WO2012137474A1

WO2012137474A1 - Active energy-ray curable inkjet ink and inkjet recording method

Info

Publication number: WO2012137474A1
Application number: PCT/JP2012/002300
Authority: WO
Inventors: 宏毅川嶋; 中村　正樹
Original assignee: コニカミノルタホールディングス株式会社
Priority date: 2011-04-01
Filing date: 2012-04-02
Publication date: 2012-10-11
Also published as: JPWO2012137474A1; JP6015651B2

Abstract

The purpose of the present invention is to provide an inkjet ink which has excellent curing sensitivity, weather resistance in the form of a cured film, solvent resistance and viscosity stability when stored for a long period, and does not cause printed materials to curl due to the curing shrinkage of the ink, said inkjet ink using a CT polymerization system and having excellent flexibility when the ink is printed. This active energy-ray curable inkjet ink contains at least one type of acceptor monomer and at least one type of donor monomer. The acceptor monomers include a polyfunctional acceptor monomer, the donor monomers include a monofunctional donor monomer, and the ratio (X) (the ratio of the double bonded functional group mol number of the acceptor monomer and the mol number of the donor monomer, per mass unit) is 0.66-2.

Description

Active energy ray-curable inkjet ink and inkjet recording method

The present invention relates to an active energy ray curable inkjet ink and an inkjet recording method using the same, and more particularly to an active energy ray curable inkjet ink using a combination of a donor monomer and an acceptor monomer and an inkjet recording method using the same. .

In recent years, inkjet recording methods have been used in various printing fields such as photographs, various printing, marking, and special printing such as color filters from the viewpoint of being able to create images easily and inexpensively.

As an inkjet ink used in such an inkjet recording system, an aqueous inkjet ink containing water as a main solvent, a non-volatile solvent that does not volatilize at room temperature, an oil-based inkjet ink that does not substantially contain water, and volatilizes at room temperature. Non-water-based inkjet ink that contains mainly solvent and contains substantially no water, hot-melt ink that heats and melts solid ink at room temperature, and active energy ray-curable inkjet that cures with actinic rays such as ultraviolet rays after printing There are various types of ink-jet inks, such as inks, and they have been properly used depending on the application. Among them, the active energy ray-curable ink-jet ink does not use a solvent and has a fast curing property. Large printing load due to the feature of printing on various recording media And aqueous inkjet ink recording medium is limited, oily inkjet ink, has attracted attention as a next-generation inkjet ink to replace the non-aqueous inkjet ink, a large expected that expanding applications.

Conventionally, active energy ray-curable inkjet inks are mainly classified into radical polymerization type and cationic polymerization type inkjet inks. Radical polymerization type ink-jet inks are widely researched and developed and put to practical use because they have a wide range of material choices and a high degree of freedom in ink design. However, there is a problem that the handling is careful because it is easily affected by the inhibition of polymerization by oxygen and the odor of the polymerizable monomer (monomer). On the other hand, although the cationic polymerization type ink-jet ink is not affected by the inhibition of polymerization by oxygen, it has been a problem that the polymerization is inhibited by the influence of humidity, and there are few material variations and the price is high.

Electron-deficient monomers (donor monomers) such as vinyl ether and maleimides, etc., for the purpose of achieving both the safety of materials used such as polymerizable monomers (monomers), polymerization initiators, and sensitizers, and practical curing sensitivity. Charge-transfer complex polymerization compound (combined with a monomer (acceptor monomer) (abbreviated as CT polymerization compound, for example, Sonny Jonsson, et.al, Polymer Materials Sci. & Engineer. 1995, 72, 470-472)) Details. ) Is applied to an active energy ray-curable composition such as ultraviolet rays (see, for example, Patent Documents 1 and 2).

Patent Document 1 includes an example in which maleic anhydride as a monofunctional acceptor monomer and triethylene glycol divinyl ether as a bifunctional donor monomer are blended at a functional group equivalent ratio of 1: 1, or maleic anhydride and a monofunctional donor. An example in which p-methoxystyrene as a monomer is blended at a functional group equivalent ratio of 1: 1 is described.

Patent Document 2 describes an example in which a polyfunctional maleimide compound that is a polyfunctional acceptor monomer and a polyfunctional vinyl ether that is a polyfunctional donor monomer are blended at a functional group equivalent ratio of 1: 1. These show that the sensitivity of curing is good, the gel fraction, which is an index of the crosslinking density of the cured product, is high, and the strength of the film is high.

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

However, although the ink composition of Patent Document 1 is not described in the document, when we investigated in detail, the curing sensitivity is low, the cured film is brittle, and the weather resistance is insufficient. I understood. Further, although the ink composition of Patent Document 2 is not described in the document, when we examined in detail, the shrinkage of the cured film is large, and in particular, the printed matter curls together with the substrate during weather resistance storage. There was a problem. In addition, the cured film has insufficient flexibility, and has a drawback of being weak against bending and pulling. Further, the viscosity of the ink is high, and it is difficult to eject the ink with an ink jet.

As described above, a cured composition composed of a monofunctional acceptor monomer and a monofunctional donor monomer, or a cured composition composed of a monofunctional acceptor monomer and a polyfunctional donor monomer has a curing sensitivity, a cured film strength, and weather resistance. The cured composition consisting of a polyfunctional acceptor monomer and a polyfunctional donor monomer monomer has problems with the shrinkage and flexibility of the cured film, and the viscosity of the ink tends to increase. There was a problem that it became a difficult composition. As described above, conventionally known CT polymerization ink compositions still have insufficient performance for use in the field of ink jet printing.

The present invention has been made in view of the above problems, and its purpose is excellent in curing sensitivity, weather resistance of the cured film, solvent resistance, excellent viscosity stability when stored for a long period of time, and curing shrinkage of the ink. It is an object of the present invention to provide an ink jet ink and an ink jet recording method using a CT polymerization system in which the printed matter is free from curling and the flexibility of the printed ink is excellent.

The above object of the present invention is achieved by the following configurations.
[1] In an active energy ray-curable inkjet ink containing at least one acceptor monomer and at least one donor monomer,
The acceptor monomer contains a polyfunctional acceptor monomer, the donor monomer contains a monofunctional donor monomer, and the compounding ratio of the acceptor monomer and the donor monomer satisfies the formulas (1) and (2). An active energy ray-curable inkjet ink characterized by the above.
Formula (1) 0.66 <= X <= 2

[In Formula (2),
a 1 _~ a _p represent mole fractions of the respective acceptor monomers A _{1 ~} A _p to the sum of all acceptor monomers and donor monomer,
b ₁ to b _p represent the number of functional groups in one molecule of each acceptor monomer A ₁ to A _p ,
d ₁ to d _q represent the mole fraction of each donor monomer D ₁ to D _q with respect to the sum of all acceptor monomers and donor monomers.
[2] The active energy ray-curable inkjet ink according to [1], which contains a radical polymerization inhibitor and a cationic polymerization inhibitor.
[3] The active energy according to [1] or [2], wherein the acceptor monomer contains at least one monomer selected from maleimides, maleates, and fumarates. Line curable inkjet ink.
[4] The active energy ray-curable inkjet ink according to any one of [1] to [3], wherein the acceptor monomer contains a maleimide compound represented by the following general formula (1).

[Where,
R ₁ and R ₂ each independently represents 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 represent a divalent organic linking group in which groups selected from an alkylene group, an alkyleneoxy group, an arylene group, an ester group, an ether group, and a thioether group are combined;
Y ₂ represents a divalent group having an asymmetric carbon when n is 1, and when n is 2 or more, each independently represents a divalent group having a single bond or an asymmetric carbon, And at least one of the plurality of Y ₂ is a divalent group having an asymmetric carbon,
Z represents a hydrogen atom, an alkyl group, an alkyloxy group, an alkyl ester group or a hydroxyl group when n is 1, and when n is 2 or more, an alkylene group, an alkyleneoxy group, an arylene group, an ester group, an ether An n-valent linking group in which a group selected from a group and a thioether group is combined;
n represents an integer of 1 to 6,
n1 and n2 each independently represent 0 or 1]
[5] The active energy ray-curable inkjet ink according to [4], wherein the polyfunctional acceptor monomer is a compound in which n is 2 in the general formula (1).
[6] The active energy ray-curable inkjet ink according to any one of [1] to [5], wherein the acceptor monomer contains a maleimide compound represented by the following general formula (2).

[Where,
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,
A ₁₂ represents a divalent hydrocarbon group having an asymmetric center,
Y 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, and n represents 0 or 1]
[7] The active energy ray-curable inkjet ink according to any one of [1] to [6], wherein the monofunctional donor monomer is a vinyl ether compound represented by the following general formula (3).

[Where,
R ₃ , R ₄ and R ₅ each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group,
R ₆ represents an alkyl group, a cycloalkyl group or an aryl group.
[8] The functional group mole fraction Y of the polyfunctional acceptor monomer represented by the following formula (3) is 0.4 or more and 0.52 or less, and any one of [1] to [7] The active energy ray-curable inkjet ink according to claim 1.

[In Formula (3),
e 1 _~ e _r represent the mole fraction of each multi-functional acceptor monomers E _{1 ~} E _r with respect to the sum of all acceptor monomers and donor monomer,
f ₁ ~ _{f r} represent the number of functional groups in one molecule of the multifunctional acceptor monomers _E 1 ~ _{E r]}
[9] The functional group mole fraction Z of the monofunctional donor monomer represented by the following formula (4) is 0.17 to 0.58, and any one of [1] to [8] The active energy ray-curable inkjet ink described.

[In Formula (4),
g ₁ to g _s represent the mole fraction of each monofunctional donor monomer G ₁ to G _s relative to the sum of all acceptor monomers and donor monomers]
[10] The acceptor monomer further includes a monofunctional acceptor monomer, and the functional group mole fraction V of the monofunctional acceptor monomer represented by the following formula (5) is 0.04 to 0.17. The active energy ray-curable inkjet ink according to any one of [1] to [9], wherein

[In Formula (5),
h ₁ to h _t represent the mole fraction of each monofunctional acceptor monomer H ₁ to H _t with respect to the sum of all acceptor monomers and donor monomers]
[11] The active energy ray-curable inkjet ink according to any one of [1] to [10], wherein the X satisfies a range of 0.75 to 1.1.
[12] The active energy ray-curable inkjet ink according to any one of [1] to [11], which contains a photopolymerization initiator.

