JP5398447B2 - Ink jet ink composition - Google Patents

Description

  The present invention relates to an inkjet ink composition. Specifically, the present invention relates to an ink-jet ink composition excellent in pigment dispersibility and storage stability, photocurability, and flexibility of a cured film after curing. The ink composition of the present invention is suitable for printing images and characters on posters, signboards, POPs, signs, tableware, furniture, automobiles, and the like.

  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 inkjet 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 an ink that can be cured in a short time by irradiation with an active energy ray as an ink 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.

  In the curable ink jet recording, a polymerizable compound is used as a curing component. As the polymerizable compound, an ethylenically unsaturated bond compound is used. However, an image formed by photocuring is poor in flexibility of the cured film, and cracking occurs when the image is bent or stretched, and improvement is desired. It was rare. In order to improve flexibility, a polymerizable compound having an alkoxy group or a heterocyclic structure, a polymerizable compound exhibiting a high glass transition temperature when made into a homopolymer, or an ink using an oligo resin is disclosed (for example, Patent Document 1). However, there was room for improvement in long-term and high-temperature stability.

  In such a curable ink composition for inkjet, a pigment is used as a coloring material from the viewpoint of forming a high-definition image having excellent color developability and enhancing the durability of printed matter. In order to impart a clear color tone and high coloring power to the ink composition for inkjet, it is essential to make the pigment finer. In particular, in an inkjet ink composition, since the ejected ink droplets greatly affect the sharpness of the image, the amount of ejected droplets is small, and the thickness of the ink cured film formed by the ink composition It is essential to use finer particles than the pores of the inkjet nozzle. However, when pigment particles are refined in order to obtain a high coloring power, it is difficult to disperse pigment fine particles, and aggregates are likely to be generated. Further, there arises a problem that the viscosity of the ink composition increases due to excessive addition of the dispersant. The occurrence of pigment aggregates and the increase in the viscosity of the ink composition both adversely affect 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 for inkjet recording 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 therefore 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.

  The following various proposals have been made on the dispersant for obtaining a stable ink composition. That is, an ink composition using a pigment derivative as a dispersant (for example, see Patent Documents 2 and 3) or poly (ethyleneimine) -poly (12-hydroxystearic acid) in order to improve the affinity with the pigment. An ink composition containing a dispersant such as a graft polymer and a specific monomer for dissolving the dispersant and not using an organic solvent (see, for example, Patent Document 4), a graft having a heterocyclic residue that forms an organic pigment An ink composition using a copolymer as a dispersant (for example, see Patent Document 5) is disclosed.

  The pigment dispersants and ink compositions disclosed in these documents can surely finely disperse the pigment and the stability of the ink composition is higher than before, but there is still room for improvement in the stability of the ink composition. was there. In addition, the stability of the mill base has also been desired to improve the stability of the ink composition.

JP-T-2004-514014 JP 2003-119414 A JP 2004-18656 A JP 2004-131589 A JP 2007-9117 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the object of the present invention is that the dispersibility of the pigment is good, the dispersibility of the pigment is excellent even when stored for a long period of time, and the curability when forming an image by ink jet printing is excellent. An object of the present invention is to provide an ink composition for inkjet which can provide a flexible image in which cracking or peeling does not occur even if the image is bent.

  As a result of intensive studies, the present inventors have found that the dispersibility and dispersion stability of the pigment can be improved by the following means, and that an ink composition for inkjet having excellent curing sensitivity and flexibility can be obtained. Completed the invention.

<1> (A) at least one selected from the group consisting of (meth) acrylates having an alkoxy group or phenoxy group, and ethylenically unsaturated compounds having a heterocyclic structure, and (B) the glass transition temperature of the homopolymer Is a polymerizable compound in the range of 50 ° C. to 190 ° C., (C) a pigment, (D) a repeating unit represented by the following general formula (1) and a repeating unit derived from N-tertbutylaminoethyl methacrylate Ink-jet ink compositions containing

In general formula (1), R represents a hydrogen atom or a methyl group. J represents —CO—, —COO—, —CONR ¹ —, —OCO—, or a phenylene group. R ¹ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. W represents a single bond or a divalent linking group. P represents a heterocyclic residue that forms an organic pigment. )

<2> P in the general formula (1) is a heterocyclic residue that forms at least one organic pigment selected from the group consisting of quinacridone, benzimidazolone, indole, quinoline, carbazole, acridine, acridone, and anthraquinone. The inkjet ink composition according to <1>.

<3> Further described in <1> or <2>, further comprising (E) a polymerizable oligomer, wherein the content of the (E) polymerizable oligomer in the ink composition is in the range of 5.0 to 20% by mass. Ink-jet ink composition.

<4> The inkjet ink according to any one of <1> to <3>, wherein the (E) polymerizable oligomer is at least one selected from the group consisting of a polyester oligomer, a polyurethane oligomer, and an acrylic oligomer. Composition.

<5> The polymerizable compound in which the glass transition temperature of the homopolymer (B) is in the range of 50 ° C. to 190 ° C. is a polymerizable compound in which the glass transition temperature of the homopolymer is in the range of 60 ° C. to 190 ° C. < The inkjet ink composition according to any one of 1> to <4>.

  In the present invention, (D) the polymer containing the repeating unit represented by the general formula (1) has high adsorptivity to the pigment (C), and this action improves the dispersibility and dispersion stability of the pigment. In addition, since aggregation of the pigment is prevented when the ink composition is prepared, it is considered that stable ejection by inkjet is maintained even when stored for a long period of time. The component (B) has a high glass transition temperature of the polymer compound obtained by polymerizing and curing it, and is compatible with the compound obtained by curing the coexisting component (A) and the component (D). Since these components are mixed, the curability is excellent, and the image formed by curing is rich in flexibility, and it is considered that the image is not easily cracked or peeled even when bent. In addition, when an ethylenically unsaturated compound having a heterocyclic structure is used as component (A), the surface curability of the ink composition and the substrate followability during image folding are improved by the action of the heterocyclic ring. it is conceivable that.

  According to the present invention, the dispersibility of the pigment is good, the dispersion stability of the pigment is excellent even when stored for a long period of time, the curability when forming an image by ink jet printing, and the formed image is bent. Even in such a case, it is possible to provide an ink-jet ink composition that can provide a flexible image in which no cracks or peeling occurs in the image.

The inkjet ink composition of the present invention comprises (A) at least one selected from the group consisting of an (meth) acrylate having an alkoxy group or a phenoxy group, and an ethylenically unsaturated compound having a heterocyclic structure, and (B ) A polymerizable compound having a glass transition temperature of 50 ° C. to 190 ° C. of the homopolymer, (C) a pigment, (D) a repeating unit represented by the following general formula (1) and N-tertbutylaminoethyl And a polymer containing a repeating unit derived from methacrylate .

In general formula (1), R represents a hydrogen atom or a methyl group. J represents —CO—, —COO—, —CONR ¹ —, —OCO—, or a phenylene group, and R ¹ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. W represents a single bond or a divalent linking group. P represents a heterocyclic residue that forms an organic pigment.

[Inkjet ink composition]
The inkjet ink composition in the present invention includes at least one selected from the group consisting of (A) an (meth) acrylate having an alkoxy group or a phenoxy group, and an ethylenically unsaturated compound having a heterocyclic structure, and (B) A polymerizable compound having a glass transition temperature in the range of 50 ° C. to 190 ° C., (C) a pigment, (D) a repeating unit represented by the general formula (1) and N-tertbutyl And a polymer containing a repeating unit derived from aminoethyl methacrylate .
Below, each component which comprises the ink composition for inkjets of this invention is demonstrated in detail.

<(A) A compound selected from the group consisting of (meth) acrylates having an alkoxy group or phenoxy group, and ethylenically unsaturated compounds having a heterocyclic structure>
The inkjet ink composition of the present invention includes (A) at least one selected from the group consisting of an (meth) acrylate having an alkoxy group or a phenoxy group, and an ethylenically unsaturated compound having a heterocyclic structure (hereinafter, (A) (referred to as a polymerizable compound).
In the present invention, (meth) acrylate refers to methacrylate or acrylate. Further, the ethylenically unsaturated compound is a compound having an ethylenically unsaturated double bond and addition-polymerizing with a radical to form a polymer. Examples of compounds exhibiting such properties include (meth) acrylates, N-vinyl compounds, styrene derivatives, (meth) acrylamides, and vinyl ether compounds.
In the present invention, at least one (A) polymerizable compound selected from these groups is used. By appropriately selecting these (A) polymerizable compounds, the curing sensitivity, flexibility and adhesion can be controlled.

