JP2014058608A - Ink composition, image forming method and photographic printed matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition having excellent discharge stability when applied to an inkjet method, with which an image having excellent solvent resistance and suppressing generation of blur can be formed.SOLUTION: The ink composition comprises: a polymeric compound having a repeating unit (a-1) having a partial structure represented by formula (1) and a repeating unit (a-2) having a hydrophilic group; a tetra-functional (meth)acrylamide compound containing a polyether chain; and water. In the formula, Rand Reach represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of Rand Ris an alkyl group having 1 to 4 carbon atoms; and * represents a bonding moiety to the main chain or side chains in the polymeric compound.

Description

  The present invention relates to an ink composition that can be applied for ink jet recording, image formation using the ink composition, and a print formed by the ink composition.

As an image recording method for forming an image on a recording medium such as paper based on an image data signal, there are an electrophotographic method, a sublimation type and a melt type thermal transfer method, an ink jet method and the like.
The electrophotographic system requires a process of forming an electrostatic latent image on a photosensitive drum by charging and exposure, and there is a problem that the system becomes complicated and consequently the manufacturing cost becomes high. In addition, although the thermal transfer system is inexpensive, there are problems such as high running costs and waste materials due to the use of ink ribbons.
On the other hand, the ink-jet method has an advantage that the ink can be used efficiently and the running cost is low because the ink is ejected only on the required image portion and the image is directly formed on the recording medium. In addition, it has less noise and is excellent as an image recording method.

Among the ink compositions used for image recording by the inkjet method, the active energy ray-curable aqueous ink composition is used for image printing, pretreatment for imparting printability to the recording medium, and protection of the printed image. -It can be used suitably for decoration post-processing, etc., and since it has water as the main component, it has excellent safety, such as being able to be applied to high-density inkjet recording due to its low viscosity, It is a technology with potential.
In recent years, an ink image formed on a resin recording medium by an ink composition has been increasingly used for applications such as large-area advertisements and outdoor advertisements. Particularly in the case of outdoor advertising, high water resistance is required. In addition, when a large area print or a large number of prints is formed continuously, a process for removing stains on the printing apparatus with an organic solvent is required, but the organic solvent used for cleaning is scattered and formed. If the ink is attached to an ink image, if the image has low solvent resistance, the portion where the solvent has adhered is dissolved and removed, and image defects such as white spots can be caused. Therefore, the image has a high level of water resistance and solvent resistance. There is a need for an ink composition that can form.

  Examples of basic constituent materials of the active energy ray-curable water-based ink composition include water, a polymerizable substance, a polymerization initiator that generates radicals by active energy rays and starts polymerization, and a coloring material (pigment or dye). be able to. Among these, a polymerizable substance and a polymerization initiator may be prepared in an emulsion state, or may be present in a solution state given water solubility by an appropriate substituent.

  As an example of the active energy ray-curable aqueous ink composition in which the polymerizable substance and the polymerization initiator are water-soluble, for example, Patent Document 1 discloses a water-soluble (meth) acrylate compound having a specific structure and a water-soluble compound. An ink composition containing an acylphosphine oxide compound is described, and according to the ink composition, an ink composition for ink jet recording is obtained in which a film having excellent adhesion and the like is obtained by light irradiation. Patent Document 2 describes an ink composition containing an active energy ray polymerizable substance having a specific maleimide structure. Patent Document 3 describes a radiation curable printing ink composition comprising a photocurable compound containing a specific maleimide derivative, a compound containing an acryloyl group or a methacryloyl group, and a photopolymerization initiator. Patent Document 4 describes a copolymer having an acidic group or basic group and a dialkylmaleimide group and a method for producing the same.

JP 2005-307199 A JP 2007-119449 A Japanese Patent Laid-Open No. 2000-160086 Japanese Patent Publication No. 2-35565

  However, the conventional active energy ray-curable water-based ink composition containing a water-soluble polymerizable substance and a polymerization initiator is still more preferable from the viewpoint of suppressing bleeding and solvent resistance of an image formed using the same. There is room for improvement. In addition, when an active energy ray-curable aqueous ink composition is used for image formation using an inkjet method, good ejection stability is also required.

The present invention has been made in light of the above circumstances, the occurrence of bleeding at the time of forming an image is suppressed, an image excellent in solvent resistance can be formed, and when applied to image formation by an inkjet method It is an object of the present invention to provide an ink composition excellent in dischargeability.
Further, the present invention suppresses the occurrence of bleeding when forming an image, can form an image with excellent solvent resistance, and suppresses the occurrence of image defects such as missing dots when the ink jet method is applied. It is an object of the present invention to provide an image forming method and a printed matter having an image with reduced bleeding and excellent solvent resistance.

Specific means for solving the above problems are as follows.
<1> (a) a polymer compound comprising a repeating unit (a-1) having a partial structure represented by the following general formula (1) and a repeating unit (a-2) having a hydrophilic group, (b) An ink composition containing a (meth) acrylamide compound represented by the following general formula (2), and (c) water.

In General Formula (1), R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of R ^a and R ^b represents an alkyl group having 1 to 4 carbon atoms. Represent. R ^a and R ^b may be bonded to each other to form a 4- to 6-membered alicyclic structure. * Indicates a binding site to the main chain or side chain in the polymer compound.

In general formula (2), R ¹ represents a hydrogen atom or a methyl group. R ² represents a linear or branched alkylene group having 2 to 4 carbon atoms. However, R ² does not take a structure in which an oxygen atom and a nitrogen atom bonded to both ends of R ² are bonded to the same carbon atom in R ² . R ³ represents a divalent linking group. k represents 2 or 3. x, y, and z each independently represent an integer of 0-6, and x + y + z satisfies 0-18.

<2> The ink composition according to <1>, wherein the repeating unit (a-1) having a partial structure represented by the general formula (1) is a repeating unit represented by the following general formula (3).

In General Formula (3), R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of R ^a and R ^b represents an alkyl group having 1 to 4 carbon atoms. Represent. R ^a and R ^b may be bonded to each other to form a 4- to 6-membered alicyclic structure. R ^c represents a hydrogen atom or a methyl group. Z represents a single bond, —COO — ** or —CONR ^d — **, R ^d represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and ** represents a bonding position with X. X represents a divalent organic group.

<3> (a) The repeating unit (a-2) having a hydrophilic group contained in the polymer compound is selected from the group consisting of alcoholic hydroxyl groups, alkyl-substituted carbamoyl groups, carboxyl groups, sulfo groups, and salts thereof. The ink composition according to <1> or <2>, which is a repeating unit having at least one hydrophilic group.
<4> The content ratio of the repeating unit (a-1) having a partial structure represented by the general formula (1) is 20 to 75% by mass with respect to the mass of the polymer compound (a), and a hydrophilic group is present. The ink composition according to any one of <1> to <3>, wherein the content ratio of the repeating unit (a-2) is 8 to 25% by mass.

<5> The ink composition according to any one of <1> to <4>, wherein the polymer compound (a) further includes a repeating unit (a-3) having a hydrophobic group.
<6> The ink composition according to <5>, wherein the repeating unit (a-3) having a hydrophobic group is a repeating unit derived from an alkyl (meth) acrylate having 4 to 22 carbon atoms.
<7> Any one of <1> to <6>, wherein the repeating unit (a-2) having a hydrophilic group is a repeating unit having at least one hydrophilic group selected from a carboxyl group and a salt thereof. The ink composition as described.

<8> The ink composition according to any one of <1> to <7>, further containing a colorant.
<9> The ink composition according to any one of <1> to <8>, further containing a polymerization initiator.
<10> The ink composition according to any one of <1> to <9>, which is for inkjet recording.
<11> The ink composition according to any one of <1> to <10>, which is for printing on a non-permeable recording medium.

<12> An ink application step of applying the ink composition according to any one of <1> to <11> onto a recording medium, and irradiating the ink composition applied onto the recording medium with active energy rays. An image forming method including an irradiation step.
<13> An ink application step of applying the ink composition according to any one of <1> to <11> onto a recording medium, and (c) water contained in the ink composition applied onto the recording medium An image forming method comprising: an ink drying step of drying and removing at least a part of the ink composition; and an irradiation step of irradiating the ink composition applied and dried on the recording medium with active energy rays.

<14> An image formed with the ink composition according to any one of <1> to <11> on a recording medium, or the image forming method according to <12> or <13>. Printed image with an image.

According to the present invention, the occurrence of bleeding at the time of forming an image is suppressed, an image having excellent solvent resistance can be formed, and the ink composition has excellent ejection properties when applied to image formation by an ink jet method. Can be provided.
In addition, according to the present invention, the occurrence of bleeding at the time of image formation is suppressed, an image excellent in solvent resistance can be formed, and image defects such as missing dots are generated when the ink jet method is applied. An object of the present invention is to provide an image forming method to be suppressed, and a printed matter having an image with reduced bleeding and excellent solvent resistance.

Hereinafter, the ink composition of the present invention (hereinafter also simply referred to as “ink composition”), an image forming method, and a printed material will be described.
In addition, in this specification, when mentioning the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, the present in the composition unless otherwise specified. It means the total amount of multiple substances.
In the ink composition of the present invention, the solid content means the total mass of all components excluding the solvent among the components contained in the ink composition at 25 ° C. The solid content in the present specification includes liquid components such as low molecular weight components other than the solvent.
In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. It is.
Moreover, in this specification, (meth) acryl means both acryl and methacryl.

[Ink composition]
The ink composition of the present invention includes (a) a polymer containing a repeating unit (a-1) having a partial structure represented by the following general formula (1) and a repeating unit (a-2) having a hydrophilic group. It is an ink composition containing a compound, (b) a (meth) acrylamide compound represented by the following general formula (2), and (c) water.

In General Formula (1), R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of R ^a and R ^b represents an alkyl group having 1 to 4 carbon atoms. Represent. R ^a and R ^b may be bonded to each other to form a 4- to 6-membered alicyclic structure. * Indicates a binding site to the main chain or side chain in the polymer compound.

In general formula (2), R ¹ represents a hydrogen atom or a methyl group. R ² represents a linear or branched alkylene group having 2 to 4 carbon atoms. However, R ² does not take a structure in which an oxygen atom and a nitrogen atom bonded to both ends of R ² are bonded to the same carbon atom in R ² . R ³ represents a divalent linking group. k represents 2 or 3. x, y, and z each independently represent an integer of 0-6, and x + y + z satisfies 0-18.

  In addition, in this specification, the high molecular compound containing the repeating unit (a-1) which has the partial structure represented by General formula (1), and the repeating unit (a-2) which has a hydrophilic group is " It may be referred to as a “specific copolymer”. In addition, the (meth) acrylamide compound represented by the general formula (2) may be referred to as “specific acrylamide”.

The ink composition of the present invention contains the above-described components, thereby suppressing the occurrence of bleeding when forming an image, forming an image excellent in solvent resistance, and forming an image by an inkjet method. Excellent dischargeability when applied.
Here, in the present invention, the solvent resistance of the image means the durability of the formed image with respect to the organic solvent.

Although the action mechanism of the present invention is not clear, the present inventors presume as follows.
The specific copolymer in the present invention includes a repeating unit (a-1) having a partial structure represented by the general formula (1), which is a structure that can be polymerized by irradiation with active energy rays such as ultraviolet rays, and a copolymer. It includes a repeating unit (a-2) having a hydrophilic group capable of improving polarity. Furthermore, in the present invention, the specific acrylamide, which is a component that functions as a polymerizable component exhibiting excellent reactivity, is contained together with the specific copolymer, thereby making the image insoluble (solvent resistant) by improving the crosslinking density and polarity. It is presumed that the property was further improved.
In addition, the ink composition of the present invention contains a specific copolymer, so that the viscosity of the ink composition increases immediately after image formation. Therefore, compared to conventional ink compositions containing a low molecular weight monomer. Therefore, it is considered that it is excellent in suppressing the occurrence of bleeding when forming an image.
Furthermore, the specific acrylamide is a component that has high hydrogen bonding property and hardly volatilizes, and the inclusion of the specific acrylamide in the ink composition of the present invention is the tip of the discharge nozzle when the ink composition is applied to image formation by an ink jet method. This effectively suppresses an increase in viscosity due to drying of the ink composition present in the part. For this reason, it is estimated that the deterioration of the discharge property with time is suppressed, and good discharge stability is exhibited.