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

According to the present invention, there are provided an inkjet ink and an inkjet recording method which are excellent in viscosity stability when stored for a long period of time, have no curled printed matter due to curing shrinkage of the ink, and have excellent flexibility of the printed ink. be able to.

It is a front view which shows an example of a structure of the principal part of the inkjet recording device used for the inkjet recording method of this invention. It is a top view which shows another example of a structure of the principal part of the inkjet recording device used for the inkjet recording method of this invention.

The present inventors first investigated the reactivity of the double bond functional group of the acceptor monomer and the double bond functional group of the donor monomer by using a technique of real-time FT-IR and gel fraction. First, in the case of a composition comprising a monofunctional acceptor monomer and a monofunctional donor monomer, the double bond functional group of the acceptor monomer and the double bond functional group of the donor monomer are polymerized at a ratio of about 1: 1. As a result of the reaction, both the acceptor monomer and the donor monomer almost disappeared together with the polymerization reaction.

Next, in the case of a composition composed of a monofunctional acceptor monomer and a bifunctional donor monomer, or composed of a bifunctional acceptor monomer and a bifunctional donor monomer, the double bond functional group of the acceptor monomer It was found that the double bond functional group of the donor monomer was polymerized at a ratio of about 1: 0.5, and almost all the donor monomer was incorporated in the polymer chain. The present inventors speculate that the bifunctional donor monomer may function as a monofunctional monomer by reacting only one of the two functional groups. From the above, the present inventors have increased the crosslink density of the cured film by using a polyfunctional monomer as the acceptor monomer, and the donor monomer functions as a monofunctional monomer, thereby reducing the flexibility and curing shrinkage of the cured film. A design philosophy of restraining was devised.

(Active energy ray-curable inkjet ink)
The active energy ray-curable inkjet ink of the present invention contains at least one acceptor monomer and at least one donor monomer. At least one acceptor monomer contains a “multifunctional acceptor monomer”, and at least one donor monomer contains a “monofunctional donor monomer”. Further, the at least one acceptor monomer may further contain a monofunctional acceptor monomer as necessary; the at least one donor monomer may further contain a multifunctional donor monomer as necessary. Also good.

The active energy ray-curable ink-jet ink does not substantially use a solvent, and the main component of the liquid contained in the ink is a polymerizable monomer. Therefore, when the active energy ray is irradiated, the monomer is cured and the ink is solid. Thus, a strong image can be formed without evaporating the solvent.

The active energy ray-curable inkjet ink contains an acceptor monomer and a donor monomer, both of which form a charge transfer complex (CT polymerization compound).

Examples of the active energy rays include X-rays, ultraviolet rays, electron beams, and visible rays, and ultraviolet rays are preferably used from the viewpoint of high curing sensitivity of the charge transfer complex and the cost of the irradiation apparatus.

(Ratio X)
Next, when used as an inkjet ink, the composition ratio of the acceptor monomer and the donor monomer can be used to achieve high curing sensitivity, strength of the cured film, that is, abrasion resistance, weather resistance, and low curing. As a result of studying whether shrinkage, flexibility, and viscosity capable of being ejected by ink jetting can be combined, it has been found that the blending can satisfy the following ratio X, and the present invention has been completed.

Formula (1) 0.66 <= X <= 2

In the formula _{_{(2), a 1 ~ a}} p represent mole fractions of the respective acceptor monomers _A 1 ~ _{A p} to the sum of all acceptor monomers and donor _monomer, _b 1 ~ b _p is the acceptor monomer A represents a number of functional groups in one molecule of _{_{_{1 ~ a p, d 1 ~}}} d q represent mole fractions of the respective donor monomers _D 1 ~ _{D q} for the sum of all acceptor monomers and donor monomer.

The molecule of ratio X indicates the number of moles of double bond functional groups of the acceptor monomer per unit mass. In the denominator of the ratio X, among the double bond functional groups of the donor monomer, the polyfunctional donor monomer reacts with only one functional group per monomer molecule, and the monofunctional donor monomer reacts as a monofunctional monomer with one functional group as it is Then, the number of moles of double bond functional groups of the donor monomer used for the reaction per unit mass is shown.

Therefore, the ratio X represents the ratio between the number of effective functional groups of the acceptor monomer and the number of effective functional groups of the donor monomer, and the effect of the present invention is exhibited by setting the ratio to 0.66 or more and 2 or less. .

That is, when the ratio X is 0.66 or more, the sensitivity of curing increases, and the strength of the cured film, that is, the abrasion resistance and weather resistance are particularly excellent. On the other hand, when the ratio X is 2 or less, the curing shrinkage of the cured film is very small, the viscosity of the ink is low, and the emission is very stable and good. Furthermore, the ratio X is more preferably 0.75 or more and 1.1 or less.

(Functional group mole fraction Y)
Furthermore, it has been found that the functional group mole fraction Y of the polyfunctional acceptor monomer is preferably 0.4 to 0.52. When the functional group molar fraction Y is 0.4 or more, the strength of the cured film, that is, the abrasion resistance and the weather resistance are increased, so that the crosslinking density is estimated to be increased. On the other hand, when the functional group molar fraction Y is 0.52 or less, curing shrinkage is small.

The functional group mole fraction Y of the polyfunctional acceptor monomer in the present invention is (the sum of the mole fraction of each polyfunctional acceptor monomer multiplied by the number of functional groups) / ((multifunctional and monofunctional acceptor monomer) The sum of those obtained by multiplying each mole fraction by the number of functional groups) + (sum of the mole fraction of each donor monomer)), and represented by the following formula. In this definition, the donor monomer is considered to react with only one functional group per molecule of the monomer, and in the case of a polyfunctional donor monomer, it is treated as a monofunctional monomer without multiplying the number of functional groups. Is calculated.

In the formula _{_{(3), e 1 ~ e}} r represent the mole fraction of each multi-functional acceptor monomers _E 1 ~ _{E r} with respect to the sum of all acceptor monomers and donor _monomer, f 1 ~ _{f r} is each multi This represents the number of functional groups in one molecule of the functional acceptor monomers E ₁ to _Er , and a ₁ to a _p , b ₁ to b _p and d ₁ to d _q have the same meanings as in formula (2).

(Functional group mole fraction Z)
Furthermore, it has been found that when the functional group mole fraction Z of the monofunctional donor monomer is 0.17 to 0.58, the ink is more suitable for ink jet ejection and has less curing shrinkage.

In the present invention, the functional group mole fraction Z of the monofunctional donor monomer means (sum of mole fractions of each monofunctional donor monomer) / ((the number of functional groups in the mole fraction of each of the polyfunctional and monofunctional acceptor monomers). (Sum of multiplied) + (sum of mole fractions of each donor monomer)) and represented by the following formula. In this definition, the donor monomer is considered to react with only one functional group per molecule of monomer, and in the case of a polyfunctional donor monomer, the number of functional groups is not multiplied, and the mole fraction is calculated by treating it as a monofunctional monomer. is doing.

In the formula (4), g ₁ to g _s represent the mole fraction of each monofunctional donor monomer G ₁ to G _s with respect to the sum of all acceptor monomers and donor monomers, and a ₁ to a _p , b ₁ to b _p and d ₁ to d _q are as defined in the formula (2).

(Functional group mole fraction V)
Further, it has been found that when the functional group mole fraction V in the definition of the present invention of the monofunctional acceptor monomer is 0.04 to 0.17, ink viscosity, curing shrinkage, and flexibility are more preferable. It was.

In the present invention, the functional group mole fraction V of the monofunctional acceptor monomer is (sum of mole fractions of each monofunctional acceptor monomer) / ((functional to the mole fraction of each of the polyfunctional and monofunctional acceptor monomers). Sum of those multiplied by the number of radicals) + (sum of mole fractions of each of the donor monomers)), and represented by the following formula. In this definition, the donor monomer is considered to react with only one functional group per molecule of monomer, and in the case of a polyfunctional donor monomer, the number of functional groups is not multiplied, and the mole fraction is calculated by treating it as a monofunctional monomer. is doing.

In formula (5), h ₁ to h _t represent the mole fraction of each monofunctional acceptor monomer H ₁ to H _t with respect to the sum of all acceptor monomers and donor monomers, and a ₁ to a _p , b ₁ ˜b _p and d ₁ to d _q are as defined in the formula (2).

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

In the present invention, “carbon constituting an unsaturated bond” means a carbon having a larger charge value among two carbons on an unsaturated bond to which an electron-withdrawing group is bonded in the case of a monomer having a low electron density. In the case of a monomer having a high electron density, the carbon having the smaller charge value out of the two carbons on the unsaturated bond to which the electron donating group is bonded is shown. When there are a plurality of such unsaturated bonds in one molecule of the polymerizable monomer, the average value of the carbon charge of each unsaturated bond is used.

In the ink composition of the present invention, it is preferable that the maximum value of the difference in charge of unsaturated bond carbons of at least two polymerizable monomers is 0.24 or more and 0.46 or less. If the maximum value of the difference in charge is 0.24 or more, CT polymerization tends to occur. In addition, when 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.

(Acceptor monomer)
The acceptor monomer in the present invention is a monomer having an electron-deficient unsaturated bond, and is a polymerization having a value of “atomic charge” of −0.3 or more in the present invention. Monomer. The value of the electric charge of the carbon atom constituting the unsaturated bond contained in the acceptor monomer in the present invention is preferably −0.28 or more.

A monofunctional acceptor monomer is a polymerizable monomer having only one electron-deficient unsaturated bond (for example, a maleimide group) in one molecule; a polyfunctional acceptor monomer is an electron-deficient in one molecule. It is a polymerizable monomer having two or more unsaturated bonds (for example, a maleimide group).

Among the polymerizable monomers having at least two kinds of unsaturated bonds contained in the ink composition of the present invention, the polymerizable monomer having one of the largest “charges of carbon atoms constituting the unsaturated bond” (one of acceptor monomers) ) Is preferably a compound having an unsaturated bond represented by the following general formula (4) or general formula (5).