The inkjet ink composition of the present invention preferably includes (A) a polymerizable compound containing (meth) acrylate having an alkoxy group or a phenoxy group.
The (meth) acrylate having an alkoxy group or phenoxy group is preferably a (meth) acrylate having a C 1-10 alkoxy group or a phenoxy group which may have a substituent. Specifically, methoxyethyl (meth) acrylate, methoxy oligoethylene glycol (meth) acrylate having 2 to 23 repeating ethylene oxide units, 2- (ethoxyethoxy) ethyl (meth) acrylate, phenoxyethyl acrylate, phenoxytetraethylene glycol Examples thereof include acrylate, neopentyl glycol propoxylated (meth) acrylate, and methoxy oligopropylene glycol (meth) acrylate having 2 to 15 repeating propylene oxide units.

In a preferred embodiment, the inkjet ink composition of the present invention also contains an ethylenically unsaturated compound having a heterocyclic structure as the polymerizable compound (A).
The heterocyclic structure contained in the ethylenically unsaturated compound having a heterocyclic structure used in the present invention has 2 to 7 carbon atoms containing at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom. It is a monocyclic 3-membered ring to 8-membered ring. Of these, cyclic ethers having 2 to 6 carbon atoms, cyclic amines, lactones, and lactams are preferable, and cyclic ethers, cyclic amines, and lactams are more preferable.

  Specific examples of these ethylenically unsaturated compounds having a heterocyclic structure include glycidyl (meth) acrylate, 3-ethyl-3- (meth) acryloyloxyethyl oxetane, tetrahydrofurfuryl (meth) acrylate, and 2-tetrahydro. Pyranyl (meth) acrylate, (meth) acryloylmorpholine, N-vinylcaprolactam, 2,2,6,6-tetramethyl-3- (meth) acryloyloxypiperidine, 1,2,2,6,6- Examples include pentamethyl-3- (meth) acryloyloxypiperidine, furfuryl acrylate, (2-oxo-1-imidazolidinyl) ethyl methacrylate, and trimethylolpropane formal monoacrylate. Among these, tetrahydrofurfuryl acrylate, N-vinylcaprolactam, and 1,2,2,6,6-pentamethyl-3-acryloyloxypiperidine are preferable from the viewpoint of curing sensitivity.

In the inkjet ink composition of the present invention, the (A) polymerizable compound is at least selected from the group consisting of the above-mentioned (meth) acrylate having an alkoxy group or phenoxy group and an ethylenically unsaturated compound having a heterocyclic structure. Contains one species.
(A) When (meth) acrylate having an alkoxy group or phenoxy group is contained in the ink composition as the polymerizable compound, the glass transition temperature is lowered to give flexibility and an ether group is included. It is thought that the inhibition of polymerization by oxygen was suppressed and the photocurability and flexibility were improved.
In addition, when an ethylenically unsaturated compound having a heterocyclic structure is contained in the ink composition as the polymerizable compound (A), the curing sensitivity is enhanced and the adhesion is increased, so that the support to the support is followed. It is considered that the photo-curability and flexibility were improved by improving the property, preventing cracking during stretching and bending.

When (A) (meth) acrylate having an alkoxy group or phenoxy group is used as the polymerizable compound (A) in the ink-jet ink composition of the present invention, the ink composition has an alkoxy group or phenoxy group (meta ) Acrylate is preferably used in the range of 1% by mass to 60% by mass, more preferably in the range of 5% by mass to 50% by mass, and still more preferably 10% by mass to 40% by mass.
Further, when an ethylenically unsaturated compound having a heterocyclic structure is used as the polymerizable compound (A), the ethylenically unsaturated compound having a heterocyclic structure is 1% by mass to 70% with respect to the ink composition. It is preferably used in the range of mass%, more preferably in the range of 5 mass% to 50 mass%, further preferably 10 mass% to 40 mass%.

  As the polymerizable compound (A) in the present invention, at least one kind may be used from the group consisting of (meth) acrylate having an alkoxy group or phenoxy group and an ethylenically unsaturated compound having a heterocyclic structure. Good. Moreover, you may use 1 or more types from the (meth) acrylate which has an alkoxy group or a phenoxy group, and the ethylenically unsaturated compound which has a heterocyclic structure, respectively.

<(B) Polymerizable compound whose homopolymer has a glass transition temperature in the range of 50 ° C. to 190 ° C.>
The polymerizable compound (hereinafter referred to as the (B) polymerizable compound as appropriate) having a glass transition temperature of (B) homopolymer in the range of 50 ° C. to 190 ° C. contained in the inkjet ink composition of the present invention. The polymeric compound whose glass transition temperature (Tg) of the homopolymer (homopolymer) of a polymeric compound is the range of 50 to 190 degreeC is shown.
In the present invention, the polymerizable compound (B) does not include the alkoxy group or phenoxy group-containing (meth) acrylate that is the polymerizable compound (A) and an ethylenically unsaturated compound having a heterocyclic structure.

The glass transition temperature of the homopolymer of the polymerizable compound (B) used in the present invention is in the range of 50 ° C to 190 ° C, more preferably 60 ° C to 190 ° C, and more preferably 75 ° C to 190 ° C. Preferably there is.
By using a polymerizable compound having a glass transition temperature in the above range, the flexibility may be lowered when cured alone. In the present invention, (B) the polymerizable compound is used together with (A) the polymerizable compound. By using it, it is possible to achieve high sensitivity, to suppress a decrease in flexibility, and to obtain an image in which no cracking or peeling occurs when cured.

  Examples of the polymerizable compound (B) suitably used in the present invention include, for example, benzyl methacrylate (glass transition temperature of homopolymer: 54 ° C., and the parentheses indicate the glass transition temperature of the homopolymer), 2- Hydroxyethyl methacrylate (55 ° C), ethyl methacrylate (65 ° C), cyclohexyl methacrylate (66 ° C), 2-methacryloyloxyethyl hexahydrophthalic acid (75 ° C), 3-hydroxypropyl methacrylate (73 ° C), 2-methacrylic acid Leuroxyethylphthalic acid (75 ° C), isobornyl acrylate (94 ° C), trimethylcyclohexyl methacrylate (97 ° C), methyl methacrylate (105 ° C), t-butyl methacrylate (107 ° C), isobornyl methacrylate (180 ° C) ), Dicyclopentani Acrylate (120 ° C.), dicyclopentenyl acrylate (120 ° C.), dicyclopentanyl methacrylate (175 ° C.), and the like. Among these, an acrylate compound having an alicyclic structure is more preferable from the viewpoint of curability.

  The glass transition temperature of the homopolymer (Homopolymer) of the (B) polymerizable compound used in the present invention is the differential scanning of the homopolymer obtained by polymerizing the (B) polymerizable compound alone by radical polymerization or the like. It is the value measured by calorimetry (DSC). The glass transition temperature can also be measured by a known method such as dynamic viscoelasticity measurement.

(B) polymeric compound in this invention may use 1 type, and may use 2 or more types together. In addition, the content of the polymerizable compound (B) in the ink composition is preferably included in the range of 1% by mass to 60% by mass with respect to the ink composition, and is included in the range of 1% by mass to 50% by mass. It is more preferable that it is contained in the range of 1% by mass to 40% by mass. Within this range, the flexibility of the cured film and the ink curing sensitivity are good.
In the present invention, the ratio of the polymerizable compound (A) to the polymerizable compound (B) is preferably (A) polymerizable compound: (B) polymerizable compound = 20: 80 to 80:20 in terms of mass, 35:65 to 75:25 is more preferable. When the ratio is within this range, an image that does not crack or peel off when cured can be obtained.

In the present invention, in addition to the polymerizable compound (A) and the polymerizable compound (B), it is also preferable to contain other ethylenically unsaturated compounds not included in these. Other ethylenically unsaturated compounds can be contained in a range that does not impair the effects of the present invention in view of the viscosity of the target ink composition, the dispersion stability of the pigment, the curing sensitivity, and the cured film properties. Since the ink composition of the present invention is cured by radical polymerization, a known radical polymerizable monomer can be used. Examples of these include, for example, (meth) acrylate compounds, (meth) acrylamide compounds, vinyl ether compounds, styrene compounds, N-vinyl compounds described in JP-A-2008-208190 and 2008-266561. Among these, (A) a polymerizable compound and (B) a monomer that does not correspond to the polymerizable compound are exemplified.
Among these, in the present invention, as the other radical polymerizable monomer, it is preferable to use one or more monomers selected from (meth) acrylate compounds, (meth) acrylamide compounds, and vinyl ether compounds. It is also preferable to use a polyfunctional polymerizable monomer having a plurality of polymerizable functional groups and a monofunctional polymerizable monomer from the viewpoints of curing speed, viscosity of the ink composition, and film physical properties of the print sample.

  The content of the polymerizable compound (A), the polymerizable compound (B), and the other polymerizable compound in the ink composition for inkjet of the present invention is suitably 50 to 95% by mass with respect to the ink composition. , Preferably it is 60-92 mass%, More preferably, it is the range of 70-90 mass%. If it is used less than this range, the curability may be lowered.

