JP5419605B2 - Ink composition and inkjet recording method - Google Patents

Description

  The present invention relates to an ink composition and an ink jet recording method.

An ink jet system that ejects an ink composition as droplets from an ink ejection port is small and inexpensive, and is used in many printers because it can form an image without contact with a recording medium. Among these inkjet methods, the piezo inkjet method that ejects ink using deformation of a piezoelectric element and the thermal inkjet method that ejects droplets of an ink composition using the boiling phenomenon of the ink composition due to thermal energy are high resolution. It has a feature that it is excellent in high-speed printability.
Recently, not only photo printing and document printing for home use or office use, but also commercial printing equipment and industrial printing equipment using an ink jet printer have been developed.
In contrast to the conventional ink jet ink composition and ink jet recording method for home or office use, the ink jet ink composition and ink jet recording method for commercial printing equipment and industrial printing equipment include ink jet dedicated paper and copy paper. In addition, there is a strong demand for not only a non-permeable recording medium such as plastic but also adhesion and excellent long-term ejection reliability. In recent years, ultraviolet curable inkjet compositions and ultraviolet curable inkjet recording methods have attracted attention as inkjet ink compositions and inkjet recording methods that satisfy these performances.

Patent Document 1 discloses an ultraviolet curable ink jet composition mainly composed of a (meth) acrylate compound as a polymerizable monomer, and means for curing these compositions, such as a high-pressure mercury lamp, a metal halide lamp, and an electrodeless discharge lamp. An ultraviolet curable ink jet recording method using the above is disclosed.
Patent Document 2 discloses an ultraviolet curable inkjet composition mainly composed of a (meth) acrylate compound as a polymerizable monomer, and an ultraviolet curable inkjet recording method using an ultrahigh pressure mercury lamp as a means for curing these compositions. Is disclosed.
Patent Document 3 discloses an ultraviolet curable inkjet composition mainly composed of an oxetane compound and an epoxy compound as polymerizable monomers, and an ultraviolet curable inkjet recording method using an ultraviolet LED as means for curing these compositions. Has been.
Further, Patent Document 4 discloses an ultraviolet curable inkjet composition mainly composed of an oxetane compound and an epoxy compound having an ester moiety as a polymerizable monomer, and ultraviolet curing using a fluorescent tube as a means for curing these compositions. A type ink jet recording method is disclosed.

Japanese Patent No. 4051928 JP 2008-183727 A JP 2004-243548 A JP 2006-206716 A

As described above, various ultraviolet light sources are used as means for curing the ink composition, and the ink composition has suitability (curability and adhesion) for various light sources. It is hoped that.
An object of the present invention, that is, a problem to be solved by the present invention is to provide an ink composition excellent in curability and adhesion to various light sources and an ink jet recording method.

The above object has been achieved by the means described in <1> or <10> below. It is shown below with <2>-<9> which are preferable embodiments.
<1> An epoxy compound and an oxetane compound, wherein the epoxy compound includes a monofunctional epoxy compound represented by the formula (1) and a polyfunctional epoxy compound having three or more epoxy groups. An ink composition,

（式（１）中、Ｒ¹〜Ｒ⁶はそれぞれ独立に、水素原子、アルキル基、−Ｒ⁷−（Ｏ−Ｒ⁸）_n−Ｒ⁹、アルコキシ基、水酸基、又は、エステル結合を有する一価の有機基を表し、Ｒ⁷は単結合、又は、アルキレン基を表し、Ｒ⁸はそれぞれ独立に、アルキレン基を表し、Ｒ⁹は水素原子、アルキル基、アルコキシ基、又は、水酸基を表し、Ｒ¹〜Ｒ⁶のうち少なくとも１つはエステル結合を有する一価の有機基であり、Ｒ¹〜Ｒ⁶のうちの２つ以上が結合して環を形成していてもよい。）

(In the formula (1), R ^{1 to} R ⁶ each independently has a hydrogen atom, an alkyl group, —R ⁷ — (O—R ⁸ ) _n —R ⁹ , an alkoxy group, a hydroxyl group, or an ester bond. R ⁷ represents a single bond or an alkylene group, R ⁸ independently represents an alkylene group, R ⁹ represents a hydrogen atom, an alkyl group, an alkoxy group, or a hydroxyl group, At least one of R ^{1 to} R ⁶ is a monovalent organic group having an ester bond, and two or more of R ^{1 to} R ⁶ may be bonded to form a ring.)

<2> The ink composition according to <1>, wherein the total content of the epoxy compound is greater than the total content of the oxetane compound;
<3> The ink composition according to <1> or <2>, wherein the epoxy compound further includes a polyfunctional epoxy compound having two epoxy groups.
<4> The total content Mmono of the monofunctional epoxy compound and the total content Mmulti of the polyfunctional epoxy compound satisfy the relationship of 3 × Mmono> Mmulti, and any one of the above items <1> to <3> Ink composition,
<5> The ink composition according to any one of <1> to <4>, wherein the polyfunctional epoxy compound having three or more epoxy groups is an alicyclic epoxy compound.
<6> The ink composition according to <3>, wherein the polyfunctional epoxy compound having two epoxy groups is an alicyclic epoxy compound.
<7> (a ¹ ) A step of discharging the ink composition according to any one of the above <1> to <6> on a recording medium, and (b ¹ ) the discharged ink composition A step of irradiating actinic radiation to cure the ink composition.

  ADVANTAGE OF THE INVENTION According to this invention, the ink composition excellent in sclerosis | hardenability and adhesiveness with respect to various light sources, and the inkjet recording method could be provided.

It is a schematic perspective view which shows a preferable example of the ultrahigh pressure mercury lamp used for an exposure process. FIG. 2 is a conceptual cross-sectional view showing an ultrahigh pressure mercury lamp unit 61 in FIG. 1.

In contrast to radical polymerization type ink jet compositions mainly composed of (meth) acrylate compounds described in Patent Documents 1 and 2, cationic polymerization types mainly composed of oxetane compounds and epoxy compounds described in Patent Documents 3 and 4. The inkjet composition is superior in curability, that is, cured even with low exposure energy, and therefore has an advantage in terms of suitability for a wide variety of light sources. However, the present inventors have found that when a cationic polymerization type ink-jet ink composition as described in Patent Document 3 is used, the adhesiveness to the recording medium varies depending on the type of light source. . This phenomenon is different in generation mechanism from the conventionally known deterioration of adhesion due to poor curing, in that adhesion deteriorates when exposed at a strong exposure intensity such as a metal halide lamp.
As a means for solving such a new problem “deterioration of adhesion due to a light source having strong exposure intensity”, the present inventors have used a monofunctional epoxy compound having an ester moiety described in Patent Document 4 as an ink composition. We found that adding was effective. However, in the ink composition as described in Patent Document 4, the curability deteriorates depending on the type of the light source, and thus the problem of the present invention has not been solved.
Therefore, the present inventors have examined and prepared an ink composition using a specific monofunctional epoxy compound having an ester bond, a polyfunctional epoxy compound having three or more epoxy groups, and an oxetane compound. Thus, it has been found that it is possible to obtain an ink composition having excellent curability and adhesion to various light sources.