In General Formula (4) or General Formula (5), EWG ₁ and EWG ₂ each represent a partial structure in which an electron-withdrawing group is directly connected to an unsaturated bond, and constituent atoms of EWG ₁ or EWG ₂ are bonded to each other. And may have a ring 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 mentioned.

EWG ₁ and EWG ₂ may form a cyclic structure via a linking group 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, and further substituted. It may have a group. Further, through the part linking group EWG ₁ or EWG _2, it may form a multifunctional polymerizable compound having two or more unsaturated bonds moiety.

In the above general formulas (a) and (b), Q ₁ represents OH, OR ′, NR′R ″ or R ′. R ′ and R ″ each represent a hydrogen atom, a linear alkyl group or a branched alkyl group. Represents a cyclic alkyl group, an alkyl group having a hydroxyl group, an aryl group or an arylalkyl group, and may further have a substituent.

Specific examples of the unsaturated compound represented by the general formula (4) or the general formula (5) 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. Acid amide monocarboxylic acid ester, vinylene dicarboxylic acid amide, vinylene nitrile compound substituted with nitrile groups at both ends of vinylene skeleton, vinyl halide compound substituted with halogen groups at both ends of vinylene skeleton, vinylene ketone compound substituted with carbonyl at both ends of vinylene skeleton , Vinylene dithiocarboxylic acid anhydride, vinylene thioimide compound, vinylene dithiocarboxylic acid, vinylene dithiocarboxylic acid ester, vinylene monothiocarboxylic acid amide monothiocarboxylic acid, vinylene monothiocarboxylic acid amide Nochiokarubon 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, preferred unsaturated compounds include maleic anhydride; vinylene imides such as maleimide; vinylene dicarboxylic acids such as maleic acid and fumaric acid; vinylene dicarboxylic acid esters such as maleic acid esters and fumaric acid esters.

In the present invention, the unsaturated compound represented by the general formula (4) or the general formula (5) is at least one selected from the following general formulas (A-1) to (A-13): An unsaturated compound is preferred.

In the formula, each of R ₁ , R ₂ , R ₃ and R ₄ independently represents a hydrogen atom, a linear alkyl group, a branched alkyl group, a cyclic alkyl group, an alkyl group having a hydroxyl group, an aryl group or an arylalkyl group. To express. These groups may further have a substituent and can be used as a linking group for forming a polyfunctional polymerizable compound having two or more unsaturated bonds. X ₁ represents a halogen atom.

Among the unsaturated compounds represented by the general formula (A-1) to the general formula (A-13), further, the general formula (A-1), the general formula (A-2) or the general formula (A-6) It is preferable that it is an unsaturated compound represented by this.

Examples of unsaturated compounds represented by general formulas (A-1) to (A-13) are shown below, but the acceptor monomer in the present invention is limited to the unsaturated compounds exemplified below. It is not a thing. Note that the charges of the unsaturated bond carbon atoms of the unsaturated compounds exemplified below all show a value of −0.30 or more.

In the present invention, examples of the monofunctional unsaturated compound represented by the general formula (A-1) to the general formula (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), examples of vinylene dicarboxylic acid, maleic acid, fumaric acid, vinylene dicarboxylic acid ester , Dimethyl maleate, diethyl maleate, diisopropyl maleate, di-n-butyl maleate, di-tert-butyl maleate, di (2-ethylhexyl) maleate, dimethyl fumarate, diethyl fumarate, diisopropyl fumarate, Examples thereof include di-n-butyl fumarate, di-tert-butyl fumarate, and di (2-ethylhexyl) fumarate, but these are not limited to these specific examples.

Further, in order to obtain a polyfunctional polymerizable monomer having a preferable unsaturated bond, it can be obtained using various conventionally known linking group skeletons. Examples thereof include polyfunctional maleimide derivatives as described in US Pat. No. 6,034,150 and JP-A-11-124403.

Hereinafter, a maleimide derivative that can be preferably used as an acceptor monomer in an active energy ray-curable inkjet ink composition will be described 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 (1). Compounds are preferred.

R ₁ and R _{2 in} the general formula (1) 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. Examples of the alkyl group represented by R ₁ or R ₂ include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. R ₁ and R ₂ may be bonded to each other to form a cyclopropylene ring, a cyclobutylene ring, a cyclopentene ring, a cyclohexene ring, or the like.

Y ₁ and Y _{3 in} the general formula (1) represent a divalent organic linking group in which groups selected from an alkylene group, an alkyleneoxy group, an arylene group, an ester group, an ether group, and a thioether group are combined. Examples of the divalent organic linking group represented by Y ₁ or Y ₃ in which a group selected from an alkylene group, an alkyleneoxy group, an arylene group, an ester group, an ether group, and a thioether group are combined.
Alkylene group (for example, methylene group, ethylene group, butylene group, hexylene group, etc.);
Alkyleneoxy group (for example, ethyleneoxy group, polyethyleneoxy group, butyleneoxy group, polybutyleneoxy group, etc.);
Alkyleneoxycarbonyl group (for example, ethyleneoxycarbonyl group, hexyleneoxycarbonyl group, etc.);
Alkylenecarbonyloxy group (for example, methylenecarbonyloxy group, hexylenecarbonyloxy group);
Arylene groups (eg, phenylene groups, methylphenylene groups);
An oxycarbonylphenylenecarbonyloxy group;
Examples include carbonyloxyphenyleneoxycarbonyl group. Y ₁ is preferably an alkylene group; Y ₃ is preferably an alkyleneoxycarbonyl group or an alkylenecarbonyloxy group.

In the general formula (1), n1 represents 0 or 1, and n2 represents 0 or 1.

Y _{2 in the} general formula (1) represents a divalent group having an asymmetric carbon (chiral carbon) when n is 1, and when n is 2 or more, each independently represents a single bond or an asymmetric group. Represents a divalent group having carbon (chiral carbon). However, at least one of the plurality of Y ₂ is a divalent group having an asymmetric carbon (chiral carbon), and preferably all of the plurality of Y ₂ are a divalent group having an asymmetric carbon (chiral carbon). It is.

Specifically, the following formula may be mentioned.

In the formula, 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 1 to 18 carbon atoms, or a hydroxyl group. Preferably, an alkyl group having 1 to 4 carbon atoms (for example, methyl group, ethyl group, propyl group, isobutyl group) can be used.

N in the general formula (1) represents an integer of 1 to 6, preferably 1 or 2.

Z in the general formula (1), when n is 1, is a hydrogen atom, an alkyl group (for example, a methyl group, an ethyl group, a hexyl group, etc.), an alkyloxy group, an alkyl ester group (an alkyloxycarbonyl group or an alkylcarbonyl group) An oxy group) or a hydroxyl group; preferably an alkyl group or an alkyloxy group; and more preferably the same as the group represented by R ₁₃ in the general formula (2) described later.

Z in the general formula (1), when n is 2 or more, an alkylene group, an alkyloxy group, an arylene group (including a heteroarylene group), an ester group (oxycarbonyl group or carbonyloxy group), an ether group, a thioether Represents an n-valent linking group in which groups selected from the group are combined; preferably an alkylene group or an alkyloxy group; and more preferably the same as the group represented by R ₁₃ in formula (2) described later.

Examples of the divalent linking group include the same groups as the divalent organic linking group represented by Y ₁ or Y _{3 in} the general formula (1). Examples of the trivalent linking group include an alkylene group derived from glycerin, trimethylolalkyl and the like; a heteroarylene group derived from triazine and the like. Examples of the tetravalent linking group include an alkylene group derived from pentaerythritol and the like. Examples of the hexavalent linking group include an alkylene group derived from bistrimethylolalkyl or the like.

The polyfunctional acceptor monomer is preferably a maleimide compound in which n is 2 or more in the general formula (1); more preferably a maleimide compound in which n is 2 in the general formula (1).

For the emission from the inkjet head, the molecular weight of the maleimide compound having a chiral group is preferably 200 to 1000, 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 1000, the viscosity becomes high and the emission becomes difficult.

More preferably, the maleimide compound represented by the following structural formula is mentioned.

Here, n11 and n12 are preferably integers of 0 to 6, and n13 is preferably an integer of 1 to 30. R _1, _{R 2} and Z have the same meanings as _R 1, _{R 2} and Z in the general formula (1). X has the same meaning as X in the formula given as an example of the divalent group having an asymmetric carbon (chiral carbon) represented by Y ₂ . Particularly preferably, R ₁ and R ₂ are hydrogen atoms, X is an alkyl group having 1 to 4 carbon atoms, n12 is 0, n is 2, and Z is an alkylene group having 1 to 18 carbon atoms. Or it is a polyoxyalkylene group.

Although the specific example of a compound represented by General formula (1) below is shown, this invention is not limited to this.

A method for synthesizing these maleimide compounds is known, and can be easily synthesized using, for example, the method described in JP-A No. 11-124403 or Macromolecular Chemical and Physics, 2009, 210, 269-278.

More preferable maleimide derivatives applicable in the ink composition of the present invention include maleimide derivatives represented by the following general formula (2) from the viewpoint of low viscosity, solubility, and ejection stability.

R ₁₁ and R _{12 in} the general formula (2) 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. Examples of the alkyl group 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 each other to form a cyclopropene ring, a cyclobutylene ring, a cyclopentene ring, a cyclohexene ring, or the like.

A ₁₁ and A _{13 in} the general formula (2) each independently represent an alkylene group. The divalent alkylene group represented by A ₁₁ or A ₁₃ includes a methylene group, an ethylene group, a butylene group, and the like, and is preferably a methylene group. In the general formula (2), m represents 0 or 1, and n represents 0 or 1.

A _{12 in the} general formula (2) represents a divalent group having an asymmetric carbon (chiral carbon). A ₁₂ is preferably —CHR ₁₄ —. R ₁₄ represents 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, an alkylcarbonyloxy group having 1 to 18 carbon atoms, or a hydroxyl group, preferably carbon Represents an alkyl group of formula 1 to 4 (methyl group, ethyl group, propyl group, isobutyl group, etc.).

Y in the general formula (2) represents carbonyloxy (—C═O—O—) or oxycarbonyl (—O—C═O—).

