JP2009235121A - Pigment dispersion and ink composition using the same, curable composition, curable ink composition, and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pigment dispersion excellent in fine pigment dispersibility and its stability, an ink composition and a colored curable composition prepared by using the pigment dispersion and having clear hue and high coloring power, a curable ink composition suitable for ink jet recording, and an inkjet recording method using the ink composition. <P>SOLUTION: The pigment dispersion contains a pigment dispersing agent and a pigment. The dispersing agent is composed of a graft polymer having a branch part, which consists of a polymer having a partial structure selected from a urea bond, a urethane bond and an aliphatic amino group in a repeating unit, and a branch part, which consists of a polymer selected from an aliphatic polyester, a poly(meth)acrylate and a polyether, in a trunk part of a polyurethane/polyurea structure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pigment dispersion, an ink composition using the pigment dispersion, a curable composition, a curable ink composition, and an ink jet recording method. Specifically, a pigment dispersion excellent in pigment dispersibility and dispersion stability, an ink composition suitably used for ink jet recording containing the pigment dispersion, a curable composition that can be cured by irradiation with actinic radiation, and the same In particular, the present invention relates to a curable ink composition capable of forming a high-quality image, and an ink jet recording method using the same.

In various colored compositions, when a pigment is used as a colorant, it is important to ensure the dispersibility and dispersion stability of the solid pigment.
By using a pigment dispersion excellent in pigment dispersibility and dispersion stability, a curable composition and an ink composition having a uniform hue can be obtained. In particular, pigments with excellent light resistance are widely used as colorants in ink compositions, but when there is a problem with the dispersibility of the pigment, a uniform color tone cannot be obtained. In the case of an ink that is difficult to form and used in an ink jet recording method, various problems such as a decrease in dischargeability are caused.

  In recent years, as an image recording method for forming an image on a recording medium such as paper or plastic sheet based on an image data signal, it can be implemented by an inexpensive apparatus, and ink is ejected only to a required image portion to be covered. Since an image is directly formed on a recording medium, an ink jet recording method has attracted attention from the viewpoint that ink can be used efficiently and running cost is low. Further, the ink jet recording method has an advantage that a high-definition image can be recorded 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, but speeding up and high image quality are important issues in printing. In addition, the time required for drying and curing of the droplets after printing has a property of greatly affecting the sharpness of the image.
As one of the ink jet methods, there is a recording method using an ink for ink jet recording that can be cured by irradiation with actinic radiation. According to this method, a sharp image can be formed by irradiating with radiation immediately after printing and curing the ink droplets.

  Such a curable inkjet ink composition is required to have high pigment dispersibility and stability over time in order to form a high-definition image excellent in color developability and to discharge ink stably. In order to impart a clear color tone and high coloring power to the ink composition, it is essential to make the pigment finer. In particular, in the ink used for inkjet recording, 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 from the ink is small. It is essential to use finer particles. As described above, when the pigment particles are further miniaturized in order to obtain a high coloring power, it becomes difficult to disperse the fine particles, and aggregates are easily generated. Moreover, the problem that the viscosity of a composition rises by addition of a dispersing agent also arises. The occurrence of pigment aggregates and the increase in viscosity of the ink composition both have an adverse effect on the ink ejection properties. Therefore, it is not preferable to use an ink composition in which pigment aggregation or thickening has occurred for inkjet recording.

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

In the curable inkjet ink, the curability for forming a sharp image and the film physical properties after curing are also important factors. In the curable inkjet ink, since the sharpness of the image is ensured by rapid curing by irradiation with radiation, a pigment dispersant that inhibits curing, a pigment dispersant containing a solvent that is a non-curing component, and a cured film A pigment dispersant that does not crosslink and lowers the surface tackiness is not preferable because it lowers curability and causes blurring and reduced productivity. When such a compound is mixed, there is a problem in that when the printed matter is stored in an overlapping manner, the printing surface and the recording medium adhere to each other, and so-called blocking occurs in which the printed surface of the recorded matter and the recording medium are soiled.
Accordingly, there is a need for an ink composition that has sufficient fluidity, stably disperses a finely divided pigment, and is excellent in curability. Various proposals have been made on dispersants for obtaining stable pigment dispersions.

In order to improve the affinity with the pigment, it is a base as a dispersant for an ink composition using a pigment derivative as a dispersant (for example, see Patent Documents 1 and 2) and specific pigments such as phthalocyanine and quinacridone series. Dispersing agents such as an ink composition using a polymer having a functional group (see, for example, Patent Document 3), poly (ethyleneimine) -poly (12-hydroxystearic acid) graft polymer, and a specific agent that dissolves the dispersing agent Ink composition containing a monomer and not using an organic solvent (for example, see Patent Document 4), an ink using a polyurethane having a neutral salt such as carboxylate, phosphate, sulfonate or quaternary ammonium as a pendant as a dispersant. (For example, refer to Patent Document 5) Grafting using nitrogen atom-containing vinyl polymerizable macromonomer Non-aqueous pigment dispersion compositions using polymers (for example, Patent Document 6), polymers containing N-vinylamide, N-vinyllactam, N-vinyl or allyl-substituted nitrogen-containing heterocycles, specifically N- Homopolymers and copolymers such as vinylformamide, N-vinylcaprolactam, N-vinylimidazole, N-vinylformamide, and other types of polymers, specifically polyethylene glycol, polyalkyl (meth) acrylate, polyester, etc. Has been proposed (for example, Reference 7).
When these pigment dispersants and ink compositions are used, the pigment can be finely dispersed, and the stability of the ink is higher than before, but the high temperature stability of the ink in the low viscosity ink composition for ink jet is sufficient. In addition, the colored curable composition and the curable ink composition still have room for improvement in curing sensitivity and blocking resistance.
JP 2003-119414 A JP 2004-18656 A JP 2003-321628 A JP 2004-131589 A JP-T-2002-503746 JP 2007-277506 A Special Table 2002-526254

An object of the present invention is to solve the conventional problems and achieve the following objects.
That is, an object of the present invention is to provide a pigment dispersion in which a pigment is finely dispersed and excellent in dispersion stability when stored for a long period of time.
In addition, the present invention provides an ink composition and a colored curable composition having a clear color tone and high coloring power obtained by using such a pigment dispersion, and also a high color strength having a clear color tone and high coloring power. An object of the present invention is to provide an ink composition suitable for inkjet recording, which can form an image of high image quality and can be cured by irradiation with actinic radiation, and an inkjet recording method using the ink composition.

As a result of intensive studies, the inventors of the present invention have excellent pigment dispersibility and long-term storage by using a graft copolymer having a specific main chain structure and side chain structure as a pigment dispersant. Alternatively, the present inventors have found that a pigment dispersion in which a decrease in dispersion stability is effectively suppressed even after repeated temperature changes has been obtained, thereby completing the present invention.
Means for solving the above problems are as follows.
<1> A branch part made of a polymer having a partial structure selected from a urea bond, a urethane bond and an aliphatic amino group in a repeating unit in a trunk part of a polyurethane or polyurethane urea structure, an aliphatic polyester, and a poly (meth) A pigment dispersant comprising a graft polymer having a branch portion made of a polymer selected from acrylate and polyether, and a pigment dispersion containing a pigment.
<2> A branch part made of a polymer having a partial structure selected from a urea bond, a urethane bond and an aliphatic amino group in a repeating unit, and an aliphatic polyester, poly (meta) A pigment dispersant and a pigment obtained by reacting at least the following (a), (b), and (c) with a graft polymer having a branch portion made of a polymer selected from acrylate and polyether): <1> The pigment dispersion according to <1>.
(A) a polymer having a hydroxyl group and having a urea bond, a urethane bond or an aliphatic amino group in a repeating unit;
(B) a polymer selected from an aliphatic polyester having a hydroxyl group or a primary amino group, poly (meth) acrylate, and polyether;
(C) Bifunctional or higher isocyanate compounds.
<3> (a) a hydroxyl group contained in a polymer having a hydroxyl group and having a urea bond, a urethane bond or an aliphatic amino group in a repeating unit; and (b) a fat having a hydroxyl group or a primary amino group <2> The pigment dispersion according to <2>, wherein the number of hydroxyl groups or primary amino groups contained in the polymer selected from the group polyester, poly (meth) acrylate, and polyether is 1 to 2 per molecule.

<4> Polyamide, polyurethane, polyurea, poly (a) having a hydroxyl group and a polymer having a urea bond, a urethane bond or an aliphatic amino group in the repeating unit and having a hydroxyl group bonded to the terminal or main chain. The pigment dispersion according to <2> or <3>, which is a (meth) acrylamide or a nitrogen-containing poly (meth) acrylate.
<5> The pigment dispersion according to any one of <2> to <4>, wherein the (c) bifunctional or higher isocyanate compound has 2 to 6 isocyanate groups.
<6> The polymer having (a) a hydroxyl group and having a urea bond, a urethane bond or an aliphatic amino group in a repeating unit is in the range of 500 to 5000, and (b) a hydroxyl group or The number average molecular weight of the polymer selected from aliphatic polyester having a primary amino group, poly (meth) acrylate, and polyether is in the range of 350 to 15000, according to any one of <2> to <5>. Pigment dispersion.

