JP5857710B2 - Active energy ray curable ink jet ink and ink jet recording method using the same - Google Patents

Description

  The present invention relates to an active energy ray-curable inkjet ink and an inkjet recording method using the same.

  The CT polymerization system consisting of acceptor monomer and donor monomer is attracting attention as a highly sensitive polymerization system that has little influence on oxygen polymerization inhibition, and can be expected to improve printer printing speed, reduce equipment costs, and drastically reduce running costs. . A composition using a CT polymerization system has a charge transfer complex obtained from at least one unsaturated compound having an electron donating group and an electron accepting group, and is polymerized by ultraviolet rays without requiring a photoinitiator. The composition which can be made to be known is known (for example, refer patent document 1).

  Moreover, as an active energy ray-curable composition, for example, a composition containing a polyfunctional maleimide compound having a molecular weight of 1,000 or more and a vinyl ether compound is known (see, for example, Patent Document 2).

Japanese Patent No. 3353020 Japanese Patent Laid-Open No. 11-124403

  It is conceivable to use a curable composition comprising a CT polymerization system comprising an acceptor monomer and a donor monomer as an active energy ray curable inkjet ink. A curable composition comprising a CT polymerization system is considered to be advantageous for forming a fine inkjet image because of its high curing sensitivity. However, a cured resin film of an active energy ray curable composition comprising a CT polymerization system sometimes cured and contracted over time when exposed to natural light.

  Furthermore, to make a curable composition comprising a CT polymerization system into an active energy ray-curable inkjet ink, a polymerization initiator is added to increase the curing sensitivity, a polymerizable monomer having a high curing sensitivity is blended, In order to reduce the viscosity, a polymerizable monomer having one polymerizable reactive group is often blended. As a result, curing shrinkage of the cured resin film may become more and more remarkable.

  Accordingly, the present invention achieves high sensitivity, scratch resistance, solvent resistance, and low viscosity suitable for inkjet emission in an active energy ray-curable inkjet ink containing a curable composition comprising a CT polymerization system. An object is to suppress curing shrinkage of an image which is a cured resin film.

That is, the present invention relates to the following active energy ray-curable inkjet ink.
[1] At least one polymerizable compound having an electron-deficient unsaturated double bond, at least one polymerizable compound having an electron-rich unsaturated double bond, a polymerization inhibitor, a radical polymerization initiator, In the active energy ray-curable inkjet ink containing
Active energy rays containing a polymerizable compound in which at least one type of terminal double bond is bonded to an alkylene oxide containing no active hydrogen at at least one terminal as the polymerizable compound having an electron rich unsaturated double bond A curable inkjet ink.

（一般式（１）において、
Ａは、炭素数１〜８の直鎖もしくは分岐のアルキル、または炭素数６〜１２の置換基を有してもよい芳香環基であり、
Ｒ_１およびＲ_２は、それぞれ独立に炭素数２〜４の直鎖または分岐のアルキレンであり、
Ｘは、一般式（２）で示される連結基であり、
Ｑは、一般式（３）で表される電子過多な二重結合を含む基であり、
ｍおよびｎは、それぞれ独立に１〜１８の自然数であり、
ｐは、０、１，２または３のいずれかの整数である）

（一般式（２）において、
Ｘ_１およびＸ_２は、それぞれ独立に−ＯＣＯ−もしくは−ＣＯＯ−で表されるエステル結合か、または−ＯＣＯＮＨ−もしくは−ＮＨＣＯＯ−で表されるウレタン結合であり、
Ｙは、炭素数１〜８の直鎖もしくは分岐のアルキレン、または炭素数６〜１２の置換基を有してもよい芳香環基である）

（一般式（３）において、
Ｚは、−Ｏ−、−ＮＲ_６−、−ＣＯＮＲ_６−、−Ｓ−、−ＳＯ−を表し、Ｒ_６は、水素原子または炭素数１〜８の直鎖又は分岐のアルキル基であり、
Ｒ_３、Ｒ_４およびＲ_５は、水素原子、炭素数１〜６の直鎖もしくは分岐のアルキル基、または炭素数１〜６の直鎖もしくは分岐のアルコキシ基である） [2] The active energy ray-curable type according to [1], wherein the polymerizable compound in which an electron-rich double bond is bonded to the alkylene oxide contains at least one compound represented by the following general formula (1). Inkjet ink.

(In general formula (1),
A is a linear or branched alkyl having 1 to 8 carbon atoms, or an aromatic ring group which may have a substituent having 6 to 12 carbon atoms,
R ₁ and R ₂ are each independently a linear or branched alkylene having 2 to 4 carbon atoms,
X is a linking group represented by the general formula (2),
Q is a group containing an electron-rich double bond represented by the general formula (3),
m and n are each independently a natural number of 1 to 18,
p is an integer of 0, 1, 2, or 3)

(In general formula (2),
X ₁ and X ₂ are each independently an ester bond represented by —OCO— or —COO—, or a urethane bond represented by —OCONH— or —NHCOO—,
Y is a linear or branched alkylene having 1 to 8 carbon atoms, or an aromatic ring group which may have a substituent having 6 to 12 carbon atoms)

(In general formula (3),
Z represents —O—, —NR ₆ —, —CONR ₆ —, —S—, —SO—, and R ₆ represents a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms,
R ₃ , R ₄ and R ₅ are a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched alkoxy group having 1 to 6 carbon atoms)

[3] The active energy ray-curable inkjet ink according to [1], wherein the polymerization inhibitor contains a radical polymerization inhibitor.
[4] The active energy ray-curable inkjet ink according to [1], wherein the polymerization inhibitor contains a radical polymerization inhibitor and a cationic polymerization inhibitor.
[5] The active energy ray curable type according to [3] or [4], wherein the radical polymerization inhibitor is piperidine 1-oxyl free radical compound, phenolic hydroxyl group-containing compound, quinone, hydroquinone, or phenothiazine. Inkjet ink.
[6] The active energy ray-curable inkjet ink according to [4], wherein the cationic polymerization inhibitor is an alkali metal compound, an alkaline earth metal compound, or an amine.

[7] The active energy ray-curable inkjet ink according to any one of [1] to [6], wherein a viscosity of 20 to 100 ° C. is 7 to 15 mPa · s.
[8] The active energy ray-curable inkjet ink according to [1], wherein the compound represented by the general formula (1) has a molecular weight of 140 or more and 650 or less.
[9] The active energy ray-curable inkjet ink according to [1], wherein Z in the general formula (3) is —O— and p is 0.

  [10] The polymerizable compound having an electron-deficient unsaturated double bond contains at least one polymerizable compound selected from maleimides, maleates and fumarates, [1] to [1] 9] The active energy ray-curable inkjet ink according to any one of [9].

（一般式（１０）において、
Ｒ_１およびＲ_２は、それぞれ独立に水素原子または炭素数１〜６のアルキル基を表し、Ｒ_１とＲ_２は互いに結合して環を形成してもよく、
Ｙ_１およびＹ_３は、それぞれ独立して、炭素数１〜１２のアルキレン基、炭素数１〜１２のアルキレンオキシ基、フェニレン基、エステル基、エーテル基およびチオエーテル基から選ばれる基が組み合わされた２価の有機連結基を表し、かつＹ_２は不斉炭素を有する２価の基であり、
ｎは、１〜６の整数を表し、
ｎ１は、０または１を表し、ｎ２は、０または１を表し、
Ｚは、炭素数１〜１２のアルキレン基、炭素数１〜１２のアルキレンオキシ基、フェニレン基、エステル基、エーテル基およびチオエーテル基から選ばれる基が組み合わされた１〜６価の有機基を表す） [11] The active energy ray-curable inkjet ink according to [10], wherein the maleimide is represented by the following general formula (10).

(In general formula (10),
R ₁ and R ₂ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ₁ and R ₂ may be bonded to each other to form a ring,
Y ₁ and Y ₃ are each independently a group selected from an alkylene group having 1 to 12 carbon atoms, an alkyleneoxy group having 1 to 12 carbon atoms, a phenylene group, an ester group, an ether group, and a thioether group. Represents a divalent organic linking group, and Y ₂ is a divalent group having an asymmetric carbon;
n represents an integer of 1 to 6,
n1 represents 0 or 1, n2 represents 0 or 1,
Z represents a 1-6 valent organic group in which a group selected from an alkylene group having 1 to 12 carbon atoms, an alkyleneoxy group having 1 to 12 carbon atoms, a phenylene group, an ester group, an ether group and a thioether group is combined. )

（一般式（１１）において、
Ｒ_１１およびＲ_１２は、それぞれ独立に水素原子または炭素数１〜６のアルキル基を表し、Ｒ_１１とＲ_１２は互いに結合して環を形成してもよく、
Ａ_１１およびＡ_１３は、それぞれ独立して炭素数１〜１２のアルキレン基を表し、
Ａ_１２は、不斉中心を有する炭素数１〜１２の２価の炭化水素基を表し、
Ｙは、独立してカルボニルオキシ（−Ｃ（＝Ｏ）−Ｏ−）またはオキシカルボニル（−Ｏ−Ｃ（＝Ｏ）−）を表し、
ｐは、１または２を表し、
Ｒ_１３は、ｐが１の場合は分子量１５〜６００のアルキル基またはアルキレンオキシ基を表し、ｐが２の場合は分子量１４〜６００のアルキレン基またはアルキレンオキシ基を表し、
ｍは、０または１を表し、
ｎは０または１を表す） [12] The active energy ray-curable inkjet ink according to [10], wherein the maleimide is represented by the following general formula (11).

(In general formula (11),
R ₁₁ and R ₁₂ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ₁₁ and R ₁₂ may be bonded to each other to form a ring;
A ₁₁ and A ₁₃ each independently represent an alkylene group having 1 to 12 carbon atoms,
A ₁₂ represents a divalent hydrocarbon group having 1 to 12 carbon atoms having an asymmetric center,
Y independently represents carbonyloxy (—C (═O) —O—) or oxycarbonyl (—O—C (═O) —);
p represents 1 or 2,
R ₁₃ represents an alkyl group or alkyleneoxy group having a molecular weight of 15 to 600 when p is 1, and represents an alkylene group or alkyleneoxy group having a molecular weight of 14 to 600 when p is 2.
m represents 0 or 1;
n represents 0 or 1)

  [13] An inkjet recording method using the active energy ray-curable inkjet ink according to any one of [1] to [12].

  Since the inkjet ink of the present invention contains a highly curable polymerizable monomer, it can be used to form a fine image. Furthermore, since the cured shrinkage of the formed image is suppressed, the image is difficult to curl.

It is a figure which shows the principal part of an example of the inkjet recording device used for this invention. It is a figure which shows the principal part of another example of the inkjet recording device used for this invention.

[Active energy ray-curable inkjet ink]
The active energy ray-curable inkjet ink contains a polymerizable compound having an electron-deficient unsaturated double bond and a polymerizable compound having an electron-rich unsaturated double bond. The polymerizable compound having an electron-deficient unsaturated double bond and the polymerizable compound having an electron-rich unsaturated double bond may each be one kind or two or more kinds. An unsaturated double bond with a small charge of the carbon atom of the unsaturated double bond is an “electron-deficient unsaturated double bond”, and an unsaturated double bond with a large charge of the carbon atom of the unsaturated double bond is “ An “electron-rich unsaturated double bond”.

  The polymerizable compound is a compound having a property of polymerizing, and may be any of a monomer and an oligomer obtained by polymerizing one or two or more of monomers in an amount of 2 to 30, or a mixture thereof. Good. The “polymerizable compound having an electron-deficient unsaturated double bond” is also referred to as “acceptor monomer”, and the “polymerizable compound having an electron-rich unsaturated double bond” is also referred to as “donor monomer”. The acceptor monomer and donor monomer undergo charge transfer polymerization when irradiated with active energy rays.

  The “electron-deficient unsaturated double bond” is a group in which an electron-withdrawing group is bonded to one or both of carbon atoms constituting the unsaturated double bond. Examples of the electron withdrawing group include a cyano group, a halogen group, a pyridyl group, a pyrimidyl group, a nitro group, and an electron withdrawing group such as an electron withdrawing linking group described later. The “electron-rich unsaturated double bond” is a group in which an electron donating group is bonded to one or both of the carbon atoms constituting the unsaturated double bond. Examples of the electron donating group include oxy group, imino group, thio group, sulfinyl group and the like.

  The acceptor monomer and the donor monomer each have one or more unsaturated double bonds, but the donor monomer includes a monofunctional donor monomer (a monomer having one electron-rich unsaturated double bond). Is preferred.

  The donor monomer is preferably a polymerizable compound having an atomic charge value of −0.45 or less, more preferably −0.50 or less, constituting an unsaturated double bond. The acceptor monomer is preferably a polymerizable compound having a value of an atomic charge of the carbon atom constituting the unsaturated double bond of −0.3 or more, more preferably −0.28 or more. .

  The maximum value of the difference in charge between carbon atoms constituting the saturated double bond between the acceptor monomer and the donor monomer is preferably 0.24 or more and 0.46 or less. If the maximum value of the charge difference is 0.24 or more, CT polymerization is likely to occur. Moreover, if the maximum value of the difference in charge is 0.46 or less, a sufficient polymerization rate can be obtained without excessively stabilizing the charge transfer complex.

  The charge of the carbon atom constituting the unsaturated double bond is an atomic charge in the ground state obtained by calculation based on the molecular orbital theory. The charge on the carbon atom of the unsaturated double bond in the ground state of the polymerizable monomer is determined by calculation using a computer. In the present invention, SPARTAN'08 for Windows (registered trademark) is used as molecular orbital calculation software, Equilibrium Geometry at Ground state with Hartree-Fock 3-21G in Vacuum is used as the calculation method, and Natural is used as the charge value. Atomic charge was used.

  In the case of a polymerizable compound having an electron-deficient unsaturated double bond, the carbon atom constituting the unsaturated double bond is the carbon having the largest charge value among the carbon atoms on the unsaturated double bond. An atom (for example, a carbon atom on an unsaturated bond to which an electron-withdrawing group is bonded). In the case of a polymerizable compound having an unsaturated double bond with a large amount of electrons, among the carbon atoms on the unsaturated double bond, the carbon atom having the smallest charge value (for example, an unsaturated bond to which an electron donating group is bonded). Upper carbon atom). When a plurality of the unsaturated double bonds are present in one molecule of the polymerizable monomer, the average value of the carbon atom charges of each unsaturated double bond is defined as the value of the carbon atom charge.

  The active energy ray is an electromagnetic wave or radiation that causes copolymerization of an acceptor monomer and a donor monomer. Examples of the active energy rays include X-rays, ultraviolet rays, electron beams, and visible rays, but ultraviolet rays are preferably used in view of the high curing sensitivity of the charge transfer complex and the cost of the irradiation apparatus.

  The composition ratio of the acceptor monomer and the donor monomer is expressed as a functional group mol ratio from the viewpoints of sensitivity, strength of the cured film, that is, abrasion resistance, weather resistance, low curing shrinkage, flexibility, and ink jettable viscosity. , Acceptor functional group / donor functional group (usually, “electron-rich unsaturated double bond” / “electron-deficient unsaturated double bond”) is preferably in the range of 6/4 to 2/8. A range of ˜3 / 7 is more preferable.

  The content of the acceptor monomer in the inkjet ink of the present invention is preferably 20 to 70% by mass, and preferably 30 to 60% by mass from the viewpoint of obtaining a copolymer having high sensitivity and sufficient cured film strength. Is more preferable. Moreover, it is preferable that it is 10-70 mass% from the viewpoint similar to the said acceptor monomer, and, as for content of the donor monomer in the inkjet ink of this invention, it is more preferable that it is 30-60 mass%. Furthermore, in the inkjet ink of the present invention, the total content of the acceptor monomer and the donor monomer is preferably 40 to 96% by mass, and more preferably 50 to 90% by mass from the viewpoint of sensitivity.