P in the general formula (2) represents 1 or 2. R _{13 in the} general formula (2) 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. To express.

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, and specifically includes a methyl group, an ethyl group, a propyl group. Group, butyl group, hexyl group, neopentyl group, dodecyl group, 2,2,4-octyl group and the like.

Examples of the alkyloxy group having a molecular weight of 15 to 600 represented by R ₁₃ when p is 1 include a hydroxy or alkoxy polyethyleneoxy group, a hydroxy or alkoxy polypropyleneoxy group, a hydroxy or alkoxy polybutyleneoxy group, and the like. It is not limited to these.

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, and specifically includes a methylene group, an ethylene group, propylene Group, butylene group, hexylene group, nepopentylene group, dodecylene group, 2,2,4-octylene group and the like.

Examples of the alkyleneoxy group having a molecular weight of 14 to 600 represented by R ₁₃ when p is 2 include a polyethyleneoxy group, a polypropyleneoxy group, and a polybutyleneoxy group.

The alkyl group, alkyloxy group, alkylene group or alkylene part of the alkyleneoxy group represented by R ₁₃ may contain an alkyleneoxy unit as a repeating unit. Examples of the alkylene group containing an alkyleneoxy unit as a repeating unit include “— (CH ₂ CH ₂ O) n—CH ₂ CH ₂ —” and “— (CH (—CH ₃ ) CH ₂ —O) m—CH. (—CH ₃ ) CH ₂ — ”and the like can be exemplified. Examples of the alkyleneoxy group containing an alkyleneoxy unit as a repeating unit include “— (OCH ₂ CH ₂ ) n—O—” and “— (OCH (—CH ₃ ) CH ₂ ) m—O—”. It is.

R ₁₃ is preferably a linear or branched alkyl group having 1 to 18 carbon atoms or a linear or branched alkylene group having 1 to 18 carbon atoms, more preferably a linear or branched alkyl group having 2 to 12 carbon atoms. Or a linear or branched alkylene group having 2 to 12 carbon atoms, more preferably a linear or branched alkylene group having 4 to 12 carbon atoms or a linear or branched alkyl group having 4 to 12 carbon atoms. .

Further, in the general formula (2), A ₁₁ and A ₁₃ are methylene groups; A ₁₂ is —CHR ₁₄ —; R ₁₃ is a linear or branched alkyl group having 2 to 12 carbon atoms or a straight chain. A chain or branched alkylene group is preferred. R ₁₄ represents 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, an alkylcarbonyloxy group having 1 to 18 carbon atoms, or a hydroxyl group as described above. Preferably, it represents an alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group, propyl group, isobutyl group, etc.).

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

In the general formulas (II) to (IV), R ₁₄ represents 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 an alkyl group having 1 to 18 carbon atoms. Represents an alkylcarbonyloxy group or a hydroxyl group. Preferably, an alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group, propyl group, isobutyl group, etc.) is used. p represents 1 or 2. R ₁₅ may be the same group as R _{13 in the} general formula (2), and preferably represents a linear alkyl group or alkylene group having 4 to 12 carbon atoms.

Specific examples of the maleimide derivative represented by the general formula (2) of the present invention are shown below.

As the acceptor monomer according to the present invention described above, maleic anhydride, maleic acid, fumaric acid, maleic esters, fumaric esters, and maleimide compounds are preferable from the viewpoint of increasing sensitivity.

(Donor monomer)
The donor monomer in the present invention is a monomer having an electron-rich unsaturated bond, and is a polymerizable monomer having a value of “charge of carbon atom constituting the unsaturated bond” (atomic charge) of −0.45 or less. . The value of the charge of the carbon atom constituting the unsaturated bond contained in the donor monomer in the present invention is preferably −0.50 or less.

A monofunctional donor monomer is a polymerizable monomer having only one electron-rich unsaturated bond (such as a vinyl ether group) in one molecule; a polyfunctional donor monomer is an electron-rich unsaturated in one molecule. It is a polymerizable monomer having two or more bonds (for example, vinyl ether groups).

In the two or more kinds of polymerizable monomers having an unsaturated bond contained in the ink composition of the present invention, a polymerizable monomer (one of the donor monomers) having the minimum charge of carbon atoms constituting the unsaturated bond, It is preferable that it is an unsaturated compound represented by following General formula (6).

In the general formula (6), X represents —O—, —NR ₄ —, —S—, or —SO—. 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 may further have a substituent. R ₁ , R ₂ , and R ₃ each independently 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; You may have. Further, a part of R ₂ or R ₃ and Y may be bonded to form a cyclic structure. Moreover, you may form the polyfunctional donor monomer which one part of Y has a 2 or more unsaturated bond through a coupling group.

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

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

In the formula, R ₅ to R ₉ each independently represents a hydrogen atom, a linear alkyl group, or a branched alkyl group, a cyclic alkyl group, an alkyl group having a hydroxyl group, an aryl group or an arylalkyl group, and further a substituent. It may be a linking group for forming a polyfunctional polymerizable compound having two or more unsaturated bond moieties. Z represents —O—, —N (R ₁₀ ) — or —S—. R ₁₀ represents a hydrogen atom, a linear alkyl group, a branched alkyl group, a cyclic alkyl group, an alkyl group having a hydroxyl group, an aryl group, or an arylalkyl group, and may further have a substituent.

(Monofunctional donor monomer)
In the monofunctional donor monomer represented by the general 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. . X represents —O—, —N (R ₁₁ ) CO—, —NR ₄ —, —S—, or —SO—, and R ₁₁ represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group. , R ₁₁ may be linked to Y to form a ring.

Specific examples of monofunctional donor monomers are shown below.

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

Examples of the polymerizable monomer having a vinylene skeleton and a cyclic 5-membered or cyclic 6-membered ring compound containing a nitrogen atom or an oxygen atom in the ring include imidazole, pyrrole, furan, dihydrofuran, pyran, dihydropyran and the like.

Specific examples of N-vinyl compounds having a structure in which a vinyl group is substituted on a nitrogen atom include, for example, N-vinylformamide, N-vinylcarbazole, N-vinylindole, N-vinylpyrrole, N-vinylacetamide, N -Vinylpyrrolidone, N-vinylcaprolactam, N-vinyl-N-ethylurea, N-vinyloxazolidone, N-vinylsuccinimide, N-vinylethylcarbamate and derivatives thereof, among these compounds, N-vinylcaprolactam N-vinylformamide is preferred. N-vinylformamide can be obtained from, for example, Arakawa Chemical Industries, Ltd.

[Monofunctional vinyl ether compound]
The donor monomer contained in the active energy ray-curable inkjet ink preferably contains a monofunctional vinyl ether compound represented by the general formula (3).

In formula (3), R ₃ , R ₄ and R ₅ each independently 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. .

Examples of monofunctional vinyl ether compounds 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, diethylene glycol monovinyl ether, dodecyl vinyl ether, triethylene glycol monovinyl ether and the like can be mentioned.

In addition to the above, various vinyl ether compounds disclosed so far can be applied. 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, Vinyl ether having an alicyclic skeleton disclosed in JP-A-2005-015396, 1-indanyl vinyl ether disclosed in JP-A-2008-137974, and JP-A-2008-150341 4-acetoxycyclohexyl vinyl ether and the like.

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

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

Next, an example of a polyfunctional donor monomer having an unsaturated bond according to the present invention represented by the general formula (D-1) to the general formula (D-9) will be shown. It is not limited. Note that the charge value of the carbon atom constituting the unsaturated bond of the polymerizable monomer exemplified below is −0.40 or less.

For example, the vinyl ether compounds include the following. 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 at least 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, Examples include 1-indanyl vinyl ether disclosed in JP-A-137974, 4-acetoxycyclohexyl vinyl ether disclosed in JP-A-2008-150341, and the like.

In addition, by introducing a substituent at the α-position or β of the vinyl ether group, such as by substituting the vinyl ether group of the above-mentioned divinyl ether with a propenyl ether group, an isopropenyl ether group, a butenyl ether group, or an isobutenyl ether group. You can also.

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 general 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, more preferably 1 or 2.

In the above general 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; an aryl group; Or thienyl group; allyl group, 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-butenyl group, 2-butenyl group or 3-butenyl group, etc. An alkenyl group having 1 to 6 carbon atoms; an aryl group such as a phenyl group, a benzyl group, a fluorobenzyl group, a methoxybenzyl group or a phenoxyethyl group; an alkoxy group such as a methoxy group, an ethoxy group or a butoxy group; a propylcarbonyl group, An alkylcarbonyl group having 1 to 6 carbon atoms such as butylcarbonyl group or pentylcarbonyl group; ethoxycarbonyl group, propoxy Examples thereof include an alkoxycarbonyl group having 1 to 6 carbon atoms such as a carbonyl group or a butoxycarbonyl group; a group such as an alkoxycarbamoyl group having 1 to 6 carbon atoms such as an ethoxycarbamoyl group, a propylcarbamoyl group or a butylpentylcarbamoyl group. 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. P, q and r are 0 or an integer of 1 or more, and p + q + r is an integer of 3 to 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 general formula (B), R ₁₂ is a linking group containing any one of an alkylene group having 1 to 6 carbon atoms such as a methylene group, an oxyalkylene group, and an ester group. p, q, l and m are each an integer of 0 or 1 or more, and the total number of p + q + l + m is an integer of 3 to 10.

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

In the above general 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.

(Other monomers)
In the present invention, as other monomers, even if the charge of the carbon atom constituting the unsaturated bond exceeds −0.45 and is less than −0.30, the effect of the present invention is not impaired. Can be added as appropriate. Such a polymerizable compound will be described below.

The polymerizable compound is a compound having an ethylenically unsaturated bond capable of radical polymerization, and the charge of carbon atoms constituting the unsaturated bond is more than −0.45 and less than −0.30, a monomer, Those having chemical forms such as oligomers and polymers are included.