<7> An ink composition containing the pigment dispersion according to any one of <1> to <6>.
<8> A curable composition containing the pigment dispersion according to any one of <1> to <6>.
<9> The curable composition according to <8>, further comprising a polymerizable compound and a polymerization initiator.
<10> A curable ink composition containing the curable composition according to <8> or <9>.
<11> The ink composition according to <7> or <10>, which is for inkjet recording.
<12> An ink jet recording method using the ink composition according to any one of <7>, <10>, and <11>.

The pigment dispersant used in the pigment dispersion of the present invention has a main chain, that is, a trunk portion, which has a polyurethane or polyurethane urea structure, and a side chain, that is, a branch portion, which has a urea bond, a urethane bond and an aliphatic group in a repeating unit. It is a graft polymer having at least two of a polymer having a partial structure selected from amino groups and a polymer selected from aliphatic polyester, poly (meth) acrylate, and polyether.
This graft polymer has a urethane skeleton formed mainly from (a) and (c) in the main chain (trunk), and (a) a repeating unit as a side chain, that is, a branch polymer. In order to have a structure in which a polymer having a urea bond, a urethane bond or an aliphatic amino group, and a polymer selected from aliphatic polyester, poly (meth) acrylate, and polyether are bonded, pigment particles It has a partial structure excellent in adsorptivity and adsorption stability and a partial side chain structure excellent in affinity with monomers and solvents, and has excellent dispersibility of the pigment and its dispersion stability. it is conceivable that.
Furthermore, the pigment dispersant having such a structure is generally different from an acrylic pigment dispersant having a main chain structure, and can be synthesized without substantially containing a non-curable solvent without providing a purification operation. For this reason, even if the amount of the pigment dispersant polymerization stock solution is increased, there is no concern about curability inhibition, and the curable composition obtained using the pigment dispersion of the present invention is good when irradiated with actinic radiation. It also has the advantage of exhibiting curability.

According to the present invention, it is possible to provide a pigment dispersion in which a pigment is finely dispersed and excellent in stability when stored for a long period of time.
In addition, by using the pigment dispersion of the present invention, an ink composition or colored curable composition having a clear color tone and high coloring power, and further, forming a high-quality image having a clear color tone and high coloring power. Ink compositions suitable for inkjet recording, which can be cured by irradiation with actinic radiation, and an inkjet recording method using the ink composition can be provided.

Hereinafter, the present invention will be described in detail.
First, the pigment dispersion of the present invention and the pigment dispersant used therefor will be described.
[Pigment dispersion]
The pigment dispersion of the present invention comprises at least a branch part composed of a polymer having a partial structure selected from a urea bond, a urethane bond and an aliphatic amino group in a repeating unit at the trunk of a polyurethane or polyurethane urea structure, A pigment dispersant comprising a graft polymer having a branch portion comprising a polymer selected from a group polyester, poly (meth) acrylate, and polyether (hereinafter, this pigment dispersant will be referred to as a specific dispersant as appropriate). ) And a pigment.

<Branch part made of a polymer having a partial structure selected from a urea bond, a urethane bond and an aliphatic amino group in a repeating unit in a trunk part of a polyurethane or polyurethane urea structure, an aliphatic polyester, a poly (meth) acrylate, And a pigment dispersant comprising a graft polymer having a branch portion comprising a polymer selected from polyethers>
The pigment dispersion of the present invention is stably dispersed without causing aggregation over time even by a fine pigment due to the action of the graft polymer functioning as a pigment dispersant.
The specific pigment dispersant is not particularly limited as long as it has the above-mentioned trunk polymer and a graft polymer structure having two types of polymer chains in the branch part. However, from the viewpoint of synthesis suitability, at least the following A graft polymer obtained by reacting (a), (b), and (c) is preferred.
(A) a polymer having a hydroxyl group and having a urea bond, a urethane bond or an aliphatic amino group in a repeating unit;
(B) a polymer selected from an aliphatic polyester having a hydroxyl group or a primary amino group, poly (meth) acrylate, and polyether;
(C) Bifunctional or higher isocyanate compounds.
Hereinafter, the pigment dispersant comprising the graft copolymer obtained as the three-component reactant (a) to (c) used in the present invention will be described in detail together with its preferred synthesis method.

The specific dispersant according to the present invention includes (a) a hydroxyl group and a graft chain comprising a polymer having a urea bond, a urethane bond or an aliphatic amino group in the repeating unit, and the hydroxyl groups of (a) and (b). And (c) are strongly adsorbed to the pigment by the polyurethane main chain (trunk part) formed by the reaction of the isocyanate group.
Further, (b) a fat derived from a polymer having a high affinity with a dispersion medium contained in the pigment dispersion, or a polymerizable compound or solvent in the curable composition or ink composition using the pigment dispersion. The steric repulsion of the graft chain selected from the group polyester, poly (meth) acrylate, and polyether effectively suppresses aggregation of the pigments, thereby achieving stable dispersion of the pigment and stability over time.
Thus, since the pigment dispersion of the present invention is excellent in stability, it can be suitably used for an ink composition and a curable composition. In particular, it can be suitably used for inkjet inks that require low viscosity and stable dispersibility of the pigment.

Hereinafter, each raw material component suitably used for synthesizing the specific pigment dispersant according to the present invention will be sequentially described.
[(A) Polymer having a hydroxyl group and having a urea bond, a urethane bond or an aliphatic amino group in the repeating unit]
(A) A polymer having a hydroxyl group and having a urea bond, a urethane bond or an aliphatic amino group in a repeating unit (hereinafter referred to as (a) polymer as appropriate) is a (c) bifunctional or higher functional isocyanate described later. The molecule has a hydroxyl group that reacts with the compound to form a urethane bond and a nitrogen atom that interacts with the pigment.
(A) The hydroxyl group of the polymer may be any group capable of reacting with an isocyanate group, and may exist as an aliphatic hydroxyl group bonded to an aliphatic group in the polymer, or may be an aromatic group. Although it may exist as a bonded aromatic hydroxyl group, it is preferably an aliphatic hydroxyl group from the viewpoint of reactivity and solubility.
It is preferable to have 1 to 2 hydroxyl groups in the polymer molecule (a).
In addition, from the viewpoint of synthesizing the graft copolymer, the position of the hydroxyl group can be preferably used at any place when the hydroxyl group is one in the polymer, but in the case of multiple hydroxyl groups, it is introduced only at one end of the polymer. It is preferred that

  When only the (a) polymer having only one hydroxyl group is used as a raw material for the formation of the specific dispersant, the specific dispersant in which the (a) polymer is introduced only at the end of the main chain is obtained. For example, when a polymer (a) having two hydroxyl groups is used, a dispersant in which a plurality of (a) polymers are introduced into the side chain can be obtained. (A) Since the adsorptivity is enhanced by increasing the number of introduced graft chains made of a polymer, the synthesis of the specific dispersant according to the present invention uses (a) a polymer having two hydroxyl groups in the molecule. Most preferred. In consideration of the adjustment of the molecular weight and the introduction amount of the side chain structure, (a) a polymer having only one hydroxyl group in the molecule and (b) a hydroxyl group or a primary amino group having a plurality of hydroxyl groups in the molecule are described later. It is also preferred to use a polymer selected from an aliphatic polyester having a group, poly (meth) acrylate, and polyether.

The polymer (a) used here contains a urea bond, a urethane bond or an aliphatic amino group, and these partial structures have a function of improving the interaction with the pigment.
It is considered that the urea bond and the urethane bond form a hydrogen bonding interaction with the pigment and the surface modifier adhering to the pigment surface, and are preferably adsorbed on the pigment. In addition, it is considered that the aliphatic amino group is adsorbed by the acid-base interaction to the acid component present in the pigment or the surface modifier of the pigment. As the amino group in the aliphatic amino group, a secondary or tertiary amino group is preferably used from the viewpoint of avoiding a reaction with isocyanate, and a tertiary amino group substituted with an alkyl group having 1 to 4 carbon atoms is more preferable. preferable.
These urea bond, urethane bond or aliphatic amino group is preferably introduced as a repeating unit in (a) the polymer, (a) the polymer is a polyamide having 1 to 4 hydroxyl groups at the terminal, polyurea, Among polyurethanes and nitrogen-containing (meth) acrylates, alkyl-substituted amino group-containing poly (meth) acrylamide, alkyl-substituted amino group-containing (meth) acrylate, urethane bond-containing (meth) acrylate, and urea bond-containing poly (meth) acrylate. The alkyl-substituted amino group-containing polyalkyl (meth) acrylamide, the alkyl-substituted amino group-containing (meth) acrylate, the urethane bond-containing (meth) acrylate, and the urea bond-containing poly (meth) acrylate are more preferable.
In the present specification, when referring to both or one of “acryl and methacryl” and “acrylate and methacrylate”, they are expressed as “(meth) acryl” and “(meth) acrylate”, respectively.