The ink composition of the present invention contains an epoxy compound and an oxetane compound, and the epoxy compound has a monofunctional epoxy compound represented by the formula (1) and a polyfunctional epoxy having three or more epoxy groups. It is characterized by including a compound.
Further, the ink composition of the present invention can be suitably used as an ink composition for ink jet recording.

（式（１）中、Ｒ¹〜Ｒ⁶はそれぞれ独立に、水素原子、アルキル基、−Ｒ⁷−（Ｏ−Ｒ⁸）_n−Ｒ⁹、アルコキシ基、水酸基、又は、エステル結合を有する一価の有機基を表し、Ｒ⁷は単結合、又は、アルキレン基を表し、Ｒ⁸はそれぞれ独立に、アルキレン基を表し、Ｒ⁹は水素原子、アルキル基、アルコキシ基、又は、水酸基を表し、Ｒ¹〜Ｒ⁶のうち少なくとも１つはエステル結合を有する一価の有機基であり、Ｒ¹〜Ｒ⁶のうちの２つ以上が結合して環を形成していてもよい。）

(In the formula (1), R ^{1 to} R ⁶ each independently has a hydrogen atom, an alkyl group, —R ⁷ — (O—R ⁸ ) _n —R ⁹ , an alkoxy group, a hydroxyl group, or an ester bond. R ⁷ represents a single bond or an alkylene group, R ⁸ independently represents an alkylene group, R ⁹ represents a hydrogen atom, an alkyl group, an alkoxy group, or a hydroxyl group, At least one of R ^{1 to} R ⁶ is a monovalent organic group having an ester bond, and two or more of R ^{1 to} R ⁶ may be bonded to form a ring.)

  Hereinafter, the present invention will be described in detail.

(Ink composition)
The ink composition of the present invention is an ink composition that can be cured by actinic radiation, and is an oil-based ink composition.
“Actinic radiation” in the present invention is not particularly limited as long as it is an actinic radiation capable of imparting energy capable of generating a starting species in the ink composition by the irradiation, and is broadly α-ray, γ-ray, X-rays, ultraviolet rays (UV), visible rays, electron beams and the like are included, and among them, ultraviolet rays and electron beams are preferable from the viewpoint of curing sensitivity and device availability, and ultraviolet rays are particularly preferable. Therefore, the ink composition of the present invention is preferably an ink composition that can be cured by irradiation with ultraviolet rays.

(A) Epoxy Compound The ink composition of the present invention contains an epoxy compound.
The ink composition of the present invention includes at least a monofunctional epoxy compound represented by the formula (1) and a polyfunctional epoxy compound having three or more epoxy groups as an epoxy compound. The ink composition of the present invention may contain an epoxy compound other than the monofunctional epoxy compound represented by the formula (1) and a polyfunctional epoxy compound having three or more epoxy groups.

(A-1) Monofunctional epoxy compound represented by formula (1) The ink composition of the present invention contains a monofunctional epoxy compound represented by formula (1).
In the formula (1), R ^{1 to} R ⁶ each independently have a hydrogen atom, an alkyl group, —R ⁷ — (O—R ⁸ ) _n —R ⁹ , an alkoxy group, a hydroxyl group, or an ester bond. Represents a monovalent organic group, and at least one of R ^{1 to} R ⁶ is a monovalent organic group having an ester bond.
Examples of the ester bond in the monovalent organic group having an ester moiety include a carboxylic acid ester bond, a sulfonic acid ester bond, and a phosphate ester bond. Among these, a carboxylic ester bond is preferable. By using a monofunctional epoxy compound having a monovalent organic group having a carboxylic acid ester bond, the substrate adhesion is improved when various light sources are used.
The monovalent organic group having an ester bond is not particularly limited as long as it has at least one ester bond, but is preferably a monovalent organic group having 2 to 50 carbon atoms, and has 4 carbon atoms. More preferably, it is a monovalent organic group of ˜20.
In addition, the monovalent organic group having an ester bond is preferably a group represented by the following formula (Es-1) or formula (Es-2).

（式（Ｅｓ−１）及び式（Ｅｓ−２）中、Ｒ^e1は単結合、又は、二価の炭化水素基を表し、Ｒ^e2は一価の炭化水素基を表し、波線部分は式（１）におけるシクロヘキサン環との結合位置を表す。）

(In the formulas (Es-1) and (Es-2), R ^e1 represents a single bond or a divalent hydrocarbon group, R ^e2 represents a monovalent hydrocarbon group, and the wavy line represents the formula ( Represents the bonding position with the cyclohexane ring in 1).

The divalent hydrocarbon group for R ^e1 may be linear, branched or have a ring structure. Further, the divalent hydrocarbon group in R ^e1 preferably has 1 to 20 carbon atoms, and more preferably 1 to 8 carbon atoms.
The monovalent hydrocarbon group for R ^e2 may be linear, branched or have a ring structure. The monovalent hydrocarbon group in R ^e2 preferably has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, and still more preferably 1 to 3 carbon atoms.
The total carbon number of R ^e1 and R ^{e2 in} the formula (Es-1) or the formula (Es-2) is preferably 1 to 50, and more preferably 3 to 20.
In addition, R ^e1 and R ^e2 in the formula (Es-1) or the formula (Es-2) may have an ethylenically unsaturated bond.
In addition, R ^e1 is preferably a single bond or an alkylene group, and more preferably a single bond.
In addition, R ^e2 is preferably an alkyl group or an alkenyl group, more preferably an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 1 to 8 carbon atoms, a methyl group, an ethyl group More preferably, it is a group or an allyl group.