  The ink composition of the present invention contains (a) a specific copolymer, (b) a specific acrylamide, and (c) water, and further, as long as the effects of the present invention are not impaired, Various solid compounds may be included as additives. Examples of the additive include (d) a colorant. By including (d) a colorant, a colored image can be obtained with the ink composition of the present invention. Further, as will be described later, other components may be included for various purposes.

  Hereinafter, the ink composition of the present invention will be described in detail.

[(A) Specific copolymer]
The specific copolymer contained in the ink composition of the present invention will be described in detail.
The specific copolymer is preferably a vinyl polymer, polyurethane, polyester, polyether, or polyamide, and more preferably a vinyl polymer or polyurethane.

(Repeating unit (a-1) having a partial structure represented by the general formula (1))
The specific copolymer includes a repeating unit (a-1) having a partial structure represented by the following general formula (1).

In General Formula (1), R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of R ^a and R ^b represents an alkyl group having 1 to 4 carbon atoms. Represent. R ^a and R ^b may be bonded to each other to form a 4- to 6-membered alicyclic structure. * Indicates a binding site to the main chain or side chain in the polymer compound.

In general formula (1), the C1-C4 alkyl group represented by R ^<a> or R ^<b > may be a linear structure or a branched structure. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group. Among these alkyl groups, an alkyl group having 1 to 2 carbon atoms (methyl group and ethyl group) is preferable, and an alkyl group having 1 carbon atom (methyl group) is particularly preferable.

In general formula (1), the alkyl group represented by R ^a or R ^b may or may not have a substituent, but preferably does not have a substituent.

R ^a and R ^b may be bonded to each other to form a 4- to 6-membered alicyclic structure.

As R ^a and R ^b , an aspect in which both are alkyl groups having 1 to 4 carbon atoms, or R ^a and R ^b are bonded to each other to form a 4- to 6-membered alicyclic structure. It is more preferable that both R ^a and R ^b are alkyl groups having 1 to 2 carbon atoms, and it is still more preferable that both R ^a and R ^b are alkyl groups having 1 carbon atom.

  Specific examples of the partial structure represented by the general formula (1) are shown below, but the present invention is not limited to these.

  The specific copolymer may have an aspect having a plurality of partial structures represented by the general formula (1) in the side chain.

  The repeating unit (a-1) having a partial structure represented by the general formula (1) is preferably a repeating unit represented by the following general formula (3).

In General Formula (3), R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of R ^a and R ^b represents an alkyl group having 1 to 4 carbon atoms. Represent. R ^a and R ^b may be bonded to each other to form a 4- to 6-membered alicyclic structure. R ^c represents a hydrogen atom or a methyl group. Z represents a single bond, —COO — **, or —CONR ^d — **, R ^d represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and ** represents a bonding position with X. X represents a divalent organic group.

In General Formula (3), R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of R ^a and R ^b represents an alkyl group having 1 to 4 carbon atoms. Represent. R ^a and R ^b may combine with each other to form a 4- to 6-membered ring structure.
^{R a} and ^{R b} in the general formula (3), the have each the same meaning as ^{R a} and ^{R b} in the general formula (1), and preferred ranges are also the same.

In the general formula (3), R ^c represents a hydrogen atom or a methyl group. R ^c is preferably a methyl group.
In General Formula (3), Z represents a single bond, —COO — **, or —CONR ^d — **, R ^d represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and ** represents X Represents the binding position. Z is preferably -COO-**.

Further, R ^d in the —CONR ^d — ** represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group having 1 to 4 carbon atoms represented by R ^d may have a linear structure or a branched structure. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group. R ^d is preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, that is, a methyl group or an ethyl group, and particularly preferably a hydrogen atom. If R ^d represents an alkyl group, the alkyl group may have a substituent, may not have a substituent, but preferably does not have a substituent.

  In the general formula (3), X represents a divalent organic group. Examples of the divalent organic group include an alkylene group or an aralkylene group, and an alkylene group having 2 to 20 carbon atoms or an aralkylene group having 6 to 12 carbon atoms is preferable. X is more preferably an alkylene group.

  When X represents an alkylene group, the alkylene group preferably has 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and still more preferably 2 to 8 carbon atoms. When the carbon number of the alkylene group represented by X is within this range, the mobility of the partial structure represented by the general formula (1) present at the end of the side chain in the specific copolymer is improved. The effect is further improved.

  The alkylene group represented by X may have a linear structure, a branched chain in the alkylene chain, or a cyclic structure. In addition, the alkylene group may contain a bond selected from —O—, —COO—, —OC (═O) —, and —CONH— in the alkylene chain. The alkylene group may be substituted with an alkyl group having 4 or less carbon atoms, a hydroxyl group, or a chlorine atom.

As the repeating unit represented by the general formula (3), R ^a and R ^b are each independently an alkyl group having 1 to 2 carbon atoms, R ^c is a methyl group, and Z is —COO — **. And X is preferably an alkylene group having 2 to 12 carbon atoms.

The content of the repeating unit (a-1) having a partial structure represented by the general formula (1) contained in the specific copolymer (preferably the repeating unit represented by the general formula (3)) is determined by the ink composition. The cured film (image) formed by the above is appropriately selected according to the intended properties. That is, the content of the repeating unit (a-1) having a partial structure represented by the general formula (1) is based on the total mass of the specific copolymer from the viewpoint of the strength and flexibility of the formed image. 20% by mass to 75% by mass, more preferably 30% by mass to 70% by mass, and still more preferably 40% by mass to 60% by mass.
The content of the repeating unit having the partial structure represented by the general formula (1) may be increased as long as a stronger image is obtained, for example, within the above content range, and a more flexible image is obtained. In some cases, it is better to use less.

  The specific copolymer may contain only 1 type of repeating unit (a-1) which has a partial structure represented by General formula (1), and may contain 2 or more types.

The repeating unit (a-1) having a partial structure represented by the general formula (1) is copolymerized using a monomer having a partial structure represented by the general formula (1) as one of the copolymerization components. By doing so, it can be introduced into the specific copolymer. When the repeating unit (a-1) represented by the general formula (1) is a repeating unit represented by the general formula (3), the following general formula (3 ′) is used for the synthesis of the specific copolymer. The monomer represented can be used.
The partial structure represented by the general formula (1) can also be introduced into the copolymer by a method using a polymer reaction. Examples of such a method include a method obtained by reacting a prepolymer having a primary amino group with a corresponding anhydride, a functional group that reacts with a functional group in the prepolymer to form a bond and a general formula ( Examples thereof include a method of reacting a compound having a partial structure represented by 1) with a prepolymer.

In the general formula ^{(3 '), R a,} R b, R c, Z and X, ^R a in the formula ^{(3), R b, R} c, are respectively the Z and X synonymous, preferable ranges It is the same.

  Preferable examples of the monomer represented by the general formula (3 ′) include monomers (3′-1) to (3′-11) shown below, but the present invention is not limited thereto. .

  Monomers containing a partial structure represented by the general formula (1) represented by the monomers (3′-1) to (3′-11) are disclosed in, for example, JP-A-52-988, It can be produced with reference to the method described in JP-A-4-251258.

(Repeating unit having a hydrophilic group (a-2))
The specific copolymer in this invention contains the repeating unit (a-2) which has a hydrophilic group.
The hydrophilic group contained in the repeating unit (a-2) is not particularly limited as long as it has a function of enhancing the hydrophilicity of the specific copolymer, and may be a nonionic hydrophilic group or an ion. It may be a hydrophilic hydrophilic group (for example, an anionic hydrophilic group or a cationic hydrophilic group).

  Nonionic hydrophilic groups include, but are not particularly limited to, for example, residues obtained by removing one hydrogen atom from a heterocyclic structure containing a nitrogen atom or oxygen atom, an amide group, a carbamoyl group, an alkyl-substituted carbamoyl group, an alcohol Nonionic hydrophilic groups such as a functional hydroxyl group or a group having a polyalkyleneoxy structure.

  Examples of the heterocyclic structure in the residue obtained by removing one hydrogen atom from a heterocyclic structure containing a nitrogen atom or an oxygen atom include lactones such as γ-butyrolactone; cyclic ureas such as 2-pyrrolidone and ethylene urea; ethylene carbonate, And cyclic carbonates such as propylene carbonate, and cyclic ethers such as tetrahydrofuran and 1,4-dioxane;

  As the amide group, an amide group having 2 to 10 carbon atoms is preferable, and a hydrogen atom is preferably bonded to a nitrogen atom in the amide group.

  The alkyl-substituted carbamoyl group is a monoalkylcarbamoyl group in which a hydrogen atom bonded to a nitrogen atom of a carbamoyl group is substituted with an alkyl group, or two hydrogen atoms bonded to a nitrogen atom of a carbamoyl group are substituted with an alkyl group And a dialkylcarbamoyl group formed. The alkyl group may further have a substituent such as a hydroxyl group. Among these alkyl-substituted carbamoyl groups, a monoalkylcarbamoyl group substituted with an alkyl group having 1 to 8 carbon atoms or an alkyl group having 1 to 4 carbon atoms substituted with a hydroxyl group is preferable.

  Although it does not specifically limit as group which has a polyalkyleneoxy structure, The polyalkyleneoxy structure which has a C1-C4 alkyleneoxy group in a repeating unit is preferable. One type of alkyleneoxy group in the polyalkyleneoxy structure may be used, or a plurality of types of alkyleneoxy groups may be combined. The terminal group of the polyalkyleneoxy structure is preferably a hydroxyl group or an alkoxy group, more preferably a hydroxyl group or a methoxy group.

  Although it does not specifically limit as an ionic hydrophilic group, For example, ionic hydrophilic groups, such as a carboxyl group, a sulfo group, a phosphoric acid group, a phosphonic acid group, a phenolic hydroxyl group, or a quaternary ammonium group, are mentioned. The ionic hydrophilic group may form a salt.

  When the ionic hydrophilic group forms a salt, examples of the counter salt include onium salts such as alkali metal salts (Li, Na, K, etc.), ammonium salts, pyridinium salts, and phosphonium salts. Among these, alkali metal salts (Li, Na, K, etc.) or ammonium salts are preferable.

  Among these hydrophilic groups, an amide group, a carbamoyl group, an alkyl-substituted carbamoyl group, an alcoholic hydroxyl group, a group having a polyalkyleneoxy structure, a carboxyl group, a sulfo group, and a salt thereof are preferable. A carbamoyl group, a carboxyl group, a sulfo group, and salts thereof are more preferable. Particularly preferred are carboxyl groups and salts thereof.

  The repeating unit (a-2) having a hydrophilic group is preferably a repeating unit represented by the following general formula (4).

In general formula (4), R ^cy represents a hydrogen atom or a methyl group. Z ^y represents —COO — ***, —CONR ^dy — ***, or a single bond, and R ^dy represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ^y represents a group selected from the group consisting of a single bond, an alkylene group, an arylene group, and an aralkylene group. A represents a hydrophilic group. *** represents a position where Z ^y is bonded to R ^y .

The general formula (4) will be described in detail.
In general formula (4), R ^cy represents a hydrogen atom or a methyl group.

In the general formula (4), Z ^y represents —COO — ***, —CONR ^dy — ***, or a single bond, and is preferably —COO — ***. Incidentally, *** is a position ^{where Z y} is bonded to ^{R y.}

R ^dy represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group having 1 to 4 carbon atoms may have a linear structure or a branched structure. Specifically, it represents a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, or a t-butyl group. R ^dy is preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms (that is, a methyl group or an ethyl group), and particularly preferably a hydrogen atom.