As a method for synthesizing the poly (meth) acrylate or poly (meth) acrylamide having a hydroxyl group at the end of the main chain of the polymer, for example, radical polymerization of a corresponding vinyl monomer using a thiol having a desired number of hydroxyl groups as a chain transfer agent. Can be easily synthesized.
Examples of the compound of the chain transfer agent suitably used in the present invention are shown below, but any compound can be used without particular limitation as long as the polymer intended by the present invention can be obtained.
For example, chain transfer agents capable of introducing one hydroxyl group at the chain end include 2-mercapto-1-ethanol, 3-mercapto-1-propanol, 3-mercapto-3-methylbutan-1-ol, 6-mercapto-1- Examples include hexanol and 11-mercapto-1-undecanol.
Examples of the chain transfer agent capable of introducing two hydroxyl groups at the end of the polymer include 1-thioglycerol.
In the present invention, an embodiment having one or two hydroxyl groups at the chain center of the polymer is also preferably used. When one or two hydroxyl groups are introduced at the center of the chain, (c) two graft chains can be introduced by reaction with the isocyanate compound, and the same effect as when hydroxyl groups are introduced at the chain ends can be obtained. .
As a chain transfer agent capable of introducing one hydroxyl group into the chain center, 2,3-dimercapto-1-propanol is exemplified. As a chain transfer agent capable of introducing two hydroxyl groups into the chain center, 1,4-dithioerythritol is exemplified. .

The polymer (a) that can be used in the present invention can be easily obtained by polymerizing a nitrogen-containing vinyl monomer in the presence of these chain transfer agents.
Examples of the nitrogen-containing vinyl monomer used herein include alkyl-substituted amino group-containing (meth) acrylamide, alkyl-substituted amino group-containing (meth) acrylate, urethane bond-containing (meth) acrylate, urea bond-containing poly (meth) acrylate, N- Examples thereof include vinyl carbazole and allylamine.
Among these, alkyl-substituted amino group-containing alkyl (meth) acrylamide, alkyl-substituted amino group-containing (meth) acrylate, urethane bond-containing (meth) acrylate, and urea bond-containing poly (meth) acrylate are preferably used.

Below, the specific example of the nitrogen-containing vinyl monomer used suitably for the synthesis | combination of (a) polymer is shown.
Examples of the alkyl (meth) acrylamide include N, N-dimethyl (meth) acrylamide, N-tert butyl acrylamide, Nn butyl acrylamide, and N-tert octyl acrylamide.
Examples of the alkyl-substituted amino group-containing alkyl (meth) acrylamide include N-3-dimethylaminopropyl (meth) acrylamide.
Examples of the alkyl-substituted amino group-containing (meth) acrylate include N-dimethylaminoethyl (meth) acrylate, N-diethylaminoethyl (meth) acrylate, N-dimethylaminopropyl (meth) acrylate, N-tertbutylaminoethyl (meta) ) Acrylate and the like.
Examples of the urethane bond-containing (meth) acrylate include n-butylcarbamoylethyl (meth) acrylate. Examples of the urea bond-containing poly (meth) acrylate include n-butylureidoethyl (meth) acrylate and imidazolone ethyl (meth) acrylate.
Specific examples of the compound preferably used as the polymer (a) are given below.

  (A) The number average molecular weight of the polymer is preferably 500 to 10,000. More preferably, it is 500-5000, and 1000-5000 are the most preferable. When the molecular weight is within this range, the resulting dispersant has excellent adsorptivity to the pigment, and there is no concern of inducing pigment aggregation due to cross-linking between the pigment particles due to this adsorptivity.

[(B) Polymer selected from aliphatic polyester, poly (meth) acrylate, polyether having hydroxyl group or primary amino group]
(B) A polymer selected from an aliphatic polyester having a hydroxyl group or a primary amino group, a poly (meth) acrylate, and a polyether [hereinafter referred to as (b) a polymer as appropriate] includes (c) an isocyanate compound described later. It has in the molecule a hydroxyl group that reacts to form a urethane bond and a polymer component that can impart affinity between the pigment and a medium such as a dispersion medium in the pigment dispersion.
The aliphatic polyester, poly (meth) acrylate, and polyether, which are components for imparting affinity with the medium, may be appropriately selected and used according to the affinity with the medium in which the pigment is to be dispersed. Any of those having good affinity can be used. For example, when a highly polar organic solvent such as an alcohol solvent is used as a dispersion medium for the pigment dispersion, a highly polar polyether, a highly polar polyester, a poly (meth) acrylate having a polar group introduced, and the like are preferable. When using a medium polarity organic solvent such as an organic solvent or an ether solvent, an aliphatic polyester or a poly (meth) acrylate substituted with a short chain alkyl group or a polar group is preferable, and a low polarity such as a hydrocarbon is used. When using an organic solvent, an aliphatic polyester or a poly (meth) acrylate substituted with a long-chain alkyl group is preferred. When using water or an aqueous solvent, a carboxylic acid and a salt thereof, a quaternary ammonium salt, Poly (meth) acrylates substituted with phosphoric acid and salts thereof, sulfonic acids and salts thereof, polyethylene oxide, polypropylene Pyrene oxide and the like are preferable.

(B) The aliphatic polyester portion in the polymer can be synthesized by ring-opening polymerization. Group polyesters can be synthesized.
The polyether is obtained, for example, by ring-opening polymerization of a cyclic ether such as ethylene oxide, propylene oxide, oxetane compound or tetrahydrofuran, and can be adjusted to have an affinity suitable for the medium by copolymerizing different cyclic ethers.
Poly (meth) acrylate can be easily synthesized by polymerizing (meth) acrylate by the same method as that for the polymer (a). As the ester substituent of poly (meth) acrylate, an alkyl group having 1 to 20 carbon atoms or an aryl group is preferably used. The alkyl group may further have a substituent, and examples of the substituent that can be introduced into the alkyl group include a hydroxyl group, a carbonyl group, a carboxyl group, an aryl group, an alkoxy group, a glycidyl group, and an alkenyl group. An alkyl group substituted with a hydroxyl group, an aryl group or an alkoxy group and an unsubstituted alkyl group are preferably used. The polymer (b) constituting the side chain portion of the specific dispersant of the present invention has a functional group having strong pigment affinity, such as an amino group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a hetero group. When a cyclic group, an aromatic group, or the like is introduced, the side chain portion is likely to be adsorbed to the pigment, and there is a concern that the steric repulsion effect due to the side chain structure may be reduced. Therefore, the introduction of such a substituent is not preferable. .
Hereinafter, specific examples of preferred compounds as the polymer (b) used in the present invention will be given.

(B) The number average molecular weight of the polymer is preferably 350 to 15000. More preferably, it is 500-12000, and 1000-10000 are the most preferable. Within the above molecular weight range, a dispersant having good pigment dispersion stability due to the steric repulsion effect can be obtained, and there is no concern of increasing the viscosity.

[(C) Bifunctional or higher functional isocyanate compound]
As the bifunctional or higher functional isocyanate compound that can be used in the synthesis of the specific dispersant of the present invention (hereinafter, appropriately referred to as (c) an isocyanate compound), a compound having 2 to 6 isocyanate groups is preferably used. Of these, compounds having two isocyanate groups are more preferred. Examples of the compound having 2 to 6 isocyanate groups include organic polyisocyanate.
As the organic polyisocyanate, any conventionally known one can be used, but aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate (MDI), 2,4- or 2,6-tolylene diisocyanate (TDI), m- or p-phenylene diisocyanate, 1,3- or 1,4-xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate (NDI), 3,3'-dimethyl-4,4'-biphenylene diisocyanate (TODI) ) And the like, for example, hexamethylene diisocyanate (HDI), hydrogenated MDI (H12MDI), isophorone diisocyanate (IPDI) and the like. Prepolymer-type, nurate-type, urea-type carbodiimide-type modified products of these diisocyanates are also preferable. It is also possible to use a mixture of two or more of these diisocyanates or modified products.