On the other hand, R ^{1 to} R ⁶ other than the monovalent organic group having an ester moiety in the formula (1) are each independently a hydrogen atom, an alkyl group, —R ⁷ — (O—R ⁸ ) _n —R ^9. An alkoxy group or a hydroxyl group, preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and a hydrogen atom or a methyl group. More preferred examples.
Wherein ^{-R 7 - (O-R 8} ) R 7 in _n -R ⁹ is a single bond or represents an alkylene group, are each R ⁸ independently represents an alkylene group, R ⁹ is a hydrogen atom, an alkyl group, Represents an alkoxy group or a hydroxyl group, and n represents an integer of 1 or more.
n is preferably an integer of 1 to 50, and more preferably an integer of 1 to 20.
Among these, as R ^{1 to} R ⁶ other than the monovalent organic group having an ester moiety, the effects of the present invention can be sufficiently obtained, and from the viewpoint of easy acquisition of ink viscosity suitable for ejection properties, A hydrogen atom or an alkyl group is preferable, and a hydrogen atom or a methyl group is particularly preferable.
In the formula (1), two or more of R ^{1 to} R ⁶ may be bonded to form a ring.
In the monofunctional epoxy compound represented by the formula (1), the number of monovalent organic groups having an ester bond is preferably one or two. Within this range, the effects of the present invention can be sufficiently obtained, and ink viscosity suitable for ejection properties can be easily obtained.
As the substitution position of the monovalent organic group having an ester bond, preferably R ² ~R ^5, R ³ and / or R ⁴ is particularly preferred. Within this range, the effects of the present invention can be sufficiently obtained, and there is little concern about the storage stability of the ink.

  Specific examples of the monofunctional epoxy compound represented by the formula (1) include (1) -1 to (1) -21 shown below.

  Among these, as a monofunctional epoxy compound represented by Formula (1), (1) -1, (1) -2, (1) -4, (1) -5, (1) -7, ( 1) -8, (1) -20, and (1) -21 are more preferable, and (1) -1, (1) -2, (1) -7, and (1) -8 are particularly preferable.

  The total content of the monofunctional epoxy compound represented by the formula (1) in the ink composition of the present invention is preferably 5 to 80% by weight, and 8 to 50% by weight based on the total weight of the ink composition. %, More preferably 10 to 40% by weight, still more preferably 12 to 30% by weight. The effect of this invention can be exhibited more as it is the said range.

(A-2) Polyfunctional epoxy compound having three or more epoxy groups The ink composition of the present invention contains a polyfunctional epoxy compound having three or more epoxy groups.
The polyfunctional epoxy compound having three or more epoxy groups is preferably an alicyclic epoxy compound from the viewpoints of adhesion, curability, and storage stability of the ink composition. In addition, the polyfunctional epoxy compound having three or more epoxy groups is a trifunctional or tetrafunctional epoxy compound, so that the effect of the present invention can be sufficiently obtained, and the storage stability of the ink composition. It is preferable in terms of small concerns.
The polyfunctional epoxy compound having three or more epoxy groups preferably has one or more ester bonds, and more preferably one or more carboxylate ester bonds.

  As the polyfunctional epoxy compound having three or more epoxy groups, for example, a trifunctional or tetrafunctional epoxy compound represented by the following formula (2) or (3) can be preferably used.

（式（２）中、ｎ１及びｎ２はそれぞれ独立に、１〜１０の整数を表し、ｍ１及びｍ２はそれぞれ独立に、０〜２５の整数を表す。）

(In formula (2), n1 and n2 each independently represent an integer of 1 to 10, and m1 and m2 each independently represent an integer of 0 to 25.)

（式（３）中、ｎ１、ｎ２、ｎ３及びｎ４はそれぞれ独立に、１〜１０の整数を表し、ｍ１、ｍ２、ｍ３及びｍ４はそれぞれ独立に、０〜２５の整数を表す。）

(In formula (3), n1, n2, n3 and n4 each independently represents an integer of 1 to 10, and m1, m2, m3 and m4 each independently represents an integer of 0 to 25.)

Examples of commercially available trifunctional or tetrafunctional epoxy compounds that can be suitably used include Epolide GT301, Epolide GT401 (manufactured by Daicel Chemical Industries, Ltd.), and the like.
Examples of the polyfunctional epoxy compound having three or more epoxy groups other than the trifunctional or tetrafunctional epoxy compound represented by the formula (2) or the formula (3) include glycerin triglycidyl ether and trimethylolpropane triglycidyl. Ether and triglycidyl isocyanurate can be exemplified, and triglycidyl isocyanurate can be preferably exemplified.

  The total content of the polyfunctional epoxy compound having three or more epoxy groups in the ink composition of the present invention is preferably 0.1 to 20% by weight with respect to the total weight of the ink composition, and 0.3 It is more preferably ˜15% by weight, still more preferably 0.5 to 10% by weight, and particularly preferably 1 to 5% by weight. The effect of this invention can be exhibited more as it is the said range.

(A-3) Polyfunctional epoxy compound having two epoxy groups The ink composition of the present invention further includes a polyfunctional epoxy compound having two epoxy groups (also referred to as “bifunctional epoxy compound”) as an epoxy compound. It is preferable to contain.
The polyfunctional epoxy compound having two epoxy groups is preferably an alicyclic epoxy from the viewpoints of adhesion, curability, and storage stability of the ink composition.
Examples of the compound that can be suitably used as the polyfunctional epoxy compound having two epoxy groups include limonene dioxide, terpinolenedioxide, 5,6-epoxy-4,7-methano-1-oxapyro-2, 5-octane, 3,4-epoxycyclohexenylmethyl-3,4-epoxycyclohexene carboxylate, 1,2,5,6-diepoxycyclooctane, vinylcyclohexene dioxide, cyclopentadiene dioxide, dipentane dioxide, etc. Is mentioned.
Moreover, as a commercially available bifunctional epoxy compound which can be used suitably, Celoxide 3000, Celoxide 2021P (made by Daicel Chemical Industries, Ltd.), etc. are mentioned.

  When the ink composition of the present invention contains a polyfunctional epoxy compound having two epoxy groups, the total content of the polyfunctional epoxy compound having two epoxy groups in the ink composition of the present invention is the total content of the ink composition. It is preferably 1 to 60% by weight, more preferably 5 to 50% by weight, still more preferably 10 to 40% by weight, and particularly preferably 15 to 40% by weight based on the weight. .

(A-4) Other epoxy compound The ink composition of the present invention includes a monofunctional epoxy compound represented by the formula (1), a polyfunctional epoxy compound having three or more epoxy groups, and two epoxy groups. An epoxy compound other than the polyfunctional epoxy compound having a cation, that is, a monofunctional epoxy compound other than the monofunctional epoxy compound represented by the formula (1) may be included, but the single compound represented by the formula (1) may be included. It is preferable not to include a monofunctional epoxy compound other than the functional epoxy compound.

  Examples of the monofunctional epoxy compound other than the monofunctional epoxy compound represented by the formula (1) include phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, and allyl glycidyl ether. 1,2-butylene oxide, 1,3-butadiene monooxide, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide and the like.

  The total content Mmono of the monofunctional epoxy compound and the total content Mmulti of the polyfunctional epoxy compound in the ink composition of the present invention preferably satisfy the relationship of 3 × Mmono> Mmulti, and 3 × Mmono> Mmulti> 0. It is more preferable to satisfy the relationship of 5 × Mmono, and it is further preferable to satisfy the relationship of 1.5 × Mmono> Mmulti> 0.8 × Mmono.

