 carbon atoms or a phenyl group.

When n is 2, M is an alkylene group having 1 to 12 carbon atoms such as an ethylene group or a propylene group, a polymethylene group having 3 to 12 carbon atoms such as a tetramethylene group, an oxypropyleneoxy group, or an oxybutyloxy group. An oxyalkyleneoxy group having 1 to 12 carbon atoms, such as cyclohexylene group, phenylene group, —CO—O—A—O—CO—, —CO—O— (CH ₂ CH ₂ O) m—CO—, Or represents -CO-A-CO-, A represents an alkylene group having 2 to 12 carbon atoms, and m represents an integer of 1 to 20. Among these, M is preferably an alkylene group having 1 to 6 carbon atoms, a polymethylene group having 1 to 6 carbon atoms, or a cyclohexylene group.

Specific examples of the oxime ester compound include 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, 3-propionyloxyiminobutane-2-one, and 2-acetoxyiminopentane-3. -One, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3-p-toluenesulfonyloxyiminotan-2-one, 2-ethoxy And carbonyloxyimino-1-phenylpropan-1-one.
Further, as commercially available oxime ester compounds, Irgacure OXE-01 (1- (4-phenylthiophenyl) -1,2-octanedione-2- (O-benzoyloxime)), Irgacure manufactured by Ciba Specialty Chemicals, Inc. Polymerization initiator available under the trade name OXE-02 (1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl] -ethanone-1- (O-acetyloxime)) Can also be used.

  Preferable specific examples of the compounds represented by the above (i) to (x) include those shown below. In the following exemplary compounds, Ar is an aryl group which is unsubstituted or substituted with an alkyl group having 1 to 4 carbon atoms.

The photoinitiator as a polymerization initiator can be used individually by 1 type or in combination of 2 or more types.
The content of the photopolymerization initiator in the ink composition is preferably in the range of 0.1 to 20% by mass, more preferably 0.5 to 15% by mass in the ink composition. It is particularly preferably 10 to 10% by mass.

(Other ingredients)
(Sensitizing dye)
A sensitizing dye may be added to the ink composition of the present invention for the purpose of improving the sensitivity of the photopolymerization initiator. As the sensitizing dye, those belonging to the following compounds and having an absorption wavelength in the range of 350 nm to 450 nm are preferable.
Examples of the sensitizing dye include polynuclear aromatics (eg, pyrene, perylene, triphenylene, anthracene), xanthenes (eg, fluorescein, eosin, erythrosin, rhodamine B, rose bengal), cyanines (eg, thiacarbox). Cyanine, oxacarbocyanine), merocyanines (eg, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), anthraquinones (eg, , Anthraquinone), squalium (eg, squalium), and coumarins (eg, 7-diethylamino-4-methylcoumarin).

  Moreover, as a sensitizing dye, the compound represented by the following general formula (IX)-(XIII) is more preferable.

In the formula (IX), A ¹ represents a sulfur atom or —NR ⁵⁰ —, R ⁵⁰ represents an alkyl group or an aryl group, and L ² represents a basic nucleus of the dye in combination with the adjacent A ² and the adjacent carbon atom. R ⁵¹ and R ⁵² each independently represents a hydrogen atom or a monovalent nonmetallic atomic group, and R ⁵¹ and R ⁵² are bonded to each other to form an acidic nucleus of the dye. May be. W represents an oxygen atom or a sulfur atom.
In formula (X), Ar ¹ and Ar ² each independently represent an aryl group and are linked via a bond with —L ³ —. Here, L ³ represents —O— or —S—. W is synonymous with that shown in the general formula (IX).
In the formula (XI), A ² represents a sulfur atom or NR ⁵⁹ , L ⁴ represents a nonmetallic atomic group that forms a basic nucleus of the dye in combination with adjacent A ² and a carbon atom, R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ each independently represent a monovalent nonmetallic atomic group, and R ⁵⁹ represents an alkyl group or an aryl group.