(Synthesis of specific dispersant)
The specific dispersant of the present invention is a reaction product of at least (a) a polymer, (b) a polymer, and (c) three components of a bifunctional or higher isocyanate compound. Agents can be used.
As the chain extender, any conventionally known one can be used, but low molecular weight polyols such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, neo Pentyl glycol, hydroquinone, bis (hydroxyethyl) benzene, 2,2'- or 4,4'-dihydroxydiphenylmethane, 2,2-bis (4-hydroxyphenyl) propane, or low molecular weight diamines such as ethylenediamine and propylene Diamine, m- or p-phenylenediamine, 1,3- or 1,4-xylylenediamine, isophoronediamine and the like can be used.

  (A) polymer used for the synthesis | combination of the specific dispersing agent of this invention, (b) The use ratio of a polymer and (c) isocyanate compound is 2 mass%-(a) polymer in a dispersing agent total mass. 50% by mass, (b) the polymer is preferably 50% by mass to 93% by mass, and (c) the isocyanate compound is preferably 0.5% by mass to 12% by mass. (A) 3% by mass to 45% by mass, (b) 55% by mass to 90% by mass, (c) 1% by mass to 10% by mass are more preferable, (a) 5% by mass to 35% by mass, (b) 60 mass%-90 mass%, (c) 1 mass%-8 mass% are the most preferable.

The specific dispersant of the present invention can be obtained by reacting the (a) polymer, (b) polymer, and (c) isocyanate compound in an organic medium.
The organic medium is not particularly limited as long as the raw material and the polymer to be generated are dissolved and does not react with the (c) isocyanate compound, and a known organic medium can be appropriately selected and used.
As the organic medium that can be used, for example, ketones, esters, amides, sulfoxides, ethers and the like are preferably used.
When the pigment dispersion of the present invention is added to the curable composition described in detail below, a polymerizable compound having an ethylenic double bond, so-called vinyl monomer, can also be preferably used as the organic medium.
When synthesizing the specific dispersant of the present invention, a catalyst such as alkylamine, dibutyltin dilaurate, or bismuth triol may be added.

  Specific examples of the specific dispersant used in the present invention [Exemplary compounds (P-1) to (P-5)] are shown below, but the present invention is not limited thereto. In addition, these graft polymers which are the specific dispersants of the present invention are synthesized using the raw material components described in Table 1 below at the charging ratios described.

Preferably, the specific dispersant, which is a reaction product of the polymer (a), the polymer (b), and the isocyanate compound (c), has a trunk and a branch as defined in the present invention. The presence of the structure can be confirmed by detecting the signals of the urethane bond and the signals of the isocyanate group and the hydroxyl group disappear by a conventionally known method such as nuclear magnetic resonance measurement or infrared spectroscopy. The molecular weight can be measured by gel permeation chromatography (GPC).
The number average molecular weight of the specific dispersant of the present invention is preferably in the range of 3000 to 150,000, more preferably 4000 to 120,000, and most preferably in the range of 6000 to 100,000. When the molecular weight is within this range, the dispersion stability becomes good, the viscosity of the dispersion is appropriately maintained, and there is no concern that the viscosity will increase.

In the pigment dispersion of the present invention, only one type of the specific dispersant may be added, 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 dispersing agent in a pigment dispersion, it is more preferable that it is 5-50 mass%.
In addition to the pigment dispersant of the present invention, a known pigment dispersant can be used in combination with the ink composition of the present invention as long as the effect is not impaired. The addition amount is preferably 50% by mass or less of the pigment dispersant of the present invention.

<Pigment>
The pigment dispersion of the present invention contains a pigment as an essential component.
Even pigment particles having a small particle size are uniformly and stably dispersed in the dispersion by the action of the specific dispersant. For this reason, the ink composition containing such a pigment dispersion can form a sharp image with excellent color developability, and the pigment dispersion of the present invention is applied to a composition containing various pigments. Can do.
There is no restriction | limiting in particular in the pigment used for the pigment dispersion of this invention, According to the objective, well-known various pigment dyes can be selected suitably and can be used. Since the pigment is contained as the colorant, the pigment dispersion of the present invention can be suitably used for applications requiring the weather resistance of the colorant, such as an ink composition and a colored curable composition. Moreover, when applying this pigment dispersion as a coloring component of various compositions, a dye may be used in combination for the purpose of adjusting the hue and the like.

As the pigment contained in the pigment dispersion of the present invention, generally used organic pigments, inorganic pigments, and those obtained by dyeing resin particles with a dye can be used. Usually, any commercially available pigment can be used, and further, a pigment pretreated with a commercially available pigment dispersion or surface treatment agent, for example, a pigment dispersed in an insoluble resin or the like as a dispersion medium, Or what grafted resin to the pigment surface etc. can be used unless the effect of this invention is impaired.
Examples of these pigments 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, and JP 2003-342503 A3.

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

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

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

Examples of the pigment exhibiting green include C.I. I. Pigment green 7 (phthalocyanine green), C.I. I. Phthalocyanine pigments such as C.I. Pigment Green 36 (phthalocyanine green); I. Pigment green 8 (nitroso green), C.I. I. And azo metal complex pigments such as CI Pigment Green 10.
Examples of orange pigments include C.I. I. An isoindoline pigment such as C.I. Pigment Orange 66 (isoindoline orange); I. Anthraquinone pigments such as C.I. Pigment Orange 51 (dichloropyrantron orange); I. Pigment orange 2, C.I. I. Pigment orange 3, C.I. I. Β-naphthol pigments such as C.I. Pigment Orange 5; I. Pigment orange 4, C.I. I. Pigment orange 22, C.I. I. Pigment orange 24, C.I. I. Pigment orange 38, C.I. I. Naphthol AS pigments such as CI Pigment Orange 74; I. Isoindolinone pigments such as CI Pigment Orange 61; I. Perinone pigments such as C.I. Pigment Orange 43; I. Pigment orange 15, C.I. I. Disazo pigments such as CI Pigment Orange 16; I. Pigment orange 48, C.I. I. Quinacridone pigments such as CI Pigment Orange 49; I. Pigment orange 36, C.I. I. Pigment orange 62, C.I. I. Pigment orange 60, C.I. I. Pigment orange 64, C.I. I. An acetolone pigment such as C.I. Pigment Orange 72; I. Pigment orange 13, C.I. I. And pyrazolone pigments such as CI Pigment Orange 34.
Examples of the pigment exhibiting brown include C.I. I. Pigment brown 25, C.I. I. And naphthron pigments such as CI Pigment Brown 32.

Examples of pigments exhibiting black color include carbon black, titanium black, C.I. I. Indazine pigments such as CI Pigment Black 1 (aniline black); I. Pigment black 31, C.I. I. And perylene pigments such as CI Pigment Black 32.
Examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), and titanium. Strontium acid (SrTiO ₃ , so-called titanium strontium white) can be used. The inorganic particles used for the white pigment may be a simple substance or, for example, oxides such as silicon, aluminum, zirconium and titanium, organometallic compounds, and composite particles with organic compounds.

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

The pigment dispersion when preparing the pigment dispersion includes, for example, ball mill, sand mill, attritor, roll mill, jet mill, homogenizer, paint shaker, kneader, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet type Any known dispersing device such as a jet mill can be used.
When dispersing the pigment, the specific dispersant can be added.
Moreover, when adding a pigment, it is also possible to use a synergist according to various pigments as a dispersion aid, if necessary, in addition to the specialty low dispersant. The dispersion aid is preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment.

As a dispersion medium for various components such as pigments in the pigment dispersion, a solvent may be added, or a polymerizable compound which is a low molecular weight component without a solvent may be used as the dispersion medium.
When a solvent is used as the dispersion medium, a known alcohol solvent, ester solvent, ether solvent, hydrocarbon solvent, or the like is preferably used as the solvent. Specifically, alkylene oxide monoalkyl ether, alkylene oxide monoalkyl ether acetate, alkylene glycol diacetate, dicarboxylic acid dialkyl ester, (meth) acrylates, divinyl ethers and the like are preferable.
Further, when this pigment dispersion is applied to a radiation curable ink composition to be described later, it is preferably solventless, and in such a case, a polymerizable compound can also be used as a dispersion medium.

Since the smaller the average particle size of the pigment used in the pigment dispersion, the better the color developability, it is preferably about 0.01 to 0.4 μm, more preferably 0.02 to 0.3 μm. The selection of pigment, dispersant, dispersion medium, dispersion conditions, and filtration conditions are set so that the maximum particle size is 3 μm or less, preferably 1 μm or less. When the pigment dispersion is used in a white ink composition, the average particle diameter of the pigment is preferably about 0.05 to 1.0 μm, more preferably about 0.0 to 1.0 μm from the viewpoint of providing sufficient hiding properties. It is about 1 to 0.4 μm.
In the present invention, since the specific dispersant excellent in dispersibility and stability is used, a uniform and stable dispersion can be obtained even when a fine particle pigment is used.
The particle diameter of the pigment in the pigment dispersion 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.
The content of the pigment in the pigment dispersion is appropriately selected according to the purpose. When the pigment is an organic pigment, it is preferably added in an amount of 1 to 20% by mass in terms of solid content, and 1.5 to 10% by mass. % Is more preferable. Moreover, when the said pigment is an inorganic pigment, 1-30 mass% is preferable in conversion of solid content, and 2-25 mass% is more preferable.
In the pigment dispersion of the present invention, the content of the dispersion medium is obtained by removing the total content of the specific dispersant and the pigment from the total amount of the composition.