  Since the acceptor monomer and the donor monomer are a main component of the active energy ray-curable inkjet ink and are a liquid, the active energy ray-curable inkjet ink need not substantially use a solvent. For this reason, by irradiating the ink with active energy rays, the acceptor monomer and donor monomer undergo CT polymerization, the ink changes to a solid and cures, and a firm image is formed without evaporation of the solvent. Can do.

[Polymerizable compound having an electron-rich unsaturated double bond]
The polymerizable compound (donor monomer) having an electron-rich unsaturated double bond includes a polymerizable compound in which an electron-rich double bond is bonded to an alkylene oxide not containing active hydrogen at at least one terminal. If there is active hydrogen at the end, the viscosity increases, so that the ink viscosity increases and the ejection property may decrease. Alkylene oxide includes methylene oxide, ethylene oxide, 1,3-propylene oxide, 1,2-propylene oxide, 1,4-butylene oxide, 1,3-butylene oxide, 1,2-butylene oxide, and the like.

The electron-rich double bond in the donor monomer is represented by, for example, general formula (3). Z in the general formula (3) represents —O—, —NR ₆ —, —CONR ₆ —, —S— or —SO—; R ₆ represents a hydrogen atom or a linear or branched group having 1 to 8 carbon atoms. It is an alkyl group. The substituent Z forms an electron-rich double bond by donating electrons to the double bond. Z is preferably -O-.

R ₃ , R ₄ and R ₅ in the general formula (3) are each a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched alkoxy group having 1 to 6 carbon atoms. .

More specifically, the donor monomer is represented by the general formula (1).

  In general formula (1), Q is a group containing a double bond having an excess of electrons. More specifically, Q has an electron-rich double bond represented by the general formula (3). Thus, the donor monomer represented by the general formula (1) has one electron-rich double bond.

In the general formula (1), R ₁ and R ₂ are each independently a linear or branched alkylene having 2 to 4 carbon atoms; m and n are each independently a natural number of 1 to 18; It is preferable that the natural number. That is, — (OR ₁ ) — and — (OR ₂ ) — are each an alkylene oxide. When m and n are not less than a certain value, curing shrinkage of the ink cured product (image) can be more effectively suppressed, and the scratch resistance and solvent resistance of the image are increased. On the other hand, if m and n are too large, the ink viscosity increases excessively, and it may be difficult to eject ink from the inkjet ink head.

  In General Formula (1), A is a C1-C8 linear or branched alkyl and C6-C12 aromatic ring group. A substituent having 1 to 8 carbon atoms may be bonded to the aromatic ring.

In the general formula (1), X is a linking group represented by the general formula (2).

In the general formula (2), X ₁ and X ₂ are each independently an ester bond represented by —OCO— or —COO—, or a urethane bond represented by —OCONH— or —NHCOO—. Y is a linear or branched alkylene having 1 to 8 carbon atoms or an aromatic ring group having 6 to 12 carbon atoms. A substituent having 1 to 8 carbon atoms may be bonded to the aromatic ring.

  In the general formula (1), p is an integer of 0, 1, 2, or 3, and is preferably 0.

  The molecular weight of the compound represented by the general formula (1) is 140 or more and 650 or less. If the molecular weight is too large, the ink viscosity may increase excessively. On the other hand, if the molecular weight is too small, curing shrinkage of the ink cured product (image) may not be sufficiently suppressed.

Specific examples of the compound represented by the general formula (1) are shown below. Compounds (1) -1 to (1) -8, general formula (1) -16, (1) -17, (1) -19, and (1) -20 are such that p in general formula (1) is 0. And Q is —O—.

Compounds (1) -9 to (1) -13, (1) -18 are compounds wherein p in formula (1) is 1, 2 or 3, and Q is —O—.

Compounds (1) -21 to (1) -23 are compounds in which p in general formula (1) is 0 and Q is N or S.

  The donor monomer may further contain another donor monomer other than the compound represented by the formula (1) as long as the effect of the present invention is obtained. The other donor monomer is preferably a compound represented by the following general formula (6) (excluding the compound of the formula (1)).

In the formula (6), X represents —O—, —NR ₄ —, —S—, or —SO—. In formula (6), Y represents a hydrogen atom, a linear alkyl group, a branched alkyl group, a cycloalkyl group, an alkyl group having a hydroxyl group, an aryl group, or an arylalkyl group, and further has a substituent. Also good. In Formula (6), the alkyl group and cycloalkyl group in Y preferably have 1 to 22 carbon atoms, the aryl group in Y preferably has 6 to 22 carbon atoms, and the arylalkyl group in Y has The number of carbon atoms is preferably 6-22. R ₄ in “—NR ₄ —” represents a hydrogen atom, a linear alkyl group, a branched alkyl group, a cycloalkyl group, an alkyl group having a hydroxyl group, an aryl group, or an arylalkyl group, It may combine to form a ring, and the alkyl group having a linear alkyl group, branched alkyl group or hydroxyl group preferably has 1 to 12 carbon atoms, and the cycloalkyl group has 3 to 12 carbon atoms. The number of carbon atoms of the aryl group or arylalkyl group is preferably 6-12.

In Formula (6), R ₁ , R ₂ and R ₃ each represent a hydrogen atom, a linear alkyl group, a branched alkyl group, a cycloalkyl group, an alkyl group having a hydroxyl group, an aryl group, or an arylalkyl group, , May have a substituent. The alkyl group in R _{1 to} R ₃ preferably has 1 to 6 carbon atoms, the cycloalkyl group preferably has 3 to 6 carbon atoms, and the aryl group in R _{1 to} R ₃ has 6 carbon atoms. preferably to 18 in which the _number of carbon atoms of the arylalkyl group for R 1 to R ₃ is preferably 6 to 18. In addition, a part of R ₂ or R ₃ and Y may be bonded to form a cyclic structure, or a part of Y may be a polyfunctional group having two or more unsaturated double bonds via a linking group. Donor monomers may be formed.

  Specific examples of the unsaturated compound represented by the formula (6) include, for example, alkenyl ethers such as vinyl ether and propenyl ether, alkenyl thioethers such as vinyl thioether and propenyl thioether, alkenyl sulfoxides such as vinyl sulfoxide and propenyl sulfoxide, Vinyl esters with a vinyl group bonded to the oxygen atom of the carboxylate ester, vinylamines with a vinyl group bonded to the nitrogen atom of the amino group, vinylamides with a vinyl group bonded to the nitrogen atom of the amide group, and nitrogen atoms of the imidazole ring Examples include vinyl imidazole having a vinyl group bonded thereto, vinyl carbazole having a vinyl group bonded to a nitrogen atom of a carbazole ring, a cyclic 5-membered ring having a vinylene skeleton and an oxygen atom in the ring, and a cyclic 6-membered ring compound.

  The compound represented by the formula (6) is more preferably a compound represented by the following general formulas (D-1) to (D-9).

In formulas (D-1) to (D-9), R _{5 to} R ₉ are each a hydrogen atom, a linear alkyl group, a branched alkyl group, a cycloalkyl group, an alkyl group having a hydroxyl group, an aryl group, or an aryl group. It represents an alkyl group, may further have a substituent, and can serve as a linking group for forming a polyfunctional polymerizable compound having two or more unsaturated double bond moieties. Wherein (D-1) ~ (D -9), it is preferable that the carbon number of the alkyl group in R 5 to R ₉ is a 1 to 22 carbon atoms in _the cycloalkyl group represented R 5 to R ₉ is 3 is preferably _22, carbon atoms in the aryl group in R 5 to R ₉ is preferably from 6 to 22 carbon atoms in _the arylalkyl group for R 5 to R ₉ is preferably 6-22. In formulas (D-1) to (D-9), Z represents —O—, —N (R ₁₀ ) —, or S—. R ₁₀ in this “Z” represents a hydrogen atom, a linear alkyl group, a branched alkyl group, a cycloalkyl group, an alkyl group having a hydroxyl group, an aryl group, or an arylalkyl group, and further may have a substituent. Good. Preferably the number of carbon atoms of the alkyl group in R ₁₀ is 1 to _12, preferably carbon number of the cycloalkyl group in _{R 10} is 3 to _12, carbon atoms in the aryl group in _{R 10} is 6 to 18 It is preferable that the arylalkyl group in R ₁₀ has 6 to 18 carbon atoms.

The compound of formula (6) may be a polyfunctional donor monomer or a monofunctional donor monomer. In the monofunctional donor monomer represented by the formula (6), in the formula (6), Y is a hydrogen atom, a linear alkyl group, a branched alkyl group, a cycloalkyl group, an alkyl group having a hydroxyl group, an aryl group, or Represents an arylalkyl group. X represents —O—, —N (R ₁₁ ) CO—, —NR ₄ —, —S—, or SO—, R ₁₁ represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group; ₁₁ may be linked to Y to form a ring. In the formula (6) in the case of a monofunctional donor monomer, the carbon number of the alkyl group in Y is preferably 1 to 22, the carbon number of the cycloalkyl group in Y is preferably 3 to 22, The aryl group preferably has 6 to 22 carbon atoms, and the arylalkyl group in Y preferably has 6 to 22 carbon atoms.

In the formula (6) for a monofunctional donor monomer, R ₄ of “—NR ₄ —” is a hydrogen atom, a linear alkyl group, a branched alkyl group, a cycloalkyl group, an alkyl group having a hydroxyl group, an aryl group, or Represents an arylalkyl group, which may be bonded to one of the carbon atoms of Y to form a ring. The linear alkyl group, branched alkyl group, cycloalkyl group, or alkyl group having a hydroxyl group has 1 to 12 carbon atoms. Preferably, the cycloalkyl group preferably has 3 to 12 carbon atoms, and the aryl group or arylalkyl group preferably has 6 to 18 carbon atoms. Further _, a part of R ₃ and Y may be bonded to form a cyclic structure.

In the formula (6) when the monofunctional donor monomer _{"- N (R} 11) CO-" _{R 11} of a hydrogen atom, a linear alkyl group, branched alkyl group, a cycloalkyl group, an alkyl group having a hydroxyl group, Represents an aryl group or an arylalkyl group, and may combine with one of the carbon atoms of Y to form a ring, and the carbon number of the linear alkyl group, branched alkyl group, cycloalkyl group, and alkyl group having a hydroxyl group is The number of carbon atoms of the cycloalkyl group is preferably 3-12, and the number of carbon atoms of the aryl group or arylalkyl group is preferably 6-18. Further _, a part of R ₄ and Y may combine to form a cyclic structure.

  Below, the specific example of a monofunctional donor monomer is shown.

  Examples of the monofunctional donor monomer include vinyl methyl sulfoxide, vinyl tert-butyl sulfide, vinyl methyl sulfide, and vinyl ethyl sulfide as polymerizable monomers containing vinyl thioether and vinyl sulfoxide.

  As the monofunctional donor monomer, for example, as a polymerizable monomer having a cyclic 5-membered ring or cyclic 6-membered ring compound containing a vinylene skeleton and a nitrogen atom or an oxygen atom in the ring, imidazole, pyrrole, furan, dihydrofuran, pyran, dihydro Examples include pyran.

  Specific examples of N-vinyl compounds having a structure in which a vinyl group is substituted on a nitrogen atom among monofunctional donor monomers include, for example, N-vinylformamide, N-vinylcarbazole, N-vinylindole, and N-vinylpyrrole. N-vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinyl-N-ethylurea, N-vinyloxazolidone, N-vinylsuccinimide, N-vinylethylcarbamate and their derivatives; Vinyl caprolactam and N-vinylformamide are preferred. N-vinylformamide can be obtained from, for example, Arakawa Chemical Industries, Ltd.

[Monofunctional vinyl ether compound]
The active energy ray-curable inkjet ink preferably contains a monofunctional vinyl ether compound represented by the general formula (7).

In formula (7), R ₃ , R ₄ , R ₅ and R ₆ represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group, and R ₆ represents an alkyl group, a cycloalkyl group or an aryl group. In formula (7), the alkyl group preferably has 1 to 12 carbon atoms, the cycloalkyl group preferably has 3 to 18 carbon atoms, and the aryl group has 6 to 18 carbon atoms. preferable.

  Examples of the monofunctional vinyl ether compound include n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, allyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, 9-hydroxy Nonyl vinyl ether, 4-hydroxycyclohexyl vinyl ether, cyclohexanedimethanol monovinyl ether, triethylene glycol monovinyl ether and the like can be mentioned.

  Further, various vinyl ether compounds disclosed so far may be used as donor monomers. For example, a compound containing a (meth) acryloyl group and a vinyl ether group in the molecule disclosed in Japanese Patent No. 3461501, a vinyl ether compound having an alicyclic skeleton containing at least an oxygen atom disclosed in Japanese Patent No. 4037856, A vinyl ether having an alicyclic skeleton disclosed in JP-A-2005-015396, a 1-indanyl vinyl ether disclosed in JP-A-2008-137974, and disclosed in JP-A-2008-150341 Examples include 4-acetoxycyclohexyl vinyl ether.

  Among the monofunctional donor monomers represented by the formula (6), a monofunctional donor monomer (monofunctional vinyl ether compound) in which X is —O— is particularly preferable from the viewpoint of stability.

[Multifunctional donor monomer]
The active energy ray-curable inkjet ink of the present invention preferably contains a polyfunctional donor monomer in addition to a monofunctional donor monomer because it improves curing sensitivity, weather resistance, and solvent resistance. In the unsaturated compound represented by the formula (6), the polyfunctional donor monomer is at least one unsaturated compound selected from the formulas (D-1) to (D-9), and R _{5 to} R ₉ are two. It is preferably a polyfunctional donor monomer which is a linking group for forming a polyfunctional polymerizable compound having one or more unsaturated double bond moieties, and in particular, a compound represented by the formula (D-1) Is particularly preferred.

  Subsequently, although an example of the polyfunctional donor monomer represented by Formula (D-1)-(D-9) is shown, it is not limited to these.

  Bifunctional vinyl ether compounds include 1,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether, neopentyl glycol divinyl ether, nonanediol divinyl ether, cyclohexanediol divinyl ether, cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether. , Triethylene glycol divinyl ether (TEGDVE), trimethylolpropane divinyl ether, ethylene oxide-modified trimethylolpropane divinyl ether, pentaerythritol divinyl ether, and the like.

  In addition, a vinyl ether compound having an alicyclic skeleton containing an oxygen atom disclosed in Japanese Patent No. 4037856, a vinyl ether having an alicyclic skeleton disclosed in Japanese Patent Laid-Open No. 2005-015396, 1-Indanyl vinyl ether disclosed in JP-A-137974 and 4-acetoxycyclohexyl vinyl ether disclosed in JP-A-2008-150341 may be used as the polyfunctional donor monomer.

  A substituent may be introduced at the α-position or β-position of the vinyl ether group of divinyl ether. For example, the vinyl ether group of the divinyl ether listed above may be a propenyl ether group, an isopropenyl ether group, a butenyl ether group, or an isobutenyl ether group.

  Among these bifunctional vinyl ether compounds, in consideration of curability, adhesion, and surface hardness, diethylene glycol divinyl ether and triethylene glycol divinyl ether, cyclohexanediol divinyl ether, cyclohexanedimethanol divinyl ether are curable, and various materials Are excellent in terms of compatibility, odor, and safety.