In formula (XII), A ³ and A ⁴ each independently represent —S— or —NR ⁶² — or —NR ⁶³ —, and R ⁶² and R ⁶³ each independently represent a substituted or unsubstituted alkyl group, or Represents a substituted or unsubstituted aryl group, L ⁵ and L ⁶ each independently represents a nonmetallic atomic group that forms a basic nucleus of a dye in cooperation with adjacent A ³ , A ⁴ and adjacent carbon atoms; R ⁶⁰ and R ⁶¹ are each independently a hydrogen atom or a monovalent nonmetallic atomic group, or can be bonded to each other to form an aliphatic or aromatic ring.
In formula (XIII), R ⁶⁶ represents an aromatic ring or a hetero ring which may have a substituent, and A ⁵ represents an oxygen atom, a sulfur atom or —NR ⁶⁷ —. R ⁶⁴ , R ⁶⁵ and R ⁶⁷ each independently represent a hydrogen atom or a monovalent non-metallic atomic group, and R ⁶⁷ and R ⁶⁴ and R ⁶⁵ and R ⁶⁷ are each aliphatic or aromatic. They can be joined to form a ring.

  Specific preferred examples of the compounds represented by the general formulas (IX) to (XIII) include the exemplified compounds (A-1) to (A-24) shown below.

(Co-sensitizer)
Furthermore, a known compound having an action such as further improving the curing sensitivity of the ink composition of the present invention or suppressing polymerization inhibition by oxygen may be added as a co-sensitizer.
Such co-sensitizers include amines 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, 84305, JP 62-18537, JP 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 thiols and sulfides, for example, thiol compounds described in JP-A-53-702, JP-B-55-500806, JP-A-5-142772, and JP-A-56- No. 75643, and more specifically, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercaptonaphthalene. Etc.

  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. 55-34414. The hydrogen donor described in JP-A-6-308727, sulfur compounds described in JP-A-6-308727 (eg, trithiane, etc.), phosphorus compounds described in JP-A-6-250387 (diethylphosphite, etc.), Japanese Patent Application No. 6-191605 Si-H and Ge-H compounds described in the above No.

In the ink composition of the present invention, in addition to the essential components of the pigment and the specific dispersant, the polymerizable compound that is a preferable optional component, the sensitizing dye used together with the polymerization initiator, and the co-sensitizer, depending on the purpose. Various additives can be used in combination. For example, an ultraviolet absorber can be used from the viewpoint of improving the weather resistance of the obtained image and preventing discoloration. In addition, an antioxidant can be added to improve the stability of the ink composition.
The additives that can be used in the ink composition of the invention are listed below.

  The ink composition of the present invention includes various organic and metal complex antifading agents, and conductive salts such as potassium thiocyanate, lithium nitrate, ammonium thiocyanate, dimethylamine hydrochloride for the purpose of controlling ejection properties. In order to improve the adhesion to the recording medium, a very small amount of an organic solvent can be added.

Various polymer compounds can be added to the ink composition of the present invention for the purpose of adjusting film 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.
A nonionic surfactant, a cationic surfactant, an organic fluoro compound, or the like can also be added to the ink composition of the present invention in order to adjust liquid properties.
In addition to this, for example, leveling additives, matting agents, waxes for adjusting film physical properties, polymerization to improve adhesion to recording media such as polyolefin and PET, and the like. A tackifier or the like that does not inhibit the above can be contained.

  The pigment dispersion of the present invention thus obtained is a pigment dispersion in which the pigment as a colorant is uniformly and stably dispersed. Even a fine pigment does not aggregate or precipitate over time. Since it is uniformly dispersed without being generated and the effect is maintained, excellent color developability can be obtained. Therefore, such pigment dispersions are widely used in applications that require good color developability, applications that require light-resistant colorants, such as curable ink compositions, nanoimprint compositions, and surface coating agents. It can be suitably used in the field.