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

The radiation curable curable ink composition, which is a preferred embodiment of the present invention, will be described below.
<Curable ink composition>
The curable ink composition of the present invention is a radiation curable ink, and after applying the ink on a recording medium, it is cured by irradiation with radiation. Preferably there is. This is because if the solvent remains in the cured ink image, there is a concern that the solvent resistance deteriorates, the blocking property decreases, the curing failure, and the physical properties of the ink image change over time due to the remaining solvent. . From such a viewpoint, a polymerizable compound is used as a dispersion medium, and in particular, a polymerizable compound having the lowest viscosity can be selected, thereby improving dispersibility and handling of the ink composition, and applying this ink to an ink jet recording method. This is preferable from the viewpoint of ink jet discharge suitability.

The smaller the average particle size of the pigment used in the ink composition other than white, the better the color developability. It is. In view of the above, it is preferable to set the pigment, the specific dispersant, the dispersion medium, the dispersion conditions, and the filtration conditions so that the maximum particle size is 3 μm or less, preferably 1 μm or less.
The average particle diameter of the pigment used in the white ink composition is preferably about 0.05 to 1.0 μm, more preferably about 0.1 to 0.4 μm from the viewpoint of providing sufficient hiding properties. preferable. As with the ink compositions of other colors, the maximum particle size is preferably adjusted to 3 μm or less, preferably 1 μm or less.
By controlling the particle size, the storage stability of the ink, the transparency of the ink, and the curing sensitivity can be maintained, and clogging of the head nozzle can be suppressed even when such an ink composition is applied to the ink jet recording method.
The ink composition of the present invention uses the specific dispersant excellent in pigment dispersibility and stability, so that even when a fine particle pigment is used, a uniform and stable dispersion is obtained.
The particle size of the pigment in the ink composition can be measured by the same method as described in the pigment dispersion.
When the pigment is an organic pigment, the pigment is preferably added in an amount of 1 to 20% by mass, more preferably 1.5 to 10% by mass in terms of solid content. Moreover, when the said pigment is an inorganic pigment, 1-30 mass% is preferable in conversion of solid content, and 2-25 mass% is more preferable.

[Curable composition]
The pigment dispersion of the present invention has a characteristic that the pigment can be finely and stably dispersed even in a so-called polymerizable compound having a polymerizable functional group such as an ethylenic double bond or a cyclic ether. It is suitably used as a coloring component.
That is, the curable composition of the present invention is a colored curable composition containing the pigment dispersion of the present invention, and is cured by applying energy such as heat and light.
The curable composition of the present invention is not particularly limited as long as it contains the pigment dispersion of the present invention, but further contains a polymerization initiator and a polymerizable compound from the viewpoint of improving effectiveness. Is preferred.
<Polymerization initiator>
When a thermal polymerization initiator is included as a polymerization initiator used in the curable composition of the present invention, good curability is exhibited by heating. Moreover, when a photoinitiator is included, it will harden | cure by irradiation of an active energy ray. Here, the active energy ray is not particularly limited as long as it can impart energy capable of generating a starting species in the ink composition by the irradiation, and is broadly α-ray, γ-ray, X-ray, Including ultraviolet rays, visible rays, electron beams, etc. Among them, ultraviolet rays and electron beams are preferable from the viewpoint of curing sensitivity and availability of the apparatus, and ultraviolet rays are more preferable.
Therefore, the curable composition of the present invention is preferably one that can be cured by irradiating ultraviolet rays as radiation. As the ultraviolet light source, a mercury lamp, a metal halide lamp, a light emitting diode (LED), a semiconductor laser, a fluorescent lamp, or the like is used. In the present invention, it is preferable to use a mercury lamp, a metal halide lamp, or a light emitting diode as a light source, and it is more preferable to have an emission wavelength of 300 nm to 400 nm.

Hereinafter, each component used for the curable composition of this invention is demonstrated one by one.
(Polymerizable compound)
The curable composition of the present invention preferably contains a polymerizable compound. The polymerizable compound is not particularly limited as long as it is a compound that causes a polymerization reaction by being imparted with some energy and cures, and can be used regardless of the type of monomer, oligomer, or polymer. Various known polymerizable monomers known as photoradical polymerizable monomers and photocationically polymerizable monomers that cause a polymerization reaction by an initiation species generated from the polymerization initiator are preferred.
One or more polymerizable compounds can be used in combination for the purpose of adjusting the reaction rate, ink physical properties, cured film physical properties, and the like. The polymerizable compound may be a monofunctional compound or a polyfunctional compound.

In the present invention, various known radically polymerizable monomers that cause a polymerization reaction with an initiating species generated from a photoradical initiator can also be used as the polymerizable compound.
Examples of the radical polymerizable monomer include (meth) acrylates, (meth) acrylamides, aromatic vinyls and the like. In the present specification, when referring to both or one of “acrylate” and “methacrylate”, when referring to both “(meth) acrylate” and “acryl” and / or “methacryl”, “(meth) acryl” And may be described respectively.

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

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

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

Examples of the trifunctional (meth) acrylate include trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane alkylene oxide-modified tri (meth) acrylate, and pentaerythritol tri (meth) acrylate. , Dipentaerythritol tri (meth) acrylate, trimethylolpropane tri ((meth) acryloyloxypropyl) ether, isocyanuric acid alkylene oxide modified tri (meth) acrylate, propionate dipentaerythritol tri (meth) acrylate, tri ((meta ) Acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde-modified dimethylolpropane tri (meth) acrylate, sorbitol tri (meth) a Relate, propoxylated trimethylolpropane tri (meth) acrylate, and the like ethoxylated glycerol triacrylate.
Examples of the tetrafunctional (meth) acrylate include pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate propionate, and ethoxylated penta Examples include erythritol tetra (meth) acrylate.
Examples of pentafunctional (meth) acrylates include sorbitol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate.
Examples of hexafunctional (meth) acrylates include dipentaerythritol hexa (meth) acrylate, sorbitol hexa (meth) acrylate, phosphazene alkylene oxide-modified hexa (meth) acrylate, and ε-captolactone-modified dipentaerythritol hexa (meth). ) Acrylate and the like.

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

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

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

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

  Examples of the cationic polymerizable monomer used as the polymerizable compound in the present invention include, for example, JP-A Nos. 6-9714, 2001-31892, 2001-40068, 2001-55507, and 2001. -310938, 2001-310937, 2001-220526, etc., epoxy compounds, vinyl ether compounds, oxetane compounds and the like.

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

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

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

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

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

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

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

The compound having such an oxetane ring is described in detail in JP-A-2003-341217, paragraph numbers [0021] to [0084], and the compounds described herein can be suitably used in the present invention. .
Among the oxetane compounds as the cationic polymerizable monomer, it is preferable to use a compound having 1 to 2 oxetane rings from the viewpoint of viscosity and adhesiveness of the ink composition.

  In the curable composition of the present invention, only one type of compound may be used as the cationic polymerizable monomer, or two or more types may be used in combination, but the viewpoint of effectively suppressing shrinkage during ink curing. Is preferably used in combination with at least one oxetane compound and at least one compound selected from an epoxy compound and a vinyl ether compound.

  When the polymerizable compound is used in the curable composition, the content of the polymerizable compound is appropriately 50 to 95% by mass, preferably 60 to 92% by mass, and more preferably 70 to 90% by mass. . In this range, good curability can be obtained.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  Preferable specific examples of the compounds represented by the above (i) to (x) include those shown below.

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 curable composition is preferably in the range of 0.1 to 20% by mass, more preferably 0.5 to 15% by mass in the curable composition. It is particularly preferably 1 to 10% by mass.

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

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

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

(Co-sensitizer)
Furthermore, you may add to the curable composition of this invention as a co-sensitizer the well-known compound which has effects, such as improving a sensitivity further or suppressing the superposition | polymerization inhibition by oxygen.
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, the sulfur compound described in JP-A-6-308727 (eg, trithiane, etc.), the phosphorus compound described in JP-A-6-250387 (diethylphosphite, etc.), Japanese Patent Application No. 6-191605 Si-H and Ge-H compounds described in the above No.

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

  The curable 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, dimethylamine hydrochloride for the purpose of controlling injection properties. In order to improve adhesion to salts and recording media, a trace amount of organic solvent can be added.