Examples of the other monomers include unsaturated carboxylic acids such as acrylic acid and methacrylic acid and salts thereof, anhydrides having ethylenically unsaturated groups, acrylonitrile, styrene, various unsaturated polyesters, and unsaturated polyethers. And radical polymerizable monomers such as 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 Acrylic acid derivatives such as dicyclopentanyl 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, from the viewpoints of curability and film properties after curing, acrylates of alcohols having an ether oxygen atom such as tetrahydrofurfuryl acrylate and 2-phenoxyethyl acrylate are preferred. 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.

(Photopolymerization initiator)
The ink composition of the present invention preferably contains a radical photopolymerization initiator and a sensitizer as the photopolymerization initiator from the viewpoint of obtaining high sensitivity.

As the radical photopolymerization initiator applicable to the ink composition of the present invention, a molecular cleavage type or a hydrogen abstraction type is suitable for the present invention. Specific examples include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, benzyl, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino-1- (4-morpholino Phenyl) -butan-1-one, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and the like are preferably used. Further, other molecular cleavage types include 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4- Isopropyl fe ) -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, etc. may be used in combination, and hydrogen abstraction photopolymerization initiators such as benzophenone, 4-phenylbenzophenone, isophthalphenone, 4- Benzoyl-4'-methyl-diphenyl sulfide, a metallocene-type polymerization initiator bis (2,4-cyclopentadien-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-acetyloxime) and the like Can be used.

For the photo radical polymerization initiator, as sensitizers, for example, trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, Radical polymerizable monomers such as N, N-dimethylbenzylamine and 4,4′-bis (diethylamino) benzophenone can be used in combination with amines that do not cause an addition reaction. Of course, the photo radical polymerization initiator and the sensitizer are preferably selected from those having excellent solubility in a radical polymerizable monomer.

The radical photopolymerization initiator and the sensitizer are in the range of 0.1 to 20% by mass, preferably 1 to 12% by mass, based on 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 containing a plurality of thioxanthones in the molecule described in International Publication No. 2009/060235, and α-hydroxypropiophenone represented by ESACURE ONE and ESACUR KIP150 marketed by Lamberti in the side chain A bonded oligomer type polymerization initiator or the like can also be preferably used.

In the present invention, when a maleimide-containing polymerizable monomer is used, the maleimide-containing polymerizable monomer itself can function as an initiator.

Next, other components of the ink composition of the present invention will be described.

[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 with 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. 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 excellent light resistance.

The organic pigment is preferably fine particles having an average particle diameter 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, the light resistance is lowered due to the small particle size, and when it exceeds 150 nm, it is difficult to maintain stable dispersion, and the precipitation of the pigment is likely to occur. Stability is lowered, and a problem that minute mist called satellite occurs. However, in the case of titanium oxide, the average particle diameter is set to 150 to 300 nm, preferably 180 to 250 nm, in order to provide whiteness and concealment.

In addition, it is preferable to remove coarse particles 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 comprising 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, finely kneaded with a kneader or the like, 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 water-soluble inorganic salts 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. After the dispersion treatment, chlorine ions (halogen ions) are washed with water in order to achieve the halogen ion content specified 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 is likely to evaporate, 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 of the pigment, surface treatment by a known technique such as acidic treatment or basic treatment, synergist, various coupling agents in order to promote adsorption with the pigment dispersant on the surface thereof. Is preferable.

In order to obtain a sufficient concentration and sufficient light resistance, the pigment ranges from 1.5 to 8% by mass in the case of colors other than white in the ink-jet ink, and from 10 to 30% by mass in the case of 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)” and “Disperbyk-101 (polyaminoamide phosphate) manufactured by BYK Chemie. 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) Silicone) "and the like.

In addition, “Efka 44, 46, 47, 48, 49, 54, 63, 64, 65, 66, 71, 701, 764, 766”, “Efka Polymer 100 (modified polyacrylate), 150” (fat) manufactured by Efka CHEMICALS 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. "Flownon 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. And the like.

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.” Mo Oleate), 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 preferably 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, these pigment dispersants preferably 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 about 10 ° C., undesired polymer gel or pigment soft agglomerates may be generated. And discharge stability may deteriorate.

[Radical polymerization inhibitor]
In the active energy ray-curable inkjet ink composition or inkjet ink of the present invention, it is preferable to add a radical polymerization inhibitor from the viewpoint of storage stability. In the ink-jet ink of the present invention, radical polymerization may occur during storage due to radicals generated by the influence of heat or light. 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.

As radical polymerization inhibitors, phenolic hydroxyl group-containing compounds, methoquinone (hydroquinone monomethyl ether), hydroquinone, 4-methoxy-1-naphthol, hindered amine antioxidants, 1,1-diphenyl-2-picrylhydrazyl free radicals , N-oxide compounds, piperidine 1-oxyl free radical compounds, pyrrolidine 1-oxyl free radical compounds, N-nitrosophenylhydroxylamines, nitrogen-containing heterocyclic mercapto compounds, thioether antioxidants, hindered phenols Antioxidants, ascorbic acids, zinc sulfate, thiocyanates, thiourea derivatives, various sugars, phosphate antioxidants, nitrites, sulfites, thiosulfates, hydroxylamine derivatives, dicyandiamide Polycondensates real sharp emission polyamines, phenothiazine, and the like.

Specific examples of the radical polymerization inhibitor include the following compounds.

Examples of the phenolic compound include the following compounds: phenol, alkylphenol, such as o-, m- or p-cresol (methylphenol), 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-dihydroxybenzol), 2 (1'-methylcyclohexyl-1'-yl) -4,6-dimethylphenol, 2- or 4- (1'-phenyleth-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 Cholesin from Aktiangesellchaft, 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-oct Decyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-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-t-butyl-4-hydroxyphenyl) propionyloxyethyl-isocyanurate, 1,3,5-tris- (2 , 6-Dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate or pentaerythrit-tetrakis- [β- (3,5-di-tert-butyl-4-hydroxyphenyl) propione , 2,6-di-t-butyl-4-dimethylaminomethylphenol, 6-s-butyl-2,4-dinitrophenol, Irganox 565, 1010, 1076, 1141, from Firma Ciba Spezialitaenchemie 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-undecanediol -Bis- [3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate], 4,8-dioxa-1,11-undecandiol-bis-[(3'-t-butyl-4 '-Hydroxy-5'-methylphenyl) propionate], 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-tert-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-t-butyl- -Hydroxy-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-t-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'-hydro Xy-2'-methylphen-1'-yl) butane and t-butylcatechol, and aminophenols such as p-aminophenol, nitrosophenols such as p-nitrosophenol, p-nitroso-o-cresol, alkoxyphenols For example, 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-me Xylbenzaldehyde (vanillin), 4-hydroxy-3-ethoxybenzaldehyde (ethylvanillin), 3-hydroxy-4-methoxybenzaldehyde (isovanillin), 1-((4-hydroxy-3-methoxyphenyl) ethanone (acetovanillin), Eugenol, dihydroeugenol, isoeugenol, tocopherol, for example 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 include hydroquinone or hydroquinone monomethyl ether (4-methoxyphenol), methylhydroquinone, 2,5-di-t-butylhydroquinone, 2-methyl-p-hydroquinone, 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-cyclohexanedione-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-dimethylindo Aniline, N, N-diphenyl-p-benzoquinonediimine, 1,4-benzo Nondioxime, cerlignon, 3,3'-di-t-butyl-5,5'-dimethyldiphenoquinone, p-rosoleic acid (orine), 2,6-di-t-butyl-4-benzylidene-benzoquinone, 2 , 5-di-tert-butyl-amylhydroquinone is preferred.

Examples of N-oxyl (nitroxyl- or N-oxyl-group, a compound having at least one> NO— group) include, for example, 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, BASF Aktinengesellchaft Ubinul 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-trimethylsilyloxypiperidine, 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-tetramethylpiperi N-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-Tetramethylpiperidin-4-yl) ester, bis- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate, 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) adipamide, N- (1-oxyl-2,2,6,6-tetramethyl Piperidin-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′-bis- (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) are preferred. is there.

As the aromatic amine or phenylenediamine, for example, N, N-diphenylamine, N-nitroso-diphenylamine, nitrosodiethylaniline, p-phenylenediamine, N, N'-dialkyl-p-phenylenediamine (in this case, the alkyl groups are the same) Or may be different, each independent of one another, containing 1 to 4 carbon atoms and may be linear or molecular)), for example N, N'-di-iso-butyl-p-phenylenediamine N, N'-di-iso-propyl-p-phenylenediamine, Irumaox 5057 from Firma Ciba Specialiaetenchemie, N-phenyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N-isopropyl- N-phenyl-p-phenylenediamine N, N'-di-s-butyl-p-phenylenediamine (BASF, Kerobit BPD), N-phenyl-N'-isopropyl-p-phenylenediamine (Vulkanox, Bayer AG 4010) ), N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, N-phenyl-2-naphthylamine, iminodibenzyl, N, N′-diphenylbenzidine, N-phenyltetraaniline, acridone 3-hydroxydiphenylamine and 4-hydroxydiphenylamine are preferred.

Examples of imines 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 sulfonamides that are effective as radical polymerization inhibitors include N-methyl-4-toluolsulfonamide, Nt-butyl-4-toluolsulfonamide, and Nt-butyl-N-oxyl-4-toluene. Allsulfonamide, N, N′-bis (4-sulfanylamide) piperidine, 3-{[5- (4-aminobenzoyl) -2,4-dimethylbenzoylsulfonyl] ethylamino} -4-methylbenzolsulfonic acid is there.

Examples of oximes effective 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, Salicylaldoxime, 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-furanylethanedio It may be a dioxime or other aliphatic or aromatic oxime or alkyl transfer agent such as its reaction product with an alkyl halogenide, -triflate, -sulfonate, -tosylate, -carbonate, -sulfate, -phosphate, etc. .

Examples of hydroxylamine include N, N-diethylhydroxylamine and compounds described in PCT / EP03 / 03139 international patent application.

As the urea derivative, for example, urea or thiourea is suitable.

The phosphorus-containing compound is, for example, triphenylphosphine, triphenylphosphite, hypophosphorous acid, trinonylphosphite, triethylphosphite, or diphenylisopropylphosphine.

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

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

Other examples include metal salts such as carbonic acid, chloride, dithiocarbamic acid, sulfuric acid, salicylic acid, acetic acid, stearic acid, and ethylhexanoic acid (copper, manganese, cerium, nickel, chromium, etc.).