[Ink composition]
The curable ink composition, which is the optimum use of the curable composition of the present invention, will be described. The ink composition of the present invention contains the pigment dispersion of the present invention. The ink composition containing the pigment dispersion can be applied to any ink composition as long as it contains a pigment as a colorant.
That is, a general ink composition containing a film-forming polymer, a colorant, and a solvent, and the film is cured by removing the solvent after coating, for example, a solvent ink using a volatile solvent such as cyclohexanone as a solvent Can also be used. Since the ink of the present invention has excellent dispersibility in an organic medium, a sharp image can be formed even when used in a non-curable ink. Further, it can be applied to a curable ink composition containing a polymerizable compound and cured by polymerization or curing reaction by applying energy such as ultraviolet exposure or heating.

The inkjet ink composition, which is a preferred embodiment of the present invention, will be described below.
The ink-jet ink composition of the present invention is a radiation curable ink, and after applying the ink on a recording medium, it is cured by irradiating with radiation. Preferably there is. This is because if the solvent remains in the cured ink image, there is a concern that the solvent resistance deteriorates, the blocking property decreases, the curing failure, and the physical properties of the ink image change over time due to the remaining solvent. . From such a viewpoint, it is preferable to use a polymerizable compound as the dispersion medium, and in particular, to select a polymerizable compound having a low viscosity from the viewpoints of dispersion suitability, improved handling of the ink composition, and ink jet discharge suitability. The ink composition to which the pigment dispersion is applied is cured with high sensitivity by actinic radiation, and there is no fear of thickening or coloration due to a decrease in pigment dispersion stability. In addition, it is suitably used for inkjet inks applied to inkjet recording methods that require viscosity stability.

When the ink composition of the present invention is used in an ink jet recording method, the ink viscosity at the temperature at the time of ejection is preferably 30 mPa · s or less, preferably 20 mPa · s or less in consideration of the ejection properties of the ink composition. More preferably, the composition ratio is suitably adjusted and determined so as to be in the above range.
The ink viscosity at 25 ° C. (room temperature) is 0.5 mPa · s to 200 mPa · s, preferably 1 mPa · s to 100 mPa · s, more preferably 2 mPa · s to 50 mPa · s. . By setting the viscosity at room temperature high, even when a porous recording medium is used, ink penetration into the recording medium can be prevented, uncured monomer can be reduced, and odor can be reduced. Dot bleeding at the time of landing can be suppressed, and as a result, the image quality is improved. When the ink viscosity at 25 ° C. is larger than 200 mPa · s, a problem occurs in the delivery of the ink liquid.

  The surface tension when the ink composition of the present invention is used for inkjet is preferably 20 to 40 mN / m, more preferably 23 to 35 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, uncoated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and 35 mN / m or less is preferable from the viewpoint of wettability.

The ink composition of the present invention thus adjusted is suitably used as an ink for inkjet recording. The ink composition is printed on a recording medium by an inkjet printer, and then the printed ink composition is irradiated with radiation to be cured and recorded.
In the printed matter obtained with this ink, the image portion is cured by irradiation with radiation such as ultraviolet rays, and the strength of the image portion is excellent. Therefore, in addition to image formation with ink, for example, an ink receiving layer (image image of a lithographic printing plate) Part), and can be used for various purposes.

  Next, the pigment dispersion of the present invention and the ink composition containing the pigment dispersion can be suitably used for inkjet ink. An ink jet recording method and an ink jet recording apparatus that can be employed in this case will be described below.

[Inkjet recording method]
In a recording method using an ink jet printer, it is preferable that the ink composition is heated to 40 to 80 ° C. and the viscosity of the ink composition is set to 30 mPa · s or less, and then ejected. Stability can be achieved.
In general, a water-insoluble ink composition generally has a higher viscosity than a water-based ink, and therefore has a large viscosity fluctuation range due to temperature fluctuations during printing. This viscosity variation of the ink composition directly affects the droplet size and droplet ejection speed as it is, which causes image quality deterioration. Therefore, it is necessary to keep the ink composition temperature as constant as possible during printing. is there. The control range of the ink composition temperature is preferably set temperature ± 5 ° C., more preferably set temperature ± 2 ° C., and particularly preferably set temperature ± 1 ° C.