(B) Oxetane compound The ink composition of the invention contains an oxetane compound.
The oxetane compound that can be used in the present invention is not particularly limited as long as it is a compound having one or more oxetanyl groups, and may be a monofunctional oxetane compound or a polyfunctional oxetane compound.

  Examples of monofunctional oxetane compounds include 3-ethyl-3-hydroxymethyloxetane, 3- (meth) allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanylmethoxy) methylbenzene, 4-fluoro- [1- (3-Ethyl-3-oxetanylmethoxy) methyl] benzene, 4-methoxy- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, [1- (3-ethyl-3-oxetanylmethoxy) ) Ethyl] phenyl ether, isobutoxymethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyl (3-ethyl-3-oxetanylmethyl) ether 2-ethylhexyl (3-ethyl-3-oxetani Methyl) ether, ethyl diethylene glycol (3-ethyl-3-oxetanylmethyl) ether, dicyclopentadiene (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, Dicyclopentenyl (3-ethyl-3-oxetanylmethyl) ether, tetrahydrofurfuryl (3-ethyl-3-oxetanylmethyl) ether, tetrabromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tetrabromophenoxy Ethyl (3-ethyl-3-oxetanylmethyl) ether, tribromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tribromophenoxyethyl (3-ethyl-3-oxetanylmethyl) ether 2-hydroxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxypropyl (3-ethyl-3-oxetanylmethyl) ether, butoxyethyl (3-ethyl-3-oxetanylmethyl) ether, pentachlorophenyl (3 -Ethyl-3-oxetanylmethyl) ether, pentabromophenyl (3-ethyl-3-oxetanylmethyl) ether, bornyl (3-ethyl-3-oxetanylmethyl) ether and the like.

  Examples of the polyfunctional oxetane compound include 3,3′-oxybismethylene bis (3-ethyloxetane), 3,7-bis (3-oxetanyl) -5-oxanonane, 3,3 ′-(1,3- (2-Methylenyl) propanediylbis (oxymethylene)) bis- (3-ethyloxetane), 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 1,2-bis [(3 -Ethyl-3-oxetanylmethoxy) methyl] ethane, 1,3-bis [(3-ethyl-3-oxetanylmethoxy) methyl] propane, ethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyl Bis (3-ethyl-3-oxetanylmethyl) ether, triethylene glycol bis (3-ethyl-3-oxetani) Methyl) ether, tetraethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, tricyclodecanediyldimethylene (3-ethyl-3-oxetanylmethyl) ether, trimethylolpropane tris (3-ethyl-3-oxetanyl) Methyl) ether, 1,4-bis (3-ethyl-3-oxetanylmethoxy) butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, pentaerythritol tris (3-ethyl-3-oxetanylmethyl) ) Ether, pentaerythritol tetrakis (3-ethyl-3-oxetanylmethyl) ether, polyethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ) Ether, dipentaerythritol pentakis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol tetrakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol hexakis (3-ethyl-3-) Oxetanylmethyl) ether, caprolactone-modified dipentaerythritol pentakis (3-ethyl-3-oxetanylmethyl) ether, ditrimethylolpropanetetrakis (3-ethyl-3-oxetanylmethyl) ether, ethylene oxide (EO) modified bisphenol A bis ( 3-ethyl-3-oxetanylmethyl) ether, propylene oxide (PO) modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, EO modified hydrogenated bisphenol Enol A bis (3-ethyl-3-oxetanylmethyl) ether, PO-modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol F (3-ethyl-3-oxetanylmethyl) ether, etc. Of polyfunctional oxetane.

  As the oxetane compound that can be used in the present invention, compounds described in detail in paragraphs 0021 to 0084 of JP-A No. 2003-341217 can also be suitably used.

The ink composition of the present invention preferably contains at least a polyfunctional oxetane compound as an oxetane compound, and more preferably contains at least a bifunctional oxetane compound.
Moreover, as an oxetane compound that can be used in the present invention, a monofunctional oxetane compound and a bifunctional oxetane compound or a bifunctional oxetane compound may be used from the viewpoint of the viscosity and tackiness of the ink composition for ink jet recording. Preferably, a bifunctional oxetane compound is used.
Moreover, the oxetane compound which can be used for this invention may use only 1 type, or may use 2 or more types together.

The total content of oxetane compounds in the ink composition of the present invention is preferably 5 to 80% by weight, more preferably 10 to 70% by weight, and more preferably 15 to 60% with respect to the total weight of the ink composition. It is more preferable that it is weight%, and it is especially preferable that it is 18-50 weight%. The effect of this invention can be exhibited more as it is the said range.
In the ink composition of the present invention, it is preferable that the total content of the epoxy compound is higher than the total content of the oxetane compound.

  The total content of the epoxy compound and the oxetane compound in the ink composition of the present invention is preferably 60 to 98% by weight, more preferably 70 to 95% by weight, and more preferably 75 to 92% by weight with respect to the total weight of the ink composition. Is more preferable. Within the above range, the curability is excellent.

Moreover, the ink composition of the present invention may contain a vinyl ether compound as a cationically polymerizable compound other than the epoxy compound and the oxetane compound.
The vinyl ether compound is not particularly limited as long as it is a compound that generates and cures a cationic polymerization reaction by applying some energy, and can be used regardless of the type of monomer, oligomer, or polymer.
The vinyl ether compound may be a monofunctional vinyl ether compound or a polyfunctional vinyl ether compound.

(C) Cationic polymerization initiator The ink composition of the present invention preferably contains a cationic polymerization initiator, and more preferably contains a photoacid generator as the cationic polymerization initiator.
As the photoacid generator that can be used in the present invention, first, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, and phosphonium are used. ^{_{-, SbF 6 -, CF 3}} SO 3 - salts. Secondly, sulfonated products that generate sulfonic acid can be mentioned. Thirdly, a halide that generates hydrogen halide can also be used. Fourthly, an iron allene complex can be mentioned.

Preferable specific examples of the cationic polymerization initiator that can be used in the present invention include the compounds (b-1) to (b-96) described in JP-A-2007-224149, and JP-A-2002-122994. The oxazole derivatives and s-triazine derivatives described in paragraphs 0029 to 0030 of the above, and the onium salt compounds and sulfonate compounds exemplified in paragraphs 0037 to 0063 of JP-A-2002-122994 are preferably used in the present invention. Can do.
A cationic polymerization initiator can be used individually by 1 type or in combination of 2 or more types.

  The content of the cationic polymerization initiator in the ink composition is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight, and 1 to 7% by weight with respect to the total weight of the ink composition. Further preferred.