Various polymer compounds can be added to the curable 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 curable composition of the present invention for adjusting liquid properties.
In addition to this, as necessary, for example, leveling additives, matting agents, waxes for adjusting film physical properties, polymerization to improve the adhesion to recording media such as polyolefin and PET, A tackifier or the like that does not inhibit the above can be contained.

  The curable composition of the present invention thus obtained is a colored curable composition in which a pigment as a colorant is uniformly and stably dispersed, and even fine pigments aggregate over time. In addition, it is uniformly dispersed without causing precipitation, and the effect is maintained, so that excellent color developability can be obtained. Therefore, such a colored curable composition is used for applications requiring good color developability, applications requiring a light-resistant colorant, such as a curable ink composition, a nanoimprint composition, and a surface coating agent. It can be suitably used in a wide range of fields.

[Curable ink composition]
The curable ink composition, which is the optimum use of the curable composition of the present invention, will be described. The curable ink composition of the present invention comprises the curable composition of the present invention.
The curable ink composition formed by applying the curable composition is cured with high sensitivity by actinic radiation, and there is no concern about the increase in viscosity and colorability due to the decrease in pigment dispersion stability. As will be described later, it is suitably used for an ink jet ink applied to an ink jet recording method requiring viscosity stability.

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

  The surface tension 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 curable ink composition of the present invention thus adjusted is suitably used as an ink for inkjet recording. The ink composition is printed on a recording medium by an inkjet printer, and then the printed ink composition is irradiated with radiation to be cured and recorded.
In the printed matter obtained with this ink, the image portion is cured by irradiation with radiation such as ultraviolet rays, and the strength of the image portion is excellent. Part), and can be used for various purposes.

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

[Inkjet recording method]
The inkjet recording method of the present invention is characterized by using the curable ink composition of the present invention.
In the ink jet recording method of the present invention, it is preferable that the ink composition is heated to 40 to 80 ° C. and the viscosity of the ink composition is adjusted to 30 mPa · s or less, and then ejected. Injection stability can be realized.
In general, radiation curable ink compositions generally have a higher viscosity than aqueous inks, so that the viscosity fluctuation range due to temperature fluctuations during printing is large. This viscosity variation of the ink composition directly affects the droplet size and droplet ejection speed as it is, which causes image quality deterioration. Therefore, it is necessary to keep the ink composition temperature as constant as possible during printing. is there. The control range of the ink composition temperature is preferably set temperature ± 5 ° C., more preferably set temperature ± 2 ° C., and particularly preferably set temperature ± 1 ° C.

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

  The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors in each piping portion and perform heating control according to the ink composition flow rate and the environmental temperature. Further, the head unit to be heated is preferably thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of thermal energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

By adding a photopolymerization initiator as the polymerization initiator to the ink composition of the present invention, an actinic radiation curable ink composition is obtained.
The irradiation conditions of actinic radiation in such an ink composition will be described. A basic irradiation method is disclosed in JP-A-60-132767. Specifically, a light source is provided on both sides of the head unit, and the head and the light source are scanned by a shuttle method. Irradiation is performed after a certain period of time after ink landing. Further, the curing is completed by another light source that is not driven. In WO99 / 54415, as an irradiation method, a method using an optical fiber or a method 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 ink composition of the present invention is used, it is desirable that the ink composition is heated to a certain temperature and the time from landing to irradiation is 0.01 to 0.5 seconds, preferably 0.8. The irradiation is performed after 01 to 0.3 seconds, more preferably from 0.01 to 0.15 seconds. Thus, by controlling the time from landing to irradiation to an extremely short time, it is possible to prevent the landing ink from bleeding before being cured.
Also, since the ink composition can be exposed to a porous recording medium before it penetrates deeper than the light source reaches, unreacted monomer remains, and as a result, odor can be reduced. Can do.
By using the inkjet recording method and the curable ink composition of the present invention in combination, a great synergistic effect is brought about. In particular, when an ink composition having an ink viscosity of 200 mPa · s or less at 25 ° C. is used, a great effect can be obtained.
By adopting such an ink jet recording method, the dot diameter of the landed ink can be kept constant even on various recording media having different surface wettability, and the image quality is improved. In addition, in order to obtain a color image, it is preferable to superimpose in order from the color with the lowest brightness. When inks with low lightness are stacked, it is difficult for the irradiation rays to reach the lower ink, and inhibition of curing sensitivity, increase of residual monomers, generation of odor, and deterioration of adhesion tend to occur. Irradiation can be performed by injecting all colors and exposing them together, but exposure for each color is preferable from the viewpoint of promoting curing.

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

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

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

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to the form in these Examples.

  In addition, the molecular weight of the polymer in the synthesis example shown below represents a number average molecular weight, and was measured by GPC (Shimadzu Corporation HPLC LC-10AD). In addition, this GPC measurement uses Shodex GPC-KF-804 manufactured by Showa Denko Co., Ltd. as a column, N-methylpyrrolidone (NMP) as an eluent, and measurement at 40 ° C. and a flow rate of 0.8 mL / second. went. The molecular weight was calculated by comparison with standard polystyrene.

(Synthesis Example 1)
<Synthesis Example 1: Synthesis of (a) Polymer (A-1)>
_{DBE di basic ester (CH 3 O} 2 C (CH 2) n CO 2 CH 3] ( trade name: Aldrich Co.) 15.0 g, 3- dimethylaminopropyl acrylamide (manufactured by Tokyo Kasei Kogyo (Co.)) 15.6 g And 0.328 g of thioglycerol (manufactured by Aldrich) are 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 105 ° C.
After adding 0.0437 g of VA-086 (2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide] (manufactured by Wako Pure Chemical Industries, Ltd.), the mixture was stirred for 2 hours. 0.0237 g of VA-086 was added, and the mixture was stirred with heating for 4 hours at 115 ° C. The reaction solution was allowed to cool at room temperature, 20 g of methyl ethyl ketone was added, and the mixture was poured into 500 g of n-hexane. The obtained polymer was dried under reduced pressure to obtain poly (3-dimethylaminopropylacrylamide) having a diol at the end [corresponding to the compound (A-1) of (a) polymer] (number average molecular weight 4, 600)

<Synthesis Example 2: Synthesis of (a) Polymer (A-3)>
DBE 15.0 g, N-dimethylaminoethyl methacrylate 15.7 g (manufactured by Tokyo Chemical Industry Co., Ltd.) and thioglycerol 0.432 g (manufactured by Aldrich) were introduced into a nitrogen-substituted three-necked flask and stirred with a stirrer. The mixture was heated to 105 ° C. while flowing nitrogen into the flask.
After adding 0.0577 g of VA-086 (2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide] (manufactured by Wako Pure Chemical Industries, Ltd.), the mixture was stirred for 2 hours. 0.0288 g of VA-086 was added, and the mixture was heated and stirred for 4 hours at 115 ° C. The reaction solution was allowed to cool at room temperature, 20 g of DBE was added, and the mixture was poured into 700 g of n-hexane. The obtained polymer was dried under reduced pressure to obtain poly (N-dimethylaminoethyl methacrylate) [corresponding to the compound (A-3) of the polymer (a)] having a diol at the terminal (number average molecular weight 3, 500)

<Synthesis Example 3: (a) Synthesis of Polymer (A-4)>
DBE 15.0 g, 2-[[(butylamino) carbonyl] oxy] ethyl acrylate 21.53 gg (manufactured by Aldrich), and thioglycerol 0.866 g (manufactured by Aldrich) were introduced into a nitrogen-substituted three-necked flask and stirred. The mixture is stirred with (Shinto Kagaku Co., Ltd .: Three-One Motor) and heated to 105 ° C. while flowing nitrogen into the flask.
After adding 0.115 g of VA-086 (manufactured by Wako Pure Chemical Industries, Ltd.), the mixture was stirred for 2 hours. Furthermore, 0.0558g of VA-086 was added, and it heated and stirred at 115 degreeC for 4 hours. The reaction solution was allowed to cool at room temperature, 20 g of DBE was added, and the mixture was poured into 700 g of n-hexane. The obtained polymer was filtered off and dried under reduced pressure, and the poly (2-[[(butylamino) carbonyl] oxy] ethyl acrylate) [(a) polymer (A-4) having a diol at the terminal was converted into the compound (A-4). Equivalent] was obtained. (Number average molecular weight 2,800)

<Synthesis Example 4: Synthesis of (b) polymer (B-1-A)>
120 g of DBE (manufactured by Wako Pure Chemical Industries, Ltd.), 100 g of methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.865 g of thioglycerol (manufactured by Aldrich) were introduced into a nitrogen-substituted three-necked flask, and a stirrer (Shinto Kagaku) (Co., Ltd .: Three-One Motor) and heated to 105 ° C. while flowing nitrogen into the flask.
After adding 0.115g of VA-086, it stirred for 2 hours. Furthermore, 0.056g of VA-086 was added, and it heated and stirred at 115 degreeC for 4 hours. The reaction solution was allowed to cool at room temperature, 100 g of DBE was added, and the mixture was poured into 6000 g of n-hexane. The precipitated solid was separated by filtration and dried under reduced pressure, thereby having a skeleton corresponding to the compound (B-1) of poly (methyl methacrylate) [(b) polymer having a diol at the terminal and a number average molecular weight of 12,000. Compound (B-1-A)] was obtained.