  One characteristic of the ink jet recording apparatus used in the ink jet recording method is that it includes a means for stabilizing the temperature of the ink composition, and the part to be kept at a constant temperature is from the ink tank (the intermediate tank if there is an intermediate tank) to the nozzle. All piping systems and members up to the injection surface are targeted.

  The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors in each piping portion and perform heating control according to the ink composition flow rate and the environmental temperature. 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 thermal energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

By adding a photopolymerization initiator as the polymerization initiator to the ink composition of the present invention, an actinic radiation curable ink composition is obtained.
The irradiation conditions of actinic radiation in such an ink composition will be described. A basic irradiation method is disclosed in JP-A-60-132767. Specifically, a light source is provided on both sides of the head unit, and the head and the light source are scanned by a shuttle method. Irradiation is performed after a certain period of time after ink landing. Further, the curing is completed by another light source that is not driven. In WO99 / 54415, as an irradiation method, 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 is disclosed. In the present invention, these irradiation methods can be used.

In addition, when the ink composition of the present invention is used, it is desirable that the ink composition is heated to a certain temperature and the time from landing to irradiation is 0.01 to 0.5 seconds, preferably 0.8. The irradiation is performed after 01 to 0.3 seconds, more preferably from 0.01 to 0.15 seconds. Thus, by controlling the time from landing to irradiation to an extremely short time, it is possible to prevent the landing ink from bleeding before being cured.
Also, since the ink composition can be exposed to a porous recording medium before it penetrates deeper than the light source reaches, unreacted monomer remains, and as a result, odor can be reduced. Can do.
By using the inkjet recording method and the ink composition of the present invention in combination, a great synergistic effect is brought about. In particular, when an ink composition having an ink viscosity of 200 mPa · s or less at 25 ° C. is used, a great effect can be obtained.
By adopting such an ink jet recording method, 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. When inks with low lightness are stacked, it is difficult for the irradiation rays to reach the lower ink, and inhibition of curing sensitivity, increase of residual monomers, generation of odor, and deterioration of adhesion tend to occur. Irradiation can be performed by injecting all the colors and exposing them together, but exposure for each color is preferable from the viewpoint of promoting curing.

There is no restriction | limiting in particular as an inkjet recording device used for this invention, A commercially available inkjet recording device can be used. That is, in the present invention, recording can be performed on a recording medium (printed material) using a commercially available inkjet recording apparatus.
According to the preferred ejection conditions, the ink composition of the present invention repeatedly heats and cools. However, due to the function of the pigment dispersant, the pigment dispersibility can be maintained even when stored under such temperature conditions. This is advantageous in that it is possible to suppress the deterioration of the color, to obtain excellent color developability over a long period of time, and to suppress the deterioration of the dischargeability due to the aggregation of the pigment.

(Recording medium)
The recording medium to which the ink composition of the present invention can be applied is not particularly limited, and various non-absorbing resin materials used for ordinary non-coated paper, coated paper, and so on, so-called soft packaging, or the like. A resin film formed into a film shape can be used, and examples of various plastic films include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film. In addition, examples of the plastic that can be used as a recording medium material include polycarbonate, acrylic resin, ABS, polyacetal, PVA, and rubbers. Metals and glasses can also be used as the recording medium.

(Printed matter)
A printed matter can be obtained by printing the ink composition of the present invention on a recording medium using an ink jet printer, and then preferably irradiating the printed ink composition with actinic radiation and curing. The printed matter produced by the ink composition of the present invention contains a high-quality image excellent in color development and sharpness because the ink used for image formation contains fine pigment particles uniformly and stably dispersed. And is excellent in weather resistance of the image, it can be applied to a wide range of fields.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the embodiments in these examples. Unless otherwise specified, “part” is based on mass.