(D) Sensitizer The ink composition of the present invention may contain a sensitizer.
The sensitizer absorbs specific active energy rays and enters an electronically excited state. The sensitizer in an electronically excited state comes into contact with the cationic polymerization initiator, and effects such as electron transfer, energy transfer, and heat generation occur. As a result, the cationic polymerization initiator undergoes a chemical change and decomposes to generate an acid or a cation.
Preferred examples of the sensitizer that can be used in the present invention include those belonging to the compounds listed below and having an absorption wavelength in the wavelength region of 350 nm to 450 nm.
For example, polynuclear aromatics (eg, pyrene, perylene, triphenylene, 9,10-dibutoxyanthracene, 2-ethyl-9,10-dimethoxyanthracene, etc.), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine) B, rose bengal, etc.), cyanines (eg, thiacarbocyanine, oxacarbocyanine, etc.), merocyanines (eg, merocyanine, carbomerocyanine, etc.), thiazines (eg, thionine, methylene blue, toluidine blue, etc.), acridines (For example, acridine orange, chloroflavin, acriflavine, etc.), anthraquinones (for example, anthraquinone, etc.), squaliums (for example, squalium), coumarins (for example, 7-diethylamino-4-methylcoumarin) ), And the like.

  Preferred examples of the sensitizer that can be used in the present invention include compounds represented by the following formulas (vi) to (xi).

In formula (vi), A ¹ represents a sulfur atom or NR ⁵⁰ , and R ⁵⁰ represents an alkyl group or an aryl group. L ¹ represents a nonmetallic atomic group that forms a basic nucleus of a dye in cooperation with the adjacent A ¹ and the adjacent carbon atom. R ⁵¹ and R ⁵² each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and R ⁵¹ and R ⁵² may be bonded to each other to form an acidic nucleus of the dye. W represents an oxygen atom or a sulfur atom.

In formula (vii), Ar ¹ and Ar ² each independently represent an aryl group and are linked via a bond with L ² . L ² represents —O— or —S—. W is synonymous with that shown in Formula (vi).

In the formula (viii), A ² represents a sulfur atom or NR ⁵⁹ , and R ⁵⁹ represents an alkyl group or an aryl group. L ³ represents a nonmetallic atomic group that forms a basic nucleus of a dye in cooperation with adjacent A ² and a carbon atom. R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ each independently represent a monovalent nonmetallic atomic group.

In formula (ix), A ³ and A ⁴ each independently represent —S—, —NR ⁶² —, or —NR ⁶³ —, wherein R ⁶² and R ⁶³ each independently represent a substituted or unsubstituted alkyl. Represents a group or a substituted or unsubstituted aryl group. L ⁴ and L ⁵ each independently represent a nonmetallic atomic group that forms a basic nucleus of a dye in cooperation with adjacent A ³ , A ⁴ and adjacent carbon atoms. R ⁶⁰ and R ⁶¹ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group. R ⁶⁰ and R ⁶¹ may be bonded to each other to form an aliphatic or aromatic ring.

In formula (x), R ⁶⁶ represents an aromatic ring or a hetero ring which may have a substituent. A ⁵ represents an oxygen atom, a sulfur atom, or —NR ⁶⁷ —. R ⁶⁴ , R ⁶⁵ and R ⁶⁷ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group. R ⁶⁷ and R ⁶⁴ , and R ⁶⁵ and R ⁶⁷ may be bonded to each other to form an aliphatic or aromatic ring.

In formula (xi), R ₆₈ and R ₆₉ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group. R ₇₀ and R ₇₁ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and n represents an integer of 0 to 4. When n is 2 or more, R ₇₀ and R ₇₁ can be bonded to each other to form an aliphatic or aromatic ring.

  Specific preferred examples of the compounds represented by formulas (vi) to (xi) include (C-1) to (C-26) shown below, but are not limited thereto. In the following chemical formula, Ph represents a phenyl group, and Me represents a methyl group.

The content of the sensitizer that can be used in the ink composition of the present invention is preferably 0.01 to 20% by weight with respect to the total weight of the ink composition, from the viewpoint of colorability of the ink. 15 weight% is more preferable and 0.5 to 10 weight% is still more preferable.
A sensitizer may be used individually by 1 type and may use 2 or more types together.

  In addition, the content ratio of the sensitizer and the cationic polymerization initiator in the ink composition is a cationic polymerization initiator in a weight ratio from the viewpoint of improving the decomposition rate of the cationic polymerization initiator and transmitting light. / Sensitizer = 100 to 0.01 is preferable, cationic polymerization initiator / sensitizer = 10 to 0.1 is more preferable, and cationic polymerization initiator / sensitizer = 2.5 to 0.5 is more preferable. .

(E) Colorant The ink composition of the present invention preferably contains (E) a colorant.
The colorant that can be used in the present invention is not particularly limited, and can be arbitrarily selected from known colorants such as pigments, oil-soluble dyes, water-soluble dyes, and disperse dyes. Among these, the colorant is preferably a pigment and / or an oil-soluble dye, more preferably a pigment, from the viewpoint of excellent weather resistance and rich color reproducibility.
The colorant that can be suitably used in the ink composition of the present invention is a compound that does not function as a polymerization inhibitor in a polymerization reaction that is a curing reaction, from the viewpoint of not reducing the sensitivity of the curing reaction by actinic radiation. preferable.

<Pigment>
The pigment is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include known organic pigments and inorganic pigments. Resin particles dyed with dyes, commercially available pigment dispersions and surfaces Treated pigments (for example, pigments dispersed in water, liquid organic compounds or insoluble resins, and pigment surfaces treated with resins, pigment derivatives, etc.) are also included. Examples of the pigment include, for example, “The Pigment Dictionary” edited by Seijiro Ito (2000, published by Asakura Shoten), Isao Hashimoto “Organic Pigment Handbook” (2006, published by Color Office), Herbst, K.M. Hunger, “Industrial Organic Pigments” (1992, issued by Wiley-VHC), JP 2002-12607 A, JP 2002-188025 A, JP 2003-26978 A, JP 2003-342503 A Can be mentioned.

Examples of the organic pigment and the inorganic pigment include a yellow pigment, a red pigment, a magenta pigment, a blue pigment, a cyan pigment, a green pigment, an orange pigment, a purple pigment, a brown pigment, a black pigment, and a white pigment.
Examples of the yellow pigment include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 10, 65, 73, 74, 75, 97, 98, 111, 116, 130, 167, 205, monoazo pigments, 61, 62, 100, 168, 169, Monoazo lake pigments such as 183, 191, 206, 209, 212, 12, 13, 14, 16, 17, 55, 63, 77, 81, 83, 106, 124, 126, 127, 152, 155, 170, 172, Disazo pigments such as 174, 176, 214 and 219, anthraquinone pigments such as 24, 99, 108, 193 and 199, monoazopyrazolone pigments such as 60, condensed azo pigments such as 93, 95, 128 and 166, 109, 110, 139, 173, 185 and other isoindoline pigments, 120, 151, 154, 175, 180, 181, 194 and other benz Izoazolone pigments, azomethine metal complex pigments such as 117, 129, 150 and 153, quinophthalone pigments such as 138, and quinoxaline pigments such as 213 are preferred.