Also, Macromol. Rapid Commun. , 28, 1929 (2007), the N-oxyl free radical compound having a vinyl ether functional group has a structure having both a polymerizable function and a radical scavenging function in the same molecule. From the viewpoint of curability and ink storage stability, It is preferable to add 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 addition amount of the radical polymerization inhibitor is preferably 1.0 to 5000 μg / g ink, and more preferably 10 to 2000 μg / g ink. If it is 1.0 μg / g or more, desired storage stability can be obtained, ink thickening and liquid repellency with respect to the ink jet nozzle can be obtained, and this is preferable from the viewpoint of ejection stability. Moreover, if it is 5000 microgram / g ink or less, the high generation sensitivity can be maintained, without impairing the acid generation efficiency of a polymerization initiator.

(Cation polymerization inhibitor)
In the active energy ray-curable inkjet ink of the present invention, it is preferable to add a cationic polymerization inhibitor together with a radical polymerization inhibitor.

Examples of the cationic polymerization inhibitor include alkali metal compounds and / or alkaline earth metal compounds or amines. As described later, it is preferable not to add alkali metal ions as much as possible, and amines are suitable.

Preferred amines are alkanolamines, N, N-dimethylalkylamines, N, N-dimethylalkenylamines, N, N-dimethylalkynylamines, and more specifically, triethanolamine, triethanolamine, Isopropanolamine, 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-dimethylundeca Nord, N, N-dimethyldodecanol N, N-dimethyltridecanolamine, N, N-dimethyltetradecanolamine, N, N-dimethylpentadecanolamine, N, N-dimethylnonadecylamine, N, N-dimethylicosylamine, N, N-dimethyleicosylamine, N, N-dimethylhenecosylamine, N, N-dimethyldocosylamine, N, N-dimethyltricosylamine, N, N-dimethyltetracosylamine, N, N-dimethyl Pentacosylamine, 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- Examples include dimethylhexadecylamine, N, N-dimethylheptadecylamine, and N, N-dimethyloctadecylamine. 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 by adding a small amount.

The addition amount of the cationic polymerization inhibitor is preferably 10 ppm to 5000 ppm. When the addition amount of the cationic polymerization inhibitor is 10 ppm or more, good storage stability is obtained, and it is preferable from the viewpoint that thickening of ink and good liquid repellency with respect to the ink jet nozzle can be obtained and discharge stability can be maintained. By setting the addition amount of the cationic polymerization inhibitor to 5000 ppm or less, the acid generation efficiency of the active energy ray initiator can be sufficiently maintained, and the curing sensitivity can be maintained.

It is also preferable to use the cationic polymerization inhibitor and the radical polymerization inhibitor in combination. It has been found that by using a radical polymerization inhibitor in combination, the storage stability of the ink can be drastically improved even if impurities and residual acid are present in the ink.

[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.

Furthermore, a small amount of solvent such as an ester solvent, an ether solvent, an ether ester solvent, a ketone solvent, an aromatic hydrocarbon solvent, or a nitrogen-containing organic solvent can be added as necessary.

Specific examples 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 Le, diethylene glycol dimethyl ether, dibasic ester, methoxybutyl acetate, etc., can be mentioned. When these are added to the ink in an amount of 1.5 to 30%, preferably 1.5 to 15%, the adhesion to a resin recording medium such as polyvinyl chloride is improved.

Other specific examples include alkylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, and alkylenes such as ethylene glycol dibutyl ether and tetraethylene glycol dimethyl ether. Examples include glycol dialkyl ethers, 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, and propylene glycol diacetate.

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-based 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.

Fluorosurfactant means a substance obtained by substituting part or all of it with fluorine instead of hydrogen bonded to carbon of a 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, Also, the product name of Licobet VPF is available from Farbeberke-Hoechst and the name of footage is available from Neos.

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 ink.

If the surface tension of the ink is 15 mN / m or more, the area around the nozzles of the inkjet head does not get wet and the discharge capacity does not decrease. If the surface tension is less than 35 mN / m, the surface energy is lower than that of normal paper. This is preferable because the recording medium made of paper or resin is well wetted and does not cause whitening.

[Ink properties]
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., the share rate dependency is as small as possible, the surface tension is in the range of 22 to 35 mN / m at 25 ° C., and when a pigment is used as a colorant, It is preferable that there is no gel-like substance having an average particle size exceeding 1.0 μm other than the particles, 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 by the electrolyte. In this case, it is necessary to adjust the electric conductivity to 0.5 mS / cm or more.

In addition, as a physical property of the ink-jet ink of the present invention, a more preferable form is that the calorific value per unit mass is measured when the DSC measurement of the ink is performed in the range of 25 ° C. to −25 ° C. at the rate of 5 ° C. The exothermic peak of 10 mJ / mg or more is not exhibited. 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.

〔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, etc., 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, 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, LLSP20133 (above, made by Sakurai Co., Ltd.), P-370B, P-400M (above , Manufactured by Kambo Plus Co., Ltd.), S02P, S 2P, 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.), MPI3023 (manufactured by Toyo Corporation), Napoleon Gloss Glossy 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 / 2, 3101 / H12 / R2, 3104 / H12 / R2, 1445 / H14 / P3, 1438 / One Way Vision (manufactured by Intrcoat), JT5129PM, JT5728P, JT5822P, JT5829P, JT5829PM, JT5829PM, JT5829PM MPI1005, MPI1900, MPI2000, MPI2001, MPI2002, MPI3000, MPI3021, MPI3500, MPI3501 (above, manufactured by Avery), AM-101G, AM-501G (above, manufactured by Ginichi Corporation), FR2 ( Hanwha Japan Co., Ltd.), AY-15P, AY-60P, AY-80P, DBSP137GGH, DBSP137GGL (above, Manufactured by Insight Co., Ltd.), SJT-V200F, SJT-V400F-1 (above, manufactured by Hiraoka Oryen 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) , SP300 GWF, SPCLEARAD vinyl (above made by Catalina), RM-SJR (made by Ryoyo Corporation), Hi Lucky, New Lucky PVC (above made by LG), SIY-110, SIY-310, SIY-320 (Above, manufactured by Sekisui Chemical Co., Ltd.), PRINT MI Frontlit, PRINT XL Light weight banner (hereinafter, manufactured by Endexex), RIJET 100, RIJET 145, RIJET 165 (above, manufactured by Ritrama), NM-SG, NM-SM, NM-SM (Manufactured by Nichiei Kako Co., Ltd.), LTO3GS (manufactured by Lucio Co., Ltd.), easy print 80, performance print 80 (manufactured by Jetgraph Co., Ltd.), DSE 550, DSB 5 0, DSE 800G, DSE 802/137, V250WG, V300WG, V350WG (manufactured by Hexis Ltd.), Digital White 6005PE, 6010PE (or, Multifix Co., Ltd.).

In addition, as a recording medium having a resin base material that does not contain a 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 not containing 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.

Also, examples of the non-absorbing inorganic base material used in the present invention include a glass plate, a metal plate such as iron or aluminum, and a ceramic plate. 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 = 36.9 N / m), Sun Lloyd Uni G400 (Sumitomo Bakelite, polyvinyl chloride, surface energy = 34.5 mN / m), Sumipex 068 (Sumitomo Chemical Co., 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).

It should be noted that the surface energy of the recording medium according to the present invention can be calculated by measuring the contact angle using two or more types of liquids with 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. Discharge methods include electro-mechanical conversion methods (eg, single cavity type, double cavity type, bender type, piston type, shear mode type, shared wall type, etc.), electro-thermal conversion methods (eg, thermal ink jet) Any ejection method such as a mold, a bubble jet (registered trademark) mold, or the like may be used.

The ink jet recording method of the present invention is a recording method in which the active energy ray-curable ink jet ink of the present invention is ejected onto a recording medium from an ink jet nozzle and then irradiated with active energy rays such as ultraviolet rays to cure the ink. .

(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 the active energy ray is not particularly limited, and can be performed by the following method, for example. A light source is provided on both sides of the head unit described in JP-A-60-132767, and the head and the light source are scanned by a shuttle method. Irradiation is performed after a certain period of time after ink landing, and is 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 the active energy ray into two stages, it is possible to further suppress 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 aspect of the texture change.

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 heating temperature is preferably 35 to 100 ° C., more preferably in view of ejection stability, irradiation with active energy rays while maintaining the temperature 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 discharged from each nozzle is preferably 2 to 20 pl from the viewpoint 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.

FIG. 1 is a front view showing an example of the configuration of the 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.

In this recording apparatus 1, a platen unit 5 is installed under the recording medium P. The platen unit 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, and arranges discharge ports 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.

An assembly of active energy ray-curable inkjet ink droplets on the recording medium P by repeating the above operation and ejecting the recording head 3 or the active energy ray-curable inkjet ink in conjunction with the head scanning means and the conveying means. Is formed.

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

Here, as the ultraviolet lamp 8, 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), etc. can be applied, and a strip-shaped metal halide lamp, A cold cathode tube, a hot cathode tube, a mercury lamp, or a black light is preferable, and an LED is particularly preferable because of its 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 d between the recording head 3 and the irradiation means 4 (d is increased).

Further, it is more preferable that a bellows structure 7 is provided 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 showing 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, that is, the rear portion of the head carriage 2 in the direction in which the recording medium P is conveyed, the entire width of the recording medium P is also covered so as to cover the entire ink printing surface. Arranged irradiation means 4 are provided.

The ultraviolet lamp used for the illumination means 4 can be the same as that described in FIG.

In this line head system, the head carriage 2 and the irradiating means 4 are fixed, and only the recording medium P is conveyed, and ink is ejected and cured 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 the component in a composition mean mass and mass ratio.