-Synthesis of specific polymer C-4-
B-6 (Beamset 101 Arakawa Chemical Industries, Ltd.) 4.0 g, N-1 (Poly (methyl methacrylate) macromonomer having a methacryloyl group at the end, AA-6, number average molecular weight 5300, manufactured by Toagosei Co., Ltd.) 16.0 g and 20 g of methyl ethyl ketone were introduced into a nitrogen-substituted three-necked flask, stirred with a stirrer (Shinto Kagaku Co., Ltd .: Three-One Motor), heated while flowing nitrogen into the flask, and heated to 65 ° C. did. To this was added 40 mg of V-65 (2,2-azobis (2,4-dimethylvaleronitrile, manufactured by Wako Pure Chemical Industries, Ltd.), and the mixture was stirred with heating at 65 ° C. for 2 hours. The resulting reaction solution was poured into 1000 mL of hexane while stirring, and the resulting precipitate was dried by heating to give a specific polymer C-4 (copolymer of B-6 / N-1). As a result of measuring the weight average molecular weight (polystyrene conversion) of the specific polymer P-4 by GPC, it was confirmed that the polymer (polymer) was obtained.

-Synthesis of specific polymers C-5 and C-9-
The specific polymers C-5 and C-9 are the same as the specific polymer C-4 except that the monomer components of the polymer C-4, the amount used thereof, and the amount of initiator used are changed as shown in Table 1. Was synthesized. Table 1 shows the molecular weight of the produced polymer by GPC. N-5 (poly (ethylene oxide) macromonomer having a methacryloyl group at the terminal, Blemmer PME-4000, manufactured by Nippon Oil & Fats), N-6 (poly (ethylene oxide) macromonomer having an acryloyl group at the terminal, Blemmer ALE-800, Japan) (Oil and fat) and t-BuAEMA (2-tertbutylaminoethyl methacrylate Aldrich) were used as they were. In Table 1, () indicates the amount used.

-Synthesis of Comparative Polymer 1-
Cyclohexyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) 4.0 g, N-1 (AA-6 manufactured by Toa Gosei Co., Ltd.) 16.0 g, and methyl ethyl ketone 20 g were introduced into a nitrogen-substituted three-necked flask and a stirrer (Shinto Kagaku Co., Ltd.). ): Three-one motor) and heated while flowing nitrogen into the flask to raise the temperature to 65 ° C. To this was added 60 mg of V-65 (2,2-azobis (2,4-dimethylvaleronitrile, manufactured by Wako Pure Chemical Industries, Ltd.), and the mixture was stirred for 2 hours at 65 ° C. After 2 hours, V-65 was further added. The resulting reaction solution was poured into 1000 mL of hexane while stirring, and the resulting precipitate was heated and dried to produce a graft copolymer (Comparative Polymer 1 cyclohexyl methacrylate / N-1 copolymer). A weight average molecular weight of 120,000 was obtained.

-Synthesis of comparative polymer C-4 (low molecular weight product)-
B-6 (Beamset 101 Arakawa Chemical Industries, Ltd.) 4.0 g, N-1 (Poly (methyl methacrylate) macromonomer having a methacryloyl group at the end, AA-6, number average molecular weight 5300, manufactured by Toagosei Co., Ltd.) 16.0 g, 1.0 g of n-dodecyl mercaptan (manufactured by Wako Pure Chemical Industries, Ltd.) and 20 g of methyl ethyl ketone were introduced into a nitrogen-substituted three-necked flask and stirred with a stirrer (Shinto Kagaku Co., Ltd .: Three-One Motor). The mixture was heated to 65 ° C. while flowing in the flask. To this was added 40 mg of V-65 (2,2-azobis (2,4-dimethylvaleronitrile, manufactured by Wako Pure Chemical Industries, Ltd.), and the mixture was stirred with heating at 65 ° C. for 2 hours. The resulting reaction solution was poured into 1000 mL of hexane while stirring, and the resulting precipitate was dried by heating to give a specific polymer C-4 (copolymer of B-6 / N-1). As a result of measuring the weight average molecular weight (polystyrene conversion) of the specific polymer P-4 by GPC, it was confirmed that the polymer (polymer) was obtained.