  Examples of the red or magenta pigment include C.I. I. Pigment Red 193 and other monoazo lake pigments, 38 and other disazo pigments, 2, 5, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 22, 23, 31, 32, 112, 114, Naphthol AS pigments such as 146, 147, 150, 170, 184, 187, 188, 210, 213, 238, 245, 253, 256, 258, 266, 268, 269, etc. β-naphthol pigments such as 3, 4, 6, etc. 49, 53, 68 etc. β-naphthol lake pigments, 237, 239, 247 etc. naphthol AS lake pigments, 41 etc. pyrazolone pigments, 48, 52, 57, 58, 63, 64: 1, 200 etc. BONA lakes Pigment, xanthene lake pigment such as 81: 1, 169, 172, thioindigo pigment such as 88, 181, 279, 123, 149, 17 Perylene pigments such as 179, 190 and 224, condensed azo pigments such as 144, 166, 214, 220, 221, 242, and 262, anthraquinone pigments such as 168, 177, 182, 226, and 263, and anthraquinone lake pigments such as 83 Benzimidazolone pigments such as 171, 175, 176, 185, 208, etc., quinacridone pigments such as 122, 202 (including mixtures with CI Pigment Violet 19), 207, 209, 254, 255, 264, 270 Preferred are diketopyrrolopyrrole pigments such as 272 and azomethine metal complex pigments such as 257 and 271.

Examples of the blue or cyan pigment include C.I. I. Naphthol AS pigments such as CI Pigment Blue 25 and 26, phthalocyanine pigments such as 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17: 1, 75, and 79 Dye lake pigments such as 1:56, 61, 62, anthraquinone pigments such as 60, indigo pigments such as 63, and dioxazine pigments such as 80 are preferable.
Examples of the green pigment include C.I. I. Dye lake pigments such as CI Pigment Green 1 and 4, phthalocyanine pigments such as 7 and 36, and azomethine metal complex pigments such as 8 are preferable.
Examples of the orange pigment include C.I. I. Monoazo pigments such as CI Pigment Orange 1, β-naphthol pigments such as 2, 3, 5 and the like, naphthol AS pigments such as 4, 24, 38 and 74, pyrazolone pigments such as 13, 34, 36, 60, 62, 64 and 72 Benzimidazolone pigments such as 15 and 16, disazo pigments such as 15 and 16, β-naphthol lake pigments such as 17 and 46, naphthalene sulfonic acid lake pigments such as 19; perinone pigments such as 43, quinacridone pigments such as 48 and 49, 51 Anthraquinone pigments such as 61, isoindolinone pigments such as 61, isoindoline pigments such as 66, azomethine metal complex pigments such as 68, and diketopyrrolopyrrole pigments such as 71, 73 and 81 are preferred.

Examples of the brown pigment include C.I. I. BONA lake pigments such as CI Pigment Brown 5, condensed azo pigments such as 23, 41 and 42, and benzimidazolone pigments such as 25 and 32 are preferred.
Examples of the purple pigment include C.I. I. Pigment violet 1, 2, 3, 27 etc. dyed lake pigments, 13, 17, 25, 50 etc. naphthol AS pigments, 5: 1 etc. anthraquinone lake pigments, 19 etc. quinacridone pigments, 23, 37 etc. dioxazine pigments A perylene pigment such as No. 29, benzimidazolone pigment such as No. 32, and a thioindigo pigment such as No. 38 are preferred.
Examples of the black pigment include C.I. I. Indazine pigments such as CI pigment black 1, carbon black as 7, graphite as 10, magnetite as 11, anthraquinone pigment as 20 and perylene pigment as 31 and 32 are preferable.
Examples of the white pigment include C.I. I. Pigment White 4 Zinc oxide, 6 Titanium oxide, 7 Zinc sulfide, 12 Zirconium oxide (zirconium white), 18 Calcium carbonate, 19 Aluminum oxide / silicon oxide (Kaolin clay), 21 Or the barium sulfate which is 22, the aluminum hydroxide (alumina white) which is 23, the silicon oxide which is 27, and the calcium silicate which is 28 are preferable.
The inorganic particles used in the white pigment may be simple substances, or may be oxides such as silicon, aluminum, zirconium, and titanium, organometallic compounds, and composite particles with organic compounds.

  The average particle size of the pigment particles is preferably 0.005 to 0.5 μm, more preferably 0.01 to 0.45 μm, and still more preferably 0.015 to 0.4 μm. It is preferable to set selection, dispersion conditions, and filtration conditions. When the average particle size is in the above range, clogging of the head nozzle can be suppressed, and the storage stability, transparency, and curing speed of the ink composition can be maintained.

<Oil-soluble dye>
The oil-soluble dye that can be used in the present invention will be described below.
The oil-soluble dye that can be used in the present invention means a dye that is substantially insoluble in water. Specifically, the solubility in water at 25 ° C. (the mass of the dye that can be dissolved in 100 g of water) is 1 g or less, preferably 0.5 g or less, more preferably 0.1 g or less. Therefore, the oil-soluble dye means a so-called water-insoluble pigment or oil-soluble dye, and among these, an oil-soluble dye is preferable.

Of the oil-soluble dyes that can be used in the present invention, any yellow dye can be used.
For example, phenols, naphthols, anilines, pyrazolones, pyridones, aryl or heteryl azo dyes having open-chain active methylene compounds as coupling components; for example, azomethine dyes having open-chain active methylene compounds as coupling components; Examples include methine dyes such as benzylidene dyes and monomethine oxonol dyes; quinone dyes such as naphthoquinone dyes and anthraquinone dyes; and other dye species such as quinophthalone dyes, nitro / nitroso dyes, Examples include acridine dyes and acridinone dyes.

Of the oil-soluble dyes that can be used in the present invention, any magenta dye can be used.
For example, aryl or heteryl azo dyes having phenols, naphthols, anilines as coupling components; for example, azomethine dyes having pyrazolones, pyrazolotriazoles as coupling components; for example arylidene dyes, styryl dyes, merocyanine dyes, oxonol dyes Methine dyes such as: diphenylmethane dyes, triphenylmethane dyes, carbonium dyes such as xanthene dyes; quinone dyes such as naphthoquinone, anthraquinone and anthrapyridone; condensed polycyclic dyes such as dioxazine dyes, etc. Can be mentioned.