Example 1
[Preparation of Pigment Dispersion 1]
As a yellow pigment, C.I. I. Pigment Yellow 150 (6.0 g), Azisper PB824 (manufactured by Ajinomoto Finetech Co., Ltd.) as a pigment dispersant (3.0 g), triethylene glycol divinyl ether (40 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 (6.0 g), Azisper PB824 (manufactured by Ajinomoto Finetech Co., Ltd.) as a pigment dispersant (3.0 g), triethylene glycol divinyl ether (40 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 (10.0 g), Azisper PB824 (manufactured by Ajinomoto Finetech Co., Ltd.) as a pigment dispersant (5.0 g), triethylene glycol divinyl ether (34 g), 0.5 mm zirconia beads (200 g) The pigment dispersion 3 was obtained by placing in a 100 ml polypropylene sealed container together with (part by mass) 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 (10.0 g), Azisper PB824 (manufactured by Ajinomoto Finetech Co., Ltd.) as a pigment dispersant, 5.0 g, Diethylene glycol monovinyl ether (34 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 4.

[Preparation of Pigment Dispersion 5]
As a black pigment, 6.0 g of carbon black MA-7, 3.0 g of Ajisper PB824 (manufactured by Ajinomoto Finetech Co., Ltd.), 40 g of triethylene glycol divinyl ether as a pigment dispersant, 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 EQUIIPMENT CO.). Got.

[Preparation of Pigment Dispersion 6]
As a cyan pigment, C.I. I. Pigment Blue 15: 4 (10.0 g), Solsperse 24000SC (manufactured by Nippon Lubrizol Co., Ltd.) as a pigment dispersant, 5.0 g, and dodecyl vinyl ether 34 g, together with 200 g (200 parts by mass) of 0.5 mm zirconia beads In a 100 ml polypropylene sealed container, dispersion was performed for 6 hours using a paint shaker (TWIN-ARM ONE-GALLON SHAKER 5400 manufactured by RED DEVIL EQUIMENT CO.) To obtain pigment dispersion 6.

[Preparation of ink]
Stir the pigment ink dispersion, acceptor monomer, donor monomer, photopolymerization initiator, radical polymerization inhibitor, and cationic polymerization inhibitor at room temperature (23 ° C.) for 30 to 60 minutes so that the compositions shown in Tables 1 to 4 are obtained. By mixing, ink jet inks, inks 1 to 15 and 18 to 45 were produced.

The materials used are as follows.

In addition, the pigment dispersion 1 was used for the yellow pigment dispersion, the pigment dispersion 2 was used for the magenta pigment dispersion, and the pigment dispersion 5 was used for the black pigment dispersion.

As the cyan pigment dispersion, the pigment dispersion 3 was used in the

inks

1, 2, 7 to 15, 18 to 21, and 23 to 45, and the pigment dispersion 6 was used in the ink 22.

Hereinafter, the compounds described in Tables 1 to 4 will be described below.

(Bifunctional acceptor monomer)
Compound 1: M-3 (charge = −0.27, molecular weight = 462.49, specific example of compound represented by general formula (1))
Compound 2: M-44 (charge = −0.27, molecular weight = 304.34, specific example of compound represented by general formula (1))

Compounds 1 and 2 were synthesized by a conventionally known method using a method described in JP-A No. 11-124403 or Macromolecular Chemical and physics, 2009, 210, 269-278.

Compound 3: Compound represented by the following formula (charge = −0.25, molecular weight = 358.34)

Compound 3 was synthesized by the following known method. Namely, in a 1 liter three-necked flask, while adding 206 g (1.2 mol) of diethyl maleate and 42.2 g (0.4 mol) of diethylene glycol and stirring, 4.7 g (27 mmol) of paratoluenesulfonic acid monohydrate, Add 0.2 g of hydroquinone. After stirring at 160 ° C. for 18 hours, the remaining diethyl maleate was distilled off under reduced pressure, and the column was purified after washing with sodium bicarbonate water and ion-exchanged water to obtain Compound 3. Pale yellow oil.

(Monofunctional acceptor monomer)
Compound 4: M-38 (charge = −0.27, molecular weight = 281.35, specific example of compound represented by general formula (1))

Compound 4 was synthesized by a conventionally known method using a method described in JP-A No. 11-124403 or Macromolecular Chemical and physics, 2009, 210, 269-278.

Dibutyl fumarate (charge = -0.27, molecular weight = 228.28)

(Bifunctional donor monomer)
TEGDVE: Triethylene glycol divinyl ether (charge = −0.54, molecular weight = 202.25, manufactured by BASF Japan Ltd.)

(Monofunctional donor monomer)
DEGMVE: Diethylene glycol monovinyl ether (charge = −0.54, molecular weight = 132.16, manufactured by Maruzen Petrochemical Co., Ltd.)
DDVE: dodecyl vinyl ether (charge = −0.54, molecular weight = 212.38, BASF Japan Ltd.)

For the charge of the above compound, use SPARTAN'08 for Windows (registered trademark) as molecular orbital calculation software, and use Equilibrium Geometry at Ground state Hartley-Fock 3-21G in Vacuum as the calculation method. The value of charge is expressed using Natural atomic charge.

(Photopolymerization initiator)
TPO: Diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide SPEEDCURE TPO (LAMBSON, LTD)
ITX: Mixture of 2-isopropylthioxanthone and 4-isopropylthioxanthone SPEEDCURE ITX (LAMBSON, LTD)

(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.)

(Radical polymerization inhibitor)
UV-10: Bis (2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl) sebacate IRGASTAB UV-10 (BASF Japan)
(Cation polymerization inhibitor)
2MAE: 2-methylaminoethanol (Kanto Chemical Co., Inc.)

The curing sensitivity, viscosity, curing shrinkage, weather resistance, solvent resistance, and flexibility of the obtained ink were evaluated by the following methods.

(Curing sensitivity)
Each ink was applied on a polyethylene terephthalate film with a wire bar (No. 3), irradiated with light by a 385 nm LED with an output of 2 W / cm ² , and touched on the surface of the film immediately after being cured. The amount of light (curing light amount) at the time when the property disappeared was measured.
A: Cured with a light amount of less than 50 mJ / cm ² ○: Cured with a light amount of 50 mJ / cm ² or more and less than 100 mJ / cm ² Δ: Cured with a light amount of 100 mJ / cm ² or more and less than 200 mJ / cm ² ×: 200 mJ / cm ² or more Is necessary for curing.

(Ink viscosity)
The viscosity (mPa · s) of the ink at 25 ° C. to 55 ° C. was measured with a rheometer (MCR300 manufactured by Paar Physica).
A: Within a viscosity range of 9 mPa · s to less than 12 mPa · s at 25 ° C. to less than 45 ° C. ○: Within a viscosity range of 9 mPa · s to less than 12 mPa · s at 45 ° C. to less than 50 ° C. Δ: 50 ° C. to 55 ° C. Fits in a viscosity range of 9 mPa · s or more and less than 12 mPa · s at ℃ or lower. ×: Fits in a viscosity range of 9 mPa · s or more and less than 12 mPa · s at a temperature exceeding 55 ° C.

(Curing shrinkage)
Each ink was applied on a polyethylene terephthalate film (Lumirror T-60, thickness 38 μm, manufactured by Toray Industries, Inc.) with a wire bar (No. 7) so that the wet thickness was 10 μm. The obtained coating layer was cured twice by irradiating light with a wavelength of 385 nm with an amount of light of 500 mJ / cm ² using an LED with an output of 2 W / cm ² . The film having the coating layer after curing was cut into a length direction of 75 mm and a width direction of 5 mm. Since the distance between both ends in the length direction is shortened by curling the coating layer due to curing shrinkage, the distance between both ends in the length direction was used as an index, and evaluation was performed as follows.
A: There is no warp in the film having a coating layer after curing (distance is 75 mm).
○: Slight warpage is observed in the film having the coating layer after curing (distance is 70 mm or more and less than 75 mm).
Δ: Warping is observed in the film having the coating layer after curing, but within an allowable range (distance is 65 mm or more and less than 70 mm)
X: Warp is large in the film having the coating layer after curing, and NG level (distance is less than 65 mm)

(Production of inkjet image)
Using piezo head KM512MH manufactured by Konica Minolta IJ Co., Ltd., each ink was 720 dpi x 720 dpi (dpi in the present invention represents the number of dots per 2.54 cm) at a droplet amount of 14 pl per dot. A solid image was printed on a polyvinyl chloride sheet (IJ180) with 8 passes, and 385 nm LED with an output of 2 W / cm ² was irradiated once (40 mJ / cm ² ) for each pass. A total of 8 times of irradiation irradiated a total amount of light of 320 mJ / cm ² to cure the image film and form an inkjet image.

(Weatherability)
The above solid image is stored for 600 hours in a low temperature xenon weather meter XL75 manufactured by Suga Test Instruments Co., Ltd., and the image density before and after storage is measured with X-rite (D65 light source, 2 degrees, status A). Was calculated.
Concentration remaining rate (%) = (concentration after storage) / (concentration before storage) * 100 (%)
◎: Remaining concentration ratio 95% or more ○: Remaining concentration ratio 90% or more and less than 95% △: Remaining concentration ratio 80% or more and less than 90% ×: Remaining concentration ratio 80% or less

(Solvent resistance)
In the above weather resistance evaluation, the surface of an image stored for 600 hours with a xenon fade meter was wiped 10 times with a cotton swab dipped in 2-propanol.
○: No change △: Slight color adheres to the cotton swab, but the color of the image surface is within the allowable range ×: The color of the image surface becomes light by wiping, NG level

(Flexibility)
The above prepared inkjet image is cut into a strip shape having a width of 1 cm and a length of 5 cm, both ends in the long direction are fixed with clamps, a tensile test is performed, and a tensile length until a crack is generated in the printed image is measured. The flexibility (%) was obtained by the following formula.
Flexibility (%) = (Length when crack occurs) / (Initial length = 5 cm) * 100 (%)
◎: flexibility 160% or more ○: flexibility 140% or more and less than 160% △: flexibility 120% or more and less than 140% ×: flexibility 120% or less

Tables 1 to 4 below show the ratio X, the functional group mole fraction Y, the functional group mole fraction Z, the functional group mole fraction V, and the evaluation results. Tables 5 and 6 show the molar fraction of each monomer determined from the composition and molecular weight of the monomers listed in Tables 1 to 4.