<(C) Pigment>
The ink-jet ink composition of the present invention contains (C) a pigment.
In the present invention, the (C) pigment functions as a color material for the ink-jet ink composition. In the present invention, a pigment having a fine particle diameter is uniformly and stably dispersed in the ink composition by the action of a polymer containing a repeating unit represented by (D) general formula (1) described later. As a result, the ink composition of the present invention is excellent in color developability and can form a sharp and excellent weather-resistant image. Further, by reducing coarse secondary particles as much as possible, an ink composition for inkjet having excellent ejection stability is provided.

As the (C) pigment in the present invention, either an organic pigment or an inorganic pigment can be used, but an organic pigment is preferred.
There is no restriction | limiting in particular as an organic pigment, Although it can select suitably according to the objective, A well-known organic pigment is mentioned preferably from a viewpoint of the similarity on the chemical structure of a pigment and a pigment dispersant. Examples of the pigment used in the present invention include, for example, “Pigment Dictionary” (2000), edited by Seijiro Ito. 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 include a yellow pigment, a magenta pigment, a cyan pigment, a green pigment, an orange pigment, a brown pigment, a violet pigment, and a black pigment.

  The yellow pigment is a pigment exhibiting a yellow color, for example, a monoazo pigment, a disazo pigment, a non-benzidine azo pigment, an azo lake pigment, a condensed azo pigment, an acidic dye lake pigment, a basic dye lake pigment, an anthraquinone pigment, or a quinophthalone pigment. And pyrazolone pigments, acetolone pigments, metal complex pigments, nitroso pigments, metal complex azomethine pigments, benzimidazolone pigments and isoindoline pigments. Of these, examples of pigments that can be preferably used in the present invention include C.I. I. Pigment Yellow (hereinafter abbreviated as PY) 1, PY3, PY12, PY13, PY14, PY16, PY17, PY18, PY24, PY60, PY74, PY83, PY93, PY94, PY95, PY97, PY100, PY109, PY110, PY115, PY117, PY120, PY128, PY138, PY139, PY150, PY151, PY153, PY154, PY155, PY166, PY167, PY173, PY175, PY180, PY181, PY185, PY194, PY213, PY213, PY213, PY214 Among them, benzimidazolone pigments such as monoazo pigments, disazo pigments, and acetolone pigments, and isoindoline are preferable, and PY74, PY120, PY151, PY155, PY180, and PY185 are preferable.

The magenta pigment is a pigment exhibiting red or magenta color, for example, a monoazo pigment, β-naphthol pigment, disazo pigment, azo lake pigment, condensed azo pigment, acidic dye lake pigment, basic dye lake pigment, anthraquinone pigment Thioindigo pigments, perinone pigments, perylene pigments, quinacridone pigments, isoindolinone pigments, alizarin lake pigments, naphtholone pigments, naphthol AS-based lake pigments, naphthol AS pigments, diketopyrrolopyrrole pigments and the like.
Of these, examples of pigments that can be preferably used in the present invention include C.I. I. Pigment Red (hereinafter abbreviated as PR) 1, PR2, PR3, PR4, PR5, PR6, PR21, PR38, PR42, PR46, PR53: 1, PR57: 1, PR52: 1, PR46, PR48, PR81, PR83, PR88, PR144, PR149, PR166, PR179, PR178, PR190, PR224, PR123, PR224, PR19, PR122, PR202, PR207, PR209, PR180, PR83, PR170, PR171, PR172, PR174, PR175, PR176, PR177, PR179, PR185, PR194, PR208, PR214, PR220, PR221, PR242, PR247, PR254, PR255, PR256, PR262, PR268, PR264 PR269, PR272, PR282, C. I. Pigment violet 19 and the like. Of these, quinacridone pigments are preferable, and PR42, PR122, PR202, PR209, PR282, C.I. I. Pigment Violet 19 is preferable.

  The cyan pigment is a pigment exhibiting blue or cyan color, and examples thereof include a disazo pigment, a phthalocyanine pigment, an acid dye lake pigment, a basic dye lake pigment, an anthraquinone pigment, and an alkali blue pigment. Examples of the pigment that can be preferably used in the present invention include C.I. I. Pigment Blue (hereinafter abbreviated as PB) 1, PB15, PB15: 1, PB15: 2, PB15: 3, PB15: 4, PB15: 6, PB16, PB18, PB24, PB25, PB60, PB79 and the like. Among these, a copper phthalocyanine pigment is preferable, and PB15, PB15: 1, PB15: 2, PB15: 3, PB15: 4, and PB15: 6 are preferable.

  The green pigment is a pigment exhibiting green, and examples thereof include phthalocyanine pigments and metal complex pigments. Examples of the pigment that can be preferably used in the present invention include C.I. I. Pigment green (hereinafter abbreviated as PG) 7, PG8, PG10, PG36, and the like.

  The orange pigment is a pigment exhibiting an orange color, for example, an isoindoline pigment, an anthraquinone pigment, Β-naphthol pigment, naphthol AS pigment, isoindolinone pigment, perinone pigment, disazo pigment, quinacridone pigment, acetron pigment, Examples include pyrazolone pigments. Examples of the pigment that can be preferably used in the present invention include C.I. I. Pigment Orange (hereinafter abbreviated as PO) 2, PO3, PO4, PO5, PO13, PO15, PO16, PO22, PO24, PO34, PO36, PO38, PO43, PO48, PO49, PO51, PO55, PO60, PO61, PO62, PO64, PO66, PO72, PO74 etc. are mentioned.

The brown pigment is a pigment exhibiting brown color, and examples thereof include naphthron pigments such as PBr25 and PBr32.
The violet pigment is a pigment exhibiting a purple color, and examples thereof include a naphthron pigment, a perylene pigment, a naphthol AS pigment, and a dioxazine pigment. Examples of the pigment that can be preferably used in the present invention include C.I. I. Pigment violet (hereinafter abbreviated as PV) 13, PV17, PV23, PV29, PV32, PV37, PV50, and the like.

  The black pigment is a pigment exhibiting black, and examples thereof include carbon black, indazine pigment, perylene pigment, and the like. I. Pigment black (hereinafter abbreviated as PBk) 1, PBk7, PBk31, PBk32, and the like.

The smaller the average particle size of the pigment used in the present invention, the better the color developability. Therefore, it is preferably 0.01 to 0.4 μm, more preferably 0.02 to 0.3 μm. The pigment, polymer, dispersion medium selection, dispersion conditions, and post-treatment process conditions are set so that the maximum particle size is 3 μm or less, preferably 2 μm or less.
In the present invention, the clogging of the ink head nozzles can be suppressed by this particle size control, and the storage stability of the ink, the transparency of the ink, and the curing sensitivity can be maintained. In the present invention, since a polymer containing a repeating unit represented by (D) general formula (1) described later is used, the pigment is excellent in dispersibility and dispersion stability, and even when a fine particle pigment is used, it is uniform. A stable ink composition is obtained.

  The particle size of the pigment in the ink composition can be measured by a known measurement method. Specifically, it 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.

  In the present invention, the pigment content is preferably added in an amount of 1% by mass to 20% by mass, more preferably 1.5% by mass to 15% by mass in terms of solid content in the ink composition.

<(D) Polymer containing repeating unit represented by general formula (1) and repeating unit derived from N-tertbutylaminoethyl methacrylate >
The ink composition for inkjet in the present invention is (D) a polymer containing a repeating unit represented by the general formula (1) (hereinafter, appropriately referred to as a specific polymer) , and the general formula (1). In addition to the repeating unit represented by the formula, a polymer containing a repeating unit derived from N-tertbutylaminoethyl methacrylate is contained .
In the present invention, the specific polymer is a polymer having a heterocyclic residue that forms an organic pigment. The specific polymer is particularly preferably used as a pigment dispersant, and has a heterocyclic residue having high affinity with the pigment due to van-der-Waals interaction, so that the adsorptivity with the pigment is good. The pigment can be stably dispersed. Moreover, since it is a polymer compound having a specific repeating unit, (C) pigment dispersion can be stabilized by the steric repulsion effect of the polymer chain.

  The specific polymer (D) in the present invention is a polymer having a repeating unit represented by the following general formula (1).

In general formula (1), R represents a hydrogen atom or a methyl group. J represents —CO—, —COO—, —CONR ¹ —, —OCO—, or a phenylene group, and R ¹ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. W represents a single bond or a divalent linking group. P represents a heterocyclic residue that forms an organic pigment.

J in the general formula (1) represents —CO—, —COO—, —CONR ¹ —, —OCO—, or a phenylene group, and R ¹ represents a hydrogen atom, an alkyl group (for example, a methyl group, an ethyl group, n -Propyl group, i-propyl group, n-butyl group, n-hexyl group, n-octyl group, 2-hydroxyethyl group, etc.) and an aryl group (for example, phenyl group).
Of these, J is preferably —COO—, —CONH—, or a phenylene group.