-Synthesis of comparative polymer C-4 (high molecular weight product)-
B-6 (Beamset 101 Arakawa Chemical Industries, Ltd.) 4.0 g, N-1 (Poly (methyl methacrylate) macromonomer having a methacryloyl group at the end, AA-6, number average molecular weight 5300, manufactured by Toagosei Co., Ltd.) 16.0 g and 5 g of methyl ethyl ketone were introduced into a nitrogen-substituted three-necked flask, stirred with a stirrer (Shinto Kagaku Co., Ltd .: Three-One Motor), heated while flowing nitrogen into the flask, and heated to 60 ° C. did. To this was added 3 mg of V-65 (2,2-azobis (2,4-dimethylvaleronitrile, manufactured by Wako Pure Chemical Industries, Ltd.), and the mixture was stirred for 2 hours at 65 ° C. After 2 hours, V-65 was further added. The resulting reaction solution was poured into 1000 mL of hexane with stirring, and the resulting precipitate was heated and dried to give a specific polymer C-4 (copolymer of B-6 / N-1). As a result of measuring the weight average molecular weight (polystyrene conversion) of the specific polymer P-4 by GPC, it was confirmed that the polymer (polymer) was obtained.

-Production of mill base 1-
(B) 8.0 g of the specific polymer C-4 was dissolved in 62 g of (c) polymerizable compound DVE-3 (triethylene glycol divinyl ether, manufactured by BASF), and (a) bead mill (motor) with 30 g of pigment PY-120 Mill M100, manufactured by Eiger Corporation, beads: zirconia beads, diameter 0.65 mm) was used for dispersion for 2.5 hours at a peripheral speed of 7.1 m / s to obtain mill base (concentrated pigment dispersion) 1.

-Production of mill bases 2-5 and comparative mill bases 11-15-
The raw materials for producing the mill base 1 were changed to the raw materials shown in Table 2, and the mill bases 2 to 5 and the comparative mill bases 11 to 15 were produced in the same manner as the production of the mill base 1.
In Table 2, a commercially available dispersant Solsperse 24000GR (manufactured by Nippon Lubrizol Co., Ltd.) was used as a comparative dispersant. The yellow pigment PY-120 used Cloperant Novoperm Yellow H2G, and the magenta pigment PR-122 used Cinquacia Red manufactured by Ciba Specialty Chemicals.

(Evaluation of mill base)
The obtained mill base was evaluated according to the following method. The results are also shown in Table 2.

-Particle size-
For each mill base, a volume-based cumulative 90% particle diameter D90 was measured and evaluated using a light scattering diffraction type particle size distribution measuring apparatus (LA910, manufactured by Horiba, Ltd.).
In the case of PY-120 A: D90 is less than 400 nm B: D90 is 400 nm or more and less than 600 nm C: D90 is 600 nm or more and PR-122 A: D90 is less than 300 nm B: D90 is 300 nm or more and less than 600 nm C: D90 is 600nm or more

  From Table 2, when the specific polymer of the present invention is used, a fine high-concentration mill base can be prepared, and furthermore, since dispersion is stable, an increase in viscosity after dispersion can be suppressed. On the other hand, when a commercially available pigment dispersant or a pigment dispersant of a comparative example was used, there was a problem that the dispersion stability was insufficient and the pigment did not become sufficiently fine or the viscosity of the mill base increased after dispersion. . In addition, since the mill base 14 using C-4 (high molecular weight product) had a high viscosity, the dispersion liquid did not circulate in the disperser and could not be dispersed.