[Trifunctional or higher polyfunctional vinyl ether compound]
Specific examples of the trifunctional or higher polyfunctional vinyl ether compound suitable for the present invention include trimethylolpropane trivinyl ether, ethylene oxide modified trimethylolpropane trivinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, ethylene oxide modified pentaerythritol trivinyl ether. Examples include vinyl ether, ethylene oxide modified pentaerythritol tetravinyl ether, dipentaerythritol hexavinyl ether, ethylene oxide modified dipentaerythritol hexavinyl ether, and the like.

  As a trifunctional vinyl ether compound, a compound having an oxyalkylene group in the molecule, such as a compound represented by the following general formula (A), is compatible with other compounds, has solubility, and adherence to a substrate. It is preferable in obtaining. The total number of oxyalkylene groups is preferably 10 or less. When it is larger than 10, the water resistance of the cured film is lowered. In the following formula (A), an oxyethylene group is exemplified, but an oxyalkylene group having a different carbon number may be used. The number of carbon atoms of the oxyalkylene group is preferably 1 to 4, and more preferably 1 or 2.

In the above formula (A), R ₁₁ represents hydrogen or an organic group. Examples of the organic group represented by R ₁₁ include an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, a fluoroalkyl group having 1 to 6 carbon atoms, a furyl group, or a thienyl group. An allyl group having 6 to 18 carbon atoms, a 1-propenyl group, a 2-propenyl group, a 2-methyl-1-propenyl group, a 2-methyl-2-propenyl group, a 1-butenyl group, a 2-butenyl group, or 3- C1-C6 alkenyl group such as butenyl group, phenyl group, benzyl group, fluorobenzyl group, methoxybenzyl group or phenoxyethyl group such as aryl group, methoxy group, ethoxy group, butoxy group Alkyl group having 1 to 18 carbon atoms such as alkoxy group having 1 to 18 carbon atoms, such as propylcarbonyl group, butylcarbonyl group or pentylcarbonyl group, and ethoxycarbonyl group Examples include groups such as an alkoxycarbonyl group having 1 to 6 carbon atoms such as a propoxycarbonyl group or a butoxycarbonyl group, an alkoxycarbamoyl group having 1 to 6 carbon atoms such as an ethoxycarbamoyl group, a propylcarbamoyl group or a butylpentylcarbamoyl group. However, it is not limited to these. Among these, as the organic group, a hydrocarbon group containing no hetero atom is preferable from the viewpoint of curability. Moreover, p, q, and r are each 0 or an integer greater than or equal to 1, and p + q + r is an integer of 3-10.

  Examples of the polyfunctional vinyl ether compound having four or more vinyl ether groups include compounds represented by the following general formulas (B) and (C).

In the above formula (B), R ₁₂ is a linking group containing any one of a methylene group, an alkylene group having 1 to 6 carbon atoms, an oxyalkylene group and an ester group, and p, q, l and m are each 0 or It is an integer of 1 or more, and the total number of p + q + l + m is an integer of 3-10.

In the general formula (C), R ₁₃ represents a linking group including any one of a methylene group, an alkylene group having 1 to 6 carbon atoms, an oxyalkylene group, and an ester group, and p1, q1, r1, l1, m1 , S1 are each an integer of 0 or 1 or more, and the total number of p1 + q1 + r1 + l1 + m1 + s1 is an integer of 3-10.

  In the above formulas (B) and (C), an oxyethylene group is exemplified, but an oxyalkylene group having a different carbon number may be used. The number of carbon atoms of the oxyalkylene group is preferably 1 to 4, and more preferably 1 or 2.

[Polymerizable compound having an electron-deficient unsaturated double bond]
In the present invention, an acceptor monomer is essential. The acceptor monomer in the present invention is a monomer and / or oligomer having an electron-deficient unsaturated double bond.

  In the inkjet ink of the present invention, the monomer and / or oligomer having an electron-deficient unsaturated double bond is a compound having an unsaturated double bond represented by the following general formula (8) or general formula (9). Preferably there is.

In the above formula (8) or formula (9), EWG ₁ and EWG ₂ each represent a partial structure in which an electron withdrawing group is directly connected to an unsaturated double bond, and a part of EWG ₁ or EWG ₂ is bonded. You may have a cyclic structure. The electron-withdrawing group represents a cyano group, a halogen group, a pyridyl group, a pyrimidyl group, a nitro group, a group represented by the following general formula (a), or a group represented by the following general formula (b).

EWG ₁ and EWG ₂ may be bonded to each other to form the following electron-withdrawing linking group to form a cyclic structure. Examples of the electron-withdrawing linking group include —CO—O—CO—, —CO—N (R _X ) —CO—, —S (O) _n —O—CO—, —S (O) _n —N ( _{R) -CO -, - S (} O) n -O-S (O) n -, or _{S (O) n -N (R} X) -S (O) n - can be exemplified.

EWG ₁ and EWG ₂ form a cyclic structure via a linking group having 1 to 12 carbon atoms such as a linear alkylene group, a branched alkylene group, a cyclic alkylene group, an alkylene group having a hydroxyl group, an arylene group or an arylalkylene group. It may also have a substituent. Further, a part of EWG ₁ or EWG ₂ may form a polyfunctional polymerizable compound having two or more unsaturated double bond portions via a linking group.

In the above formulas (a) and (b), Q ₁ represents OH, OR ′, NR′R ″ or R ′, and n represents an integer of 1 or 2. R ′ and R ″ each represents a hydrogen atom. A linear alkyl group having 1 to 18 carbon atoms, a branched alkyl group having 1 to 18 carbon atoms, a cyclic alkyl group having 3 to 18 carbon atoms, an alkyl group having 1 to 18 carbon atoms having a hydroxyl group, and 6 to 18 carbon atoms Represents an aryl group or an arylalkyl group having 6 to 18 carbon atoms, and may further have a substituent.

  Specific examples of the unsaturated compound represented by the formula (8) or the formula (9) include, for example, a vinylene imide compound, a vinylene dicarboxylic acid, a vinylene dicarboxylic acid ester, a vinylene monocarboxylic acid amide monocarboxylic acid, and a vinylene monocarboxylic acid amide. Monocarboxylic acid esters, vinylene dicarboxylic acid amides, vinylene nitrile compounds substituted with nitrile groups at both ends of the vinylene skeleton, vinyl halide compounds substituted with halogen groups at both ends of the vinylene skeleton, vinylene ketone compounds substituted with carbonyl at both ends of the vinylene skeleton, vinyl Dienethiocarboxylic anhydride, vinylenethioimide compound, vinylenethiocarboxylic acid, vinylenethiothiolic acid ester, vinylene monothiocarboxylic acid amide monothiocarboxylic acid, vinylene monothiocarboxylic acid amide monothiocar Phosphate esters, vinyl range thio carboxylic acid amide, compounds pyridyl group which is substituted vinylene backbone ends, but such compounds structure pyrimidyl group is substituted on vinylene skeleton ends include, but are not limited to.

  Among these, preferable unsaturated compounds include vinylene imides such as maleic anhydride and maleimide, vinylenedicarboxylic acids such as maleic acid and fumaric acid, and vinylene carboxylic acid esters such as maleic acid ester and fumaric acid ester.

  In the present invention, the unsaturated compound represented by formula (8) or formula (9) is at least one unsaturated compound selected from the following formulas (A-1) to (A-13). Is preferred.

In formulas (A-1) to (A-8) and (A-13), R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, a linear alkyl group having 1 to 22 carbon atoms, Or a branched alkyl group having 1 to 22 carbon atoms, a cyclic alkyl group having 3 to 22 carbon atoms, an alkyl group having 1 to 22 carbon atoms having a hydroxyl group, an aryl group having 6 to 22 carbon atoms, or 6 to 22 carbon atoms It represents an arylalkyl group, may further have a substituent, and can be a linking group for forming a polyfunctional polymerizable compound having two or more unsaturated double bond moieties. In formulas (A-11) and (A-12), X ₁ represents a halogen atom.

  In the unsaturated compound represented by Formula (8) or Formula (9) according to the present invention, among the unsaturated compounds represented by Formulas (A-1) to (A-13), further, Formula (A-1) to Formula (A-13) It is preferable that it is an unsaturated compound represented by A-1), Formula (A-2), or Formula (A-6).

  Although an example of the unsaturated compound which is a polymerizable monomer represented by formula (A-1)-(A-13) below is shown, in this invention, it is not limited to the polymerizable monomer illustrated here. .

  In the present invention, examples of monofunctional unsaturated compounds represented by formulas (A-1) to (A-13) include the following examples. Examples of compounds having vinylene dicarboxylic anhydride include maleic anhydride, examples of compounds having vinylene imide, maleimide, N-methylmaleimide, N-ethylmaleimide, N-butylmaleimide, N-2-ethylhexylmaleimide, N- Dodecylmaleimide, N-octadecylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide, N- (p-carbomethoxyphenyl) maleimide, 4,4'-dimaleimidobisphenol F, N-butylmaleimide, N- (2-chlorophenyl) ) Maleimide, N- (4-chlorophenyl) maleimide, 2,3-dimethyl-1-N- (2-methacryloxyethylmaleimide, vinylene dicarboxylic acid, maleic acid, fumaric acid, vinylene dicarboxylic acid ester , Dimethyl maleate, maleic acid Diethyl, diisopropyl maleate, di-n-butyl maleate, di-tert-butyl maleate, di (2-ethylhexyl) maleate, dimethyl fumarate, diethyl fumarate, diisopropyl fumarate, di-n-butyl fumarate , Di-tert-butyl fumarate, di (2-ethylhexyl) fumarate, and the like, but are not limited to these specific examples.

  Moreover, in order to obtain the polyfunctional polymerizable monomer which has a preferable unsaturated double bond, it can obtain using various conventionally well-known coupling group frame | skeletons. Examples thereof include polyfunctional maleimide derivatives as described in US Pat. No. 6,034,150 and JP-A-11-124403.

  Below, the maleimide derivative (maleimide) which can be preferably used for the inkjet ink of this invention is demonstrated in detail.

  The maleimide derivative is preferably a maleimide compound having a chiral structure in the molecule from the viewpoints of solubility, low viscosity, and ejection stability required as an inkjet ink composition.

  In the present invention, the maleimide compound having a chiral group is not particularly limited as long as it has at least one chiral carbon atom in the molecule. The preferable maleimide compound is represented by the following general formula (10). Compounds are preferred.

In the above formula (10), R ₁ and R ₂ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ₁ and R ₂ may be bonded to each other to form a ring. Y ₁ and Y ₃ are each independently 2 in which a group selected from an alkylene group having 1 to 12 carbon atoms, an alkyleneoxy group having 1 to 12 carbon atoms, a phenylene group, an ester group, an ether group, and a thioether group is combined. Represents a valent organic linking group. Y ₂ represents a divalent group having an asymmetric carbon. n represents an integer of 1 to 6, n1 represents 0 or 1, and n2 represents 0 or 1. Z represents a 1-6 valent organic group in which a group selected from an alkylene group having 1 to 12 carbon atoms, an alkyleneoxy group having 1 to 12 carbon atoms, a phenylene group, an ester group, an ether group and a thioether group is combined. .

Examples of the alkyl group represented by R ₁ and R ₂ in Formula (10) include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. R ₁ and R ₂ may combine to form a cyclopropylene ring, a cyclobutylene ring, a cyclopentene ring, a cyclohexene ring, or the like.

In formula (10), as the divalent organic linking group represented by Y ₁ or Y ₃ , an alkylene group having 1 to 12 carbon atoms (for example, methylene group, ethylene group, butylene group, hexylene group, etc.), carbon C 1-12 alkyleneoxy group (for example, ethyleneoxy group, polyethyleneoxy group, butyleneoxy group, polybutyleneoxy group), C2-12 alkyleneoxycarbonyl group (for example, ethyleneoxycarbonyl group, hexyleneoxy) Carbonyl group etc.), C2-C12 alkylene ester group (for example, methylene ester group, hexylene ester group), phenylene group (for example, phenylene group, methylphenylene group, oxycarbonylphenylenecarbonyloxy group, carbonyloxyphenylene) Oxycarbonyl group).

In formula (10), Y ₂ represents a divalent group having an asymmetric carbon (chiral carbon). Specific examples include groups represented by the following formula (10a).

  In formula (10a), X represents an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 1 to 18 carbon atoms, an alkyloxy group having 1 to 18 carbon atoms, an alkylcarbonyloxy group having 2 to 18 carbon atoms, or a hydroxyl group. . Preferably, it is a C1-C4 alkyl group, for example, a methyl group, an ethyl group, a propyl group, and an isobutyl group are mentioned.

In formula (10), Z represents an n-valent linking group. When n = 1, hydrogen atom, alkyl group (methyl group, ethyl group, hexyl group), hydroxyl group, carboxyl group, alkyl ester group having 2 to 22 carbon atoms, etc. When n = 2, the above Y ₁ , Y ₃ is synonymous with the divalent organic linking group represented by 3, when n = 3, glycerol group, trimethylol alkyl group having 4 to 22 carbon atoms, triazine group, etc., when n = 4, pentaerythritol When n = 6, a bistrimethylol alkyl group or the like is represented.

  For emission from the inkjet head, the molecular weight of the maleimide compound having a chiral group is preferably 200 to 1,000, and more preferably 200 to 800. If it is less than 200, crystallization is likely and clogging is likely to occur during emission. On the other hand, if the molecular weight is larger than 1,000, the viscosity becomes high and the emission becomes difficult.

  More preferably, maleimide compounds represented by the following formulas (10-1) to (10-5) are exemplified.

In formulas (10-1) to (10-5), it is preferable that n11 and n12 each independently represents an integer of 0 to 6, and n13 independently represents an integer of 1 to 30. R _{1, R} 2, Z, and n have the same meanings as _{R 1, R} 2, Z, and n in formula (10). X is synonymous with X in Formula (10a). Particularly preferably, R ₁ and R ₂ are a hydrogen atom, X is an alkyl group having 1 to 4 carbon atoms, n12 is 0, and Z is an alkylene or polyoxyalkylene having 1 to 18 carbon atoms.

Specific examples (M-1) to (M-45) of the compound represented by formula (10) are shown below, but the present invention is not limited thereto.

  Methods for synthesizing these maleimide compounds are known, and can be easily synthesized using, for example, the methods described in JP-A-11-124403 or Macromolecular Chemical and Physics, 2009, 210, 269-278.

More preferred maleimide derivatives applicable in the inkjet ink of the present invention include maleimide derivatives represented by the following general formula (11) from the viewpoint of low viscosity, solubility, and ejection stability.

In the above formula (11), R ₁₁ and R ₁₂ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ₁₁ and R ₁₂ may be bonded to each other to form a ring, A ₁₁ and A ₁₃ each independently represent an alkylene group having 1 to 12 carbon atoms, A ₁₂ independently represents a divalent hydrocarbon group having 1 to 12 carbon atoms having an asymmetric center, and Y represents , Independently represents carbonyloxy (—C (═O) —O—) or oxycarbonyl (—O—C (═O) —), p represents 1 or 2, and R ₁₃ represents p = 1 Represents an alkyl group or an alkyleneoxy group having a molecular weight of 15 to 600, and when p is 2, it represents an alkylene group or an alkyleneoxy group having a molecular weight of 14 to 600, m represents 0 or 1, and n represents 0 or 1.

In the formula (11), examples of the alkyl group having 1 to 6 carbon atoms represented by R ₁₁ and R ₁₂ include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. R ₁₁ and R ₁₂ may be bonded to form a cyclopropene ring, a cyclobutylene ring, a cyclopentene ring, a cyclohexene ring, or the like.

In formula (11), as the divalent organic linking group represented by A ₁₁ or A ₁₃ , methylene group, ethylene group, butylene group, hexylene group ethyleneoxy group, polyethyleneoxy group, butyleneoxy group, polybutyleneoxy Group, ethyleneoxycarbonyl group, hexyleneoxycarbonyl group, methylene ester group, hexylene ester group, phenylene group, methylphenylene group, oxycarbonylphenylenecarbonyloxy group, carbonyloxyphenyleneoxycarbonyl group.