Among the oil-soluble dyes that can be used in the present invention, any cyan dye can be used.
For example, indoaniline dyes, indophenol dyes or azomethine dyes having pyrrolotriazoles as coupling components; polymethine dyes such as cyanine dyes, oxonol dyes, merocyanine dyes; carboniums such as diphenylmethane dyes, triphenylmethane dyes, xanthene dyes Examples include dyes; phthalocyanine dyes; anthraquinone dyes; aryl or heteryl azo dyes having phenols, naphthols, and anilines as coupling components; indigo / thioindigo dyes, and the like.

  Each of the above dyes may exhibit yellow, magenta, and cyan colors only after a part of chromophore (chromogenic atomic group) is dissociated. In this case, the counter cation may be an alkali metal or ammonium. Such inorganic cations may be used, organic cations such as pyridinium and quaternary ammonium salts may be used, and polymer cations having such a structure may be used.

Although not limited to the following, specific examples of preferable oil-soluble dyes include C.I. I. Solvent Black 3, 7, 27, 29 and 34; C.I. I. Solvent Yellow 14, 16, 19, 29, 30, 56, 82, 93 and 162; C.I. I. Solvent Red 1, 3, 8, 18, 24, 27, 43, 49, 51, 72, 73, 109, 122, 132 and 218; I. Solvent Violet 3; C.I. I. Solvent Blue 2,11,25,35,38,67 and 70; I. Solvent Green 3 and 7; I. Solvent Orange 2 etc. are mentioned.
Among these, particularly preferred are the Black Black PC-0850, Oil Black HBB, Oil Yellow 129, Oil Yellow 105, Oil Pink 312, Oil Red 5B, Oil Scallet 308, Vali Fast Blue chemistry 2606e Bile 2OSe 2B eO (Manufactured by Co., Ltd.), Aizen Spillon Blue GNH (manufactured by Hodogaya Chemical Co., Ltd.), Neopen Yellow 075, Neopen Magenta SE1378, Neopen Blue 808, Neopen Blue FF4012, and Neo42 Cy FF4012.

<Disperse dye>
In the present invention, a disperse dye can be used as long as it is soluble in a water-immiscible organic solvent. The disperse dye generally includes a water-soluble dye, but in the present invention, the disperse dye is preferably used as long as it is soluble in a water-immiscible organic solvent.
Preferable specific examples of the disperse dye include C.I. I. Disperse Yellow 5,42,54,64,79,82,83,93,99, 100,119,122,124,126,160,184: 1,186,198,199,201,204,224 and 237 C. I. Disperse Orange 13, 29, 31: 1, 33, 49, 54, 55, 66, 73, 118, 119 and 163; I. Disperse Red 54, 60, 72, 73, 86, 88, 91, 92, 93, 111, 126, 127, 134, 135, 143, 145, 152, 153, 154, 159, 164, 167: 1,177 , 181, 204, 206, 207, 221, 239, 240, 258, 277, 278, 283, 311, 323, 343, 348, 356 and 362; I. Disperse Violet 33; C.I. I. Disperse Blue 56, 60, 73, 87, 113, 128, 143, 148, 154, 158, 165, 165: 1, 165: 2, 176, 183, 185, 197, 198, 201, 214, 224, 225 , 257, 266, 267, 287, 354, 358, 365 and 368; I. Disperse Green 6: 1 and 9 etc. are mentioned.

The colorant that can be used in the present invention may be used alone or in combination of two or more.
In the present invention, the content of the colorant can be appropriately selected depending on the physical properties of the colorant (specific gravity, coloring power, color, etc.), and how many colors of the ink composition are combined to produce a printed material. From the viewpoint of hiding power and coloring power, it is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, and more preferably 1 to 10% by weight with respect to the weight of the whole ink composition. % Is particularly preferred.

  In the present invention, the colorant may be directly added together with each component in the preparation of the ink composition, but is used in advance for general-purpose organic solvents (methyl ethyl ketone, toluene, butanol, butyl acetate, etc.) or the present invention. A pigment dispersion (also referred to as “mill base”) may be added to a liquid medium such as a cationic polymerizable compound and dispersed to prepare a pigment dispersion. In order to avoid the problem of the solvent resistance deterioration when the medium remains in the cured image and the problem of the remaining VOC (Volatile Organic Compound), the colorant is dispersed in the cationic polymerizable compound in advance. It is preferable to mix. In consideration of workability at the time of blending, it is more preferable to select a cationically polymerizable compound having the lowest viscosity as the medium to be used.

In the ink composition of the present invention, it is preferable to use a pigment as a colorant. When used, it is preferable to contain a dispersant in order to disperse the pigment stably in the ink composition.
As the dispersant that can be used in the present invention, a polymer dispersant is preferable. The “polymer dispersing agent” in the present invention means a dispersing agent having a weight average molecular weight of 1,000 or more.
The main chain skeleton of the polymer dispersant is not particularly limited, and examples thereof include a polyurethane skeleton, a polyacryl skeleton, a polyester skeleton, a polyamide skeleton, a polyimide skeleton, a polyurea skeleton, and the like, from the viewpoint of storage stability of the ink composition. A polyurethane skeleton, a polyacryl skeleton, and a polyester skeleton are preferable. The structure of the polymer dispersant is not particularly limited, and examples thereof include a random structure, a block structure, a comb structure, and a star structure. Similarly, in terms of storage stability, a block structure or a comb structure is used. preferable.

  As the polymer dispersant, the wet dispersant DISPERBYK series 101, 102, 103, 106, 108, 109, 110, 111, 112, 116, 130, 140, 142, 145, 161, commercially available from Big Chemie, 162, 163, 164, 166, 167, 168, 170, 171, 174, 180, 182, 183, 184, 185, 2000, 2001, 2020, 2050, 2070, 2096, 2150, commercially available from Ciba Specialty Chemicals EFKA Series 4008, 4009, 4010, 4015, 4020, 4046, 4047, 4050, 4055, 4060, 4080, 4300, 4330, 4340, 4400, 4401, 4402, 4403, 4406, 4800, 5400 10, 5044, 5054, 5055, 5063, 5064, 5065, 5066, 5070, 5244, SOLSPERSE series 3000, 11200, 13240, 13650, 13940, 16000, 17000, 18000, 20000, 21000, commercially available from Lubrizol. , 24000SC, 24000GR, 26000, 28000, 31845, 32000, 32500, 32550, 32600, 33000, 34750, 35100, 35200, 36000, 36600, 37500, 38500, 39000, 53095, 54000, 55000, 56000, 71000 DISPARLON series 1210, 1220, 1831, 1850, 18 available from 0, 2100, 2150, 2200, 7004, KS-260, KS-273N, KS-860, KS-873N, PW-36, DN-900, DA-234, DA-325, DA-375, DA-550, DA-1200, DA-1401, DA-7301, Ajisper series PB-711, PB-821, PB-822, PN-411, PA-111, commercially available from Ajinomoto Co., Inc., commercially available from Air Products Surfinol series 104A, 104C, 104E, 104H, 104S, 104BC, 104DPM, 104PA, 104PG-50, 420, 440, DF110D, DF110L, DF37, DF58, DF75, DF210, CT111, CT121, CT131, CT136 , GA, TG, TGE, Olfin series STG commercially available from Nissin Chemical Industry Co., Ltd., E1004, SN Sparse Series 70, 2120, 2190 manufactured by San Nopco Co., Ltd., Adeka Coal and Adekator series commercially available from ADEKA, Examples include Sannonic series, Naroacty CL series, Emarmin series, New Pole PE series, Ionette M series, Ionette D series, Ionette S series, Ionette T series, and Sanseparr 100 available from Sanyo Chemical Industries, Ltd. .