From the results of the inks 1 to 12, 30 to 37, and 38 to 45, the ratio X is between 0.66 and 2, more preferably between 0.75 and 1.1, so that the curing sensitivity is excellent and the weather resistance is improved. Ink jet ink excellent in properties, solvent resistance, ink viscosity, curing shrinkage, and flexibility can be obtained. When the ratio X is less than 0.66, curing sensitivity, weather resistance, solvent resistance, flexibility and the like are not achieved. When the ratio X exceeds 2, ink viscosity, curing shrinkage, and flexibility are not achieved.

It can also be seen that the effect of the present invention is further improved when the functional group mole fraction Y in the definition of the present invention of the polyfunctional acceptor monomer is 0.4 to 0.52.

In the inks 13 to 15 and 18 to 22, when the functional group mole fraction Z in the definition of the present invention of the monofunctional donor monomer is 0.17 to 0.58, the ink viscosity, curing shrinkage, and flexibility are better. I understand that there is. However, if it is 0.34 or more, the sensitivity is slightly lowered.

Inks 23 to 25 and 26 to 29, when the functional group mole fraction V in the definition of the present invention of the monofunctional acceptor monomer is 0.04 to 0.17, the ink viscosity, curing shrinkage, and flexibility are better. It turns out that it is. However, if it exceeds 0.10, the sensitivity is slightly lowered.

From the results of the inks 1 to 12, 30 to 37, and 38 to 45, when the polyfunctional acceptor monomer is a maleimide compound, the curing sensitivity and weather resistance are good, and further, it is represented by the general formula (2). It can be seen that by using maleimide, ink viscosity, curing shrinkage, and flexibility are improved.

Example 2
[Preparation of ink]
Inks 46 to 69 were produced in the same manner except that the compositions shown in Tables 7 to 12 were used in the production of the ink 1 of Example 1.

The pigment dispersion and materials used were the same as those used in Example 1 and the evaluation method.

The compounds described in Tables 7 to 12 newly used in Example 2 are described below.

(Bifunctional acceptor monomer)
Compound 5: M-2 (charge = −0.27, molecular weight = 420.41, specific example of compound represented by general formula (1))

Compound 5 was synthesized by a conventionally known method using a method described in JP-A No. 11-124403 or Macromolecular Chemical and physics, 2009, 210, 269-278.

(Monofunctional donor monomer)
2EHVE: 2-ethylhexyl vinyl ether (charge = −0.53, molecular weight = 156.27)
CHMMVE: 1,4-cyclohexanedimethanol monovinyl ether (charge = −0.54, molecular weight = 170.25)
The charge of the compound was determined in the same manner as in Example 1.

(Radical polymerization inhibitor)
BHT: 2,6-di-t-butyl-p-cresol p-methoxyphenol (cationic polymerization inhibitor)
TIPA: Triisopropanolamine KOH: Potassium hydroxide value

As additional evaluation, for ink stored at 60 ° C. for 1 week in a sealed container, curing sensitivity 2 (the same evaluation method as described in Example 1), ink viscosity change (evaluation criteria are shown below), and ink odor (evaluation) The criteria are shown below).

(Ink viscosity change)
The viscosity of the ink before storage was measured with a rheometer (MCR300 manufactured by Paar Physica) while changing the temperature, and a temperature T1 at which the viscosity was 10 mPa · s was obtained. Next, the viscosity of the ink after storage at temperature T1 was measured in the same manner. At this time, the fluctuation rate (%) of the viscosity after storage with respect to the viscosity before storage was determined as follows.
Fluctuation rate (%) = | (viscosity after storage−10 mPa · s) / (10 mPa · s) | * 100 (%)
A: Fluctuation rate is less than 5% B: Fluctuation rate is 5% or more and less than 10% Δ: Fluctuation rate is 10% or more, less than 15% X: Fluctuation rate is 15% or more.

(Ink odor)
The odor of the ink after storage was sensory evaluated.
A: No odor B: Slight odor but not unpleasant.
Δ: Odor is present, but within an acceptable range for ink jet printing.
X: There is an unpleasant odor and it is outside the allowable range. Ventilation or odor reduction measures such as masks and drafts are required.

Tables 7 to 12 below show the ratio X, the functional group mole fraction Y, the functional group mole fraction Z, the functional group mole fraction V, and the evaluation results. Tables 13 and 14 show the molar fraction of each monomer determined from the composition and molecular weight of the monomers listed in Tables 7 to 12.

The ratio X of the present invention (between 0.66 and 2), the functional group mole fraction Y in the definition of the present invention of the polyfunctional acceptor monomer is (0.4 to 0.52), the monofunctional donor monomer book The functional group mol fraction Z in the definition of the invention is (0.17 to 0.58), and the functional group mol fraction V in the definition of the present invention of the monofunctional acceptor monomer is (0.04 to 0.17). In the ink-jet ink that satisfies, when combined with radical polymerization inhibitor and cationic polymerization inhibitor, it has excellent curing sensitivity, weather resistance, solvent resistance, ink viscosity, curing shrinkage, flexibility, and curing sensitivity after storing the ink. It can be seen that the ink viscosity change rate and odor are more preferable. Even when only a radical polymerization inhibitor is added, or when only a cationic polymerization inhibitor is added, the curing sensitivity, ink viscosity change rate, and odor after ink storage are within the allowable range. It can be seen that when a cationic polymerization inhibitor is used in combination, the performance is further improved.

This application claims priority based on Japanese Patent Application No. 2011-081530 filed on Apr. 1, 2011. The contents described in the application specification and the drawings are all incorporated herein.

The inkjet ink of the present invention is excellent in curing sensitivity, weather resistance of the cured film, solvent resistance, excellent in viscosity stability when stored for a long period of time, and has been printed without curling of printed matter due to curing shrinkage of the ink. The flexibility of the ink is excellent, and it is suitable as an inkjet ink using a CT polymerization system.

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 Ultraviolet lamp 31 Ink ejection part P Recording medium h1 Distance between irradiation means 4 and recording medium P h2 Ink ejection part 31 and recording medium P D Distance between the recording head 3 and the irradiation means 4

Claims

In an active energy ray-curable inkjet ink containing at least one acceptor monomer and at least one donor monomer,
The acceptor monomer contains a polyfunctional acceptor monomer, the donor monomer contains a monofunctional donor monomer,
An active energy ray-curable inkjet ink, wherein a compounding ratio of the acceptor monomer and the donor monomer satisfies the formulas (1) and (2).
Formula (1) 0.66 <= X <= 2

[In Formula (2),
a 1 ~ a p represent mole fractions of the respective acceptor monomers A 1 ~ A p to the sum of all acceptor monomers and donor monomer,
b 1 to b p represent the number of functional groups in one molecule of each acceptor monomer A 1 to A p ,
d 1 to d q represent the mole fraction of each donor monomer D 1 to D q with respect to the sum of all acceptor monomers and donor monomers.
The active energy ray-curable inkjet ink according to claim 1, comprising a radical polymerization inhibitor and a cationic polymerization inhibitor.
2. The active energy ray-curable inkjet ink according to claim 1, wherein the acceptor monomer contains at least one monomer selected from maleimides, maleate esters, and fumarate esters.
The active energy ray-curable inkjet ink according to claim 1, wherein the acceptor monomer contains a maleimide compound represented by the following general formula (1).

[Where,
R 1 and R 2 each independently represents 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 represent a divalent organic linking group in which groups selected from an alkylene group, an alkyleneoxy group, an arylene group, an ester group, an ether group, and a thioether group are combined;
Y 2 represents a divalent group having an asymmetric carbon when n is 1, and when n is 2 or more, each independently represents a divalent group having a single bond or an asymmetric carbon, And at least one of the plurality of Y 2 is a divalent group having an asymmetric carbon,
Z represents a hydrogen atom, an alkyl group, an alkyloxy group, an alkyl ester group or a hydroxyl group when n is 1, and when n is 2 or more, an alkylene group, an alkyleneoxy group, an arylene group, an ester group, an ether An n-valent linking group in which a group selected from a group and a thioether group is combined;
n represents an integer of 1 to 6,
n1 and n2 each independently represent 0 or 1]
The active energy ray-curable inkjet ink according to claim 4, wherein the polyfunctional acceptor monomer is a compound in which n is 2 in the general formula (1).
The active energy ray-curable inkjet ink according to claim 1, wherein the acceptor monomer contains a maleimide compound represented by the following general formula (2).

[Where,
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,
A 12 represents a divalent hydrocarbon group having an asymmetric center,
Y 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, and n represents 0 or 1]
The active energy ray-curable inkjet ink according to claim 1, wherein the monofunctional donor monomer is a vinyl ether compound represented by the following general formula (3).

[Where,
R 3 , R 4 and R 5 each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group,
R 6 represents an alkyl group, a cycloalkyl group or an aryl group.
The active energy ray-curable inkjet according to claim 1, wherein the functional group mole fraction Y of the polyfunctional acceptor monomer represented by the following formula (3) is 0.4 or more and 0.52 or less. ink.

[In Formula (3),
e 1 ~ e r represent the mole fraction of each multi-functional acceptor monomers E 1 ~ E r with respect to the sum of all acceptor monomers and donor monomer,
f 1 ~ f r represent the number of functional groups in one molecule of the multifunctional acceptor monomers E 1 ~ E r]
2. The active energy ray-curable inkjet ink according to claim 1, wherein the monofunctional donor monomer represented by the following formula (4) has a functional group mole fraction Z of 0.17 to 0.58.

[In Formula (4),
g 1 to g s represent the mole fraction of each monofunctional donor monomer G 1 to G s relative to the sum of all acceptor monomers and donor monomers]
The acceptor monomer further comprises a monofunctional acceptor monomer;
2. The active energy ray-curable inkjet according to claim 1, wherein the monofunctional acceptor monomer represented by the following formula (5) has a functional group mole fraction V of 0.04 to 0.17. ink.

[In Formula (5),
h 1 to h t represent the mole fraction of each monofunctional acceptor monomer H 1 to H t with respect to the sum of all acceptor monomers and donor monomers]
The active energy ray-curable inkjet ink according to claim 1, wherein the X satisfies a range of 0.75 to 1.1.
The active energy ray-curable inkjet ink according to claim 1, further comprising a photopolymerization initiator.
An ink jet recording method using the active energy ray-curable ink jet ink according to claim 1.