W in the general formula (1) represents a single bond or a divalent linking group. Examples of the divalent linking group include a linear, branched or cyclic alkylene group, an aralkylene group, and the like, and these may have a substituent. The alkylene group represented by W is preferably an alkylene group having 1 to 10 carbon atoms, and more preferably an alkylene group having 1 to 4 carbon atoms. For example, a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, an octylene group, a decylene group, and the like can be given. Among them, a methylene group, an ethylene group, a propylene group, and the like are particularly preferable. The aralkylene group represented by W is preferably an aralkylene group having 7 to 13 carbon atoms, and examples thereof include a benzylidene group and a cinnamylidene group. The arylene group represented by W is preferably an arylene group having 6 to 12 carbon atoms, and examples thereof include a phenylene group, a cumenylene group, a mesitylene group, a tolylene group, and a xylylene group, and among them, a phenylene group is particularly preferable. Further, in each divalent linking ^{group, -NR 2 -, - NR 2} R 3 -, - COO -, - OCO -, - O -, - SO 2 NH -, - NHSO 2 -, - NHCOO- , -OCONH-, or a group derived from a heterocyclic ring may be interposed as a linking group. R ² and R ³ each independently represents a hydrogen atom or an alkyl group, and preferred examples include a hydrogen atom, a methyl group, an ethyl group, and a propyl group.
Among the linking groups represented by W, a single bond and an alkylene group are particularly preferable, and a methylene group, an ethylene group, and a 2-hydroxypropylene group are particularly preferable.

P in the general formula (1) represents a heterocyclic residue that forms an organic pigment, and is a phthalocyanine series, an insoluble azo series, an azo lake series, an anthraquinone series, a quinacridone series, a benzimidazolone series, an indole series, a quinoline series, or a carbazole series. , Acridine series, acridone series, dioxazine series, diketopyrrolopyrrole series, anthrapyrimidine series, ansanthrone series, indanthrone series, flavanthrone series, perinone series, perylene series, thioindigo series, quinophthalone series Residue. Examples of the heterocyclic residue include thiophene, furan, xanthene, pyrrole, imidazole, isoindoline, isoindolinone, benzimidazolone, indole, quinoline, carbazole, acridine, acridone, quinacridone, anthraquinone, naphthalimide, phthalimide, quinaldine, quinophthalone. Etc. Of these, quinacridone, benzimidazolone, indole, quinoline, carbazole, acridine, acridone, and anthraquinone are particularly preferred. Furthermore, it is particularly preferred that these heterocyclic residues are heterocyclic residues similar to the pigment used. Specifically, for quinacridone pigments, acridone, anthraquinone and the like are particularly preferably used in the present invention.
Preferred specific examples of the structural unit represented by the general formula (1) are given below. Note that the present invention is not limited to this.

  The specific polymer in the present invention is particularly preferably a graft copolymer containing a macromonomer having an ethylenically unsaturated double bond at the terminal as a copolymer unit.

The macromonomer optionally used for the specific polymer in the present invention comprises a polymer chain portion and a polymerizable functional group portion 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.
Moreover, it is preferable that this macromonomer has the number average molecular weight (Mn) of polystyrene conversion in the range of 1000-10000, and the range of 2000-9000 is especially preferable.
The polymer chain part 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 macromonomer is preferably a macromonomer represented by the following general formula (2).

In General Formula (2), R ¹¹ and R ¹³ each independently represent a hydrogen atom or a methyl group, and R ¹² is an alkylene group having 1 to 12 carbon atoms (preferably an alkylene group having 2 to 4 carbon atoms). Yes, it may have a substituent (for example, a hydroxyl group, and may be further linked via an ester bond, an ether bond, an amide bond, etc.). Y is a phenyl group, a phenyl group having an alkyl group having 1 to 4 carbon atoms, or —COOR ¹⁴ (wherein R ¹⁴ is an alkyl group having 1 to 12 carbon atoms, a phenyl group, or a carbon group having 7 to 10 carbon atoms). Represents an arylalkyl group), and q is an integer of 20 to 200.
Y is preferably a phenyl group or —COOR ¹⁴ (wherein R ¹⁴ is an alkyl group having 1 to 12 carbon atoms).

  Preferred examples of the macromonomer include polymethyl (meth) acrylate, poly-n-butyl (meth) acrylate and poly-i-butyl (meth) acrylate, poly (butyl methacrylate-co-2-hydroxyethyl methacrylate), poly (Methyl methacrylate-co-2-hydroxyethyl methacrylate), a polymer in which a (meth) acryloyl group is bonded to one molecular end of polystyrene can be exemplified. 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 Toagosei Chemical Industry Co., Ltd.) and one-terminal methacryloylated poly-n-butyl acrylate oligomer (Mn = 6000, trade name: AB-6, Toagosei Chemical Industry Co., Ltd.) )), And poly (butyl methacrylate-co-2-hydroxyethyl methacrylate) oligomer (Mn = 6000, trade name: AX-707S, manufactured by Toagosei Co., Ltd.).

  The macromonomer is preferably not only a macromonomer represented by the general formula (2) but also a macromonomer represented by the following general formula (3), which is appropriately selected depending on the polymerizable compound to be used. You can choose.

In General Formula (3), R ²¹ represents a hydrogen atom or a methyl group, and R ²² represents an alkylene group having 1 to 8 carbon atoms. X ²¹ represents —OR ²³ or —OCOR ²⁴ . Here, R ²³ and R ²⁴ represent a hydrogen atom, an alkyl group, or an aryl group. n represents an integer of 2 to 200.

In the general formula (3), R ²¹ represents a hydrogen atom or a methyl group. R ²² represents an alkylene group having 1 to 8 carbon atoms, among which an alkylene group having 1 to 6 carbon atoms is preferable, and an alkylene group having 2 to 3 carbon atoms is more preferable. X ²¹ represents —OR ²³ or —OCOR ²⁴ . Here, R ²³ represents 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. R ²⁴ represents an alkyl group having 1 to 18 carbon atoms. Moreover, n represents the integer of 2-200, the integer of 5-100 is preferable and the integer of 10-100 is especially preferable.
Examples of the polymerizable oligomer represented by the general formula (3) 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 macromonomer represented by the general formula (3) according to the present invention is also available as a commercial product as described above, and as a commercial product, methoxypolyethylene glycol methacrylate (trade name: NK ester M-40G, M- 90G, M-230G (above, manufactured by Toa Synthetic Chemical Industry Co., Ltd.); trade names: Bremer PME-100, PME-200, PME-400, PME-1000, PME-2000, PME-4000 (above, Nippon Oil & Fats) ), Polyethylene glycol monomethacrylate (trade names: Blemmer PE-90, PE-200, PE-350, manufactured by NOF Corporation), polypropylene glycol monomethacrylate (trade names: Blemmer PP-500, PP) -800, PP-1000, manufactured by NOF Corporation), polyethylene glycol polymer Propylene glycol monomethacrylate (trade name: Blemmer 70PEP-370B, manufactured by NOF Corporation), polyethylene glycol polytetramethylene glycol monomethacrylate (trade name: BREMMER 55PET-800, manufactured by NOF Corporation), polypropylene glycol polytetra And methylene glycol monomethacrylate (trade name: BLEMMER NHK-5050, manufactured by NOF Corporation).
The macromonomer is preferably not only a macromonomer represented by the general formula (2) and the general formula (3) but also a macromonomer represented by the following general formula (4) or the general formula (5). These are particularly preferably selected as appropriate according to the polymerizable compound used.

In the general formula (4), R ³¹ represents a hydrogen atom or a methyl group, and R ³² represents an alkylene group having 1 to 1 carbon atoms. R ³³ represents an optionally branched alkylene group having 3 to 11 carbon atoms, and R ³⁴ represents a hydrogen atom or an optionally branched alkyl group or aryl group having 1 to 12 carbon atoms. L ³¹ is from the group consisting of a single bond, —O—, —S—, —C (═O) —, —NH—, —C (OH) —, —C (CH ₃ ) —, —CH ₂ —. It is a divalent linking group comprising a combination of 1 to 6 selected. m ¹ represents 1 to 60.
In General Formula (5), R ³⁵ represents a hydrogen atom or a methyl group, and R ³⁶ represents an alkylene group having 1 to 1 carbon atoms. R ³⁷ represents an alkylene group having 3 to 11 carbon atoms which may be branched, and R ³⁸ represents a hydrogen atom or an alkyl group or aryl group having 1 to 12 carbon atoms which may be branched. L ³² is from the group consisting of a single bond, —O—, —S—, —C (═O) —, —NH—, —C (OH) —, —C (CH ₃ ) —, —CH ₂ —. It is a divalent linking group comprising a combination of 1 to 6 selected. m ² represents 1 to 60.

  As the macromonomer used for the specific polymer in the present invention, among the macromonomers, a macromonomer including a polymer obtained by addition polymerization of a monomer having a cyclic ether, a lactone, and an ethylenically unsaturated bond is used as a copolymerization component. It is preferable.