In formula (11), A ₁₂ represents a divalent group having an asymmetric carbon (chiral carbon). Examples of A ₁₂ include a group represented by the formula (10a).

Further, in the formula (11), A ₁₁ and A ₁₃ are methylene groups, A ₁₂ is —CHR ₁₄ —, R ₁₃ is an alkyl group having 2 to 12 carbon atoms, or an alkylene group having 2 to 12 carbon atoms. It is preferable that At this time, R ₁₄ represents an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, an alkyloxy group having 1 to 18 carbon atoms, an alkylcarbonyloxy group having 2 to 18 carbon atoms, or a hydroxyl group. R ₁₄ is preferably an alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group, propyl group, isobutyl group, etc.).

In formula (11), the alkyl group having a molecular weight of 15 to 600 represented by R ₁₃ when p is 1 represents a linear or branched alkyl group having 1 to 18 carbon atoms, specifically, methyl A group, an ethyl group, a propyl group, a butyl group, a hexyl group, a neopentyl group, a dodecyl group, a 2,2,4-octyl group, and the like.

In formula (11), the alkylene group having a molecular weight of 14 to 600 represented by R ₁₃ when p is 2 represents a linear or branched alkylene group having 1 to 18 carbon atoms, specifically methylene Group, ethylene group, propylene group, butylene group, hexylene, group, nepopentylene group, dodecylene group, 2,2,4-octylene group and the like.

In formula (11), the alkyleneoxy group represented by R ₁₃ when p is 1 includes a hydroxy or alkoxy polyethyleneoxy group, a hydroxy or alkoxypolyproleneoxy group, a hydroxy or alkoxypolybutyleneoxy group, and the like. However, it is not limited to these.

In formula (11), R ₁₃ is preferably a linear or branched alkylene group having 1 to 18 carbon atoms, or a linear or branched alkyl group having 1 to 18 carbon atoms, and more preferably 4 to 12 carbon atoms. A linear or branched alkylene group, or a linear or branched alkyl group having 4 to 12 carbon atoms.

Further preferred maleimide derivatives include maleimide derivatives represented by the following general formulas (II) to (IV).

In the above formulas (II) to (IV), R ₁₄ is independently an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 1 to 18 carbon atoms, an alkyloxy group having 1 to 18 carbon atoms, or 1 to 1 carbon atoms. 18 alkylcarbonyloxy groups or hydroxyl groups are represented. R ₁₄ is preferably an alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group, propyl group, isobutyl group, etc.). p represents 1 or 2. R ₁₅ represents a linear alkyl group having 4 to 12 carbon atoms or a linear alkylene group having 4 to 12 carbon atoms.

Specific examples (M-51) to (M-82) of maleimide derivatives represented by the formula (11) of the present invention are shown below.

  As the monomer and / or oligomer having an electron-deficient unsaturated double bond according to the present invention described above, maleic acid esters, fumaric acid esters, and maleimides are preferable from the viewpoint of increasing sensitivity.

  The acceptor monomer contains a polymerizable compound having a molecular weight of 350 or more and 600 or less in an amount of 80% by mass or more based on the entire polymerizable compound having an electron-deficient unsaturated double bond, and represented by the formula (1). The molecular weight of the donor monomer is preferably 300 or more and 600 or less from the viewpoints of ink viscosity and light emission. The molecular weight referred to here means an average molecular weight when the polymerizable compound includes a repeating molecular structure and the polymerizable compound has two or more molecular weights.

[Other monomers]
In the present invention, the effects of the present invention can be obtained even if the other monomer is a polymerizable compound in which the charge of the carbon atom constituting the unsaturated double bond is more than −0.45 and less than −0.30. It can add suitably in the range. Such other polymerizable compounds will be described below.

  The other polymerizable compound is a compound having an ethylenically unsaturated double bond capable of radical polymerization, and a charge of a carbon atom constituting the unsaturated double bond exceeds −0.45, and −0.30. And those having chemical forms such as monomers, oligomers and polymers.

  Examples of the other polymerizable compounds include unsaturated carboxylic acids such as acrylic acid and methacrylic acid and their salts, anhydrides having ethylenically unsaturated groups, acrylonitrile, styrene, various unsaturated polyesters, unsaturated Examples include radical polymerizable monomers such as polyether, unsaturated polyamide, and unsaturated urethane.

  Specifically, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, tridecyl acrylate, 2-phenoxyethyl acrylate, bis (4-acryloxypolyethoxyphenyl) Propane, polyethylene glycol diacrylate, polypropylene glycol diacrylate, dipentaerythritol tetraacrylate, trimethylolpropane triacrylate, oligoester acrylate, N-methylolacrylamide, diacetone acrylamide, epoxy acrylate, isobornyl acrylate, dicyclopentenyl acrylate, Dicyclopentenyloxyethyl acrylate, disic Acrylic acid derivatives such as lopentanyl acrylate; methyl methacrylate, n-butyl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis (4- Methacryl derivatives such as methacryloxypolyethoxyphenyl) propane; and other derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, and triallyl trimellitate. More specifically, Shinzo Yamashita, “Crosslinker Handbook”, (1981 Taiseisha); Kato Kiyosumi, “UV / EB Curing Handbook (Materials)” (1985, Polymer Publications); Radtech Study Group, “Application and Market of UV / EB Curing Technology”, p. 79, (1989, CMC); Eiichiro Takiyama, “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun) Commercially available products or radically polymerizable and crosslinkable monomers, oligomers and polymers known in the industry can be used.

  Among these acrylates and methacrylates, an acrylate of an alcohol having an ether oxygen atom such as tetrahydrofurfuryl acrylate and 2-phenoxyethyl acrylate is preferable from the viewpoint of curability and film properties after curing. For the same reason, an acrylate of an alcohol having an alicyclic structure is also preferable, and a bicyclo ring structure or a tricyclo ring structure such as isobornyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentanyl acrylate, etc. Specific examples of preferable acrylates include dicyclopentenyl acrylate and dicyclopentenyloxyethyl acrylate having a double bond in the alicyclic structure.

  The content of the other polymerizable compound in the inkjet ink of the present invention is preferably 0.1 to 40% by mass from the viewpoint of further obtaining the effect of the addition of the other polymerizable compound, and is 1.0 to More preferably, it is 25 mass%.

[Photopolymerization initiator]
From the viewpoint of obtaining high sensitivity, the inkjet ink of the present invention preferably contains a radical polymerization initiator as a photopolymerization initiator, and may further contain a sensitizer.

  The radical polymerization initiator contained in the inkjet ink of the present invention may be either a molecular cleavage type or a hydrogen abstraction type. Preferred examples of the radical polymerization initiator include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, benzyl, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino- 1- (4-morpholinophenyl) -butan-1-one, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine Oxides and the like are included.

  In addition, examples of molecular cleavage type radical polymerization initiators other than these include 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyldimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one, -(4-Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 1- [4- (2 -Hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one and the like. Further, examples of the hydrogen abstraction type photopolymerization initiator include benzophenone, 4-phenylbenzophenone, isophthalphenone, 4-benzoyl-4′-methyl-diphenyl sulfide, and bis (2,4- Cyclopentadiene-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium, an oxime ester type polymerization initiator 1,2-octanedione, 1- (4- (phenylthio) -2- (O-benzoyloxime)), ethanone, 1- (9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl) -1- (O-acetyl) Oxime) and the like.

  Moreover, you may contain a sensitizer with a radical polymerization initiator. Examples of sensitizers include trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, N-dimethylbenzylamine and 4, Amines that do not cause an addition reaction with a polymerizable monomer such as 4′-bis (diethylamino) benzophenone are included. Of course, it is preferable that the photodipolymerization initiator and the sensitizer have excellent solubility in the polymerizable monomer.

  The content of the photo radical polymerization initiator and the sensitizer is 0.1 to 20% by mass, preferably 1 to 12% by mass with respect to the total mass of the active energy ray-curable inkjet ink composition. .

  In addition, a dendrimer core described in European Patent 1,674,499A is bound to an amine-based initiator as an initiator structure, European Patent 2,161,264A, European Patent No. An initiator having a polymerizable group described in the specification of 2,189,477A, an amine-based initiator, and a plurality of amine-based initiators described in EP 1,927,632B1 are contained in one molecule. A type having a plurality of thioxanthones in the molecule described in WO2009 / 060235, an α hydroxypropiophenone represented by ESACURE ONE and ESACUR KIP150 marketed by Lamberti Oligomer type polymerization initiators bonded to can also be preferably used.

  Further, the maleimide-containing polymerizable monomer itself can function as an initiator.

[Radical polymerization inhibitor]
The active energy ray-curable inkjet ink of the present invention preferably further contains a radical polymerization inhibitor from the viewpoint of storage stability. In the inkjet ink of the present invention, radical polymerization may occur due to radicals generated under the influence of heat or light during storage. The use of a radical polymerization inhibitor in the active energy ray-curable inkjet ink composition or inkjet ink of the present invention has the effect of preventing radical polymerization that occurs during storage, but does not inhibit the curing of photocationic polymerization. This is a very preferable embodiment because it has the effect of enhancing only the storage stability of the ink over time without inhibiting the photocuring of the ink mainly composed of vinyl ether as in the present invention and having excellent curability.

  Examples of radical polymerization inhibitors include phenolic hydroxyl group-containing compounds, quinones or hydroquinones, phenothiazines, N-oxyls and the like. Specific examples of the radical polymerization inhibitor include the following compounds.

  Examples of the phenolic hydroxyl group-containing compound as a radical polymerization inhibitor include the following compounds: phenol, alkylphenols such as o-, m- or p-cresol, 2-t-butyl-4-methylphenol, 6 -t-butyl-2,4-dimethylphenol, 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2 -Methyl-4-t-butylphenol, 4-t-butyl-2,6-dimethylphenol, or 2,2'-methylene-bis- (6-t-butyl-methylphenol), 4,4'-oxydiphenyl 3,4-methylenedioxydiphenol (sesame oil), 3,4-dimethylphenol, benzcatechin (1,2-dihydroxybenzole), 2- (1′-methylcyclohexyl-1′-yl) -4, 6-Dimethylpheno 2,2- or 4- (1'-phenylethyl-1'-yl) phenol, 2-t-butyl-6-methylphenol, 2,4,6-tris-t-butylphenol, 2,6-di-t -Butylphenol, nonylphenol [CAS-Nr. 11066-49-2], octylphenol [CAS-Nr. 140-66-9], 2,6-dimethylphenol, bisphenol A, bisphenol B, bisphenol C, bisphenol F, bisphenol S, 3,3 ′, 5,5′-tetrabromobisphenol A, 2,6-di- t-Butyl-p-cresol, BASF Aktigensellschaft's Cholesin, 3,5-Di-t-butyl-4-hydroxybenzoic acid methyl ester, 4-t-butylbenzcatechin, 2-hydroxybenzyl alcohol, 2- Methoxy-4-methylphenol, 2,3,6-trimethylphenol, 2,4,5-trimethylphenol, 2,4,6-trimethylphenol, 2-isopropylphenol, 4-isopropylphenol, 6-isopropyl-m- Cresol, n-octadecyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) Lopionate, 1,1,3-tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris- (3,5-di-) -t-butyl-4-hydroxybenzyl) benzol, 1,3,5-tris- (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris- (3, 5-Di-tert-butyl-4-hydroxyphenyl) propionyloxyethyl-isocyanurate, 1,3,5-tris- (2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate or penta Erythlit-tetrakis- [β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,6-di-t-butyl-4-dimethylaminomethylphenol, 6-s-butyl- 2,4-dinitrophenol, Firma Ciba Specialiaetenc Emie Irganox 565, 1010, 1076, 1141, 1192, 1222 and 1425, 3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionic acid octadecyl ester, 3- ( 3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionic acid hexadecyl ester, 3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionic acid octyl ester, 3-thia-1,5-pentanediol-bis- [3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate], 4,8-dioxa-1,11-undecandiol-bis- [3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate], 4,8-dioxa-1,11-undecandiol-bis-[(3'-t-butyl-4'-hydroxy -5'-methylphenyl) propionate G] 1,9-nonanediol-bis-[(3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate], 1,7-heptanediamine-bis [3- (3 ′, 5'-di-t-butyl-4'-hydroxyphenyl) propionic acid amide], 1,1-methanediamine-bis [3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) Propionic acid amide], 3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionic acid hydrazide, 3- (3 ′, 5′-dimethyl-4′-hydroxyphenyl) propionic acid hydrazide Bis- (3-t-butyl-5-ethyl-2-hydroxyphen-1-yl) methane, bis- (3,5-di-t-butyl-4-hydroxyphen-1-yl) methane, bis -[3- (1′-Methylcyclohex-1′-yl) -5-methyl-2-hydroxyphen-1-yl] methane, bis- (3-tert-butyl-2-hydro Ci-5-methylphen-1-yl) methane, 1,1-bis- (5-tert-butyl-4-hydroxy-2-methylphen-1-yl) ethane, bis- (5-tert-butyl-4-) Hydroxy-2-methylphen-1-yl) sulfide, bis- (3-tert-butyl-2-hydroxy-5-methylphen-1-yl) sulfide, 1,1-bis- (3,4-dimethyl-2- Hydroxyphen-1-yl) -2-methylpropane, 1,1-bis- (5-tert-butyl-3-methyl-2-hydroxyphen-1-yl) butane, 1,3,5-tris- [ 1 '-(3 ", 5" -di-t-butyl-4 "-hydroxyphen-1" -yl) methy-1'-yl] -2,4,6-trimethylbenzol, 1,1,4- Tris- (5′-t-butyl-4′-hydroxy-2′-methylphen-1′-yl) butane and t-butylcatechol, and aminophenols such as p-aminophenol, nitrosophe (Eg, p-nitrosophenol, p-nitroso-o-cresol), alkoxyphenol (eg, 2-methoxyphenol (guaiacol, benzcatechin monomethyl ether), 2-ethoxyphenol, 2-isopropoxyphenol, 4- Methoxyphenol (hydroquinone monomethyl ether), mono- or di-t-butyl-4-methoxyphenol, 3,5-di-t-butyl-4-hydroxyanisole, 3-hydroxy-4-methoxybenzyl alcohol, 2.5 -Dimethoxy-4-hydroxybenzyl alcohol (syringa alcohol), 4-hydroxy-3-methoxybenzaldehyde (vanillin), 4-hydroxy-3-ethoxybenzaldehyde (ethylvanillin), 3-hydroxy-4-methoxybenzaldehyde (isovanillin) 1-((4-H Loxy-3-methoxyphenyl) ethanone (acetovanillin), eugenol, dihydroeugenol, isoeugenol), tocopherol (eg, α-, β-, γ-, δ- and ε-tocopherol, tocol, α-tocopherol hydroquinone), And 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran (2,2-dimethyl-7-hydroxycoumaran).