<Synthesis Example 5: (b) Synthesis of polymer (B-1-B)>
120 g of DBE (manufactured by Wako Pure Chemical Industries, Ltd.), 100 g of methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) and 1.97 g of thioglycerol (manufactured by Aldrich) were introduced into a nitrogen-substituted three-necked flask, and a stirrer (Shinto Kagaku Co., Ltd.) ): Three-one motor), and the mixture is heated to 105 ° C. while flowing nitrogen into the flask. After adding 0.262g of VA-086, it stirred for 2 hours. Further, 0.131 g of VA-086 was added, and the mixture was stirred at 115 ° C. for 4 hours. The reaction solution was allowed to cool at room temperature, 100 g of DBE was added, and the mixture was poured into 6000 g of n-hexane. The precipitated solid was separated by filtration and dried under reduced pressure, thereby having a skeleton corresponding to the compound (B-1) of poly (methyl methacrylate) [(b) polymer having a diol at the terminal and a number average molecular weight of 6,000. Compound (B-1-B)] was obtained.

<Synthesis Example 6: Synthesis of specific dispersant (P-1) DBE solution>
DBE 23.3 g (manufactured by Aldrich), (a) 0.86 g of polymer (A-1) obtained in Synthesis Example 1 and (b) polymer (B-1-A) obtained in Synthesis Example 4 9.0 g and (c) 0.14 g of tolylene diisocyanate (TDI, manufactured by Tokyo Chemical Industry Co., Ltd.) were introduced into a three-necked flask and stirred with a stirrer (Shinto Kagaku Co., Ltd .: Three-One Motor). The temperature is raised to 60 ° C. By stirring for 4 hours, a DBE solution of the specific pigment dispersant (P-1) according to the present invention was obtained. The number average molecular weight of the obtained specific dispersant (P-1) was 33,000.

<Synthesis Example 7: Synthesis of Specific Dispersant (P-1) DVE-3 Solution>
23.3 g of DVE-3 (manufactured by Aldrich), 0.86 g of (a) polymer (A-1) obtained in Synthesis Example 1 and (b) polymer (B-1-) obtained in Synthesis Example 4 A) 9.0 g and (c) 0.14 g of tolylene diisocyanate (TDI, manufactured by Tokyo Chemical Industry Co., Ltd.) were introduced into a three-necked flask and stirred with a stirrer (Shinto Kagaku Co., Ltd .: Three-One Motor). The temperature is raised to 60 ° C. The DVE-3 solution of the specific pigment dispersant (P-1) according to the present invention was obtained by stirring for 4 hours. The number average molecular weight of the obtained specific dispersant (P-1) was 37,000.
<Synthesis Example 8: Synthesis of Specific Dispersant (P-2) DVE-3 Solution>
DVE-3 23.3 g (manufactured by Aldrich), (a) 0.64 g of polymer (A-1) obtained in Synthesis Example 1, and (b) polymer (B-1-) obtained in Synthesis Example 5 B) 9.11 g and (c) tolylene diisocyanate 0.25 g (TDI, manufactured by Tokyo Chemical Industry Co., Ltd.) were introduced into a three-necked flask and stirred with a stirrer (Shinto Kagaku Co., Ltd .: Three-One Motor). The temperature is raised to 60 ° C. By stirring for 4 hours, a DBE-3 solution of the specific pigment dispersant (P-2) according to the present invention was obtained. The number average molecular weight of the obtained specific dispersant (P-2) was 53,000.

<Synthesis Example 9: Synthesis of Specific Dispersant (P-6) DVE-3 Solution>
DVE-3 23.3 g (manufactured by Aldrich), (a) polymer (A-1) 1.9 g obtained in Synthesis Example 1, and (b) polymer (B-1-) obtained in Synthesis Example 5 B) 74.5 g and (c) tolylene diisocyanate 0.51 g (TDI, manufactured by Tokyo Chemical Industry Co., Ltd.) and diethylene glycol 0.14 g (manufactured by Wako Pure Chemical Industries, Ltd.) were introduced into a three-necked flask, and a stirrer The mixture is stirred with (Shinto Kagaku Co., Ltd .: Three-One Motor) and heated to 60 ° C. By stirring for 4 hours, a DVE-3 solution of the specific pigment dispersant (P-6) according to the present invention was obtained. The number average molecular weight of the obtained specific dispersant (P-6) was 48,000.

<Synthesis Example 10: Synthesis of Comparative Dispersant (P-7) DBE Solution>
12 g of dehydrated methoxypropylene glycol, 9.9 g of N, N-dimethylacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.67 g of 6-mercaptohexanol (manufactured by Aldrich) were introduced into a nitrogen-substituted three-necked flask, and a stirrer ( The mixture is stirred with Shinto Kagaku Co., Ltd. (Three-One Motor) and heated to 105 ° C. while flowing nitrogen into the flask.
After adding 0.072g of VA-086, it stirs for 2 hours. Further, 0.026 g of VA-086 was added, and the mixture was heated and stirred at 115 ° C. for 4 hours. After cooling the reaction solution to 50 ° C., 0.93 g of Karenz MOI (2-methacryloyloxyethyl isocyanate, manufactured by Showa Denko KK) is added and stirred for 5 hours. After pouring the reaction solution into 500 g of n-hexane and removing the supernatant by decantation, 21 g of DBE was added to obtain a polymerizable oligomer solution 1 having nitrogen atoms. (Solid content 28%, number average molecular weight 1,400)
In a three-necked flask purged with nitrogen, 20 g of DBE, 16 g of terminal methacryloylated poly (methyl methacrylate) (number average molecular weight 6000, AA-6 manufactured by Toagosei Co., Ltd.), and 14.3 g of polymerizable oligomer solution 1 (solid content concentration 28%) were placed. Then, the mixture is stirred with a stirrer (Shinto Kagaku Co., Ltd .: Three-One Motor) and heated to 68 ° C. while flowing nitrogen into the flask. Next, 0.08 g of V-65 (2,2′-azobis [2,4-dimethylvaleronitrile], manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred for 3 hours, 0.08 g of V-65 was added, and the mixture was heated to 78 ° C. For 4 hours. 36.4g of DBE was added to the reaction solution, and the 30 mass% DBE solution of the comparative pigment dispersant (P-7) was obtained. The number average molecular weight of the obtained comparative dispersant (P-7) was 28,000. The comparative dispersant (P-7) is different from the specific dispersant according to the present invention in that the main chain structure is a vinyl polymer.

<Synthesis Example 11: Synthesis of Comparative Dispersant (P-9) THF Solution>
Tetrahydrofuran (THF: manufactured by Wako Pure Chemical Industries, Ltd.) 5 g, vinylpyrrolidone 4.5 g (manufactured by Tokyo Chemical Industry Co., Ltd.), 6-mercaptohexanol 0.54 g (manufactured by Aldrich) were introduced into a nitrogen-substituted three-necked flask. Then, the mixture is stirred with a stirrer (Shinto Kagaku Co., Ltd .: Three-One Motor), heated to 105 ° C. while flowing nitrogen into the flask. After adding 0.028 g of VA-086, the mixture is stirred for 2 hours. Further, 0.016 g of VA-086 was added to obtain a polymer (P-8) solution having a number average molecular weight of 1,100.
Tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.) 20 g, methyl methacrylate 22 g (manufactured by Tokyo Chemical Industry Co., Ltd.) and 6-mercaptohexanol 0.27 g (manufactured by Aldrich) were introduced into a nitrogen-substituted three-necked flask and a stirrer ( The mixture is stirred with Shinto Kagaku Co., Ltd. (Three-One Motor) and heated to 105 ° C. while flowing nitrogen into the flask.
After adding 0.014g of VA-086, it stirred for 2 hours. To this solution, 1.01 g of trimer hexamethylene diisocyanate (Basonat HB 100, manufactured by BASF) and 0.05 g of dibutyltin laurate were added. Thereafter, 10.5 g of the previously synthesized polymer (P-8) solution was added to obtain a comparative dispersant (P-9) tetrahydrofuran solution.

Example 1
In accordance with the formulation shown below, first, the pigment dispersant (P-1) DBE solution is dissolved in a polymerizable compound (radical polymerizable compound), put into a motor mill M50 (manufactured by Eiger) together with the pigment, and a diameter of 0.65 mm. The zirconia beads were dispersed at a peripheral speed of 9 m / s for 6 hours to obtain a stock solution of the active energy ray-curable ink composition.
Next, the following polymerization initiator was added to the ink stock solution and mixed gently, and then pressure filtered with a membrane filter to obtain the ink composition for inkjet of Example 1.