-Preparation of ink composition 1 for inkjet-
(C) A polymerizable compound and (d) a polymerization initiator were added to the mill base 1 and mixed gently, and then pressure filtered with a membrane filter to obtain an ink composition 1 for inkjet.
The amounts of millbase 1, polymerizable compounds (i), (ii), and (iii) and polymerization initiators (i), (ii), and (iii) added are shown below.

・ Millbase 1 10g
Polymerizable compound:
(i) 30 g of dipropylene glycol diacrylate (SR508, manufactured by Sartomer)
(ii) 1,6-hexanediol diacrylate (SR238, manufactured by Sartomer) 30 g
(iii) 2-phenoxyethyl acrylate (SR339, manufactured by Sartomer) 19.8 g
・ Polymerization initiator:
(i) Acylphosphine oxide compound (Lucirin TPO-L, manufactured by BASF) 8.0 g
(ii) Irgacure 184 (Ciba Specialty Chemicals) 2.0g
(iii) Benzophenone (Wako Pure Chemical Industries, Ltd.) 2.0g
・ Surfactant BYK-307 (by Big Chemie) 0.1g
・ Polymerization inhibitor Methoxyhydroquinone (Tokyo Kasei Co., Ltd.) 0.1g

-Preparation of Inkjet Ink Compositions 2-5, Comparative Inkjet Ink Compositions 11-13, 15-
Except for changing the mill base 1 used in the production of the ink-jet ink composition 1 to the mill bases 2 to 5 and 11 to 13 and 15 obtained in the production of the mill base, respectively, the same as the production of the ink-jet ink composition 1 Inkjet ink compositions 2 to 5 and comparative inkjet ink compositions 11 to 13 and 15 were obtained. In addition, since the mill base 14 was poorly dispersed, no ink jet ink was prepared.

(Evaluation of ink composition for inkjet)
The obtained ink-jet ink composition was evaluated according to the following method. The results are shown in Table 4.

-Viscosity-
The viscosity at 40 ° C. of each ink-jet ink composition was measured using an E-type viscometer.
A: Less than 15 mPa · s B: 20 mPa · s or more, less than 40 mPa · s C: 40 mPa · s or more (a level causing a problem in ejection)

-Viscosity stability-
The dispersion state after each ink-jet ink composition was stored at 25 ° C. for 1 month and stored at 60 ° C. for 1 week was evaluated by viscosity. The viscosity was measured at 40 ° C. and compared with the viscosity immediately after the ink composition was produced.
A: The increase in viscosity is less than 2%, and there is no problem with ejection properties.
○: The increase in viscosity is 2% or more and less than 5%, and there is no problem with the discharge property.
(Triangle | delta): The level which discharge stability falls when the increase in viscosity is 5% or more and less than 10%.
X: A level at which the increase in viscosity is 10% or more and the ejection stability is remarkably lowered.

-Particle size-
For each ink composition, a volume-based cumulative 90% particle diameter D90 was measured and evaluated using a light scattering diffraction type particle size distribution measuring apparatus (LA910, manufactured by Horiba, Ltd.).
In the case of PY-120 A: D90 is less than 400 nm B: D90 is 400 nm or more and less than 600 nm C: D90 is 600 nm or more and PR-122 A: D90 is less than 300 nm B: D90 is 300 nm or more and less than 600 nm C: D90 is 600nm or more

-Curability-
The obtained ink composition was printed on a vinyl chloride film with an inkjet printer (printing density 300 dpi, droplet ejection frequency 4 kHz, nozzle number 64), and then 1000 mJ / cm ² with a Deep UV lamp (USHIO SP-7). The sample was exposed under the conditions of energy of 1 to obtain a print sample.
The cured film was touched with a finger, and the presence or absence of stickiness was evaluated according to the following criteria.
A: No stickiness B: Slightly sticky C: Extremely sticky

  When an inkjet ink composition is prepared using the obtained mill base, it can be seen from Table 3 that the inkjet ink composition of the present invention using a specific dispersant can be stored stably for a long period of time not only at room temperature but also at a high temperature. Was found to be possible. Further, since the particle diameter was fine, the image was excellent in sharpness and the dischargeability was also good. On the other hand, the comparative ink compositions using commercially available dispersants and comparative polymers were particularly inferior in stability at high temperatures, the ejection stability after storage at high temperatures was deteriorated, and the image was uneven.