The specific polymer used in the present invention is particularly preferably a copolymer with a monomer having a nitrogen atom. Specific examples of the monomer having a nitrogen atom include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, 1- (N, N-dimethylamino) -1, 1- Dimethylmethyl (meth) acrylate, N, N-dimethylaminohexyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-diisopropylaminoethyl (meth) acrylate, N, N-di-n- Butylaminoethyl (meth) acrylate, N, N-di-i-butylaminoethyl (meth) acrylate, morpholinoethyl (meth) acrylate, piperidinoethyl (meth) acrylate, 1-pyrrolidinoethyl (meth) acrylate, N, N -Methyl-2-pyrrolidylaminoethyl (meth) acrylate DOO and N, N- methylphenyl aminoethyl (meth) acrylate, N-tert-butylaminoethyl methacrylate (or (meth) acrylates);
Dimethyl (meth) acrylamide, diethyl (meth) acrylamide, diisopropyl (meth) acrylamide, di-n-butyl (meth) acrylamide, di-i-butyl (meth) acrylamide, morpholino (meth) acrylamide, piperidino (meth) acrylamide, N-methyl-2-pyrrolidyl (meth) acrylamide and N, N-methylphenyl (meth) acrylamide (above (meth) acrylamides);
2- (N, N-dimethylamino) ethyl (meth) acrylamide, 2- (N, N-diethylamino) ethyl (meth) acrylamide, 3- (N, N-diethylamino) propyl (meth) acrylamide, 3- (N , N-dimethylamino) propyl (meth) acrylamide, 1- (N, N-dimethylamino) -1,1-dimethylmethyl (meth) acrylamide and 6- (N, N-diethylamino) hexyl (meth) acrylamide (above) Aminoalkyl (meth) acrylamides);
p-vinylbenzyl-N, N-dimethylamine, p-vinylbenzyl-N, N-diethylamine, p-vinylbenzyl-N, N-dihexylamine (above vinylbenzylamines);
And 2-vinylpyridine, 4-vinylpyridine, and N-vinylimidazole.

Among these, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N-tertbutylaminoethyl methacrylate, 3- ( N, N-diethylamino) propyl (meth) acrylamide and 3- (N, N-dimethylamino) propyl (meth) acrylamide are preferred. In the present invention, among these, a specific polymer that is a copolymer with N-tertbutylaminoethyl methacrylate is essential.
It is also a preferred embodiment that the specific polymer used in the present invention is a copolymer with another copolymerizable monomer. Examples of other copolymerizable monomers include unsaturated carboxylic acids (eg, (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid and fumaric acid), aromatic vinyl compounds (eg, styrene, α-methylstyrene) , Vinyltoluene, 2-vinylpyridine, 4-vinylpyridine, N-vinylimidazole, etc.), (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), (meth) acrylic acid substituted alkyl esters (eg, glycidyl (meth) acrylate, 2-hydroxy Ethyl (meth) acrylate), carboxylic acid vinyl ester Examples, vinyl acetate and vinyl propionate), vinyl cyanides (e.g., (meth) and acrylonitrile and α- chloro acrylonitrile), and aliphatic conjugated dienes (e.g., 1,3-butadiene and isoprene). Among these, unsaturated carboxylic acids, (meth) acrylic acid alkyl esters, (meth) acrylic acid alkyl aryl esters and carboxylic acid vinyl esters are preferred.

The specific polymer in the present invention is a copolymer composed of a unit represented by the general formula (1) and a unit given from the polymerizable oligomer (macromonomer), or a unit represented by the general formula (1), It is preferably a copolymer comprising units given from the macromonomer and units given from a monomer having a nitrogen atom.
It is preferable that the copolymer has a repeating unit represented by the general formula (1) in a range of 5 to 70% by mass (particularly 5 to 30% by mass) of all repeating units. Furthermore, the unit given by the macromonomer is 30 to 80% by mass (particularly 50 to 80% by mass) of all repeating units, and the repeating unit derived from the monomer having a nitrogen-containing group is 5 to 80% by mass of all repeating units. % (Especially 5 to 50% by mass).

  Furthermore, when using the other monomer copolymerizable with these, it is preferable to have the repeating unit derived from this monomer in the range of 5-30 mass% of all the repeating units.

  The weight average molecular weight (Mw) of the specific polymer in the present invention can be arbitrarily determined from the viewpoints of the viscosity and dispersion stability of the ink composition for inkjet. That is, when the viscosity is set low, the viscosity is preferably low, and the molecular weight is preferably set high from the viewpoint of improving dispersion stability. In the inkjet ink composition of the present invention, Mw is preferably in the range of 5,000 to 250,000, and particularly preferably in the range of 10,000 to 200,000 because of low viscosity and high dispersibility. If it exists in this range, the inkjet ink composition which can be stably discharged even if it preserve | saves with time as an inkjet ink composition can be obtained. The weight average molecular weight is a polystyrene equivalent weight average molecular weight measured by gel permeation chromatography (carrier: N-methylpyrrolidone).

Although the example of a specific polymer is shown below, this invention is not restrict | limited to these.
Monomer / terminal methacryloylated polymethylmethacrylate copolymer giving the above exemplified structural unit M-1 Monomer / polyethylene glycol mono (meth) acrylate copolymer giving the above exemplified structural unit M-1 above exemplified structural unit M- Monomer / terminal methacryloylated polycaprolactone copolymer to give 1 Monomer / terminal methacryloylated polymethyl methacrylate copolymer to give the structural unit M-4 exemplified above Monomer / polyethylene glycol mono (1) to give the structural unit M-4 exemplified above (Meth) acrylate copolymer Monomer giving the above exemplified structural unit M-4 / Terminal methacryloylated polycaprolactone copolymer Monomer giving the above exemplified structural unit M-4 / 3- (N, N-dimethylamino) propylacrylamide / Terminal methacrylo Monomer / 3- (N, N-dimethylamino) propylacrylamide / polyethylene glycol mono (meth) acrylate copolymer giving the structural unit M-4 exemplified above Monomer that gives 4 / 3- (N, N-dimethylamino) propylacrylamide / terminal methacryloylated polymethyl methacrylate / polyethylene glycol mono (meth) acrylate copolymer Monomer that gives the structural unit M-4 exemplified above / 2- ( N, N-dimethylamino) ethyl (meth) acrylate / terminal methacryloylated polymethyl methacrylate copolymer Monomer to give the structural unit M-4 exemplified above / 2-tert-butylaminoethyl methacrylate / terminal methacryloylated polymethyl methacrylate Copolymer / monomer giving the structural unit M-4 exemplified above / p-vinylbenzyl-N, N-dimethylamine / polyethylene glycol mono (meth) acrylate copolymer monomer giving the structural unit M-4 exemplified above / 3- (N, N-dimethylamino) ethyl (meth) acrylate / terminal methacryloylated poly n-butyl methacrylate copolymer Monomer / styrene / terminal methacryloylated polymethyl methacrylate copolymer to give the structural unit M-4 exemplified above Monomer giving the above exemplified structural unit M-4 / N, N-dimethylacrylamide / terminated methacryloylated polymethyl methacrylate copolymer Monomer giving the above exemplified structural unit M-6 / 3- (N, N-dimethylamino) Propylacrylamide / terminal methacryloylated polymethylmeta Crylate copolymer Monomer giving structural unit M-6 exemplified above / 3- (N, N-dimethylamino) propylacrylamide / polyethylene glycol mono (meth) acrylate copolymer Monomer giving structural unit M-6 exemplified above / 3- (N, N-dimethylamino) propylacrylamide / terminated methacryloylated polymethyl methacrylate copolymer Monomer giving structural unit M-13 as exemplified above / 3- (N, N-dimethylamino) ethyl (meth) acrylate / Terminal methacryloylated polymethyl methacrylate copolymer Monomer giving the structural unit M-17 illustrated above / 3- (N, N-dimethylamino) propylacrylamide / terminal methacryloylated polymethyl methacrylate copolymer Structural unit M illustrated above Monomer to give -13/3 (N, N-dimethylamino) ethyl (meth) acrylate / polyethylene glycol mono (meth) acrylate copolymer Monomer giving structural unit M-14 as exemplified above / 3- (N, N-dimethylamino) ethyl (meth) Acrylate / terminated methacryloylated polymethylmethacrylate copolymer

  Such a specific polymer can be obtained by radical polymerization of a polymerizable oligomer, a monomer having a nitrogen atom-containing group used in combination as desired, and other monomers in a solvent. At that time, a radical polymerization initiator is generally used, but in addition to the initiator, a chain transfer agent (eg, 2-mercaptoethanol, dodecyl mercaptan, etc.) may be added and synthesized.

Only one type of specific polymer may be added to the ink composition of the present invention, or two or more types may be used in combination.
1-100 mass% is preferable with respect to the addition amount of a pigment, and, as for content of the specific polymer in an ink composition, it is still more preferable that it is 5-50 mass%. By including the specific polymer in this range, the dispersibility of the pigment becomes good, and a viscosity that can be discharged by an ink jet printer can be realized.
In the ink composition of the present invention, a known pigment dispersant can be used in combination with the specific polymer as long as the effect is not impaired. The addition amount is preferably 50% by mass or less of the specific polymer.