  Examples of quinone and hydroquinone as radical polymerization inhibitors include hydroquinone or hydroquinone monomethyl ether (4-methoxyphenol), methyl hydroquinone, 2,5-di-t-butyl hydroquinone, 2-methyl-p-hydroquinone, and 2,3. -Dimethylhydroquinone, trimethylhydroquinone 4-methylbenzcatechin, t-butylhydroquinone, 3-methylbenzcatechin, benzoquinone, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone, trimethylhydroquinone, t-butylhydroquinone, 4- Ethoxyphenol, 4-butoxyphenol, hydroquinone monobenzyl ether, p-phenoxyphenol, 2-methylhydroquinone, tetramethyl-p-benzoquinone, diethyl-1,4-cyclohexanedio 2,5-dicarboxylate, phenyl-p-benzoquinone, 2,5-dimethyl-3-benzyl-p-benzoquinone, 2-isopropyl-5-methyl-p-benzoquinone (thymoquinone), 2,6-diisopropyl -p-benzoquinone, 2,5-dimethyl-3-hydroxy-p-benzoquinone, 2,5-dihydroxy-p-benzoquinone, envelope, tetrahydroxy-p-benzoquinone, 2,5-dimethoxy-1,4-benzoquinone, 2-amino-5-methyl-p-benzoquinone, 2,5-bisphenylamino-1,4-benzoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-anilino-1,4-naphthoquinone, anthraquinone, N, N-dimethylindoaniline, N, N-diphenyl-p-benzoquinonediimine, 1,4-benzoquinonedioxime, cerlignon, 3,3'-di-t-butyl-5,5'-dimethyldiphenoquino P-rosoleic acid (oline), 2,6-di-t-butyl-4-benzylidene-benzoquinone, and 2,5-di-t-butyl-amylhydroquinone are preferred.

  N-oxyl (nitroxyl- or N-oxyl-group, compound having at least one> N-O.-group) as a radical polymerization inhibitor is, for example, a piperidine N-oxyl compound. A free radical compound of piperidine N-oxyl is preferable. Examples of N-oxyl as radical polymerization inhibitor include 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl- Piperidine-N-oxyl, 4-methoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 2, 2,6,6-Tetramethyl-piperidine-N-oxyl, USF of BASF Aktingesellchaft, 4040P, 4,4 ', 4 "-tris- (2,2,6,6-tetramethyl-piperidine-N- Oxyl) phosphite, 3-oxo-2,2,5,5-tetramethyl-pyrrolidine-N-oxyl, 1-oxyl-2,2,6,6-tetramethyl-4-methoxypiperidine, 1-oxyl- 2,2,6,6-tetramethyl-4-trimethylsilyloxypi Peridine, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-2-ethylhexanoate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-sebacate 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-stearate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-benzoate, 1-oxyl- 2,2,6,6-tetramethylpiperidin-4-yl- (4-t-butyl) benzoate, bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate, Bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate 1,10-decanedioic acid-bis- (1-oxyl-2,2,6,6-tetramethylpiperidine -4-yl) ester, bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butyl Malonate, bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate, bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) Isophthalate, bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) terephthalate, bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) ) Hexahydroterephthalate, N, N'-bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipinamide, N- (1-oxyl-2,2,6,6) -Tetramethylpiperidin-4-yl) caprolactam, N- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) dodecylsuccinimide, 2,4,6-tris- [N-butyl- N- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl] triazine, N, N′-bi -(1-Oxyl-2,2,6,6-tetramethylpiperidin-4-yl) -N, N'-bis-formyl-1,6-diaminohexane, 4,4'-ethylene-bis- (1 -Oxyl-2,2,6,6-tetramethylpiperazin-3-one) is preferred.

  As an aromatic amine or phenylenediamine as a radical polymerization inhibitor, for example, N, N-diphenylamine, N-nitroso-diphenylamine, nitrosodiethylaniline, p-phenylenediamine, N, N′-dialkyl-p-phenylenediamine (this The alkyl groups may be the same or different, each independent of one another, containing 1 to 4 carbon atoms and may be linear or molecular)), for example N, N′-diisobutyl-p— Phenylenediamine, N, N′-diisopropyl-p-phenylenediamine, Irganox 5057 from Firma Ciba Specialiaetenchie, N-phenyl-p-phenylenediamine, N, N′-diphenyl-p-phenylenediamine, N-isopropyl-N— Phenyl-p-phenylenediamine, N, N'-di-s-butyl-p-phen Nylenediamine (Kerobit BPD from BASF Aktiengesellschaft), N-phenyl-N′-isopropyl-p-phenylenediamine (Vulkanox 4010 from Bayer AG), N- (1,3-dimethylbutyl) -N ′ -Phenyl-p-phenylenediamine, N-phenyl-2-naphthylamine, iminodibenzyl, N, N'-diphenylbenzidine, N-phenyltetraaniline, acridone, 3-hydroxydiphenylamine, 4-hydroxydiphenylamine are preferred.

  Examples of imines as radical polymerization inhibitors include methylethylimine, (2-hydroxyphenyl) benzoquinoneimine, (2-hydroxyphenyl) benzophenoneimine, N, N-dimethylindoaniline, and thionine (7-amino-3-imino). -3H-phenothiazine), methylene violet (7-dimethylamino-3-phenothiazinone).

  Examples of the sulfonamide as a radical polymerization inhibitor include N-methyl-4-toluolsulfonamide, Nt-butyl-4-toluolsulfonamide, Nt-butyl-N-oxyl-4-toluene. Allsulfonamide, N, N′-bis (4-sulfanilamide) piperidine, 3-{[5- (4-aminobenzoyl) -2,4-dimethylbenzoylsulfonyl] ethylamino} -4-methylbenzolsulfonic acid is there.

  Examples of oximes as radical polymerization inhibitors include aldoxime, ketoxime or amidoxime, preferably diethyl ketoxime, acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, benzaldehyde oxime, benzyldioxime, dimethylglyoxime, 2-pyridine aldoxime, salicyl. Aldoxime, phenyl-2-pyridylketoxime, 1,4-benzoquinone dioxime, 2,3-butanedione dioxime, 2,3-butanedione monooxime, 9-fluorenone oxime, 4-t-butyl-cyclohexanone oxime N-ethoxy-acetimidic acid ethyl ester, 2,4-dimethyl-3-pentanone oxime, cyclododecanone oxime, 4-heptanone oxime and di-2-furanylethanedione dioxime or other aliphatic or Aroma It may be a group oxime or an alkyl transfer agent such as its reaction product with an alkyl halide, -triflate, -sulfonate, -tosylate, -carbonate, -sulfate, -phosphate and the like.

  Examples of hydroxylamine as a radical polymerization inhibitor include N, N-diethylhydroxylamine and compounds described in the international patent application PCT / EP03 / 03139.

  As the urea derivative as the radical polymerization inhibitor, for example, urea or thiourea is suitable.

  Examples of the phosphorus-containing compound as the radical polymerization inhibitor include triphenylphosphine, triphenylphosphite, hypophosphorous acid, trinonylphosphite, triethylphosphite, and diphenylisopropylphosphine.

  As the sulfur-containing compound as a radical polymerization inhibitor, for example, diphenyl sulfide, phenothiazine and sulfur-containing natural substances such as cysteine are suitable.

  Complexing agents based on tetraazaannulene (TAA) are described, for example, in Chem. Soc. Rev. 1998, 27, 105-115, for example, dibenzotetraaza [14] ring and porphyrin.

  In addition, each metal salt (copper, manganese, cerium, nickel, chromium, etc.) such as carbonic acid, chloride, dithiocarbamic acid, sulfuric acid, salicylic acid, acetic acid, stearic acid, and ethylhexanoic acid can be exemplified.

  In addition, the N-oxyl free radical compound having a vinyl ether functional group described in Macromol. Rapid Commun., 28, 1929 (2007) has a structure having both a polymerizable function and a radical scavenging function in the same molecule. From the viewpoint of ink storage stability, it is preferably added to the ink of the present invention. In addition, the polymer obtained by polymerizing this N-oxyl free radical compound having a vinyl ether functional group is a polymer having a structure having a free radical in the side chain, and is cured such as solvent resistance, scratch resistance and weather resistance. From the viewpoint of film physical properties and ink storage stability, it is preferably added to the ink of the present invention.

  The content of the radical polymerization inhibitor in the inkjet ink of the present invention is preferably 1.0 to 5,000 μg / g ink, and more preferably 10 to 2,000 μg / g ink. If it is 1.0 μg / g or more, curing shrinkage of the formed image can be effectively suppressed. Moreover, desired ink storage stability can be obtained, ink thickening can be suppressed, and liquid repellency with respect to the inkjet nozzle can be obtained, which is preferable from the viewpoint of ejection stability. Moreover, if it is 5,000 microgram / g or less, it is preferable when maintaining high hardening sensitivity, without impairing the acid radical generation | occurrence | production efficiency of a polymerization initiator when using a radical photopolymerization initiator together.

[Cation polymerization inhibitor]
It is preferable that a cationic polymerization inhibitor is blended with the radical polymerization inhibitor in the active energy ray-curable inkjet ink of the present invention.

  Examples of the cationic polymerization inhibitor include alkali metal compounds, alkaline earth metal compounds, and amines.

  Preferred amines as cationic polymerization inhibitors include alkanolamines, N, N-dimethylalkylamines, N, N-dimethylalkenylamines, N, N-dimethylalkynylamines and the like. Specifically, triethanolamine, triisopropanolamine, tributanolamine, N-ethyldiethanolamine, propanolamine, n-butylamine, sec-butylamine, 2-aminoethanol, 2-methylaminoethanol, 3-methylamino-1 -Propanol, 3-methylamino-1,2-propanediol, 2-ethylaminoethanol, 4-ethylamino-1-butanol, 4- (n-butylamino) -1-butanol, 2- (t-butylamino) ) Ethanol, N, N-dimethylundecanol, N, N-dimethyldodecanolamine, N, N-dimethyltridecanolamine, N, N-dimethyltetradecanolamine, N, N-dimethylpentadecanolamine N, N-dimethylnonadecylamine, N, N-dimethylicosylamine, N, N-dimethyleicosi Amine, N, N-dimethylhenicosylamine, N, N-dimethyldocosylamine, N, N-dimethyltricosylamine, N, N-dimethyltetracosylamine, N, N-dimethylpentacosylamine, N, N -Dimethylpentanolamine, N, N-dimethylhexanolamine, N, N-dimethylheptanolamine, N, N-dimethyloctanolamine, N, N-dimethylnonanolamine, N, N-dimethyldecanolamine, N , N-dimethylnonylamine, N, N-dimethyldecylamine, N, N-dimethylundecylamine, N, N-dimethyldodecylamine, N, N-dimethyltridecylamine, N, N-dimethyltetradecylamine, N, N-dimethylpentadecylamine, N, N-dimethylhexadecylamine, N, N-dimethylheptadecylamine, N, N-dimethyloctade Silamine is mentioned. In addition to these, quaternary ammonium salts and the like can also be used. Among them, 2-methylaminoethanol is preferable because it can improve storage stability without reducing curability when added in a small amount.

  The content of the cationic polymerization inhibitor in the inkjet ink of the present invention is preferably 10 mass ppm to 5,000 mass ppm. By setting it as 10 mass ppm or more, the cure shrinkage of a formed image can be suppressed effectively. Further, it is preferable in that good ink storage stability is obtained, suppression of ink viscosity increase, good liquid repellency with respect to the ink jet nozzle, and discharge stability can be maintained. Moreover, by setting it as 5,000 mass ppm or less, it becomes possible to fully maintain the acid radical generation | occurrence | production efficiency of a radical photopolymerization initiator in the case of using a radical photopolymerization initiator together, and it is preferable when maintaining curing sensitivity. .

[Colorant]
When coloring the inkjet ink of this invention, it is preferable to use a pigment as a coloring agent. As the pigment, colorless inorganic pigments such as carbon black, titanium oxide, calcium carbonate, or colored organic pigments can be used. Examples of organic pigments include insoluble azo pigments such as toluidine red, toluidine maroon, Hansa yellow, benzidine yellow and pyrazolone red, soluble azo pigments such as ritole red, heliobordeaux, pigment scarlet, and permanent red 2B; alizarin, indanthrone, thio Derivatives from vat dyes such as indigo maroon; phthalocyanine organic pigments such as phthalocyanine blue and phthalocyanine green; quinacridone organic pigments such as quinacridone red and quinacridone magenta; perylene organic pigments such as perylene red and perylene scarlet; isoindolinone Isoindolinone organic pigments such as yellow and isoindolinone orange; Pyranthrone organic pigments such as pyranthrone red and pyranthrone orange; Thioindigo Machine pigments, condensed azo organic pigments, benzimidazolone organic pigments, quinophthalone organic pigments such as quinophthalone yellow; isoindoline organic pigments such as isoindoline yellow; other pigments such as flavanthron yellow, acylamide yellow, nickel Azo yellow, copper azomethine yellow, perinone orange, anthrone orange, dianthraquinonyl red, dioxazine violet and the like can be mentioned.

  Organic pigments are exemplified below by color index (CI) numbers.

C. I. Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 109, 110, 117, 120, 125, 128, 129, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185,
C. I. Pigment Orange 16, 36, 43, 51, 55, 59, 61,
C. I. Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 177, 180, 192, 202, 206, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240,
C. I. Pigment violet 19, 23, 29, 30, 37, 40, 50,
C. I. Pigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 60, 64,
C. I. Pigment Green 7, 36,
C. I. Pigment brown 23, 25, 26,

  Among the above pigments, quinacridone-based, phthalocyanine-based, benzimidazolone-based, isoindolinone-based, condensed azo-based, quinophthalone-based, and isoindoline-based organic pigments are preferable because of their excellent light resistance.

  The organic pigment preferably has an average particle size in the ink of 10 to 150 nm as measured by laser scattering. When the average particle size of the pigment is less than 10 nm, a decrease in light resistance may occur due to a decrease in the particle size. When the thickness exceeds 150 nm, it is difficult to maintain stable dispersion, and pigment precipitation is likely to occur, and discharge stability is lowered, which may cause a problem that minute mist called satellite is generated. However, in the case of titanium oxide, the average particle diameter is 150 to 300 nm, preferably 180 to 250 nm, in order to provide whiteness and concealment.

  In addition, it is preferable that coarse particles are removed by sufficient dispersion or filtration so that the maximum particle size of the pigment in the ink does not exceed 1.0 μm. When coarse particles are present, the ejection stability tends to be lowered.

  The organic pigment can be refined by the following method. That is, a mixture composed of at least three components of an organic pigment, a water-soluble inorganic salt of 3 mass times or more of the organic pigment, and a water-soluble solvent is made into a clay, and is kneaded strongly with a kneader or the like to be refined, and then poured into water. Stir with a high speed mixer or the like to form a slurry. Next, filtration and washing of the slurry are repeated, and the water-soluble inorganic salt and the water-soluble solvent are removed by aqueous treatment. In the miniaturization step, a resin, a pigment dispersant and the like may be added.

  Examples of the water-soluble inorganic salt include sodium chloride and potassium chloride. These inorganic salts are used in the range of 3 to 20 times the mass of the organic pigment, but after the dispersion treatment, chlorine ions (halogen ions) are washed with water in order to achieve the halogen ion content defined in the present invention. Perform the operation to remove. If the amount of the inorganic salt is less than 3 times by mass, a treated pigment having a desired size cannot be obtained, and if it is more than 20 times by mass, the washing process in the subsequent step is enormous, Processing amount is reduced.

  The water-soluble solvent is not particularly limited as long as it is a solvent that can be used for making an appropriate clay state of an organic pigment and a water-soluble inorganic salt used as a crushing aid and performing sufficient crushing efficiently, and is soluble in water. However, since the temperature rises during kneading and the solvent easily evaporates, a high boiling point solvent having a boiling point of 120 to 250 ° C. is preferable from the viewpoint of safety. As water-soluble solvents, 2- (methoxymethoxy) ethanol, 2-butoxyethanol, 2- (i-pentyloxy) ethanol, 2- (hexyloxy) ethanol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether , Triethylene glycol, triethylene glycol monomethyl ether, liquid polyethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, low molecular weight Examples thereof include polypropylene glycol.