  The specific polymer of the present invention is considered to have excellent adsorptivity to the pigment by having a resin acid residue as a basic component. In addition, when a graft copolymer is used, it is considered that the structure is further designed so that the steric repulsion action by the polymer chain works effectively. It is presumed that the pigment is stabilized in the organic medium by this excellent adsorption action and dispersion stabilization action.

Claims (9)

The weight average molecular weight having at least an ethylenically unsaturated double bond at the terminal as a copolymer unit and at least (a) a pigment, (b) a repeating unit represented by the following general formula (I), and 500 to 20000 A pigment dispersion comprising a graft copolymer containing a repeating unit derived from a certain polymerizable oligomer and having a weight average molecular weight of 10,000 to 1,000,000, and (c) a radical polymerizable monomer .

In general formula (I), Q ¹ represents a hydrogen atom or a methyl group. Z ¹ represents —CO—, —COO—, —CONQ ² —, —OCO—, or a phenylene group, and Q ² represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. Z ² represents a single bond or a divalent linking group. Y ¹ represents a resin acid residue. The pigment dispersion according to claim 1, wherein the graft copolymer (b) further contains a repeating unit derived from dialkylaminoalkyl (meth) acrylate or alkylaminoalkyl (meth) acrylate as a copolymerization unit. The repeating unit derived from a polymerizable oligomer (macromonomer) which is a copolymer unit contained in the graft copolymer (b) is a repeating unit derived from a polymerizable oligomer represented by the following general formula (III): Item 3. The pigment dispersion according to item 1 or 2.

In general formula (III), Q ⁵ And Q ⁷ Each independently represents a hydrogen atom or a methyl group; ⁶ Represents an alkylene group having 1 to 12 carbon atoms. Y ² Is a phenyl group, a phenyl group having an alkyl group having 1 to 4 carbon atoms, or -COOQ ⁸ Represents. Q ⁸ Represents an alkyl group having 1 to 6 carbon atoms, a phenyl group, or an arylalkyl group having 7 to 10 carbon atoms. q1 represents an integer of 15 to 200. The pigment dispersion according to any one of claims 1 to 3, wherein Y ¹ in the general formula (I) is a residue of a resin acid derivative represented by the following general formula (II).

In general formula (II), Q ³ and Q ⁴ represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and Z ³ and Z ⁴ represent a single bond or a carbon-carbon double bond. . B is bonded to the carbon to which Z ⁴ is bonded, and forms a 6-membered ring including any of cyclohexane, cyclohexene, cyclohexadiene and benzene, including Z ⁴ . The 6-membered ring has one or two alkyl groups having 1 to 3 carbon atoms or alkenyl groups. Residue of the resin acid derivative represented by the general formula (II) is selected from abietic acid, neoabietic acid, parastrinic acid, levopimaric acid, dihydroabietic acid, tetrahydroabietic acid, pimaric acid, isopimaric acid, and dehydroabietic acid The pigment dispersion according to any one of claims 1 to 4, which is a residue of a resin acid derivative. Wherein (b) the graft copolymer has the general formula pigment dispersion according to any one of claims 5 repeating unit represented by the formula (I) from 2% to 50% by weight including claim 1. An ink composition comprising the pigment dispersion according to any one of claims 1 to 6 and (d) a photopolymerization initiator. The ink composition according to claim 7, wherein the viscosity at 25 ° C. is 0.5 mPa · s or more and 200 mPa · s or less. The ink composition according to claim 7 or 8 , which is used for inkjet.