<(E) Polymerizable oligomer>
It is also a preferred embodiment that the inkjet ink composition of the present invention further contains (E) a polymerizable oligomer as a polymerizable compound. Here, (E) polymerizable oligomer is a compound having at least one polymerizable functional group at the end of the oligomer and has a weight average molecular weight in the range of 300 to 10,000.
(E) As the terminal polymerizable functional group of the polymerizable oligomer, a (meth) acryloyl group, vinyl ether group, or styryl group is preferably introduced from the viewpoint of polymerizability. Of these, oligomers into which an acryloyl group has been introduced are more preferred. (E) As the polymerizable oligomer, it is preferable to use at least one selected from polyester oligomers, urethane oligomers, modified polyether oligomers, acrylic oligomers, and epoxy oligomers. By containing these polymerizable oligomers, the ink composition for inkjet according to the present invention can make the viscosity suitable for ejection, and the curing sensitivity and adhesion to the substrate can be further improved.

  The polyester oligomer used in the present invention refers to a polyester having one or more polymerizable functional groups, the urethane oligomer refers to a polyurethane having one or more polymerizable functional groups, and a modified polyether oligomer is 2 A modified polyether resin having one or more polymerizable functional groups, an acrylic oligomer is an acrylic resin having one or more polymerizable functional groups, and an epoxy oligomer is an epoxy having one or more polymerizable functional groups The modified resin is shown. From the viewpoint of improving curability, these oligomers are preferably blended with epoxy acrylate or urethane acrylate. From the viewpoint of improving adhesion, it is preferable to use epoxy acrylate or urethane acrylate. From the viewpoint of improving film physical properties such as property, it is preferable to use a polyether oligomer, an acrylic oligomer, or a polyester oligomer. These blends are adjusted according to the type of substrate and the performance of the cured film suitable for the application. Among these, it is more preferable to use polyester acrylate or urethane acrylate from the viewpoints of sensitivity, adhesion, flexibility, and viscosity balance.

  Examples of the (E) polymerizable oligomer used in the present invention include CN9001, CN9002, CN902J75, CN961H81, CN963A80, CN963B80, CN963E75, CN964, CN964B85, CN965, CN968, CN981, CN982A75, CN983, CN984, CN9893, CN996, CN970A60, CN972, CN975, CN978, CN991, CN992, CN999, CN816, CN817, CN818, CN292, CN293, CN294, CN294, CN736, CN738, CN750, CN2100, CN2200, CN2101 (above, manufactured by Sartomer) Ebecryl 230, Ebecryl 244, Ebecryl 245, Ebecryl 270, Ebecryl 284, Ebecryl 285, Ebecryl 4830, Ebecryl 4858, Ebecryl 8402, Ebecryl 8804, Ebecryl 8807, Ebecryl 8803, Ebecryl 8800, Ebecryl 254, Ebecryl 264, Ebecryl 264, Eberyl Ebecryl 8210, Ebecryl 5129, Ebecryl 1290, Ebecryl 210, Ebecryl 204, Ebecryl 220, Ebecryl 4450, Ebecryl 770, Ebecryl 81, Ebecryl 84, Ebecryl 83, Ebecryl 80, Ebecryl 657, Ebecryl 800, Ebecryl 657, Ebecryl 657 , Ebecryl 450, Ebecryl 670, Ebecryl 830, Ebecryl 870, Ebec ryl 2870, Ebecryl 1870, Ebecryl 745, Ebecryl 767, Ebecryl 1701, Ebecryl 1755 (above, manufactured by Daicel Cytec), Laromer LR8765, Laromer LR8986, Laromer LR88987, Laromer LR8739, Laromer LR8983 (above, BASF Oligo, manufactured by BASF Oligo) Examples include EA-6310, NK oligo EA1020, NK oligo EA-6320 (above, Shin-Nakamura Chemical).

  The content of the (E) polymerizable oligomer in the ink composition in the invention is preferably 5% by mass to 20% by mass, and more preferably 5% by mass to 10% by mass with respect to the ink composition. When the amount of the polymerizable oligomer is within this range, an ink composition in which the viscosity of the ink falls within an appropriate range as an inkjet ink composition and an excellent effect on curability and adhesion can be obtained.

(Preparation of pigment dispersion)
In the ink composition of the present invention, it is preferable that the (C) pigment is dispersed in advance with the (D) specific polymer to prepare a pigment dispersion. The pigment dispersion may further contain (A) a polymerizable compound and / or (B) a polymerizable compound, if necessary, or a pigment dispersant having a structure other than the specific polymer, a solvent, etc. You may use together.

For the dispersion of the pigment, for example, known dispersion apparatuses such as a ball mill, a sand mill, an attritor, a roll mill, a jet mill, a homogenizer, a paint shaker, a kneader, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, and a wet jet mill. Can be used.
When dispersing the pigment, it is preferable to add a specific polymer.

It is preferable that the pigment dispersion has a pigment concentration higher than that of the ink composition, and is used by diluting the pigment dispersion when preparing the ink composition. The concentration of the pigment in the pigment dispersion is preferably 10% by mass to 50% by mass, more preferably 10% by mass to 30% by mass, and further preferably 15% by mass to 30% by mass. In this range, in the dispersing apparatus, the force for crushing the aggregation of the pigment by the media or the like is efficiently transmitted, and the dispersion can be completed in a relatively short time.
In dispersing the pigment, a pigment dispersant may be added as necessary, and a synergist that is an analog of a pigment or a dye can be used as the pigment dispersant. The synergist is preferably added in an amount of 1 to 10 parts by mass with respect to 100 parts by mass of the pigment.

As a dispersion medium of the pigment dispersion for producing the ink composition for inkjet of the present invention, a solvent may be added, or a solvent-free polymerizable compound that is a low molecular weight component is used as a dispersion medium. Also good. Since the inkjet ink composition of the present invention is curable, it is preferable to use a polymerizable compound as the dispersion medium. In the present invention, (A) polymerizable compound, (B) polymerizable compound, and other polymerizable compounds can be appropriately used.
When a non-polymerizable compound is used as the dispersion medium, the content when the ink composition is adjusted is preferably 10% by mass or less with respect to the ink composition, and is preferably 5% by mass or less. More preferably, it is most preferably 2% by mass or less. By setting the amount within this range, the curability of the ink composition can be maintained, and the solvent resistance and the blocking property of the cured ink image can be prevented from being deteriorated.

<Polymerization initiator>
The ink-jet ink composition of the present invention preferably contains a polymerization initiator from the viewpoint of improving the curing sensitivity.
As the polymerization initiator, a radical polymerization initiator is preferable, and a photopolymerization initiator is more preferable.
The photopolymerization initiator is a compound that generates a radical by causing a chemical change through the action of an active energy ray or the interaction with an electronically excited state of a sensitizing dye.
The photopolymerization initiator is an active energy ray to be irradiated, for example, ultraviolet rays having a wavelength of 400 to 200 nm, far ultraviolet rays, g rays, h rays, i rays, KrF excimer laser rays, ArF excimer laser rays, electron rays, X rays. Those having sensitivity to a molecular beam or an ion beam can be appropriately selected and used.

  In the present invention, 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 irradiation, and α ray, γ ray, X ray. It includes a wide range of particle beams such as high energy radiation such as ultraviolet rays, visible rays, rays ranging from ultraviolet rays such as infrared rays to infrared rays, and electron beams. Of these, ultraviolet rays and electron beams are preferred from the viewpoint of curing sensitivity and device availability, and ultraviolet rays are more preferred. Accordingly, the ink composition of the present invention is preferably one that can be cured by irradiation with ultraviolet rays. As an 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, a light emitting diode, or a fluorescent lamp as a light source, and it is more preferable to have an emission wavelength in the range of 300 nm to 400 nm.

  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. Faussier “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, compounds used in chemically amplified photoresists described in “Organic Materials for Imaging” edited by Organic Electronics Materials Study Group, Bunshin Publishing (1993), pages 187 to 192 can be used. .

  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.

  As the photopolymerization initiator, for example, photopolymerization initiators described in JP-A-2008-208190 and 2008-266561 can be used. Aromatic ketones, aromatic onium salt compounds, organic peroxides, hexa An arylbiimidazole compound, a ketoxime ester compound, an azinium compound, a metallocene compound, an active ester compound, a compound having a carbon halogen bond, and the like are preferable, and aromatic ketones, ketoxime salt compounds, and acylphosphine oxide compounds are particularly preferable.

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.

In the ink composition of the present invention, the following components may be further used as necessary.
<Sensitizing dye>
A sensitizing dye may be added to the inkjet 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 General 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 basicity of the dye in combination with the adjacent A ² and the adjacent carbon atom. Represents a nonmetallic atomic group forming a nucleus, R ⁵¹ and R ⁵² each independently represent 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 General 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 general 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 general 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, and L ⁵ and L ⁶ each independently represent 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 non-metallic atomic group, or may be bonded to each other to form an aliphatic or aromatic ring.