  In addition, in order to ensure the dispersion stability, the surface treatment of the pigment by a known technique such as an acid treatment or a basic treatment, a synergist, or various coupling agents in order to promote the adsorption with the pigment dispersant on the surface thereof. Is preferred.

  In order to obtain a sufficient concentration and sufficient light resistance, the pigment is in the range of 1.5 to 8% by mass in the case of a color excluding white in the inkjet ink, and in the range of 10 to 30% by mass in the case of a white ink using titanium oxide. It is preferable that it is contained.

[Pigment dispersant]
Examples of the pigment dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a salt of a long chain polyaminoamide and a polar acid ester, a high molecular weight unsaturated acid ester, Polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonyl Examples thereof include phenyl ether, stearylamine acetate, and pigment derivatives.

  Specific examples include “Anti-Terra-U (polyaminoamide phosphate)”, “Anti-Terra-203 / 204 (high molecular weight polycarboxylate)” manufactured by BYK Chemie, “Disperbyk-101 (polyaminoamide phosphate) Salt (acid ester), 107 (hydroxyl group-containing carboxylic acid ester), 110 (copolymer containing acid group), 130 (polyamide), 161, 162, 163, 164, 165, 166, 170 (polymer copolymer) ) "," 400 "," Bykumen "(high molecular weight unsaturated acid ester)," BYK-P104, P105 (high molecular weight unsaturated acid polycarboxylic acid) "," P104S, 240S (high molecular weight unsaturated acid polycarboxylic acid) And silicone) ”,“ Lactimon (long chain amine and unsaturated acid polycarboxylic acid) Recone) "and the like.

  Further, “Efka CHEMICALS” “Efka 44, 46, 47, 48, 49, 54, 63, 64, 65, 66, 71, 701, 764, 766”, “Efka Polymer 100 (modified polyacrylate), 150 (fat) Group modified polymer), 400, 401, 402, 403, 450, 451, 452, 453 (modified polyacrylate), 745 (copper phthalocyanine)); “Floren TG-710 (urethane oligomer)” manufactured by Kyoei Chemical Co., Ltd. "Flonon SH-290, SP-1000", "Polyflow No. 50E, No. 300 (acrylic copolymer)"; "Disparon KS-860, 873SN, 874 (polymer dispersing agent) manufactured by Enomoto Kasei Co., Ltd. , # 2150 (aliphatic polyvalent carboxylic acid), # 7004 (polyether ester type) ”, etc. It is below.

  Furthermore, “Demol RN, N (Naphthalenesulfonic acid formalin condensate sodium salt), MS, C, SN-B (aromatic sulfonic acid formalin condensate sodium salt), EP”, “Homogenol L-18” manufactured by Kao Corporation. (Polycarboxylic acid type polymer) "," Emulgen 920, 930, 931, 935, 950, 985 (polyoxyethylene nonyl phenyl ether) "," Acetamine 24 (coconut amine acetate), 86 (stearyl amine acetate) "; “Solspers 5000 (phthalocyanine ammonium salt type), 13240, 13940 (polyesteramine type), 17000 (fatty acid amine type), 24000, 32000, 7000” manufactured by Zeneca Corporation; “Nikkor T106 (polyoxyethylene sorbitan) manufactured by Nikko Chemical Co., Ltd.” mono Rate), MYS-IEX (polyoxyethylene monostearate), Hexagline4-0 (hexaglyceryl ruthenate Huwei Rate) ", manufactured by Ajinomoto Fine-Techno Co., of AJISPER 821,822,824, and the like.

  These pigment dispersants are contained in an amount of 5 to 70% by mass, preferably 10 to 50% by mass, based on the pigment 100. If it is less than 5%, it may be difficult to obtain dispersion stability, and if it is more than 70%, ejection stability may be deteriorated.

  Furthermore, it is preferable that these pigment dispersants have a solubility of 5% by mass or more with respect to the whole cationic polymerizable monomer at 0 ° C. When the solubility is less than 5% by mass, when the ink is stored at a low temperature between about 0 ° C. and 10 ° C., undesired polymer gel or pigment soft agglomerates may occur, and the ink storage stability And discharge stability may deteriorate.

[Other additives]
In the active energy ray-curable ink-jet ink composition or ink-jet ink of the present invention, in addition to the above description, emission stability, print head and ink packaging container compatibility, storage stability, image storage stability, etc. Various known additives such as surfactants, lubricants, fillers, antifoaming agents, gelling agents, thickeners, specific resistance adjusting agents, film forming agents, ultraviolet absorbers depending on the purpose of improving the performance of An agent, an antioxidant, a discoloration inhibitor, an antibacterial agent, a rust inhibitor, and the like can be appropriately selected and used.

  Further, if necessary, a small amount of solvent such as ester solvent, ether solvent, ether ester solvent, ketone solvent, aromatic hydrocarbon solvent, nitrogen-containing organic solvent may be added.

  Specific examples of various additives include dimethyl sulfoxide, diethyl sulfoxide, methyl ethyl sulfoxide, diphenyl sulfoxide, tetraethylene sulfoxide, dimethyl sulfone, methyl ethyl sulfone, methyl-isopropyl sulfone, methyl-hydroxyethyl sulfone, sulfolane, or N- Methyl-2-pyrrolidone, 2-pyrrolidone, β-lactam, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, 3-methyl -2-Oxazolidinone, γ-butyrolactone, γ-valerolactone, isophorone, cyclohexanone, propylene carbonate, anisole, methyl ethyl ketone, acetone, ethyl lactate, butyl lactate, dioxane, ethyl acetate, butyl acetate, diethylene glycol And coal dimethyl ether, dibasic acid ester, methoxybutyl acetate, and the like. When these are added to the ink in an amount of 1.5 to 30% by mass, preferably 1.5 to 15% by mass, adhesion to a resin recording medium such as polyvinyl chloride is improved.

  Other specific examples of various additives include alkylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol dibutyl ether, tetraethylene glycol Alkylene glycol dialkyl ethers such as dimethyl ether, alkylene glycol monoalkyl ether acetates such as ethylene glycol monobutyl ether acetate, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, ethylene glycol diacetate, propylene glycol diacetate, etc. Cited .

  Examples of the surfactant that can be used in the active energy ray-curable inkjet ink composition or inkjet ink of the present invention include anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, Nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, and cationic such as alkylamine salts and quaternary ammonium salts Surfactants, silicone-based and fluorine-based surfactants are exemplified, and silicone-based or fluorine-based surfactants are particularly preferable.

  By adding a silicone-based or fluorine-based surfactant, it is possible to further suppress ink mixing on recording media made of various hydrophobic resins such as vinyl chloride sheets and recording media that absorb slowly such as printing paper. And high-quality printed images can be obtained. The surfactant is particularly preferably used in combination with the low surface tension water-soluble organic solvent.

  The silicone surfactant is preferably a polyether-modified polysiloxane compound. For example, KF-351A, KF-642, X-22-4272 manufactured by Shin-Etsu Chemical Co., Ltd., BYK307, BYK345, BYK347 manufactured by Big Chemie, BYK348, TSF4452 manufactured by Toshiba Silicone Co., etc. can be mentioned.

  The fluorosurfactant means a compound in which a part or all of the fluorosurfactant is substituted with fluorine in place of hydrogen bonded to carbon of the hydrophobic group of a normal surfactant. Of these, those having a perfluoroalkyl group in the molecule are preferred.

  Among the fluorosurfactants, some are from DIC under the trade name Megafac F and from Asahi Glass under the trade name Surflon, Minnesota Mining and Manufacturing Company Under the trade name Fluorad FC from the company, under the trade name Monflor from Imperial Chemical Industry, and under the trade name Zonyls from EI Dupont Nemeras & Company, Alternatively, they are commercially available from Rubevelke Hoechst under the trade name Licobet VPF and from Neos as the aftertaste.

  The addition amount of the surfactant is preferably 0.1% by mass or more and less than 2.0% by mass with respect to the total mass of the inkjet ink.

[Ink properties]
If the surface tension of the ink-jet ink is 15 mN / m or more, the periphery of the nozzle of the ink-jet head does not get wet and the discharge capacity does not decrease. This is preferable because it does not wet well with coated paper or resin recording media and does not cause whitening. The surface tension of the inkjet ink can be determined by the Wilhelmy method (plate method). Further, the surface tension of the ink-jet ink can be adjusted by selecting the aforementioned monomer, adjusting the blending ratio, and adding the aforementioned surfactant.

  The physical properties of the inkjet ink of the present invention preferably have the same physical properties as those of a normal active energy ray-curable inkjet ink. That is, the viscosity is 2 to 50 mPa · s at 25 ° C., and the ink temperature at the time of ejection is 20 ° C. or more and less than 100 ° C., preferably 25 ° C. or more and 60 ° C. or less. Is preferably 7 mPa · s to 15 mPa · s, more preferably 8 mPa · s to 13 mPa · s. The viscosity of the inkjet ink can be determined by a rotational viscometer. Moreover, the viscosity of the inkjet ink can be adjusted by the above-mentioned monomer selection and blending ratio adjustment.

  The inkjet ink of the present invention has a surface tension in the range of 22 to 35 mN / m at 25 ° C., and when a pigment is used as a colorant, the average particle size exceeds 1.0 μm in addition to the pigment particles. It is preferable that there is no gel substance, the conductivity is 10 μS / cm or less, and the ink is free from electrical corrosion inside the head. In the continuous type, it is necessary to adjust the electric conductivity with the electrolyte. In this case, it may be necessary to adjust the electric conductivity to 0.5 mS / cm or more. The electric conductivity of the ink-jet ink can be determined by immersing two electrodes separated by a certain distance in the ink, applying a certain voltage between both electrodes, and measuring the value of the current flowing between the electrodes. In addition, the conductivity of the ink-jet ink can be adjusted by the selection of the monomer, polymerization initiator, and sensitizer described above, the blending ratio, and the water content of the ink-jet ink.

  In addition, as a physical property of the ink-jet ink of the present invention, a more preferable form is a unit mass when the DSC (differential scanning calorimetry) measurement of the ink is performed in a range of 25 ° C. to −25 ° C. at a rate of 5 ° C. per minute. The exothermic amount per unit area does not show an exothermic peak of 10 mJ / mg or more. By selecting a material according to the configuration of the present invention, it is possible to suppress heat generation of a certain amount or more in DSC measurement. By adopting such a configuration, even when the ink is stored at a low temperature, the generation of gel and the generation of precipitates can be suppressed.

[Ink preparation method]
When the inkjet ink of the present invention uses a polymerizable monomer that is an active energy ray-curable compound, a photopolymerization initiator, a pigment dispersant that is a colorant, and a pigment as a colorant, a normal mill such as a sand mill is used together with the pigment. It is manufactured by well dispersing using a disperser. It is preferable to prepare a concentrated solution having a high pigment concentration in advance and dilute with a polymerizable monomer. Sufficient dispersion is possible even with dispersion by ordinary dispersers. Therefore, excessive dispersion energy is not applied and a large amount of dispersion time is not required, so it is difficult to cause deterioration during dispersion of ink components, and stability. Can be prepared. The prepared ink is preferably filtered through a filter having a pore diameter of 3 μm or less, and more preferably 1 μm or less.

  The inkjet recording method of the present invention uses the active energy ray-curable inkjet ink of the present invention. That is, in the inkjet recording method of the present invention, the active energy ray-curable inkjet ink of the present invention is ejected from a inkjet nozzle onto a recording medium, and then the active energy rays such as ultraviolet rays are irradiated onto the coating film on the recording medium. This is a recording method for curing the ink.

[recoding media]
As a recording medium used in the inkjet recording method of the present invention, a wide range of conventional synthetic resins used in various applications are all targeted, and specifically, for example, polyester, polyvinyl chloride, polyethylene, polyurethane, polypropylene , Acrylic resin, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, polybutadiene terephthalate and the like, and the thickness and shape of these synthetic resin substrates are not limited at all. In addition, metals, glass, printing paper, etc. can be used.

  Specific examples of polyvinyl chloride, which is one of the recording media used in the ink jet recording method of the present invention, include SOL-371G, SOL-373M, SOL-4701 (manufactured by Big Technos Co., Ltd.), glossy PVC (Co., Ltd.). Systemgraph Co., Ltd.), KSM-VS, KSM-VST, KSM-VT (above, manufactured by Kimoto Co., Ltd.), J-CAL-HGX, J-CAL-YHG, J-CAL-WWWG (above, Showa Co., Ltd.) (Made in Osaka), BUS MARK V400 F vinyl, litecal V-600F vinyl (above, made by Flexcon), FR2 (made by Hanwha) LLBAU13713 (above, made by Sakurai Co., Ltd.), P-370B, P-400M (above , Manufactured by Kambo Plus Co., Ltd.), S02P, S12P S13P, S14P, S22P, S24P, S34P, S27P (above, manufactured by Grafityp), P-223RW, P-224RW, P-249ZW, P-284ZC (above, manufactured by Lintec Corporation), LKG-19, LPA-70 , LPE-248, LPM-45, LTG-11, LTG-21 (above, manufactured by Shinsei Co., Ltd.), MPI 3023 (manufactured by Toyo Corporation), Napoleon Gloss gloss PVC (manufactured by Futaki Electronics Co., Ltd.), JV-610, Y-114 (above, manufactured by ICC Corporation), NIJ-CAPVC, NIJ-SPVCGT (above, manufactured by Nichie Corporation), 3101 / H12 / P4, 3104 / H12 / P4, 3104 / H12 / P4S 9800 / H12 / P4, 3100 / H12 / R2, 3 101 / H12 / R2, 3104 / H12 / R2, 1445 / H14 / P3, 1438 / One Way Vision (manufactured by Inetrcoat), JT5129PM, JT5728P, JT5822P, JT5829P, JT5829R, JT5829PM, JT5829PM, JM59t MPI1005, MPI1900, MPI2000, MPI2001, MPI2002, MPI3000, MPI3021, MPI3500, MPI3501 (above, manufactured by Avery), AM-101G, AM-501G (above, manufactured by Ginichi Co., Ltd.), FR2 (Hanfa Japan Co., Ltd.), AY-15P, AY-60P, AY-80P, DBSP137GGH, DBSP137GGL (above, Inc.) Insight Co., Ltd.), SJT-V200F, SJT-V400F-1 (above, manufactured by Hiraoka Orizome Co., Ltd.), SPS-98, SPSM-98, SPSH-98, SVGL-137, SVGS-137, MD3-200, MD3-301M, MD5-100, MD5-101M, MD5-105 (manufactured by Metamark), 640M, 641G, 641M, 3105M, 3105SG, 3162G, 3164G, 3164M, 3164XG, 3164XM, 3165G, 3165SG, 3165M, 3169M , 3451SG, 3551G, 3551M, 3631, 3641M, 3651G, 3651M, 3651SG, 3951G, 3641M (above, manufactured by Orafol), SVTL-HQ130 (manufactured by Lamy Corporation), SP 00 GWF, SPCLEARAD vinyl (above, manufactured by Catalina), RM-SJR (produced by Ryoyo Corporation), Hi Lucky, New Lucky PVC (above, made by LG), SIY-110, SIY-310, SIY-320 ( As described above, Sekisui Chemical Co., Ltd., PRINT MI Frontlit, PRINT XL Light weight banner (hereinafter, manufactured by Endutex), RIJET 100, RIJET 145, RIJET 165 (above, manufactured by Ritrama), NM-SG, NM-SM NEIEI KAKO Co., Ltd.), LTO3GS (Lukio Co., Ltd.), Easy Print 80, Performance Print 80 (above, Jetgraph Co., Ltd.), DSE 550, DSB 550, DSE 800 G, DSE 802/137, V250WG, V300WG, V350WG (above, manufactured by Hexis), Digital White 6005PE, 6010PE (above, made by Multifix), and the like.