R ^dy may or may not have a substituent, but preferably does not have a substituent. Examples of the substituent that R ^dy may have include an aryl group having 6 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a hydroxyl group, a carboxyl group, and a halogen atom (F, Cl, Br, I, etc.). Etc.

In General Formula (4), R ^y represents a single bond or a group selected from the group consisting of an alkylene group, an arylene group, and an aralkylene group, an alkylene group having 1 to 20 carbon atoms, and an arylene having 6 to 20 carbon atoms. It is preferably a group or an aralkylene group having 7 to 20 carbon atoms.
When ^Ry is a group selected from the group consisting of an alkylene group, an arylene group, and an aralkylene group, these groups may or may not have a substituent. The alkylene group, arylene group, and aralkylene group represented by R ^y may have an ether bond, an ester bond, an amide bond, or a urethane bond in the structure.
In the general formula (4), R ^y is preferably a single bond.

When ^Ry is a group selected from the group consisting of an alkylene group, an arylene group, and an aralkylene group, these groups may further have a substituent. Examples of the substituent include an aryl group having 6 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a hydroxyl group, a carboxyl group, a halogen atom (F, Cl, Br, I, etc.) and the like.

When ^Ry is an alkylene group having 1 to 20 carbon atoms, the alkylene group may have a linear structure, a branched structure, or a cyclic structure. When ^Ry is an alkylene group, the number of carbon atoms is more preferably 2 to 12, and further preferably 2 to 8. Specific examples of the alkylene group for R ^y include —CH ₂ —, —C ₂ H ₄ —, —C (CH ₃ ) ₂ —CH ₂ —, —CH ₂ C (CH ₃ ) ₂ CH ₂ —, —C. _{6 H 12 -, - C 4} H 7 (C 4 H 9) C 4 H 8 -, C 18 H 36 -, 1,4-trans- cyclohexylene _{group, -C 2 H 4 -OCO-C} 2 H 4 _{-, - C 2 H 4 -OCO} -, - C 2 H 4 -O-C 5 H 10 -, - CH 2 -O-C 5 H 9 (C 5 H 11) -, - C 2 H 4 -CONH _{-C 2 H 4 -, - C} 4 H 8 -OCONH-C 6 H 12 -, - CH 2 -OCONHC 10 H 20 -, - CH 2 CH (OH) CH 2 -, and the like.

When ^Ry is an arylene group having 6 to 20 carbon atoms, the arylene group preferably has 6 to 18 carbon atoms, more preferably 6 to 14 carbon atoms, and particularly preferably 6 to 10 carbon atoms. . Specific examples of the arylene group represented by R ^y include a phenylene group, a biphenylene group, —C ₆ H ₄ —CO—C ₆ H ₄ —, a naphthylene group, and the like.

When ^Ry is an aralkylene group having 7 to 20 carbon atoms, the aralkylene group preferably has 7 to 18 carbon atoms, more preferably 7 to 14 carbon atoms, and particularly preferably 7 to 10 carbon atoms. . Specific examples of the aralkylene group represented by R ^y _{is, -C 3 H 6 -C 6 H} 4 -, - C 2 H 4 -C 6 H 4 -C 6 H 4 -, - CH 2 -C 6 H _{4 -C 6 H 4 -C 2 H} 4 -, - C 2 H 4 -OCO-C 6 H 4 - , and the like.

  Examples of the hydrophilic group represented by A in the general formula (4) include the hydrophilic groups described above, and the preferred range is also the same.

When the specific copolymer has a repeating unit represented by the general formula (4), the content of the repeating unit represented by the general formula (4) in the specific copolymer is as follows.
When the hydrophilic group A in General formula (4) is an ionic hydrophilic group, content of the repeating unit represented by General formula (4) is 5 mass%-50 mass% in a specific copolymer. It is preferably 5% by mass to 40% by mass, more preferably 1% by mass to 20% by mass.
When the hydrophilic group A in the general formula (4) is a nonionic hydrophilic group, the specific copolymer preferably has 20% by mass to 95% by mass, more preferably 30% by mass to 80% by mass, 30 mass%-70 mass% is especially preferable.

  The repeating unit represented by the general formula (4) is derived from a monomer represented by the following general formula (4 ′), and the specific copolymer is obtained by including these monomers as a copolymerization component. The repeating unit (a-2) is introduced therein.

In the general formula ^{(4 '), R cy,} Z y, R y, and A, ^R cy in the general formula ^{(4), Z y, R} y, and A and have the same meanings, the preferred range is also the same is there.

  Preferable examples of the monomer represented by the general formula (4 ′) include the following monomer compounds, but the present invention is not limited thereto.

Methoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, poly (ethylene glycol-co-propylene glycol) (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycerol (meth) Acrylate (meth) acryloyloxyethyl ethylene urea, vinylpyrrolidone, 3- (meth) acryloyloxy-γ-butyrolactone, acrylamide, tert-butylacrylamide, N, N-dimethyl (meth) acrylamide, diacetone acrylamide, (meth) Sodium acrylate, potassium (meth) acrylate, tetrabutylammonium (meth) acrylate, mono (meth) acryloyloxyethyl succinic acid, Sodium (meth) acryloyloxyethyl succinate, sodium mono (meth) acryloyloxyethyl phthalate, (meth) acryloyloxyethyl acid phosphate, sodium 2-acrylamido-2-methylpropanesulfonate, 2-acrylamide- Examples include 2-methylpropane sulfonic acid, styrene sulfonic acid, sodium styrene sulfonate, and vinyl benzoic acid.

  As the monomer represented by the general formula (4 ′), a commercially available compound can be used, and the monomer can be produced by a generally known method.

  In the present invention, in addition to the monomer represented by the general formula (4 ′), unsaturated dicarboxylic acids such as maleic acid, maleic anhydride, and fumaric acid, and anhydrides thereof, and further derived therefrom. Dicarboxylic acid salts can also be preferably used.

The content of the repeating unit (a-2) having a hydrophilic group in the specific copolymer varies depending on the type of the hydrophilic group, but the specific copolymer may be water-soluble. preferable.
Here, that the specific copolymer exhibits water solubility means that the specific copolymer can be dissolved in 3% by mass or more in water at 25 ° C.

The content of the repeating unit (a-2) having a hydrophilic group in the specific copolymer is preferably 8% by mass to 25% by mass, more preferably 10% by mass to 23% by mass. More preferably, it is 20 mass%-20 mass%.
When the content of the repeating unit (a-2) having a hydrophilic group is within the above range, the polarity of the specific copolymer is more appropriately maintained, and more suitable water resistance is obtained.
The specific copolymer may contain only one type of repeating unit (a-2) having a hydrophilic group, or may contain two or more types.

(Repeating unit having a hydrophobic group (a-3))
The specific copolymer preferably contains a repeating unit (a-3) having a hydrophobic group.
By including a repeating unit having a hydrophobic functional group, the polarity of the specific copolymer is more appropriately maintained, and the ink image formed by the ink composition is further excellent in water resistance and non-absorbing recording. It also has excellent adhesion to the medium.

The repeating unit (a-3) having a hydrophobic group has a solubility (25 ° C.) in water of a homopolymer having only a repeating unit (a-3) having a weight average molecular weight of 10,000 or more. It is preferably a repeating unit derived from a vinyl monomer that is less than 0.0% by mass. Any repeating unit derived from the vinyl monomer can be used without limitation, and among them, a repeating unit derived from a monomer selected from alkyl esters of (meth) acrylic acid and aralkyl esters is preferred.
Among them, from the viewpoint of adjusting the polarity of the specific copolymer to an appropriate range, the hydrophobic group is preferably a monomer having an alkyl group having 5 to 22 carbon atoms, and an alkyl group having 8 to 22 carbon atoms. Are more preferable, and monomers having an alkyl group having 8 to 14 carbon atoms are more preferable. That is, in the case of alkyl acrylate, it is an ester having an alkyl group having 4 to 19 carbon atoms, and an ester having an alkyl group having 4 to 13 carbon atoms is preferred. In the case of alkyl methacrylate, it is an ester having an alkyl group having 4 to 18 carbon atoms, and an ester having an alkyl group having 4 to 10 carbon atoms is preferred.
The alkyl group may be linear or branched, and may be cyclic. Further, aralkyl esters such as benzyl group and phenoxyethyl group may be used.

  Although the repeating unit (a-3) which has a hydrophobic group which a specific copolymer can contain is illustrated below, the repeating unit (a-3) which has a hydrophobic group in this invention is not limited to these. Specific examples of the repeating unit (a-3) having a hydrophobic group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl ( (Meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) Acrylate, stearyl (meth) acrylate, cyclohexyl methacrylate, benzyl methacrylate, phenoxyethyl (meth) acrylate, isobornyl methacrylate, tetrahydrofurfuryl (meth) acrylate, acetoacetoxye (Meth) acrylic acid esters such as ru (meth) acrylate, styrenes such as styrene, α-methylstyrene and 4-methylstyrene, vinyl ethers such as chloroethyl vinyl ether, etc. N-propyl methacrylate, isopropyl methacrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, which are (meth) acrylic acid esters substituted with 5 to 22 alkyl groups, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl methacrylate, benzyl methacrylate Relate, phenoxyethyl (meth) acrylate, isobornyl methacrylate, etc. are preferable, n-propyl methacrylate, isopropyl methacrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (Meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, benzyl methacrylate, phenoxyethyl (meth) acrylate, and the like are more preferable. Further, n-butyl methacrylate, isobutyl methacrylate, tert-butyl (meth) acrylate, cyclohexyl methacrylate, isobornyl methacrylate, 2-ethylhexyl methacrylate, and phenoxyethyl (meth) acrylate are particularly preferable.

The specific copolymer may contain only 1 type of repeating unit (a-3) which has a hydrophobic group, and may contain 2 or more types.
From the viewpoint of reducing the polarity of the copolymer, the repeating unit (a-3) having a hydrophobic group is preferably in the range of 5% by mass to 72% by mass, and 20% by mass to 65% by mass in the specific copolymer. Is more preferable, and 25% by mass to 60% by mass is most preferable.

(SP value of specific copolymer)
Specific copolymer is preferably SP value of ^{20.7MPa 1/2 ~23.0MPa 1/2,} preferably from 21.2MPa ^1/2 ~22.8MPa 1/2, 21.5MPa 1/2 ˜22.5 MPa ^1/2 is particularly preferred.

  The SP value referred to in the present invention is a solubility parameter calculated by the Okitsu method (Adhesion 38, No. 6, page 6 (1994) Polymer publication society), and the molar attractive constant, mol for each unit in the molecular structure. The estimated value proposed by Okitsu who can give the volume is shown. In addition, when calculating the SP value of the polymer, the carboxylic acid in (meth) acrylic acid is calculated in an unneutralized state, and the SP value in this specification is a value calculated by this method. Yes.

The SP values of typical monomer units that can be used in the present invention are described below. The numerical value described in parentheses after the monomer name is the SP value, and the unit is MPa ^1/2 .
The following monomer 1 (24.41), the following monomer 2 (23.22), the following monomer 3 (22.75), methacrylic acid (24.02), 2-hydroxyethyl methacrylate (22.89), 2-hydroxyethyl Acrylamide (32.87) methyl methacrylate (19.5), n-butyl methacrylate (18.33), isobutyl methacrylate (17.76), tert-butyl methacrylate (17.97), 2-ethylhexyl methacrylate (17.30) ), Stearyl methacrylate (17.08), 2-hydroxyethyl methacrylate (22.89), tetrahydrofurfuryl methacrylate (21.29), cyclohexyl methacrylate (18.79), benzyl methacrylate (20.21), 2-phenoxy Echi Methacrylate (20.23), isobornyl methacrylate (18.09)

  The weight average molecular weight of the specific copolymer contained in the ink composition of the present invention is preferably in the range of 5,000 to 150,000 from the viewpoint of water resistance, and the ejection stability when applied to the inkjet method is improved. From the viewpoint of enhancing, a range of 5,000 to 100,000 is more preferable.