In General Formula (XIII), R ⁶⁶ represents an aromatic ring or a hetero ring that 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 nonmetallic atomic group, and R ⁶⁷ and R ⁶⁴ and R ⁶⁵ and R ⁶⁷ each have an aliphatic or aromatic ring. Can be combined to form.

  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, the ink-jet ink composition of the present invention may contain a known compound having a function of further improving sensitivity or suppressing polymerization inhibition by oxygen 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.

The ink-jet ink composition of the present invention can be used in combination with various additives depending on the purpose. 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.
Below, the additive which can be used for the ink composition for inkjets of this invention is mentioned.

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

Various polymer compounds can be added to the inkjet 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 be added to the ink composition for inkjet 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 ink composition for inkjet according to the present invention preferably has an ink viscosity of 0.5 to 30 mPa · s at a temperature at the time of discharge in consideration of dischargeability from the inkjet nozzle, and is 0.5 to 20 mPa · s. More preferably, it is most preferably 1 to 15 mPa · s. It is preferable that the composition ratio is appropriately adjusted and determined so as to be within this range.
The ink viscosity at 25 ° C. (room temperature) is 1 mPa · s to 200 mPa · s, preferably 2 mPa · s to 50 mPa · s, more preferably 2.5 mPa · s to 30 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 of the curable ink composition of the present invention 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-jet ink composition of the present invention thus prepared is printed on a recording medium by an ink-jet printer, and then cured by irradiating the printed ink composition with active energy rays. Make a record.
In the printed matter obtained with this ink composition, the image portion is cured by irradiation with active energy rays, and the strength of the image portion is excellent. Therefore, in addition to image formation with the ink composition, for example, ink reception of a lithographic printing plate It can be used for various purposes such as formation of a layer (image portion).

[Inkjet recording method]
The inkjet ink composition of the present invention preferably forms an image with an inkjet printer and fixes the image with active energy rays. As the ink jet ink recording method of the present invention, it is preferable to discharge the ink composition after heating the ink composition to 40 to 80 ° C. and setting the viscosity of the ink composition to 30 mPa · s or less. High ejection stability can be realized by using.
In general, an active energy ray-curable ink composition generally has a higher viscosity than an aqueous ink, and thus 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 the droplet discharge speed as it is, which causes image quality deterioration. Therefore, it is necessary to keep the temperature of the ink composition during printing as constant as possible. 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 an ink jet recording apparatus used for ink jet recording is that it is provided with a means for stabilizing the temperature of the ink composition, and the part to be kept at a constant temperature is ejected from an ink tank (an intermediate tank if an intermediate tank is provided). All piping systems and members up to the 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 flow rate of the ink composition 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.

  The ink composition of the present invention is an inkjet ink composition that can be cured by irradiation with active energy rays. The irradiation conditions of active energy rays 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 in which a collimated light source is applied to a mirror surface provided on the side surface of the head unit to irradiate the recording unit with UV light is disclosed. In the present invention, these irradiation methods can be used.

In addition, when the inkjet 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 The active energy ray is irradiated after 0.01 to 0.3 seconds, more preferably 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 a 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 ejecting all colors at once, 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 preferable discharge conditions, the ink composition of the present invention repeatedly heats and cools. However, due to the function of the pigment dispersant, even when stored under such temperature conditions, the pigment dispersibility 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-jet ink composition of the present invention can be applied is not particularly limited, and various non-absorbent resin materials used for ordinary non-coated paper, coated paper and other papers, so-called soft packaging, or The resin film which shape | molded it in the film form can be used, and as a various plastic film, PET film, OPS film, OPP film, ONy film, PVC film, PE film, TAC film etc. are mentioned, for example. 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.

  The ink-jet ink composition of the present invention thus obtained has excellent color developability because fine pigments are uniformly dispersed, and exhibits excellent fluidity because of low viscosity. Further, since the dispersion state is excellent in that the dispersion state is maintained for a long time, there is little sedimentation and aggregation, and the long-term storage stability is also good. Because of these characteristic performances, the ink composition for ink jets that requires strict viscosity management is suitably used for the purpose of drawing images and characters with an ink jet printer.

  Moreover, since the inkjet ink composition of the present invention contains a specific combination of a polymerizable compound and a specific polymer, it can be used as a curable inkjet ink composition that can be cured by irradiation with active energy rays. it can. The inkjet ink composition of the present invention has a clear color tone and high coloring power, and can form a high-quality image. In addition, such ink-jet ink compositions can be used suitably for the production of large-area printed materials because high-quality images can be directly formed on non-absorbable recording media based on digital data. Is done.

  The inkjet ink composition of the present invention has a characteristic that it can be cured even at a low exposure amount by curing a specific combination of polymerizable compounds. For this reason, it seems that it contributes to the improvement of the printing speed by reducing the system and running cost by using an inexpensive light source with low exposure intensity, and shortening the exposure time. Furthermore, since the curing speed after exposure is high, blurring of the image can be suppressed, and a clear image can be formed.

  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.

<Synthesis of specific polymer>
-Synthesis of monomer M-4-
15 g of 9 (10H) acridone (manufactured by Wako Pure Chemical Industries, Ltd.) and 3.4 g of sodium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) were dissolved in 84 g of dimethyl sulfoxide (manufactured by Wako Pure Chemical Industries, Ltd.) and heated to 45 ° C. To this, 17.6 g of CMS-P (chloromethylstyrene, manufactured by Seimi Chemical Co., Ltd.) was dropped, and the mixture was further heated and stirred at 50 ° C. for 5 hours. The reaction solution was poured into a mixed solution of 30 g of distilled water and 30 g of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) with stirring, and the resulting precipitate was separated by filtration and washed with 300 g of a solution in which distilled water and methanol were mixed in the same mass. As a result, 17.5 g of monomer M-4 was obtained.

-Synthesis of Monomer M-17-
355.0 g of 1,8-naphthalimide (manufactured by Kanto Chemical Co., Inc.) is dissolved in 1500 mL of N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.), and 0.57 g of nitrobenzene (manufactured by Wako Pure Chemical Industries, Ltd.) is added at 25 ° C. Here, 301.4 g of DBU (diazabicycloundecene) (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise. After stirring for 30 minutes, 412.1 g of CMS-P was added dropwise, and the mixture was further heated and stirred at 60 ° C. for 4 hours. To this reaction solution, 2.7 L of isopropanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.9 L of distilled water were added and stirred while cooling to 5 ° C. The obtained precipitate was filtered off and washed with 1.2 L of isopropanol to obtain 544.0 g of monomer M-17.

-Synthesis of specific polymer 1-
Monomer M-4 10.0 g, 2- (tert-butylamino) ethyl methacrylate (manufactured by tBuAEMA Aldrich), poly (methyl methacrylate) macromonomer having a methacryloyl group at the terminal (trade name: AA-6, Toago 35.0 g of Synthetic Co., Ltd.) and 100 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), and heated while flowing nitrogen into the flask. The temperature was raised to 75 ° C. To this, 270 mg of 2,2-azobis (dimethyl isobutyrate) (V-601, manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was heated and stirred at 75 ° C. for 2 hours. Two hours later, 270 mg of V-601 was further added, and the mixture was heated and stirred for 6 hours. After adding 150 mL of acetone to the obtained reaction solution, the mixture was poured into 5000 mL of hexane with stirring, and the resulting precipitate was heated and dried to obtain the specific polymer 1.
As a result of measuring the weight average molecular weight (polystyrene conversion) of the specific copolymer 1 by GPC, it was 150,000, and it confirmed that the specific polymer (polymer) was obtained.

-Synthesis of specific polymer 2-
Monomer M-17 10.0 g, N, N-dimethylaminopropylacrylamide (DMAPAAm Wako Pure Chemical Industries, Ltd.) 10.0 g, poly (butyl acrylate-co-2-hydroxyethyl methacrylate) 50.0 g having a methacryloyl group at the terminal (Product name: AX-707S, 60% toluene solution, manufactured by Toagosei Co., Ltd.) and 100 g of methyl ethyl ketone were introduced into a nitrogen-substituted three-necked flask, stirred with a stirrer, and heated while flowing nitrogen into the flask. The temperature was raised to ° C. 1.0g of V-601 was added to this, and it heat-stirred at 75 degreeC for 2 hours. Two hours later, 0.5 g of V-601 was further added, and the mixture was heated and stirred for 6 hours. The obtained reaction solution was diluted with 100 mL of acetone, poured into 5000 mL of hexane with stirring, and the resulting precipitate was heated and dried to obtain the specific polymer 2 (weight average molecular weight 64,000).