  Moreover, as a recording medium having a resin base material containing no plasticizer or a non-absorbing inorganic base material as a constituent element, the following various base materials are used as constituent elements, and one kind of base material is used alone, or a plurality of kinds are used. These substrates can be used in combination. Examples of the resin base material containing no plasticizer used in the present invention include ABS resin, polycarbonate (PC) resin, polyacetal (POM) resin, polyamide (PA) resin, polyethylene terephthalate (PET) resin, and polyimide (PI). Examples thereof include a resin, an acrylic resin, a polyethylene (PE) resin, a polypropylene (PP) resin, and a hard polyvinyl chloride (PVC) resin that does not contain a plasticizer.

  These resins are characterized by not containing a plasticizer, but there are no particular restrictions on other properties such as thickness, shape, color, softening temperature, and hardness.

  The recording medium used in the present invention is preferably ABS resin, PET resin, PC resin, POM resin, PA resin, PI resin, hard PVC resin containing no plasticizer, acrylic resin, PE resin, or PP resin. More preferred are ABS resin, PET resin, PC resin, PA resin, hard PVC resin not containing plasticizer, and acrylic resin.

  Moreover, as a non-absorbing inorganic base material used for this invention, a metal plate, such as a glass plate, iron, and aluminum, a ceramic plate etc. are mentioned, for example. These inorganic substrates are characterized by not having an ink-absorbing layer on the surface. These non-absorbing inorganic base materials are not particularly limited with respect to other properties such as thickness, shape, color, softening temperature, and hardness.

  The inkjet ink of the present invention can exhibit the effects of the present invention particularly well in a recording medium having a surface energy of 25 mN / m or more and less than 50 mN / m. Examples of the surface energy of the recording medium include, for example, IJ180CV2 (manufactured by 3M, polyvinyl chloride, surface energy = 38.0 mN / m), MD5 (manufactured by Metamark, polyvinyl chloride, surface energy = 36.6 mN / m). ), ORAJET (manufactured by ORACAL, polyvinyl chloride, surface energy = 33.1 mN / m), OPAQUE MATT FILM (manufactured by Oce, polyethylene terephthalate, surface energy = 35.4 mN / m), Tokuhishi Art (Mitsubishi Paper) Manufactured, art paper, surface energy = 37.6 mN / m), HANITA (manufactured by Hanita Coating, polyethylene terephthalate, surface energy = 35.4 mN / m), Lumirror 38-T60 (manufactured by Toray Industries, untreated polyethylene terephthalate, surface Energy = 36.9m N / m), Sun Lloyd Uni G400 (manufactured by Sumitomo Bakelite Co., Ltd., polyvinyl chloride, surface energy = 34.5 mN / m), Sumipex 068 (manufactured by Sumitomo Chemical Co., Ltd., acrylic cast, surface energy = 39.5 mN / m), Sun Lloyd Pet Ace EPG400 (Sumitomo Bakelite, non-crystalline polyethylene terephthalate, surface energy = 35.7 mN / m), Lintec gloss (cast coated paper, surface energy 27 mN / m), Maru Adhesive White PET # 50 solvent strength Examples thereof include viscous PGS (polyethylene terephthalate, surface energy 50 mN / m).

  The surface energy of the recording medium according to the present invention can be calculated by measuring the contact angle using two or more kinds of liquids having known surface tensions.

[Injet recording method]
The ink-jet head used in the in-jet recording method of the present invention for ejecting the ink-jet ink of the present invention to form an image may be an on-demand system or a continuous system. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, thermal ink jet) Any ejection method such as a mold, a bubble jet (registered trademark) mold, or the like may be used.

[Activation energy ray irradiation conditions after ink landing]
In the ink jet recording method of the present invention, the active energy ray is preferably irradiated for 0.001 second to 1.0 second after ink landing, more preferably 0.001 second. ~ 0.5 seconds.
In order to form a high-definition image, it is preferable that the irradiation timing is as early as possible.

  The irradiation method of an active energy ray is not specifically limited, For example, it can carry out with the following method.

  A light source is provided on both sides of the head unit described in JP-A-60-132767, the head and the light source are scanned by a shuttle method, and irradiation is performed after a certain period of time after ink landing, and further accompanied by driving. A method for completing the curing by using another light source, a method using an optical fiber described in US Pat. No. 6,145,979, or a collimated light source is applied to a mirror surface provided on the side surface of the head unit, to the recording unit A method of irradiating ultraviolet rays can be given.

  Any of these irradiation methods can be used in the inkjet recording method of the present invention.

  Also, the irradiation of active energy rays is divided into two stages. First, the active energy rays are irradiated by the above-described method within 0.001 to 2.0 seconds after ink landing, and after the completion of all printing, the active energy rays are further irradiated. The method of irradiating is also a preferred embodiment.

  By dividing the irradiation of active energy rays into two stages, it is more effective in suppressing the shrinkage of the recording material that occurs during ink curing.

[Total ink film thickness after ink landing]
In the ink jet recording method of the present invention, the total ink film thickness after ink has landed on the recording medium and cured by irradiation with active energy rays is 2 to 20 μm. It is preferable from the viewpoint of suppressing inconveniences to the appearance and texture such as a change in texture of the material.

  Here, “total ink film thickness” means the maximum value of the film thickness of the ink drawn on the recording medium, and even for a single color, other two color layers (secondary colors), three color layers, Even when recording is performed using a four-color overlapping (white ink base) inkjet recording method, the meaning of the total ink film thickness is the same.

[Ink heating and ejection conditions]
In the inkjet recording method of the present invention, it is preferable from the viewpoint of ejection stability that the active energy ray-curable inkjet ink is heated and irradiated with the active energy ray.

  The temperature for heating is preferably 35 to 100 ° C., and more preferably in view of discharge stability and irradiation with active energy rays while being kept at 35 to 80 ° C.

  There is no particular limitation on the method of heating and keeping the ink-jet ink at a predetermined temperature.For example, an ink supply system such as an ink tank constituting a head carriage, a supply pipe, a front chamber ink tank immediately before the head, a pipe with a filter, There is a method in which a piezo head or the like is insulated and heated to a predetermined temperature by a panel heater, a ribbon heater, warm water or the like.

  The control range of the ink temperature is preferably set temperature ± 5 ° C., more preferably set temperature ± 2 ° C., and particularly preferably set temperature ± 1 ° C. from the viewpoint of ejection stability.

  The amount of liquid droplets ejected from each nozzle is preferably 2 to 20 pL in terms of recording speed and image quality.

  Next, an ink jet recording apparatus (hereinafter simply referred to as a recording apparatus) that can be used in the ink jet recording method of the present invention will be described.

  Hereinafter, the recording apparatus will be described with reference to the drawings as appropriate.

FIG. 1 is a front view showing a configuration of a main part of the recording apparatus.
The recording apparatus 1 includes a head carriage 2, a recording head 3, an irradiation unit 4, a platen unit 5, and the like.

  The platen unit 5 is installed under the recording medium P. The platen portion (recording medium support member) 5 has a function of absorbing ultraviolet rays and absorbs excess ultraviolet rays that have passed through the recording medium P. As a result, a high-definition image can be reproduced very stably.

  The recording medium P is guided by the guide member 6 and moves from the near side to the far side in FIG. 1 by the operation of the conveying means (not shown). A head scanning unit (not shown) scans the recording head 3 held by the head carriage 2 by reciprocating the head carriage 2 in the Y direction in FIG.

  The head carriage 2 is installed on the upper side of the recording medium P, and accommodates a plurality of recording heads 3 to be described later according to the number of colors used for image printing on the recording medium P, with the discharge ports arranged on the lower side.

  The head carriage 2 is installed with respect to the main body of the recording apparatus 1 in such a manner that it can reciprocate in the Y direction in FIG. 1, and reciprocates in the Y direction in FIG. 1 by driving the head scanning means.

  In FIG. 1, the head carriage 2 is white (W), yellow (Y), magenta (M), cyan (C), black (K), light yellow (Ly), light magenta (Lm), and light cyan (Lc). In the drawing, the recording head 3 for light black (Lk) and white (W) is drawn. However, in practice, the number of colors of the recording head 3 stored in the head carriage 2 is appropriately determined. Is.

  The recording head 3 is operated by a discharge means (not shown) provided with a plurality of active energy ray curable inkjet inks (for example, UV curable ink) supplied by an ink supply means (not shown). The ink is discharged from the discharge port toward the recording medium P.

  The recording head 3 is a certain area (landing possible area) in the recording medium P during the scanning in which the recording head 3 moves from one end of the recording medium P to the other end of the recording medium P in the Y direction in FIG. On the other hand, UV ink is ejected as ink droplets, and ink droplets are landed on the landable area.

  The above-described scanning is performed as many times as necessary, and the active energy ray-curable inkjet ink is ejected toward one landable area. Then, the recording medium P is appropriately moved from the front to the back in FIG. While performing scanning by the head scanning means, the recording head 3 discharges UV ink to the next landable area adjacent to the rearward direction in FIG.

  By repeating the above-described operation and ejecting the recording head 3 or the active energy ray-curable ink jet ink in conjunction with the head scanning means and the conveying means, an aggregate of active energy ray-curable ink jet ink droplets on the recording medium P Is formed.

  The irradiation unit 4 includes a light source 8, for example, an ultraviolet lamp that emits ultraviolet rays in a specific wavelength region with stable exposure energy, and a filter that transmits ultraviolet rays of a specific wavelength.

  Here, as the ultraviolet lamp, a mercury lamp, a metal halide lamp, an excimer laser, an ultraviolet laser, a cold cathode tube, a hot cathode tube, a black light, an LED (light emitting diode) and the like can be applied. Cathode tubes, hot cathode tubes, mercury lamps or black lights are preferred, and LEDs are particularly preferred because of their long life and low cost.

  By using the LED as a radiation source of the irradiation means 4, the irradiation means 4 for curing the UV ink can be produced at low cost.

  However, in general, an LED is a single wavelength light source, and its illuminance tends to be lower than a light source having a plurality of emission line spectra such as a high-pressure mercury lamp. In the case of curing by radical polymerization as in the present invention, if the illuminance is low, the proportion of radicals combined with oxygen and deactivated increases, so that even if the time is extended and the integrated light quantity is the same, curing becomes difficult. Therefore, the ink is required to be curable with low illuminance and low integrated light quantity.

In order to use an inexpensive LED light source, the illuminance is preferably 8 W / cm ² or less, and more preferably 2 W / cm ² or less.

  The irradiating means 4 has substantially the same shape as the maximum one that can be set by the recording apparatus (UV inkjet printer) 1 among the landable areas in which the recording head 3 ejects UV ink by one scan driven by the head scanning means. , Having a shape larger than the landable area.

  The irradiation means 4 is fixed on both sides of the head carriage 2 so as to be substantially parallel to the recording medium P.

  As described above, as a means for adjusting the illuminance of the ink discharge portion, not only the entire recording head 3 is shielded, but in addition, the ink discharge of the recording head 3 is determined from the distance h1 between the irradiation means 4 and the recording medium P. It is effective to increase the distance h2 between the portion 31 and the recording medium P (h1 <h2), or to increase the distance between the recording head 3 and the irradiation means 4 (to increase the distance).

  Further, as shown in FIG. 1, it is preferable to form a bellows structure 7 between the recording head 3 and the irradiation means 4.

  Here, the wavelength of the ultraviolet rays irradiated by the irradiation means 4 can be changed as appropriate by replacing the ultraviolet lamp or filter provided in the irradiation means 4.

  FIG. 2 is a top view illustrating another example of the configuration of the main part of the ink jet recording apparatus.

  The ink jet recording apparatus shown in FIG. 2 is called a line head system, and a plurality of ink jet recording heads 3 of each color are fixedly arranged on the head carriage 2 so as to cover the entire width of the recording medium P. ing.

  On the other hand, on the downstream side of the head carriage 2 in the recording medium conveyance direction, that is, on the rear portion of the head carriage 2 with respect to the recording medium P to be conveyed, the entire width of the recording medium P is also covered so as to cover the entire area of the ink printing surface. Irradiation means 4 arranged so as to cover is provided.

  As the ultraviolet lamp used for the irradiation means 4, the same one as described in FIG. 1 can be used.

  In this line head system, the head carriage 2 and the irradiation means 4 are fixed, and only the recording medium P is transported, and ink ejection and curing are performed to form an image.

  Hereinafter, the present invention will be described specifically by way of examples. In addition, unless otherwise indicated in an Example, the quantity and ratio of a component in a composition mean mass and mass ratio.

[Preparation of Pigment Dispersion] Pigment dispersions 1 to 4 were prepared using the following pigment and pigment dispersant.
(Pigment)
CB: Carbon black MA-7 (Mitsubishi Chemical Corporation)
PY: C.I. I. Pigment Yellow 150 (LANXESS Corporation)
PR: C.I. I. Pigment Red 122 (Daiichi Seika Co., Ltd.)
PB: C.I. I. Pigment Blue 15: 4 (Daiichi Seika Co., Ltd.)

(Pigment dispersant)
PB824: Ajisper PB-824 (Ajinomoto Fine Techno Co., Ltd.)

[Preparation of Pigment Dispersion 1]
As a yellow pigment, C.I. I. Pigment Yellow 150 (8.0 g), Azisper PB824 (manufactured by Ajinomoto Finetech Co., Ltd.) as a pigment dispersant, 4.0 g, Triethylene glycol divinyl ether (38 g), 0.5 mm zirconia beads (200 g) ) And a paint shaker (TWIN-ARM ONE-GALLON SHAKER 5400 manufactured by RED DEVIL EQUIMENT CO.) For 6 hours to obtain pigment dispersion 1.

[Preparation of Pigment Dispersion 2]
As a magenta pigment, C.I. I. Pigment Red 122 (8.0 g), Azisper PB824 (manufactured by Ajinomoto Finetech Co., Ltd.) as a pigment dispersant, 4.0 g, Triethylene glycol divinyl ether (38 g), 0.5 mm zirconia beads (200 g) ) And a paint shaker (TWIN-ARM ONE-GALLON SHAKER 5400, manufactured by RED DEVIL EQUIMENT CO.) For 6 hours to obtain a pigment dispersion 2.

[Preparation of Pigment Dispersion 3]
As a cyan pigment, C.I. I. Pigment Blue 15: 4 8.0 g, Azisper PB824 (Ajinomoto Finetech Co., Ltd.) 4.0 g as a pigment dispersant, Triethylene glycol divinyl ether 38 g, 0.5 mm zirconia beads 200 g (200 The pigment dispersion 3 was obtained by putting it in a 100 mL polypropylene closed container together with (mass parts) and using a paint shaker (TWIN-ARM ONE-GALLON SHAKER 5400, manufactured by RED DEVICE EQUIMENT CO.) For 6 hours.

[Preparation of Pigment Dispersion 4]
As a cyan pigment, C.I. I. Pigment Blue 15: 4 (8.0 g), Azisper PB824 (manufactured by Ajinomoto Finetech Co., Ltd.) as a pigment dispersant, 4.0 g, Exemplified Compound (1) -4 (38 g), 0.5 mm zirconia beads (200 g) (200 parts by mass) and put into a 100 mL polypropylene sealed container, and dispersion is performed for 6 hours using a paint shaker (TWIN-ARM ONE-GALLON SHAKER 5400, manufactured by RED DEVIL EQUIMENT CO.) To obtain pigment dispersion 4 It was.