  In addition, the weight average molecular weight of a specific copolymer is measured by a gel permeation chromatograph (GPC). GPC uses HLC-8020GPC (manufactured by Tosoh Corporation), TSKgel SuperHZM-H, TSKgel SuperHZ4000, TSKgel SuperHZ200 (4.6 mm ID × 15 cm, Tosoh Corporation) as columns and THF (tetrahydrofuran) as an eluent. And the column oven was set at a set temperature of 40 ° C. Standard polystyrene was used for calculation of molecular weight.

  Specific examples of the specific copolymer [Exemplary Compounds A-1 to A-5] are shown together with the weight average molecular weight and SP value, but the specific copolymer in the present invention is limited to these. is not. In the following exemplary compounds, the copolymerization ratios indicated using a, b, c, d and e are based on mass.

  Specific examples of the specific copolymer further include exemplary compounds A-6 to A-24 shown in Table 1 below. In Table 1, exemplary compounds A-1 to A-4 are also shown. In addition, all copolymerization ratios (%) of the exemplary compounds shown in Table 1 below are based on mass.

The abbreviations shown in Table 1 are as follows.
Monomer 1: The following compound

・ MAA: Methacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd.)
MAA-Na: Methacrylic acid sodium salt (generated by neutralizing a polymer copolymerized with methacrylic acid)
BMA: n-butyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)
IBMA: Isobutyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)
・ TBMA: tert-butyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)
・ IBOMA: Isoboronyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)
C18MA: Octadecyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)
CyHMA: cyclohexyl methacrylate (Wako Pure Chemical Industries, Ltd.)
PEMA: Phenoxyethyl methacrylate (NK ester PHE-1G, manufactured by Shin-Nakamura Chemical Co., Ltd.)
EHMA: 2-ethylhexyl methacrylate (Wako Pure Chemical Industries, Ltd.)
・ BnMA: benzyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)

  The specific copolymer includes, for example, a monomer for forming a repeating unit (a-1) having a partial structure represented by the general formula (1), and a repeating unit (a-2) having a hydrophilic group. A monomer for forming a monomer and a monomer for forming a repeating unit (a-3) having a hydrophobic group optionally used are polymerized by a known polymerization method, and if necessary, acidic It can be obtained by neutralizing the group with an alkali metal hydroxide or the like. Specifically, for example, a method according to the polymerization method described in JP-A-52-988, JP-A-55-154970, Langmuir Vol. 18, No. 14, pages 5414-5421 (2002), etc. Copolymers can be produced.

  The ink composition of the present invention may contain only one type of specific copolymer, or may contain two or more types in combination.

  The content of the specific copolymer in the ink composition of the present invention is preferably 2% by mass to 20% by mass with respect to the total mass of the ink composition, from the viewpoint of suppressing bleeding and improving ejection stability. Is more preferably 5% by mass to 20% by mass, and further preferably 5% by mass to 15% by mass.

[(B) Specific acrylamide]
The specific acrylamide contained in the ink composition of the present invention will be described in detail.
The specific acrylamide in the present invention is a (meth) acrylamide compound represented by the following general formula (2).

In general formula (2), R ¹ represents a hydrogen atom or a methyl group. R ² represents a linear or branched alkylene group having 2 to 4 carbon atoms. However, R ² does not take a structure in which an oxygen atom and a nitrogen atom bonded to both ends of R ² are bonded to the same carbon atom in R ² . R ³ represents a divalent linking group. k represents 2 or 3. x, y, and z each independently represent an integer of 0-6, and x + y + z satisfies 0-18.

  The specific acrylamide has four acrylamide groups or methacrylamide groups as polymerizable groups in the molecule, and has high polymerization ability and curing ability. The specific acrylamide polymerizes and exhibits curability by applying energy such as active energy rays such as α rays, γ rays, X rays, ultraviolet rays, visible rays, infrared rays, electron rays, and heat.

  Moreover, specific acrylamide shows water solubility and melt | dissolves favorably in water-soluble organic solvents, such as water and alcohol. Here, the specific acrylamide being water-soluble means that the specific acrylamide is dissolved in 5% by mass or more in water at 25 ° C.

  In addition, since specific acrylamide has high hydrogen bonding property and hardly volatilizes, when the ink composition of the present invention is applied to image formation by an ink jet method, an increase in viscosity due to drying near the nozzle can be suppressed, and a humectant It can serve the same function as the organic solvent used.

  The (meth) acrylamide compound (specific acrylamide) represented by the general formula (2) will be described in more detail.

In general formula (2), R ¹ represents a hydrogen atom or a methyl group. Several R < ¹ > may mutually be same or different. R ¹ is preferably a hydrogen atom.

In general formula (2), R ² represents a linear or branched alkylene group having 2 to 4 carbon atoms. A plurality of R ² may be the same as or different from each other. R ² is preferably an alkylene group having 3 to 4 carbon atoms, more preferably an alkylene group having 3 carbon atoms, and particularly preferably a linear alkylene group having 3 carbon atoms. The alkylene group represented by R ² may further have a substituent, and examples of the substituent include an aryl group and an alkoxy group.

However, R ² does not take a structure in which an oxygen atom and a nitrogen atom bonded to both ends of R ² are bonded to the same carbon atom in R ² . R ² is a linear or branched alkylene group linking an oxygen atom and a nitrogen atom of the (meth) acrylamide group. When the alkylene group has a branched structure, the oxygen atom at both ends and the nitrogen of the (meth) acrylamide group It is also conceivable to take an —O—C—N— structure (hemaminal structure) in which an atom is bonded to the same carbon atom in an alkylene group. However, the compound represented by the general formula (2) used in the present invention does not include a compound having such a structure. According to a study by the present inventors, it was found that if the molecule has an —O—C—N— structure, decomposition is likely to occur at the position of the carbon atom. Such a compound is easily decomposed during storage, and decreases the storage stability of the ink composition. Therefore, in the present invention, such a compound is not used.

In general formula (2), R ³ represents a divalent linking group.
Examples of the divalent linking group represented by R ³ include an alkylene group, an arylene group, a heterocyclic group, or a group composed of a combination thereof, and an alkylene group is preferable. When the divalent linking group includes an alkylene group, the alkylene group may further include at least one group selected from —O—, —S—, and —NR ^a —. R ^a represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

When R ³ contains an alkylene group, examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, and a nonylene group. The alkylene group represented by R ³ preferably has 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, and particularly preferably 1 carbon atom.
The alkylene group for R ³ may further contain at least one selected from —O—, —S—, and —NR ^a —. Examples of the alkylene group containing —O— include: _{-C 2 H 4 -O-C 2} H 4 -, - C 3 H 6 -O-C 3 H 6 - , and the like.
The alkylene group in R ³ may further have a substituent, and examples of the substituent include an aryl group and an alkoxy group.

When R ³ includes an arylene group, examples of the arylene group include a phenylene group and a naphthylene group. The arylene group of R ³ preferably has 6 to 14 carbon atoms, and preferably has 6 to 10 carbon atoms. Is more preferable, and 6 is particularly preferable.
The arylene group in R ³ may further have a substituent, and examples of the substituent include an alkyl group and an alkoxy group.

When R ³ contains a heterocyclic group, the heterocyclic group is preferably a 5-membered or 6-membered ring, which may be further condensed. Further, it may be an aromatic heterocyclic ring or a non-aromatic heterocyclic ring. Specific examples of the heterocyclic group when R ³ includes a heterocyclic group include pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, isoquinoline, quinazoline, cinnoline, phthalazine, quinoxaline, pyrrole, indole, furan, benzofuran, and thiophene. , Benzothiophene, pyrazole, imidazole, benzimidazole, triazole, oxazole, benzoxazole, thiazole, benzothiazole, isothiazole, benzisothiazole, thiadiazole, isoxazole, benzisoxazole, pyrrolidine, piperidine, piperazine, imidazolidine, thiazoline, etc. Is mentioned. Of these, an aromatic heterocyclic group is preferable, and pyridine, pyrazine, pyrimidine, pyridazine, triazine, pyrazole, imidazole, benzimidazole, triazole, thiazole, benzothiazole, isothiazole, benzisothiazole, and thiadiazole are preferable. In addition, although the heterocyclic group shown above is illustrated in a form in which the substitution position is omitted, the substitution position is not limited. For example, in the case of pyridine, substitution is made at the 2-position, 3-position, and 4-position. And can include all of these substitutions. The heterocyclic group may further have a substituent, and examples of the substituent include an alkyl group, an aryl group, and an alkoxy group.

In general formula (2), k represents 2 or 3. Several k may mutually be same or different. C _k H _2k may have a linear structure or a branched structure.

  In general formula (2), x, y, and z each independently represent an integer of 0 to 6, preferably an integer of 0 to 5, and more preferably an integer of 0 to 3. x + y + z satisfies 0-18, is preferably 0-15, and is more preferably 0-9.

  Specific examples [Exemplary compounds B-1 to B-6] of the (meth) acrylamide compound represented by the general formula (2) are shown below, but the present invention is not limited thereto.

  The (meth) acrylamide compound represented by the general formula (2) can be produced, for example, according to the following scheme 1 or scheme 2.

  Details of each step in Scheme 1 are as follows.

(First step)
The first step is a step of obtaining a polycyano compound by reaction of acrylonitrile and trishydroxymethylaminomethane. The reaction in this step is preferably performed at 3 to 60 ° C. for 2 to 8 hours.
(Second step)
The second step is a step of reacting a polycyano compound with hydrogen in the presence of a catalyst to obtain a polyamine compound by a reduction reaction. The reaction in this step is preferably performed at 20 to 60 ° C. for 5 to 16 hours.
(Third process)
The third step is a step of obtaining a polyfunctional acrylamide compound by an acylation reaction between a polyamine compound and acrylic acid chloride or methacrylic acid chloride. The reaction in this step is preferably performed at 3 to 25 ° C. for 1 to 5 hours. The acylating agent may be diacrylic anhydride or dimethacrylic anhydride instead of acid chloride. In addition, by using both acrylic acid chloride and methacrylic acid chloride in the acylation step, a compound having an acrylamide group and a methacrylamide group in the same molecule can be obtained as the final product.

  Details of each step in Scheme 2 are as follows.

(First step)
The first step is a step of obtaining a nitrogen-protected aminoalcohol compound by introducing a protecting group with a benzyl group, benzyloxycarbonyl group or the like into the nitrogen atom of the aminoalcohol. The reaction in this step is preferably performed at 3 to 25 ° C. for 3 to 5 hours.
(Second step)
The second step is a step of obtaining a sulfonyl compound by introducing a leaving group such as a methanesulfonyl group or a p-toluenesulfonyl group into the OH group of the nitrogen-protected amino alcohol compound. The reaction in this step is preferably performed at 3 to 25 ° C. for 2 to 5 hours.
(Third process)
The third step is a step of obtaining an amino alcohol addition compound by SN2 reaction between a sulfonyl compound and trishydroxymethylnitromethane. The reaction in this step is preferably performed at 3 to 70 ° C. for 5 to 10 hours.
(Fourth process)
The fourth step is a step in which an amino alcohol addition compound is reacted with hydrogen in the presence of a catalyst to obtain a polyamine compound by hydrogenation reaction. The reaction in this step is preferably performed at 20 to 60 ° C. for 5 to 16 hours.
(Fifth process)
The fifth step is a step of obtaining a polyfunctional acrylamide compound by an acylation reaction between a polyamine compound and acrylic acid chloride or methacrylic acid chloride. The reaction in this step is preferably performed at 3 to 25 ° C. for 1 to 5 hours. The acylating agent may be diacrylic anhydride or dimethacrylic anhydride instead of acid chloride. In addition, by using both acrylic acid chloride and methacrylic acid chloride in the acylation step, a compound having an acrylamide group and a methacrylamide group in the same molecule can be obtained as the final product.

  The compound obtained by the above steps can be purified from the reaction product solution by a conventional method. For example, it can be purified by liquid separation extraction using an organic solvent, crystallization using a poor solvent, column chromatography using silica gel, and the like.