-Synthesis of Comparative Polymer 1-
Methyl methacrylate (MMA, manufactured by Wako Pure Chemical Industries, Ltd.) 10.0 g, N, N-dimethylaminopropylacrylamide (Wako Pure Chemical Industries, Ltd.) 10.0 g, AX-707S 50.0 g, and methyl ethyl ketone 100 g were replaced with nitrogen. It introduce | transduced into the flask, stirred with the stirrer, and heated up and heated up to 75 degreeC, supplying nitrogen in a flask. 1.0g of V-601 was added to this, and it heat-stirred at 75 degreeC for 2 hours. Two hours later, 0.5 g of V-601 was further added, and the mixture was heated and stirred for 6 hours. The obtained reaction solution was diluted with 120 mL of acetone, poured into 5000 mL of hexane with stirring, and the resulting precipitate was heated and dried to obtain Comparative Polymer 1 (weight average molecular weight 52,000).
The compositions (mass%) of the obtained specific polymers 1 and 2 and comparative polymer 1 are summarized in Table 1.

-Preparation of mill base (pigment dispersion) 1-
8.0 g of the specific polymer 1 is dissolved in 72 g of 2-phenoxyethyl acrylate (trade name: SR339, manufactured by Sartomer, (A) polymerizable compound) and yellow pigment PY120 (trade name: Novoperm Yellow H2G, manufactured by Clariant) Using 20 g together with a bead mill (motor mill M50, manufactured by Eiger, beads: zirconia beads, diameter 0.65 mm), dispersion was performed at a peripheral speed of 9.0 m / s for 2.0 hours to obtain a mill base (pigment dispersion) 1. It was.

-Preparation of mill bases 2-5-
In the preparation of the mill base 1, instead of the specific polymer 1, the specific polymer 2, the comparative polymer 1, and a commercially available pigment dispersant Solsperse 32000 (manufactured by Lubrizol, a pigment dispersant not corresponding to the specific polymer of the present invention) Millbases 2 to 5 having the compositions shown in Table 2 were prepared in the same manner as in the preparation of millbase 1 except that they were used.

Table 2 shows the composition used to prepare the millbase. In Table 2, the amount in parentheses indicates the amount used in mass units.
The chemical names of THFA and IBOA used in Table 2 are shown below together with the compounds used in Table 3.

[Examples 1 to 4, Reference Examples 1 and 2 , Comparative Examples 1 to 4]
-Preparation of ink composition for inkjet-
In the composition shown in Table 3, a polymerizable compound, a polymerization initiator, a surfactant, a polymerization inhibitor, and an ultraviolet absorber were added to the mill base and mixed, and then this was pressure filtered with a membrane filter. 4, Inkjet ink compositions of Reference Examples 1 and 2 and Comparative Examples 1 to 4 were obtained. The abbreviations and chemical names of the compounds used for the preparation of the ink composition, the manufacturers, etc. are as follows.

(A) (meth) acrylate having an alkoxy group or a phenoxy group corresponding to the polymerizable compound EDEGA: ethoxydiethylene glycol acrylate (trade name Light Acrylate EC-A, manufactured by Kyoeisha Chemical Co., Ltd.)
PEA: 2-phenoxyethyl acrylate (trade name SR339, manufactured by Sartomer)

(A) Ethylenically unsaturated compound having a heterocyclic structure corresponding to the polymerizable compound THFA: Tetrahydrofurfuryl acrylate (trade name: Light acrylate THF-A, manufactured by Kyoeisha Chemical Co., Ltd.)
NVC: N-vinylcaprolactam (manufactured by BASF)

(B) Compound corresponding to polymerizable compound IBOA: Isobornyl acrylate (trade name IBXA, manufactured by Osaka Organic Chemical Industry Co., Ltd.), Glass transition temperature Tg: 94 ° C.
Other polymerizable compound HDDA: 1,6-hexanediol diacrylate (trade name SR2389, manufactured by Sartomer)
-(E) Polymerizable oligomer CN964: (urethane acrylate, manufactured by Sartomer)

・ Polymerization initiator Irgacure 369: (Ciba Specialty Chemicals)
Irgacure 651 (Ciba Specialty Chemicals)
Irgacure 819: (Ciba Specialty Chemicals)
・ Surfactant BYK-307: (Bic Chemie)
-Polymerization inhibitor MEHQ: Methoxyhydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.)

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

-Viscosity-
The viscosity at 40 ° C. of each ink-jet ink composition was measured using an E-type viscometer (manufactured by Toki Sangyo).
A: Less than 25 mPa · s B: 25 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 2 months and stored at 60 ° C. for 2 weeks was evaluated by viscosity.
A: The increase in viscosity is less than 5%, and there is no problem with ejection properties.
B: The increase in viscosity is 5% or more and less than 10%, and there is no problem with ejection properties.
C: A level at which the increase in viscosity is 10% or more and less than 20%, and the ejection stability is lowered.
D: Level at which the increase in viscosity is 20% or more and the ejection stability is significantly reduced.

-Curability-
Each obtained ink-jet ink composition was printed on a vinyl chloride film using a piezo-type ink jet head (CA3 head, manufactured by Toshiba Tec Corporation, printing density 300 dpi, droplet ejection frequency 4 kHz, nozzle number 64). After that, the sample was exposed with a Deep UV lamp (US-7, SP-7) under the condition of energy of 300 mJ / cm ² to obtain a print sample.
The curability was evaluated by touching the cured film with a finger and the presence or absence of stickiness according to the following evaluation criteria.
A: There is no stickiness.
B: Slightly sticky
C: Remarkably sticky.

-Flexibility evaluation-
After solid printing on a vinyl chloride film with the piezo-type inkjet head, it was exposed at 600 mJ / cm ² with a Deep UV lamp (US-7, SP-7) to obtain an image. The cured film of the surface which the image was bent once and bent once so that the front surfaces may be combined, and the back surfaces were combined, was observed and evaluated according to the following evaluation criteria.
A: Good flexibility and no cracking or peeling.
B: Slight cracking but no peeling.
C: Cracking and peeling occurred.

From Table 4, each inkjet ink composition of Examples 1 to 4 using the specific polymer 1 as a pigment dispersant could be stably stored for a long period of time not only at room temperature but also at a high temperature. The ink compositions of Comparative Example 1 using a pigment dispersant (Comparative Polymer 1) that does not have a heterocyclic residue that forms a pigment instead of the specific polymer, and Comparative Example 2 using a commercially available dispersant are storage stable. The dispersion stability of the pigment was inferior (especially stored at 60 ° C.), and there was a practically problematic level. Even when a pigment dispersant having a heterocyclic residue that forms a pigment is used, the ink composition of Comparative Example 4 containing no polymerizable compound (B) has a problem in practical use because the dispersibility of the pigment is reduced. There was a level.
The sensitivity at the time of curing was that (A) the polymerizable compound and (B) the examples 1-4 containing the polymerizable compound were all cured well, but the comparison lacking the (A) polymerizable compound. In Example 3, curability and flexibility were greatly reduced. Moreover, the comparative example 4 which lacked the (B) polymerizable compound was inferior in curability and flexibility.

From the above, the ink composition for inkjet according to the present invention is at least one selected from the group consisting of (A) (meth) acrylate having an alkoxy group or phenoxy group, and an ethylenically unsaturated compound having a heterocyclic structure. and species, (B) a polymerizable compound ranges glass transition temperature of 50 ° C. to 190 ° C. homopolymer, (C) a pigment and, (D) repeating units and N represented by the following general formula (1) -By including a polymer containing a repeating unit derived from tertbutylaminoethyl methacrylate, it is presumed that curing sensitivity and high flexibility are expressed and high storage stability is expressed.

Claims (5)

(A) at least one selected from the group consisting of (meth) acrylates having an alkoxy group or phenoxy group, and an ethylenically unsaturated compound having a heterocyclic structure, and (B) the glass transition temperature of the homopolymer is 50 ° C. Polymer containing a polymerizable compound having a temperature range of ˜190 ° C., a (C) pigment, (D) a repeating unit represented by the following general formula (1) and a repeating unit derived from N-tertbutylaminoethyl methacrylate And an ink-jet ink composition comprising:


(R represents a hydrogen atom or a methyl group. J represents —CO—, —COO—, —CONR ¹ —, —OCO—, or a phenylene group. R ¹ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. Represents a group, W represents a single bond or a divalent linking group, and P represents a heterocyclic residue forming an organic pigment.   P in the general formula (1) is a heterocyclic residue forming at least one organic pigment selected from the group of quinacridone, benzimidazolone, indole, quinoline, carbazole, acridine, acridone, and anthraquinone. 2. The ink composition for inkjet according to 1.   3. The inkjet according to claim 1, further comprising (E) a polymerizable oligomer, wherein the content of the (E) polymerizable oligomer in the ink composition is in the range of 5.0 to 20% by mass. Ink composition.   The inkjet ink composition according to any one of claims 1 to 3, wherein the polymerizable oligomer (E) is at least one selected from the group consisting of a polyester oligomer, a polyurethane oligomer, and an acrylic oligomer.   The polymerizable compound (B) having a glass transition temperature of the homopolymer in the range of 50 ° C to 190 ° C is a polymerizable compound having a glass transition temperature of the homopolymer in the range of 60 ° C to 190 ° C. The inkjet ink composition according to claim 4.