-Pigment (organic pigment: Acetone pigment PY120) 3.0 parts by mass-Pigment dispersant (P-1DBE solution) 3.0 parts by mass-Polymerizable compound (dicyclopentenyloxyethyl acrylate,
FA-512A, manufactured by Hitachi Chemical Co., Ltd.) 40.0 parts by mass ・ Polymerizable compound (phenoxyethylene glycol acrylate,
AMP-10G, manufactured by Shin-Nakamura Chemical Co., Ltd.) 25.4 parts by mass-Polymerizable compound (hexaacrylate, DPCA-60:
Nippon Kayaku Co., Ltd.) 5.0 parts by mass Polymerization initiator (acylphosphine oxide compound,
Lucirin TPO-L: manufactured by BASF Japan Ltd.) 5.0 parts by mass

(Examples 2 to 4)
As shown in Table 1 below, the specific dispersant (P-1) DBE solution used in Example 1 is the specific dispersant (P-1) DVE-3 solution and (P-2) DVE-, respectively. Ink-jet ink compositions of Examples 2 to 4 were obtained in the same manner as Example 1 except that the solution was changed to 3 solutions and (P-6) DVE solution.

(Comparative Example 1)
Instead of the specific dispersant (P-1) DBE solution used in Example 1, “Disperbuk-168” (manufactured by Big Chemie Japan), which is a commercially available pigment dispersant having a base in the main chain, was used. Except for the above, the inkjet ink composition of Comparative Example 1 was obtained in the same manner as Example 1.
(Comparative Example 2)
In place of the specific dispersant (P-1) DBE solution used in Example 1, “SOLSPERSE55000” (manufactured by Nippon Lubrizol Co., Ltd.), which is a commercially available polyurethane-based dispersant, was used. Similarly, an inkjet ink composition of Comparative Example 2 was obtained.

(Comparative Examples 3 and 4)
Instead of the specific dispersant (P-1) DBE solution used in Example 1, the comparative dispersant (P-7) DBE solution obtained in Synthesis Example 10 and the comparative dispersant obtained in Synthesis Example 11 ( P-9) Inkjet ink compositions of Comparative Examples 3 and 4 were obtained in the same manner as Example 1 except that each tetrahydrofuran (THF) solution was used.

<Evaluation of ink composition>
The obtained inkjet ink was evaluated according to the following method. The results are shown in Table 1.
-Viscosity-
The viscosity at 40 ° C. of each inkjet ink was measured using an E-type viscometer.
A: Less than 30 mPas B: 30 mPas or more, less than 100 mPas C: 100 mPas or more (a level causing a discharge problem)

-Stability-
Each ink-jet ink was evaluated by visual observation and viscosity change after storage at 25 ° C. for 6 weeks and after storage at 60 ° C. for 48 hours.
◎: Precipitation does not occur and viscosity does not increase ○: Precipitation does not occur and viscosity increases slightly, but there is no problem with ejection performance △: Precipitation does not occur, but ejection performance decreases due to increase in viscosity However, it is a practically problematic level ×: the occurrence of precipitates is observed

-Average particle size-
About each inkjet ink, the median diameter was measured and evaluated using the light-scattering diffraction type particle size distribution measuring apparatus (LB500, the Horiba, Ltd. make).
A: Median diameter is less than 100 nm B: Median diameter is 100 nm or more and less than 250 nm C: Median diameter is 250 nm or more

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

-Blocking resistance-
The obtained ink composition was printed on a vinyl chloride sheet with an inkjet printer (printing density 300 dpi, droplet ejection frequency 4 kHz, nozzle number 64), and then 2000 mJ / cm with a Deep UV lamp (USHIO, SP-7). It exposed on the conditions used as the energy of ² , and obtained the printing sample.
Three print samples were stacked and a weight was placed so as to be 1 (g / cm 3). After 6 hours, the degree of adhesion of the print surface to the overlapped sheet was evaluated according to the following criteria.
A: Not adhered at all B: Slightly adhered, but no print surface peeling.
C: There is peeling of the printing surface.

-Nozzle missing-
The obtained ink composition was subjected to a temperature increase / decrease cycle of 25 ° C. to 60 ° C. 10 times, then printed with the ink jet printer, observed for the absence of nozzles, and evaluated according to the following criteria.
○: High quality image formed with no missing nozzles Δ: Some satellites were observed and image defects were observed x: Nozzle missing occurred and image defects were significant

From Table 2, the ink composition of the present invention can be cured with high sensitivity to radiation, can form a high-quality image without stickiness, and can disperse the pigment even when stored for a long period of time. Both the dispersibility and dispersion stability of the pigment were good without causing thickening due to the decrease. Moreover, the printed matter which was excellent also in blocking resistance was able to be obtained.
From the results of the dispersibility and dispersion stability of the pigment in this ink composition, it was confirmed that the pigment dispersion of the present invention is also excellent in dispersibility and stability of the pigment.
On the other hand, in Comparative Examples 1 and 2 using a commercially available polymer dispersant and Comparative Examples 3 and 4 using a comparative dispersant having a structure different from that of the present invention, the initial pigment dispersibility is good to slightly good. In particular, the storage stability (stability (60 ° C.)) under high temperature conditions was inferior, and it was at a level causing practical problems. Further, curability and blocking resistance were inferior to the inks of the examples.

The curable composition of the present invention can be used for normal printing as an ink composition to form a sharp image with excellent color developability and obtain a high-quality printed material, as well as a resist, a color filter, and an optical disk. It can also be suitably used in the production of a laser and is also useful as an optical modeling material.
Further, by applying the ink jet recording method, a high-quality image can be directly formed on a non-absorbable recording medium based on digital data. Therefore, the ink composition of the present invention is a large-area printed material. It is also suitably used for production.

Claims (12)

  A trunk part of a polyurethane or polyurethane urea structure, a branch part made of a polymer having a partial structure selected from a urea bond, a urethane bond and an aliphatic amino group in a repeating unit; an aliphatic polyester; a poly (meth) acrylate; and A pigment dispersant comprising a graft polymer having a branch part comprising a polymer selected from polyethers, and a pigment dispersion comprising a pigment. Branches made of a polymer having a partial structure selected from a urea bond, a urethane bond and an aliphatic amino group in a repeating unit, and an aliphatic polyester, poly (meth) acrylate, 2. The graft polymer comprising a branch part composed of a polymer selected from polyethers is a graft polymer obtained by reacting at least the following (a), (b), and (c): Pigment dispersion.
(A) a polymer having a hydroxyl group and having a urea bond, a urethane bond or an aliphatic amino group in a repeating unit;
(B) a polymer selected from an aliphatic polyester having a hydroxyl group or a primary amino group, poly (meth) acrylate, and polyether;
(C) Bifunctional or higher isocyanate compounds.   (A) a hydroxyl group contained in a polymer having a hydroxyl group and having a urea bond, a urethane bond or an aliphatic amino group in the repeating unit; and (b) an aliphatic polyester having a hydroxyl group or a primary amino group, The pigment dispersion according to claim 2, wherein the number of hydroxyl groups or primary amino groups contained in the polymer selected from poly (meth) acrylate and polyether is 1 to 2 per molecule, respectively.   The polymer (a) having a hydroxyl group and having a urea bond, a urethane bond or an aliphatic amino group in a repeating unit is selected from polyamide, polyurethane, polyurea, poly (meth) acrylamides and nitrogen-containing poly (meth) acrylate. The pigment dispersion according to claim 2 or 3, wherein the pigment dispersion is a polymer having a hydroxyl group bonded to a terminal or main chain.   The pigment dispersion according to any one of claims 2 to 4, wherein the (c) bifunctional or higher isocyanate compound has 2 to 6 isocyanate groups.   The number average molecular weight of the polymer (a) having a hydroxyl group and having a urea bond, a urethane bond or an aliphatic amino group in the repeating unit is in the range of 500 to 5,000, and (b) the hydroxyl group or primary amino group. The pigment dispersion according to any one of claims 2 to 5, wherein the number average molecular weight of the polymer selected from aliphatic polyester having a group, poly (meth) acrylate, and polyether is in the range of 350 to 15000. .   An ink composition comprising the pigment dispersion according to any one of claims 1 to 6.   A curable composition containing the pigment dispersion according to any one of claims 1 to 6.   Furthermore, the curable composition of Claim 8 containing a polymeric compound and a polymerization initiator.   A curable ink composition comprising the curable composition according to claim 8.   The ink composition according to claim 7 or 10, which is for inkjet recording.   An inkjet recording method using the ink composition according to any one of claims 7, 10, and 11.