  The ink composition of the present invention may contain only one kind of specific acrylamide, or may contain two or more kinds in combination.

  In the ink composition of the present invention, the specific acrylamide content is preferably 0.1 to 30% by mass, more preferably 0.1 to 25% by mass, and more preferably 0.1 to 25% by mass with respect to the total mass of the ink composition. 20% by mass is particularly preferred. When the content of the specific acrylamide is within the above range, it is preferable because curability can be improved and storage stability of the ink can be improved.

[(C) water]
The ink composition of the present invention contains water.
(C) As water, it is preferable to use ion-exchange water, distilled water, etc. which do not contain an impurity.
The water content in the ink composition of the present invention is preferably 10% by mass to 97% by mass, more preferably 30% by mass to 95% by mass, based on the total mass of the ink composition. It is more preferable that it is mass%-85 mass%.

[Other ingredients]
In addition to the essential components (a) specific copolymer, (b) specific acrylamide, and (c) water, the ink composition of the present invention includes a colorant, Organic solvents, photopolymerization initiators, water-soluble organic solvents, other radical polymerization initiators, and known additives can be used in combination. Hereinafter, other components that can be used in the ink composition of the present invention will be described.

<Colorant>
The ink composition of the present invention may contain one or more colorants, and becomes a colored ink composition by containing a colorant.
Examples of the colorant include dyes and pigments, and pigments are preferable from the viewpoint of durability such as heat resistance, light resistance, and water resistance.

  When a pigment is used as the colorant, the pigment can be contained in the ink composition as a pigment dispersion. Use of a pigment dispersion as a colorant is preferable from the viewpoint of improving solvent resistance. As the pigment dispersion, a self-dispersed pigment can be used in addition to a pigment dispersed with a pigment dispersant.

(Pigment)
As the pigment used as the colorant, 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 C.I. Pigment Yellow 18 (Thioflavin Lake, etc.); I. Anthraquinone pigments such as CI Pigment Yellow 24 (Flavantrone Yellow), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), C.I. I. Quinophthalone pigments such as C.I. Pigment Yellow 138 (Kinophthalone Yellow); I. An isoindoline pigment such as C.I. Pigment Yellow 139 (isoindoline yellow); 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 154, C.I. I. Pigment yellow 175, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 181, C.I. I. An acetolone pigment such as C.I. Pigment Yellow 194; I. And nickel azo pigments such as CI Pigment Yellow 150. Among these, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment Yellow 180 or the like is preferably used.

  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 CI Pigment Red 194 (perinone red, etc.)

C. 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 CI Pigment Red 209, and quinacridone pigments which are solid solutions of the plurality of quinacridone pigments; 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. Among these, C.I. 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. A quinacridone pigment such as CI Pigment Red 209 and a quinacridone pigment which is a solid solution containing a plurality of these quinacridone pigments are preferred.

  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). Among these, C.I. 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. Copper phthalocyanine pigments such as CI Pigment Blue 15: 6 are preferred.

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. Among these, carbon black is preferable.
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, and among these, titanium oxide is preferable. The inorganic particles used for the white pigment may be a simple substance or, for example, oxides such as silicon, aluminum, zirconium and titanium, organometallic compounds, and composite particles with organic compounds.

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

Since the non-white pigment has a better color developability as the average particle size is smaller, if the pigment dispersion is applied to a pigment dispersion other than white, the average particle size of the pigment contained in the pigment dispersion is: The thickness is preferably about 0.01 μm to 0.4 μm, more preferably 0.02 μm to 0.3 μm.
The maximum particle diameter of the pigment is 3 μm or less, preferably 1 μm or less. The particle size of the pigment can be adjusted by selecting a pigment, a dispersant, a dispersion medium, setting dispersion conditions, and filtering conditions. Further, when the ink composition of the present invention is prepared as a white ink composition, the average particle size of the pigment contained in the pigment dispersion is 0.05 μm to The thickness is preferably about 1.0 μm, more preferably about 0.1 μm to 0.4 μm. Also in the case of using a white pigment dispersion, the maximum particle size of the pigment is preferably 3 μm or less, more preferably 1 μm or less.

(Dispersant)
When a pigment is used as the colorant, a pigment dispersant may be used as necessary when preparing the pigment particles. Examples of the pigment dispersant that can be used include higher fatty acid salts and alkyl sulfates. , Alkyl ester sulfate, alkyl sulfonate, sulfosuccinate, naphthalene sulfonate, alkyl phosphate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin Activators such as esters, sorbitan esters, polyoxyethylene fatty acid amides, amine oxides, or styrene, styrene derivatives, vinyl naphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, Mar acids, block copolymers of two or more monomers selected from fumaric acid derivatives, random copolymers and can be exemplified salts thereof.

  A self-dispersing pigment can also be used in the ink composition of the present invention. The self-dispersing pigment as used in the present invention refers to a pigment that can be dispersed without a dispersant, and particularly preferably pigment particles having a polar group on the surface.

The pigment particles having a polar group on the surface as used in the present invention are a pigment whose surface is directly modified with a polar group, or an organic substance having an organic pigment mother nucleus, which is bonded directly or via a joint. (Hereinafter referred to as pigment derivative).
Examples of the polar group include a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a boric acid group, and a hydroxyl group, preferably a sulfonic acid group and a carboxylic acid group, and more preferably a sulfonic acid group.

  Examples of a method for obtaining pigment particles having a polar group on the surface include, for example, WO 97/48769, JP-A-10-110129, JP-A-11-246807, JP-A-11-57458, 11-189739, JP-A-11-323232, JP-A-2000-265094, etc., oxidize the pigment particle surface with an appropriate oxidizing agent, so that at least a part of the pigment surface has a sulfonic acid group or The method of introduce | transducing polar groups, such as the salt, is mentioned. Specifically, it is prepared by oxidizing carbon black with concentrated nitric acid or, in the case of color pigments, by oxidizing with sulfamic acid, sulfonated pyridine salt, amidosulfuric acid, etc. in sulfolane or N-methyl-2-pyrrolidone. can do. In these reactions, the pigment dispersion can be obtained by removing and purifying the substance that has been excessively oxidized and becomes water-soluble. Moreover, when a sulfonic acid group is introduced to the surface by oxidation, the acidic group may be neutralized with a basic compound as necessary.

  As other methods for obtaining pigment particles having polar groups on the surface, the pigment particles described in JP-A-11-49974, JP-A-2000-273383, JP-A-2000-303014, etc. are treated with a treatment such as milling. Examples include a method of adsorbing to the surface, a method described in Japanese Patent Application Nos. 2000-377068, 2001-1495, and 2001-234966, and a method of crystallizing in a poor solvent after dissolving the pigment derivative together with a solvent. In any method, pigment particles having a polar group on the surface can be easily obtained.

  The polar group on the pigment surface may be free or in a salt state, or may have a counter salt. Examples of the counter salt include inorganic salts (lithium, sodium, potassium, magnesium, calcium, aluminum, nickel, ammonium) and organic salts (triethylammonium, diethylammonium, pyridinium, triethanolammonium, etc.), preferably 1 A counter salt having a valence.

  The content of the colorant with respect to the total amount of the ink composition of the present invention is preferably 0.5% by mass to 10% by mass, and more preferably 0.5% by mass to 5% by mass.

<Water-soluble organic solvent>
The ink composition of the present invention contains water as a main solvent, but further contains a water-soluble organic solvent.
Here, the water-soluble organic solvent means an organic solvent having a solubility in water at 25 ° C. of 10% by mass or more.

Examples of water-soluble organic solvents that can be used in the present invention include the following.
Alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.),
Polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, 2- Methylpropanediol, etc.)
Polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, tripropylene Glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol Monophenyl ether, propylene glycol monophenyl ether, etc.),

-Amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentane Methyldiethylenetriamine, tetramethylpropylenediamine, etc.),
Amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), methoxypropionamide, N-methylmethoxypropionamide, N, N-dimethylmethoxypropionamide, n-butoxypropionamide, N-methyl n-butoxypropionamide, N, N-dimethyl n-butoxypropionamide, etc.), heterocycles (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1, 3-dimethyl-2-imidazolidinone, γ-butyrolactone, propylene carbonate, ethylene carbonate, ethylene urea, etc.),
・ Sulphoxides (for example, dimethyl sulfoxide),
-Sulfones (for example, sulfolane),
・ Others (urea, acetonitrile, acetone, etc.)

  Preferable water-soluble organic solvents include polyhydric alcohol ethers and heterocyclic rings, and these may be used in combination.

Among the polyhydric alcohol ethers, so-called glycol ethers are preferable, specifically, tripropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol dimethyl ether are preferable, and 2-dipropylene glycol monomethyl ether is more preferable.
As the heterocyclic ring, 2-pyrrolidone, γ-butyrolactone, propylene carbonate, ethylene urea and the like are preferable, and 2-pyrrolidone and γ-butyrolactone are particularly preferable.
In particular, a solvent having a high boiling point can be preferably used, and the boiling point at normal pressure is preferably 120 ° C. or higher, more preferably 150 ° C. or higher.

  One or more water-soluble organic solvents may be used in combination. When the water-soluble organic solvent is added, the addition amount in the ink composition is preferably 1% by mass to 60% by mass, and more preferably 2% by mass to 35% by mass.

  In addition, as described above, the specific acrylamide in the present invention can replace the function expected of the water-soluble organic solvent. Therefore, the ink composition of the present invention does not contain a water-soluble organic solvent or 10 It can also be made into content of the mass% or less. Therefore, the ink composition of the present invention is also suitable for applications that require a reduction in the content of the water-soluble organic solvent.

<Polymerization initiator>
The ink composition of the present invention may contain one or more polymerization initiators as long as the effects of the present invention are not impaired. The polymerization initiator is preferably water-soluble, and the degree of water solubility is preferably 0.5% by mass or more, preferably 1% by mass or more, preferably 3% by mass in distilled water at 25 ° C. It is particularly preferable to dissolve the above. The polymerization initiator in the present invention may be a thermal polymerization initiator or a photopolymerization initiator, but is preferably a photopolymerization initiator. Moreover, it can be used even in a state where a non-aqueous polymerization initiator is dispersed.

  As the photopolymerization initiator in the present invention, it is preferable to use a polymerization initiator selected from the group consisting of α-hydroxyketones, α-aminoketones and acylphosphine oxides. Specifically, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methyl] -1-propan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2- A water-soluble polymerization initiator such as methyl-1-phenylpropan-1-one or a non-aqueous polymerization initiator of [bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide] can also be used. .

  Moreover, as a photoinitiator, you may use a commercial item, for example, Irgacure 29595 (brand name) (1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methyl]- 1-propan-1-one, manufactured by BASF), Darocur 1173 (trade name) (2-hydroxy-2-methyl-1-phenylpropan-1-one, manufactured by BASF), Irgacure 817DW (trade name) ([Bis An aqueous dispersion of (2,4,6-trimethylbenzoyl) -phenylphosphine oxide] manufactured by BASF).

  The content of the polymerization initiator in the ink composition of the present invention is preferably 0% by mass to 10% by mass, more preferably 0.1% by mass to 6% by mass with respect to the total amount of the ink composition, and 0.5 A mass% to 4 mass% is preferred.

<Other radical polymerizable compounds>
The ink composition of the present invention may contain, in addition to (b) the specific (meth) acrylamide, other radical polymerizable compounds as long as the effects of the present invention are not impaired.

  The other radical polymerizable compound used in the ink composition of the present invention is not limited as long as it is a compound in which a polymerization reaction proceeds by radicals.

  Other radically polymerizable compounds can be used alone or in combination. Further, the other radical polymerizable compound may be a monofunctional compound or a polyfunctional compound. When the proportion of the monofunctional compound is large, the cured product tends to be flexible, and when the proportion of the polyfunctional compound is large, the curability tends to be excellent. Accordingly, the ratio between the monofunctional compound and the polyfunctional compound is arbitrarily determined according to the application.