[Preparation of Pigment Dispersion 5]
As a black pigment, 8.0 g of carbon black MA-7, 4.0 g of Ajisper PB824 (manufactured by Ajinomoto Finetech Co., Ltd.), 38 g of triethylene glycol divinyl ether, 0.5 mm zirconia Along with 200 g (200 parts by mass) of beads, the mixture is placed in a 100 mL polypropylene sealed container, and dispersed for 6 hours using a paint shaker (TWIN-ARM ONE-GALLON SHAKER 5400 manufactured by RED DEVIL EQUIMENT CO.). Got.

[Preparation of acceptor monomer (compounds 1 to 4)]
Compounds 1, 2 and 4 were synthesized using the method described in JP-A-11-124403 or Macromolecular Chemical and physics, 2009, 210, 269-278.

[Synthesis of Compound 3]
Into a 1 liter three-necked flask, 206 g (1.2 mol) of diethyl maleate and 42.2 g (0.4 mol) of diethylene glycol were added and stirred, while 4.7 g (27 mmol) of paratoluenesulfonic acid monohydrate, 0. Add 2 g of hydroquinone. After stirring at 160 ° C. for 18 hours, the remaining diethyl maleate was removed by distillation under reduced pressure, washed with sodium bicarbonate water and ion-exchanged water, and purified by column purification to obtain pale yellow oily compound 3.

[Preparation of donor monomer]
Polyfunctional vinyl ether compounds (1) -1 to (1) -20: each synthesized by the method described in JP-A-5-279284.
TEGDVE: Triethylene glycol divinyl ether (manufactured by Nippon Carbide Industries Co., Ltd.)

(Photopolymerization initiator)
TPO: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (manufactured by BASF)
ITX: Isopropylthioxanthone (manufactured by LAMBSON)
ESACURE ONE: Oligo [2-hydroxy-2-methyl-1- {4- (1-methylvinyl) phenyl} propanone] (manufactured by Lamberti)

(Radical polymerization inhibitor)
UV-10: Bis (2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl) sebacate IRGASTAB UV-10 (BASF Japan)
BHT: 2,6-t-butylhydroxytoluene (Kanto Chemical Co., Inc.)
Kinopower MNT: 4-Methoxy-1-naphthol (Kawasaki Chemical Industry Co., Ltd.)
Phenothiazine (Kanto Chemical Co., Ltd.)
Hydroquinone (Kanto Chemical Co., Ltd.)

(Cation polymerization inhibitor)
TIPA: Triisopropanolamine (Kanto Chemical Co., Inc.)
KOH: Potassium hydroxide (Flake) (Kanto Chemical Co., Inc.)
2MAE: 2-methylaminoethanol (Kanto Chemical Co., Inc.)

[Example 1]
[Preparation of ink]
In order to obtain the composition shown in Table 1, the pigment ink dispersion, the acceptor monomer, the donor monomer, other monomers, the photopolymerization initiator, the radical polymerization inhibitor, and the cationic polymerization inhibitor were stirred and mixed, and the inkjet inks 1 to 45 were mixed. Prepared.

  The ink 37 was prepared using the pigment dispersion 1, the ink 38 was prepared using the pigment dispersion 2, and the ink 39 was prepared using the pigment dispersion 5. Ink 1 to 30, Ink 33 to 36 and Ink 41 to 45 were prepared using Pigment Dispersion 3, and Ink 31 and 32 were prepared using Pigment Dispersion 4.

  Inks 1 to 20 shown in Table 1 and Table 2 are different in the type of donor monomer. Each of the inks 21 to 24 has a different type of radical polymerization inhibitor. The inks 25 to 26 have different types of cationic polymerization initiators, and the ink 27 does not contain a cationic polymerization initiator. Inks 28 to 32 have different ratios of compound (1) -4, which is a donor monomer, and TEGDVE, respectively. Each of the inks 33, 34, and 36 has a different acceptor monomer type. The ink 34 and the ink 35 are different in the type of photopolymerization initiator. The inks 37 to 39 have different types of pigment, and the ink 40 does not contain a pigment.

The inks 41 and 42 do not contain the donor monomer represented by the general formula (1) (comparative example). The ink 43 does not contain a polymerization inhibitor (comparative example). The ink 44 does not contain an acceptor monomer (comparative example). Ink 45 contains no donor monomer (comparative example).

〔Evaluation method〕
(Production of inkjet image)
Using piezo head KM512MH manufactured by Konica Minolta IJ, each ink was 720 dpi × 720 dpi with a droplet amount of 14 pL per dot (dpi in the present invention represents the number of dots per 2.54 cm). A solid image is printed on a polyvinyl chloride sheet (made by IJ180 3M) in four passes, and irradiation is performed once (100 mJ / cm ² ) for each pass by a 395 nm LED with an output of 2 W / cm ^2. A total of four irradiations were performed to irradiate a total amount of light of 400 mJ / cm ² to cure the image film and form an inkjet image.

(Abrasion resistance)
The image prepared as described above was subjected to a 50 reciprocal wiping test with a load of 500 g using a canakin cloth, and evaluated according to the following criteria.
A: No change in image gloss and density. No transfer marks on the kanakin cloth.
○: There is no change in the gloss and density of the image, but there is a transfer mark on the kanakin cloth.
Δ: Slight decrease in image gloss and density is observed, but within practically acceptable range.
X: Gloss and density reduction of the image are conspicuous and are unacceptable for practical use.

(Solvent resistance)
The images prepared as described above were impregnated with a polyolefin wipe member (Technoporous IWX STICK, manufactured by Fushimi Pharmaceutical Co., Ltd.), subjected to a 50 reciprocal wiping test, and evaluated according to the following criteria.
A: No change in image gloss and density. No transfer mark on wipe cloth.
○: There is no change in gloss and density of the image, but there is a transfer mark on the wipe cloth.
Δ: Slight decrease in image gloss and density is observed, but within practically acceptable range.
X: Gloss and density reduction of the image are conspicuous and are unacceptable for practical use.

(Curing shrinkage 1)
In the production of the inkjet image, the polyvinyl chloride sheet (IJ180 3M) was changed to untreated PET (Toray Lumirror film thickness 38 microns), and the inkjet was applied to the front surface of the substrate 75 mm in the length direction and 15 cm in the width direction. The image forming process was repeated twice to produce an image with twice the amount of ink applied to the inkjet image. After image formation, the degree of curling due to curing shrinkage on the next day after normal temperature aging was evaluated according to the following criteria. The distance between both ends in the length direction curled and warped (string length) was measured, and the ratio (%) to the base material width of 75 mm was determined and evaluated as follows.
A: Curling is 95% to 100% (100% indicates no curling)
○: Curling is 90% to less than 95%. Δ: Curling is 80% to less than 90%. Within practical tolerance.
X: Curling is less than 80%. Practically unacceptable level.

(Curing shrinkage 2)
Immediately after the image was created in the same manner as in the test for curing shrinkage 1, a total of 300 was performed while repeating UV light irradiation with a Xe lamp and humidification assuming rain in a low-temperature xenon weather meter XL75 manufactured by Suga Test Instruments Co., Ltd. The image was stored for a period of time, and the occurrence of curling due to curing shrinkage of the image after storage was evaluated according to the same criteria as curing shrinkage 1.

(Exit drive voltage suitability)
After each ink was prepared and stored at 50 ° C. for 3 days, it was continuously used with a piezoelectric head KM512MH manufactured by Konica Minolta IJ Co., Ltd. at a driving voltage such that the droplet velocity was 6 m / s at a driving frequency of 10 kHz. Emission was performed. The suitability was evaluated from the driving voltage at this time according to the following criteria. The ink was emitted at a temperature of 60 ° C.
A: The ink viscosity at the time of ejection is in the range of 8 to 13 mPa · s, and the drive voltage has a margin of 4 V or more with respect to the upper limit of the specification conforming range of the inkjet head.
○: The ink viscosity at the time of emission is in the range of 7 to 15 mPa · s, and the drive voltage has a margin of 2 V or more with respect to the upper limit of the specification conforming range of the inkjet head.
Δ: The ink viscosity at the time of emission is in the range of 7 to 20 mPa · s, and the drive voltage is less than 2 V with respect to the upper limit of the specification conforming range of the inkjet head, but is within the upper limit.
X: The ink viscosity at the time of emission is out of the range of 7 to 20 mPa · s, and the drive voltage exceeds the upper limit of the specification conforming range of the inkjet head.

(Continuous emission stability)
The emission is continuously continued for 1 hour by the same method as the evaluation of the emission drive voltage suitability, and the flying state of the droplets of 100 predetermined nozzles is observed and discharged with a CCD camera. The presence or absence of nozzles that were not present was examined and evaluated according to the following criteria.
◎: All nozzles are emitting normally. ○: Out of all nozzles, 2 or less nozzles are not discharging normally.
Δ: No more than 5 nozzles out of all nozzles.
×: Six or more nozzles not discharging normally among all nozzles

  Inks 1 to 20 each have a different type of donor monomer. Although all can suppress the curing shrinkage of the image; the inks 1 to 8, the inks 14 to 17, and the ink 19 can more effectively suppress the curing shrinkage than the inks 9 to 13, the ink 18, and the ink 20. ing. From this, it can be seen that a compound in which p in the general formula (1) is 0 is preferable from the viewpoint of suppressing curing shrinkage of an image.

  Each of the inks 21 to 24 has a different type of radical polymerization initiator. In both cases, good results have been obtained. Therefore, it can be seen that high curing sensitivity and suppression of curing shrinkage can be realized regardless of the type of these radical polymerization initiators.

  Since the ink 27 did not contain a cationic polymerization inhibitor, it slightly cured and contracted. The inks 28 to 32 have different ratios of the monofunctional donor monomer and the bifunctional donor monomer, but all have suppression of curing shrinkage and high curing sensitivity. However, the ink 28 having a low ratio of the monofunctional donor monomer was slightly cured and contracted.

  Inks 33 and 36 were formulated with compounds 2 and 4 as acceptor monomers, so the ink viscosity was slightly increased and the emission stability was slightly decreased. Inks 34 and 35 used compound 3 as an acceptor monomer, and therefore, scratch resistance and solvent resistance were slightly lowered. It seems that the curing sensitivity of the inks 34 and 35 is slightly lowered.

  Although the inks 37 to 39 are different in pigment, it can be seen that both can achieve high curing sensitivity and suppression of curing shrinkage. Since the ink 40 did not contain a pigment, it slightly cured and contracted.

  Inks 41 and 42 did not contain a monofunctional donor monomer, so the cure shrinkage was severe. Since the ink 43 did not contain a polymerization inhibitor, the curing shrinkage was still severe. Since the inks 44 and 45 did not contain either a donor monomer or an acceptor monomer, the curing sensitivity was lowered, and the scratch resistance and solvent resistance were lowered.

  The active energy ray-curable ink-jet ink of the present invention is effective for forming a fine image, and further, the cured shrinkage of the formed image is suppressed, so that it can be applied to image formation for various uses.

DESCRIPTION OF SYMBOLS 1 Recording device 2 Head carriage 3 Recording head 4 Irradiation means 5 Platen part 6 Guide member 7 Bellows structure 8 Light source 31 Ink discharge part h1 Distance between irradiation means and recording medium Distance P2 between ink discharge part and recording medium P Recording medium Y Head carriage movement direction

Claims (13)

Containing at least one polymerizable compound having an electron-deficient unsaturated double bond, at least one polymerizable compound having an electron-rich unsaturated double bond, a polymerization inhibitor, and a radical polymerization initiator In the active energy ray curable inkjet ink,
The polymerizable compound having an electron-deficient unsaturated double bond contains at least one polymerizable compound selected from maleimides, maleates and fumarates, and the electron-rich unsaturated double bond. The polymerizable compound having a bond is an active energy ray-curable inkjet ink containing at least one compound represented by the following general formula (1) .

(In general formula (1),
A is a linear or branched alkyl having 1 to 8 carbon atoms, or an aromatic ring group which may have a substituent having 6 to 12 carbon atoms,
R ₁ and R ₂ are each independently a linear or branched alkylene having 2 to 4 carbon atoms,
X is a linking group represented by the general formula (2),
Q is a group containing an electron-rich double bond represented by the general formula (3),
m and n are each independently a natural number of 1 to 18,
p is an integer of 0, 1, 2, or 3)

(In general formula (2),
X ₁ and X ₂ are each independently an ester bond represented by —OCO— or —COO—, or a urethane bond represented by —OCONH— or —NHCOO—,
Y is a linear or branched alkylene having 1 to 8 carbon atoms, or an aromatic ring group which may have a substituent having 6 to 12 carbon atoms)

(In general formula (3),
Z represents —O—, —NR ₆ —, —CONR ₆ — , —S—, —SO—, and R ₆ represents a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms,
R ₃ , R ₄ and R ₅ are a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched alkoxy group having 1 to 6 carbon atoms)   The active energy ray-curable inkjet ink according to claim 1, wherein the polymerization inhibitor contains a radical polymerization inhibitor.   The active energy ray-curable inkjet ink according to claim 1, wherein the polymerization inhibitor contains a radical polymerization inhibitor and a cationic polymerization inhibitor. The active energy ray-curable inkjet ink according to claim 2 or 3 , wherein the radical polymerization inhibitor is piperidine 1-oxyl free radical compound, phenolic hydroxyl group-containing compound, quinone, hydroquinone, or phenothiazine. The active energy ray-curable inkjet ink according to claim 3 , wherein the cationic polymerization inhibitor is an alkali metal compound, an alkaline earth metal compound, or an amine. The active energy ray-curable inkjet ink according to any one of claims 1 to 5 , wherein a viscosity of 20 to 100 ° C is 7 to 15 mPa · s. The active energy ray-curable inkjet ink according to any one of claims 1 to 6, wherein the molecular weight of the compound represented by the general formula (1) is 140 or more and 650 or less. The active energy ray-curable inkjet ink according to claim 1, wherein p in the general formula (1) is 0. The active energy ray-curable inkjet ink according to any one of claims 1 to 8, wherein Z in the general formula (3) is -O- and p is 0. The maleimides are represented by the following general formula (10), the active energy ray curable ink-jet ink according to any one of claims 1 to 9.

(In general formula (10),
R ₁ and R ₂ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ₁ and R ₂ may be bonded to each other to form a ring,
Y ₁ and Y ₃ are each independently a group selected from an alkylene group having 1 to 12 carbon atoms, an alkyleneoxy group having 1 to 12 carbon atoms, a phenylene group, an ester group, an ether group, and a thioether group. Represents a divalent organic linking group, and Y ₂ is a divalent group having an asymmetric carbon;
n represents an integer of 1 to 6,
n1 represents 0 or 1, n2 represents 0 or 1,
Z represents a 1-6 valent organic group in which a group selected from an alkylene group having 1 to 12 carbon atoms, an alkyleneoxy group having 1 to 12 carbon atoms, a phenylene group, an ester group, an ether group and a thioether group is combined. ) The active energy ray-curable inkjet ink according to claim 10, wherein the maleimide is represented by the following general formula (11).

(In general formula (11),
R ₁₁ and R ₁₂ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ₁₁ and R ₁₂ may be bonded to each other to form a ring;
A ₁₁ and A ₁₃ each independently represent an alkylene group having 1 to 12 carbon atoms,
A ₁₂ represents a divalent hydrocarbon group having 1 to 12 carbon atoms having an asymmetric center,
Y independently represents carbonyloxy (—C (═O) —O—) or oxycarbonyl (—O—C (═O) —);
p represents 1 or 2,
R ₁₃ represents an alkyl group or alkyleneoxy group having a molecular weight of 15 to 600 when p is 1, and represents an alkylene group or alkyleneoxy group having a molecular weight of 14 to 600 when p is 2.
m represents 0 or 1;
n represents 0 or 1) The active energy ray-curable inkjet ink according to claim 1, further comprising a pigment.   An inkjet recording method using the active energy ray-curable inkjet ink according to claim 1.

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