As the other radical polymerizable compound, for example, various known radical polymerizable compounds that cause a polymerization reaction by a partial structure represented by the general formula (1) or an initiation species generated from a polymerization initiator can be used.
As other radically polymerizable compounds, not only radically polymerizable monomers but also radically polymerizable oligomers can be added. The radical polymerizable oligomer is a compound having at least one radical polymerizable group at the end of the oligomer and having a weight average molecular weight in the range of 400 to 10,000.

  Preferred examples of the other radical polymerizable compound include compounds having an ethylenically unsaturated bond capable of radical polymerization. More specifically, it is a compound having at least one ethylenically unsaturated bond capable of radical polymerization in the molecule.

  Examples of other radical polymerizable compounds include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, unsaturated carboxylic acid esters and salts thereof; ethylenically unsaturated groups (Meth) acrylamide; styrene derivatives; vinyl ethers, N-vinyl and the like.

  Other radical polymerizable compounds include, in particular, radical polymerizable monofunctional monomers and radical polymerizable polyfunctional monomers.

  Examples of the radical polymerizable monofunctional monomer include acrylamide, 2-hydroxyethyl acrylamide, 2-hydroxymethyl acrylamide, t- in addition to the polymerizable compounds described in the following (2-1-1) to (2-1-27). Butylacrylamide, 3-dimethylaminopropylacrylamide, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, methoxy oligoethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, tetrahydrofur Furyl acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and the like can be used.

  Radical polymerizable polyfunctional monomers include (meth) acrylates such as oligoethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, bis [2- (methacryloyloxy) ethyl] phosphate, and methylene bisacrylate. Known compounds such as acrylamides such as 4,7,10-trioxa-1,13-tridecanbisacrylamide and vinyl ethers such as triethylene glycol divinyl ether can be used.

  Moreover, although the following compounds are also mentioned as radically polymerizable polyfunctional monomers other than the above, this invention is not limited to these.

  As the radical polymerizable oligomer, it is preferable to use at least one selected from polyester oligomers, urethane oligomers, modified polyether oligomers, acrylic oligomers, and epoxy oligomers.

The other radical polymerizable compound preferably has a (meth) acryloyloxy group or a (meth) acrylamide group, and more preferably has a plurality of (meth) acryloyloxy groups or (meth) acrylamide groups.
Here, the (meth) acryloyloxy group represents at least one of an acryloyloxy group and a methacryloyloxy group, and the (meth) acrylamide group represents at least one of an acrylamide group and a methacrylamide group.

  The radically polymerizable compound having a (meth) acryloyloxy group preferably used in the present invention is more preferably a compound represented by the following general formula (M-1).

In the general formula ^{(M-1), Q} 1 represents a ^{n 1} valent connecting ^{group, R 1 m} is a hydrogen atom or a methyl group. N ¹ represents an integer of 1 or more.

Compound represented by the general formula (M-1) are unsaturated monomers are those bound to the linking group Q ¹ by an ester bond. R ^1m represents a hydrogen atom or a methyl group, preferably a hydrogen atom. The valency ^{n 1} of the linking group ^{Q 1, n} 1 = 2 or more is ^{preferable, n} 1 = 2 or 6, more preferably ^{less, n} 1 = 2 to 4 is more preferred.

Furthermore, the linking group Q ¹ is not particularly limited as long as it is capable of linking groups and (meth) acryloyloxy structure. Specific examples include residues from which n ¹ hydrogen atoms or hydroxyl groups have been removed from the following compound group X.

-Compound group X-
Ethylene glycol, edylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,4-pentanediol, 1,3-pentanediol, 2,4-pentanediol, 3-methyl, 1,5- Pentanediol, 2-methyl, 2,4-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 2,5-hexanediol, glycerin, 1,2,4-butanediol, 1,2, 5-pentanetriol, 1,2,6-hexanetriol, trimethylolpropane, tri Thiolethane, ditrimethylolpropane, ditrimethylolethane, thiodiglycol, neopentylglycol, pentaerythritol, dipentaerythritol, and their condensates, polyols such as sugars, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, polypropylenediamine Such as polyamines.

  Furthermore, saturated or unsaturated such as methylene, ethylene, propylene, butylene group or the like substituted or unsubstituted alkylene chain having 4 or less carbon atoms, pyridine ring, imidazole ring, pyrazine ring, piperidine ring, piperazine ring, morpholine ring, etc. The functional group etc. which have the heterocyclic ring of can be illustrated.

Among these, the linking group Q ¹ is preferably a residue of a polyol containing an oxyalkylene group (preferably an oxyethylene group), and contains three or more oxyalkylene groups (preferably an oxyethylene group). A residue of a polyol is particularly preferable.

  The radically polymerizable compound having a (meth) acrylamide group preferably used in the present invention is more preferably a compound represented by the following general formula (M-2).

In the general formula ^{(M-2), Q} 2 represents a ^{n 2} divalent linking ^{group, R 2m} represents a hydrogen atom or a methyl group. N ² represents an integer of 1 or more.

The compound represented by formula (M-2), the unsaturated monomer, in which bonded to the linking group Q ² by an amide bond. R ^2m represents a hydrogen atom or a methyl group, preferably a hydrogen atom. The valence ^{n 2} of the linking group ^{Q 2, n} 2 = 2 or more ^{preferably, n} 2 = 2 or 6, more preferably ^{less, n} 2 = 2 to 4 is more preferred.

The connecting group Q ² is not particularly limited as long as it is capable of linking groups and (meth) acrylamide structure. Specific examples include residues from which n ² hydrogen atoms or hydroxyl groups have been removed from the above-mentioned compound group X.

Among these, the linking group Q ² is preferably a residue of a polyol containing an oxyalkylene group (preferably an oxyethylene group), and contains 3 or more oxyalkylene groups (preferably an oxyethylene group). A residue of a polyol is particularly preferable.

  When the ink composition of the present invention further contains another radical polymerizable compound, the content ratio is preferably 20% by mass or less with respect to the total mass of the ink composition from the viewpoint of curability. 15 mass% or less is more preferable, and 10 mass% or less is more preferable.

<Surfactant>
The ink composition of the present invention can contain a surfactant.
As surfactants preferably used, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, Nonionic surfactants such as polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. In particular, an anionic surfactant and a nonionic surfactant can be preferably used.

In the present invention, a polymer surfactant can also be used, and the following water-soluble resins are mentioned as preferred polymer surfactants. As the water-soluble resin, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer are preferably used. Polymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer Etc.
In the present invention, a silicone surfactant having a polyalkylsiloxane and a fluorine surfactant having a fluorinated alkyl group can also be preferably used.

  In the ink composition of the present invention, when a surfactant is used, the content thereof is preferably 0.1% by mass or more and 5% by mass or less, and 0.1% by mass with respect to the solid content of the ink composition. The content is particularly preferably 2% by mass or less.

<Sensitizing dye>
In the present invention, a known sensitizing dye can be used in combination, and a sensitizing dye is preferably used in combination. As solubility of a sensitizing dye, what dissolve | melts 0.5 mass% or more at room temperature with distilled water is preferable, and what dissolve | melts 1 mass% or more is more preferable. Those that dissolve 3% by mass or more are particularly preferable. Further, as the sensitizing dye, a water-insoluble sensitizing dye can be dispersed and used.

  Examples of known sensitizing dyes that can be used in combination include N- [2-hydroxy-3- (3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy) propyl] -N, N, N. -Trimethylaluminum chloride, benzophenone, thioxanthone, anthraquinone derivatives and 3-acylcoumarin derivatives, terphenyl, styryl ketone and 3- (aroylmethylene) thiazoline, camphorquinone, eosin, rhodamine and erythrosine, and their modified forms And dispersions thereof. Moreover, the compound represented by the general formula (i) described in JP-A 2010-24276 and the compound represented by the general formula (I) described in JP-A-6-107718 can also be suitably used. .

  In addition to the components described above, the ink composition of the present invention has an object of improving ejection stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances as necessary. Depending on the type, various known additives such as viscosity modifiers, surface tension modifiers, specific resistance modifiers, film forming agents, preservatives, dispersants, UV absorbers, antioxidants, fading inhibitors, anticorrosives Agents, rust preventives, solid wetting agents, silica fine particles and the like can be appropriately selected and used. For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, JP-A-57-74193 No. 5, JP-A 57-87988 and JP-A 62-261476, UV absorbers described in JP-A 57-74192, JP-A 57-87989, Japanese Patent Application Laid-Open No. 60-72785, Japanese Patent Application Laid-Open No. 61-14659, Japanese Patent Application Laid-Open No. 1-95091, Japanese Patent Application Laid-Open No. 3-13376, etc., Japanese Patent Application Laid-Open No. 59-42993, JP-A 59-52689, JP-A 62-280069, JP-A 61-242871, JP-A 4-219266, and the like, fluorescent whitening agents, sulfuric acid, phosphoric acid, Examples include pH adjusters such as citric acid, sodium hydroxide, potassium hydroxide, and potassium carbonate.

<Method for Preparing Ink Composition>
The method for preparing the ink composition of the present invention is not particularly limited, and each component is mixed with a container drive medium mill such as a ball mill, a centrifugal mill or a planetary ball mill, a high-speed rotating mill such as a sand mill, or a medium agitation such as a stirring tank mill. It can be prepared by stirring, mixing and dispersing with a simple disperser such as a mill or a disper. About the addition order of each component, it is arbitrary. Preferably, a pigment, a polymer dispersant, and an organic solvent are premixed and then subjected to a dispersion treatment, and the obtained dispersion is mixed with a resin containing a specific copolymer, water, and an organic solvent. In this case, at the time of addition or after addition, the mixture is uniformly mixed with a simple stirrer such as a three-one motor, a magnetic stirrer, a disper, or a homogenizer. You may mix using mixers, such as a line mixer. Further, in order to make the dispersed particles finer, they may be mixed using a dispersing machine such as a bead mill or a high-pressure jet mill. Depending on the type of pigment or polymer dispersant, a resin may be added during premixing before pigment dispersion.

  The ink composition of the present invention preferably has a surface tension at 25 ° C. of 20 mN / m to 40 mN / m. The surface tension is measured under the condition of 25 ° C. using an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.). The viscosity is preferably 1 mPa · s to 40 mPa · s, and more preferably 3 mPa · s to 30 mPa · s. The viscosity of the ink composition is measured under conditions of 25 ° C. using VISCOMETER TV-22 (manufactured by TOKI SANGYOCO. LTD).

<Image forming method>
The image forming method of the present invention includes an ink applying step of applying the ink composition of the present invention onto a recording medium, and an irradiation step of irradiating the applied ink composition with active energy rays. By performing these steps, an image of the ink composition fixed on the recording medium is formed.

(Ink application process)
Hereinafter, the ink application process in the image forming method of the present invention will be described.
The ink application process in the present invention is not limited as long as it is a process of applying the ink composition of the present invention onto a recording medium.

  As an embodiment of applying the ink composition of the present invention on a recording medium, an embodiment of applying an ink composition by an inkjet method onto a recording medium is particularly preferable.

  In the image forming method of the present invention, the ink jet recording apparatus used when the ink applying process ink jet method is applied is not particularly limited, and a known ink jet recording apparatus capable of achieving a target resolution is arbitrarily selected. Can be used. That is, any known inkjet recording apparatus including a commercially available product can discharge the ink composition onto the recording medium in the image forming method of the present invention.

Examples of the ink jet recording apparatus that can be used in the present invention include an apparatus including an ink supply system, a temperature sensor, and a heating unit.
Examples of the ink supply system include an original tank containing the ink composition of the present invention, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, a piezo-type inkjet head, and the like. The piezo-type inkjet head preferably has a multi-size dot of 1 to 100 pl, more preferably 8 to 30 pl, preferably 320 × 320 to 4,000 × 4,000 dpi (dot per inch), more preferably 400 × 400. ˜1,600 × 1,600 dpi, more preferably 720 × 720 dpi. The dpi referred to in the present invention represents the number of dots per 2.54 cm (1 inch).

In the ink application step, it is desirable that the discharged ink composition has a constant temperature. Therefore, the ink jet recording apparatus preferably includes a means for stabilizing the ink composition temperature. The parts to be kept at a constant temperature are all the piping systems and members from the ink tank (intermediate tank if there is an intermediate tank) to the nozzle ejection surface. That is, heat insulation and heating can be performed from the ink supply tank to the inkjet head portion.
The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors in each piping portion and perform heating control according to the flow rate of the ink composition and the environmental temperature. The temperature sensor can be provided near the ink supply tank and the nozzle of the inkjet head. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of thermal energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

  The ink composition is discharged using the ink jet recording apparatus, and the ink composition is preferably heated to 25 to 80 ° C., more preferably 25 to 50 ° C., and the viscosity of the ink composition is preferably 3 mPa · s to It is preferable to carry out after lowering to 15 mPa · s, more preferably 3 mPa · s to 13 mPa · s. In particular, it is preferable to use an ink composition having a viscosity of 50 mPa · s or less at 25 ° C. as the ink composition of the present invention, since it can be discharged satisfactorily. By using this method, high ejection stability can be realized.

  The temperature of the ink composition during ejection is preferably constant, and the control range of the temperature of the ink composition is more preferably ± 5 ° C. of the set temperature, more preferably ± 2 ° C. of the set temperature, and most preferably set. A temperature of ± 1 ° C. is appropriate.

In the present invention, the recording medium is not particularly limited, and a known recording medium can be used as a support or a recording material. Examples of the recording medium include paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, polyvinyl chloride resin, two Cellulose acetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic on which the above metals are laminated or deposited A film etc. are mentioned.
Since the ink composition of the present invention contains (a) a specific copolymer and can suppress bleeding, it can be suitably used for non-permeable recording media. Here, the non-permeable recording medium means a recording medium having such a property that the ink composition does not penetrate inside when the ink composition is applied to the surface.
The non-permeable recording medium is preferably a plastic substrate such as polyvinyl chloride, polyethylene terephthalate, or polyethylene, more preferably a polyvinyl chloride resin substrate, and even more preferably a polyvinyl chloride resin sheet or film.

(Irradiation process)
Hereinafter, the irradiation step in the image forming method of the present invention will be described.
The irradiation step in the present invention is not limited as long as it is a step of irradiating the ink composition applied on the recording medium with active energy rays.

  Examples of active energy rays that can be used in the irradiation step include ultraviolet rays (hereinafter also referred to as UV light), visible light glands, electron beams, and the like, and UV light is preferably used.

  Although the peak wavelength of UV light depends on the absorption characteristics of the sensitizing dye used as necessary, it is preferably, for example, 200 nm to 405 nm, more preferably 220 nm to 390 nm, and 220 nm to 350 nm. More preferably. In this invention, when not using a sensitizing dye and a photoinitiator together, it is preferable that it is 200 nm-310 nm, and 200 nm-280 nm are more preferable.

UV light is the illumination intensity on the exposed surface is, for ^{example, 10mW / cm 2 ~2,000mW / cm} 2, ^is preferably a suitably be irradiated with ^{20mW / cm 2 ~1,000mW / cm 2} .

  As the UV light source, a mercury lamp, a gas / solid laser or the like is mainly used, and a mercury lamp, a metal halide lamp and a UV fluorescent lamp are widely known. In addition, replacement with GaN-based semiconductor ultraviolet light-emitting devices is very useful industrially and environmentally. LED (UV-LED) and LD (UV-LD) are small, have long life, high efficiency, and low cost. Yes, it is expected as a UV light source. In the present invention, when a sensitizing dye and a photopolymerization initiator are used in combination, a metal halide lamp, a high pressure mercury lamp, a medium pressure mercury lamp, a low pressure mercury lamp, and a UV-LED are preferable, and a sensitizing dye and a photopolymerization initiator are used in combination. If not, a medium pressure mercury lamp or a low pressure mercury lamp is preferred, and a low pressure mercury lamp is particularly preferred.

In the irradiation step, the ink composition of the present invention applied on the recording medium is irradiated with such UV light, for example, for 0.01 seconds to 120 seconds, preferably 0.1 seconds to 90 seconds. Is appropriate.
As the irradiation conditions and the basic irradiation method, the irradiation conditions and the irradiation method disclosed in JP-A-60-132767 can be similarly applied to the present invention. Specifically, a method in which a light source is provided on both sides of a head unit including an ink ejection device and the head unit and the light source are scanned by a so-called shuttle method, or a method in which a separate light source without driving is used is preferable. The irradiation with the active energy ray is performed after a certain period of time (for example, 0.01 seconds to 120 seconds, preferably 0.01 seconds to 60 seconds) after ink landing and heat drying.

(Ink drying process)
The image forming method of the present invention preferably further includes an ink drying step (also referred to as “heat drying step”) after the ink application step and before the irradiation step.
In the heat drying step, the ink composition discharged onto the recording medium is preferably fixed by evaporating (b) water and a water-soluble organic solvent used in combination as necessary.

A process of heating and drying and fixing the discharged ink composition of the present invention (heat drying process) will be described.
The heating means is not limited as long as (c) water and a water-soluble organic solvent used in combination can be dried, if necessary. Heat drum, hot air, infrared lamp, heat oven, heat plate heating, etc. Can be used.
The heating temperature is preferably 40 ° C or higher, more preferably about 40 ° C to 150 ° C, and still more preferably about 40 ° C to 80 ° C. The drying / heating time can be appropriately set in consideration of the composition and printing speed of the ink composition to be used.

  The ink composition fixed by heating is irradiated with an active energy ray in an irradiation step as necessary, and further photofixed. As described above, in the irradiation step, fixing with UV light is preferable.

[Printed matter]
The printed matter of the present invention is characterized by having an image formed by the ink composition of the present invention or an image formed by the image forming method of the present invention. The printed matter of the present invention has an image with reduced bleeding and excellent solvent resistance.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” are based on mass.

Specific copolymers A-1 to A-5, comparative polymer C-1, specific acrylamides B-1 and B-2, and comparative polymerizable compound D-3 used in the examples were synthesized as follows.
The specific copolymers A-1 to A-5 are the compounds listed above as exemplary compounds A-1 to A-5 of the specific copolymer, and the specific acrylamides B-1 and B-2 are specific acrylamides. These are the compounds listed above as exemplary compounds B-1 and B-2.

[Synthesis Example 1: Synthesis of specific copolymers A-1 to A-5]
<Synthesis of Monomer 1>
Toluene 75 g and dimethylmaleic anhydride 42.0 g (manufactured by Sigma-Aldrich Japan) were introduced into a 500 ml three-necked flask equipped with a Dean-Stark distillation tube and stirred with a stirrer (Shinto Kagaku Co., Ltd .: Three-One Motor). While heating, the temperature was raised to 50 ° C. 2-Amino-1-propanol (25.0 g) was added dropwise over 30 minutes, followed by stirring for 4 hours. After dropping the temperature to 60 ° C, 0.042 g of p-methoxyphenol (Wako Pure Chemical Industries) and 6.2 g of sulfuric acid (Wako Pure Chemical Industries) are added, and 43.0 g of methacrylic acid (Wako Pure Chemical Industries) is added in 30 minutes. It was dripped. After completion of the dropwise addition, the temperature was raised until the solvent was refluxed, and the reaction was performed for 3 hours. The reaction solution was neutralized with 29 g of a 50 w / v% aqueous sodium hydroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.), and 200 ml of toluene and 100 ml of water were added to separate the solution. The organic layer was washed twice with saturated brine, 30 mg of p-methoxyphenol was added to the organic layer, and the solvent was distilled off under reduced pressure in vacuo to obtain 64.5 g of monomer 1. The formation of the target product was confirmed by ¹ H NMR.

<Synthesis of Specific Copolymer A-1>
20 g of 2-pyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) was added to a three-necked flask equipped with 200 mL of the stirrer substituted with nitrogen. After heating to 80 ° C. under a nitrogen stream, 20 g of 2-pyrrolidone, 10.0 g of the monomer 1 6.8 g of n-butyl methacrylate (manufactured by Wako Pure Chemical Industries), 3.2 g of methacrylic acid, 3-mercaptopropionic acid 0 A mixed solution of 0.030 g (manufactured by Tokyo Chemical Industry Co., Ltd.) and dimethyl 2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 3 hours. After dropping, 2 hours and 4 hours later, 0.050 g of dimethyl 2,2′-azobisisobutyrate was added, and the reaction was further performed for 2 hours. Next, 30 g of the obtained solution in a 200 ml eggplant-shaped flask, 0.70 g of sodium bicarbonate (manufactured by Wako Pure Chemical Industries) and 20 g of water were added and stirred at 60 ° C. After dissolution of the polymer, the solid content was adjusted to 20% by addition of water to obtain an aqueous solution of the specific copolymer A-1. Further, the solution after polymerization was measured by GPC, and it was confirmed that the weight average molecular weight was 72,300.

<Synthesis of Specific Copolymers A-2 to A-5>
About specific copolymer A-2-A-5, it polymerizes by adjusting the quantity of a raw material monomer and a mercaptopropionic acid suitably so that it may become the structure described as structural formula of each copolymer, and predetermined neutralization The amount of sodium hydrogen carbonate was adjusted so as to obtain a 20% aqueous solution.

[Synthesis Example 2: Synthesis of Comparative Polymer C-1]
7.00 g of 2-pyrrolidone was added to a three-necked flask equipped with 500 mL of the agitator purged with nitrogen. After raising the temperature to 80 ° C. under a nitrogen stream, a mixed solution of 7.0 g of 2-pyrrolidone, 10.0 g of methacrylic acid, 0.022 g of 3-mercaptopropionic acid, and 0.02 g of dimethyl 2,2′-azobisisobutyrate is added for 2 hours. It was dripped over. After dropping, 2 hours and 4 hours later, 0.013 g of dimethyl 2,2′-azobisisobutyrate was added, and the reaction was further carried out at 90 ° C. for 2 hours. Next, 8.75 g of glycidyl methacrylate, 0.05 g of tetrabutylammonium bromide, 0.05 g of p-methoxyphenol and 15.0 g of 2-pyrrolidone were added and reacted at 60 ° C. for 2 hours. Furthermore, 4.59 g of sodium hydrogen carbonate, 40.1 g of water, and 11.1 g of 2-pyrrolidone were added, heated at 50 ° C. for 2 hours, and 20% aqueous solution of comparative polymer C-1 (structure will be described later). Got.

[Synthesis Example 3: Synthesis of specific acrylamide B-1]
To a 1 L three-necked flask equipped with a stir bar, 121 g (1 equivalent) of tris (hydroxymethyl) aminomethane (manufactured by Tokyo Chemical Industry Co., Ltd.), 84 ml of 50% potassium hydroxide aqueous solution (manufactured by Wako Pure Chemical Industries), and 423 ml of toluene were added. The mixture was stirred and the reaction system was maintained at 20 to 25 ° C. in a water bath, and 397.5 g of acrylonitrile (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 2 hours. After dripping, after stirring for 1.5 hours, 540 ml of toluene was added to the reaction system, the reaction mixture was transferred to a separatory funnel, and the aqueous layer was removed. The remaining organic layer was dried with magnesium sulfate (manufactured by Wako Pure Chemical Industries, Ltd.), filtered through Celite, and the solvent was distilled off under reduced pressure to obtain an acrylonitrile adduct. The structure of the obtained compound was confirmed by ¹ H NMR and MS.
In a 1 L autoclave, 24 g of the previously obtained acrylonitrile adduct, 48 g of Ni catalyst (Raney nickel 2400, manufactured by WR Grace & Co.), 600% of 25% aqueous ammonia: methanol = 1: 1 solution are suspended. The reaction vessel was sealed. 10 Mpa of hydrogen was introduced into the reaction vessel and reacted at a reaction temperature of 25 ° C. for 16 hours.
The disappearance of the raw materials was confirmed by ¹ H NMR, the reaction mixture was filtered through celite, and the celite was washed several times with methanol. The filtrate was evaporated under reduced pressure to obtain a polyamine compound.
To a 2 L three-necked flask equipped with a stirrer, 30 g of the polyamine obtained previously, 120 g of sodium hydrogen carbonate, 1 L of dichloromethane (manufactured by Wako Pure Chemical Industries), and 50 ml of water were added, and acrylic acid chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was added in an ice bath. 92.8g was dripped over 3 hours, and it stirred at room temperature after that for 3 hours. After confirming the disappearance of the raw materials by ¹ H NMR, the reaction mixture was evaporated under reduced pressure, the reaction mixture was dried over magnesium sulfate, filtered through celite, and the solvent was evaporated under reduced pressure. Finally, it was purified by column chromatography (ethyl acetate / methanol = 4: 1) to obtain a white solid (yield 40%) at room temperature. The yield of the above three steps was 40%. The obtained compound was confirmed by ¹ H-NMR to be the specific acrylamide B-1 as the target product.

[Synthesis Example 4: Synthesis of specific acrylamide B-2]
In the first step of the synthesis scheme of the specific acrylamide B-1 shown in Synthesis Example 3, the specific acrylamide B-1 was synthesized in the same manner as in the synthesis example of the specific acrylamide B-1, except that 74.7 g of methacrylonitrile was added instead of acrylonitrile. -2 (colorless liquid) was synthesized. The yield of 3 steps was 37%.
The colorless liquid obtained by the synthesis was identified by ¹ H-NMR in the same manner as in the synthesis example of the specific acrylamide B-1, and confirmed to have a structure represented by the specific acrylamide B-2.

[Synthesis of Comparative Polymerizable Compound D-3]
The comparative polymerizable compound D-3 (the structure is described later) was synthesized by combining known synthesis methods with reference to the description in JP-A-2005-307198.

[Examples 1-15, Comparative Examples 1-8]
1. Preparation of ink composition (a) Specific copolymer or comparative polymer compound, (b) Specific acrylamide, (c) Water, (d) Colorant (pigment dispersion), solvent, and surfactant A crude ink composition was prepared by mixing and stirring at 250 rpm using a mixer (Silverson L4R) so that the composition shown in FIG. However, the content of (d) the colorant represents the content of the colorant (pigment) in the pigment dispersion.
Each obtained crude ink composition is packed in a plastic disposable syringe and filtered through a polyvinylidene fluoride (PVDF) pore size 5 μm filter (Millex-SV, Millipore, diameter 25 mm) to obtain a finished product. Ink compositions of Examples 1 to 15 and Comparative Examples 1 to 8 were obtained.

  In Table 2, “-” indicates that the component shown in the corresponding column is not contained in the ink composition.

The detail of each compound used for Examples 1-15 and Comparative Examples 1-8 is shown below.
In addition, the composition ratio of each structural unit written together in the (a) specific copolymer and comparative polymer shown below is a mass reference | standard.

<(A) Specific copolymer>
The specific specific copolymers A-1 to A-5 obtained in Synthesis Example 1 were used.

<Comparative polymer>
The comparative polymer C-1 (the following structure) obtained in Synthesis Example 2 was used.

<(B) Specific acrylamide>
The specific acrylamides B-1 and B-2 (the following structures) obtained in Synthesis Examples 2 and 3 were used.

<Comparative polymerizable compound>
As the comparative polymerizable compound D-1 (the following structure), the one synthesized above was used.
As the comparative polymerizable compound D-2 (the following structure), a compound synthesized by combining known methods with reference to the description in JP-A-2005-307198 was used.
As HEAA (the following structure), (N)-(2-hydroxyethyl) acrylamide (manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

<(C) Water>
(C) Ion exchange water was used as water.

<(D) Colorant (Pigment Dispersion)>
M dispersion: Magenta pigment dispersion (trade name: Projet Magenta APD 1000, manufactured by Fuji Film Imaging Colorant Co., Ltd., 14% pigment concentration)
C dispersion: Cyan pigment dispersion (trade name: Projet Cyan APD 1000, manufactured by FUJIFILM Imaging Colorant Co., Ltd., 14% pigment concentration)
K dispersion: Black pigment dispersion (trade name: Projet Black APD 1000, manufactured by Fuji Film Imaging Colorant Co., Ltd., 14% pigment concentration)
Y dispersion: Yellow pigment dispersion (trade name: Projet Yellow APD 1000, manufactured by FUJIFILM Imaging Colorant Co., Ltd., 14% pigment concentration)

(E) Water-soluble organic solvent 2-pyrrolidone (Wako Pure Chemical Industries, Ltd.)

<Photopolymerization initiator>
Irgacure 29595 (trade name) (1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methyl] -1-propan-1-one, manufactured by BASF)

<Surfactant>
・ ZONYL FSN (trade name) (fluorine surfactant, manufactured by Aldrich)

When the viscosity of the ink composition of each obtained Example was measured using VISCOMETER TV-22 (made by TOKI SANGYOCO.LTD), all were in the range of 4 mPa * s-10 mPa * s at room temperature (25 degreeC). there were.
Moreover, when the surface tension of the obtained ink composition of each Example was measured using Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.), all were 20 mN / m at room temperature (25 ° C.). The range was ˜40 mN / m.

2. Evaluation The following evaluations were performed using the ink compositions obtained in Examples and Comparative Examples. The evaluation results are shown in Table 2.

<Bludge suppression evaluation>
A commercially available inkjet printer (manufactured by Fuji Film Dimatics, product name: DMP-2831) was prepared as an inkjet recording apparatus.
Each obtained ink composition was loaded into the above-described ink jet printer and heated at 35 ° C., and the width in a direction perpendicular to the head scanning direction on a polyvinyl chloride substrate (Avery 400 GLOSS WHITE PERMANENT, manufactured by Avery Dennison) Twenty straight lines having a length of 100 μm and a length of 1 cm were printed at intervals of 100 μm. The shape of the obtained straight line was visually observed and evaluated according to the following criteria. Note that the levels of A and B are levels that have no practical problem.
-Evaluation criteria-
A: The linearity is high and the edge is hardly disturbed. B: The edge of the straight line is slightly disturbed but is not mixed with the adjacent straight line.
C: A thing with a large blur and a part mixed with the adjacent straight line.

<Solvent resistance evaluation>
Each of the obtained ink compositions was subjected to No. of K hand coater manufactured by RK PRINT COAT INSTRUMENTS. Using 2 bars, it was applied to an 8 cm square vinyl chloride sheet (Avery 400 GLOSS WHITE PERMANENT, manufactured by Avery Dennison Co., Ltd.) with a thickness of 12 μm. Further, after moisture was dried at 60 ° C. for 3 minutes, exposure was performed with a low-pressure mercury lamp under the condition of an energy of 1000 mJ / cm ² to obtain a printed matter having a cured film (solid image) on the vinyl chloride sheet.
The surface on the side having the cured film (image) in the obtained printed material was rubbed with a cotton swab impregnated with isopropyl alcohol and evaluated according to the following evaluation criteria. In addition, A and B are levels with no practical problem.
-Evaluation criteria-
A: No change was observed in the image even after rubbing 50 times or more.
B: The image density decreased after rubbing 10 to 49 times.
C: The image density was remarkably lowered after 0 to 9 rubbing.

<Discharge stability>
As an inkjet recording apparatus, a commercially available inkjet printer (product name: DMP-2831 manufactured by FUJIFILM Dimatics) was used, and on a polyvinyl chloride substrate (Avery 400 GLOSS WHITE PERMANENT, manufactured by Avery Dennison) A solid image of 20 cm × 20 cm was printed. The formed image was visually evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: No dot defect due to defective ejection was observed, and a good image was obtained.
B: The occurrence of dot missing due to ejection failure was slightly observed, but it was of a level that would not cause any practical problems.
C: An image that could not be put to practical use was generated due to occurrence of missing dots due to ejection failure.

  As shown in Table 2, the ink compositions of Examples containing (a) a specific copolymer and (b) a specific acrylamide are both bleed-suppressing and solvent resistant in comparison with the ink compositions of Comparative Examples. It can be seen that it is excellent in performance and ejection stability.

Claims (14)

(A) a polymer compound comprising a repeating unit (a-1) having a partial structure represented by the following general formula (1) and a repeating unit (a-2) having a hydrophilic group, (b) the following general formula An ink composition comprising a (meth) acrylamide compound represented by (2) and (c) water.


(In General Formula (1), R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of R ^a and R ^b is an alkyl group having 1 to 4 carbon atoms. R ^a and R ^b may be bonded to each other to form a 4- to 6-membered alicyclic structure, and * represents a bonding site with a main chain or a side chain in the polymer compound.

(In the general formula (2), ^{R 1,} .R ² represents a hydrogen atom or a methyl group, represents a linear or branched alkylene group having 2 to 4 carbon atoms. However, in ^{R 2,} the ^{R 2} An oxygen atom and a nitrogen atom bonded to both ends are not bonded to the same carbon atom in R ^2. R ³ represents a divalent linking group, k represents 2 or 3. x, y, and z each independently represent an integer of 0-6, and x + y + z satisfies 0-18.) The ink composition according to claim 1, wherein the repeating unit (a-1) having a partial structure represented by the general formula (1) is a repeating unit represented by the following general formula (3).


(In General Formula (3), R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and at least one of R ^a and R ^b is an alkyl group having 1 to 4 carbon atoms. R ^a and R ^b may combine with each other to form a 4- to 6-membered alicyclic structure, R ^c represents a hydrogen atom or a methyl group, Z represents a single bond, —COO— * * Or -CONR ^d -**, R ^d represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and ** represents a bonding position with X. X represents a divalent organic group. )   The repeating unit (a-2) having a hydrophilic group contained in the polymer compound (a) is at least one selected from the group consisting of alcoholic hydroxyl groups, alkyl-substituted carbamoyl groups, carboxyl groups, sulfo groups, and salts thereof. The ink composition according to claim 1, wherein the ink composition is a repeating unit having a hydrophilic group.   The content of the repeating unit (a-1) having a partial structure represented by the general formula (1) is 20 to 75% by mass with respect to the mass of the (a) polymer compound, and the hydrophilicity is 4. The ink composition according to claim 1, wherein the content of the repeating unit (a-2) is 8 to 25% by mass with respect to the mass of the polymer compound (a). .   The ink composition according to any one of claims 1 to 4, wherein the polymer compound (a) further comprises a repeating unit (a-3) having a hydrophobic group.   The ink composition according to claim 5, wherein the repeating unit (a-3) having a hydrophobic group is a repeating unit derived from an alkyl (meth) acrylate having 4 to 22 carbon atoms.   7. The repeating unit according to claim 1, wherein the repeating unit (a-2) having a hydrophilic group is a repeating unit having at least one hydrophilic group selected from a carboxyl group and a salt thereof. Ink composition.   Furthermore, the ink composition of any one of Claims 1-7 containing a coloring agent.   Furthermore, the ink composition of any one of Claims 1-8 containing a polymerization initiator.   The ink composition according to any one of claims 1 to 9, which is for inkjet recording.   The ink composition according to any one of claims 1 to 10, which is for printing on a non-permeable recording medium.   An ink application step of applying the ink composition according to any one of claims 1 to 11 onto a recording medium, and an irradiation step of irradiating the ink composition applied onto the recording medium with active energy rays. And an image forming method.   An ink application step of applying the ink composition according to any one of claims 1 to 11 onto a recording medium, and (c) at least one of water contained in the ink composition applied onto the recording medium. An image forming method comprising: an ink drying step of drying and removing the portion; and an irradiation step of irradiating the ink composition applied and dried on the recording medium with active energy rays.   An image formed by the ink composition according to any one of claims 1 to 11 or an image formed by the image forming method according to claim 12 or 13 on a recording medium. Prints that have.