  The preferred addition amount of the dispersant in the ink composition is such that the weight ratio (D / P) is P where the weight of the pigment in the ink composition is P and the weight of the polymer dispersant in the ink composition is D. 0.01 ≦ D / P ≦ 2.0 is preferable, 0.03 ≦ D / P ≦ 1.5 is more preferable, and 0.05 ≦ D / P ≦ 0.6 is satisfied. Is more preferable. Within the above range, pigment aggregation / sedimentation and ink viscosity increase do not occur, and an ink composition having excellent storage stability can be obtained, and an ink composition having low ink viscosity and excellent ejection stability can be obtained.

  Furthermore, at the time of dispersion, in addition to the dispersant, a dispersion aid generally called synergist (for example, SOLPERSE (Solsperse series) 5000, 12000, 22000, commercially available from Lubrizol, commercially available from Ciba Specialty Chemicals It is also preferable to improve the dispersibility and wettability of the pigment by adding various surfactants and antifoaming agents.

In the present invention, when a pigment is used as the colorant, the pigment and the dispersant are mixed and then added to the cationic polymerizable compound and dispersed, or the cationic polymerizable compound and the dispersant are mixed. It is preferable to add and disperse the pigment. For the dispersion, for example, various dispersion devices such as a ball mill, a bead mill, a sand mill, a salt mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker can be used. Among these, a bead mill dispersing device is preferable because of its excellent dispersibility.
The beads used when performing bead mill dispersion are preferably those having an average diameter of 0.01 to 3.0 mm, more preferably 0.05 to 1.5 mm, and still more preferably 0.1 to 1.0 mm. Thus, a pigment dispersion having excellent stability can be obtained.

(F) Other additives In addition to the components described above, various other additives may be used in combination with the ink composition of the present invention in accordance with the purpose.
For example, an ultraviolet absorber can be used from the viewpoint of improving the weather resistance of the obtained image. In addition, an antioxidant can be added to improve stability.
Further, various organic and metal complex anti-fading agents, conductive salts such as potassium thiocyanate, lithium nitrate, ammonium thiocyanate, dimethylamine hydrochloride for the purpose of controlling ejection properties, ink compositions and substrates In order to improve the adhesiveness, an extremely small amount of organic solvent can be added.
Moreover, various polymer compounds can be added to adjust film physical properties. High molecular compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination.
Moreover, it is preferable to contain a polymerization inhibitor. There is no restriction | limiting in particular as a polymerization inhibitor, A well-known polymerization inhibitor, a basic compound, etc. can be used.
In addition to this, if necessary, for example, leveling additives, matting agents, waxes for adjusting film properties, polyolefins, polyethylene terephthalate (PET), etc., in order to improve the adhesion to inhibit polymerization The tackifier (tackifier) which does not do etc. can be contained.

(Inkjet recording method)
In the inkjet recording method of the present invention, the ink composition of the present invention is ejected onto a recording medium (support, recording material, etc.) for inkjet recording, and actinic radiation is applied to the ink composition ejected onto the recording medium. This is a method of forming an image by irradiating and curing the ink composition.
More specifically, the inkjet recording method of the present invention comprises (a ¹ ) a step of ejecting the ink composition of the present invention onto a recording medium, and (b ¹ ) actinic radiation on the ejected ink composition. And curing the ink composition.
By including the steps (a ¹ ) and (b ¹ ), the ink jet recording method of the present invention forms an image with the ink composition cured on the recording medium.
The printed matter of the present invention is a printed matter recorded by the inkjet recording method of the present invention.
In the step (a ¹ ), an ink jet recording apparatus described in detail below can be used.

There is no restriction | limiting in particular as an inkjet recording device which can be used for the inkjet recording method of this invention, The well-known inkjet recording device which can achieve the target resolution can be selected arbitrarily and can be used. That is, any known ink jet recording apparatus including a commercially available product can discharge the ink composition onto the recording medium in the step (a ¹ ).

  Examples of the ink jet recording apparatus that can be used in the present invention include an apparatus including an ink supply system, a temperature sensor, and an actinic radiation source.

  The ink supply system includes, for example, an original tank containing the ink composition of the present invention, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head. The piezo-type inkjet head preferably has a multi-size dot of 1 to 100 pl, more preferably 8 to 30 pl, preferably 320 × 320 to 4,000 × 4,000 dpi, more preferably 400 × 400 to 1,600 ×. It can be driven so that it can discharge at a resolution of 1,600 dpi, more preferably 720 × 720 dpi. In the present invention, dpi represents the number of dots per 2.54 cm.

In the ink jet recording method using the ink composition of the present invention, the amount of applied liquid droplets per pixel of the ink composition is preferably ² pL or more and 10 pL or less, and the maximum application amount is 2.2 mg / cm ^2. It is preferably less than 8.8 mg / cm ² . More preferably the maximum application amount is 3.3 mg / cm ² or more 7.7 mg / cm ² or less.

  In the ink composition of the present invention, it is preferable that the ejected ink composition has a constant temperature. Therefore, the ink jet recording apparatus preferably includes a means for stabilizing the temperature of the ink composition. The parts to be kept at a constant temperature are all the piping systems and members from the ink tank (intermediate tank if there is an intermediate tank) to the nozzle ejection surface. That is, heat insulation and heating can be performed from the ink supply tank to the inkjet head portion.

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

  Using the above inkjet recording apparatus, the ink composition of the present invention is ejected by heating the ink composition to preferably 25 to 80 ° C., more preferably 25 to 50 ° C. Preferably it is performed after lowering to 3 to 15 mPa · s, more preferably 3 to 13 mPa · s. In particular, it is preferable to use an ink composition having an ink viscosity at 25 ° C. of 50 mPa · s or less as the ink composition of the present invention, since it can be discharged satisfactorily. By using this method, high ejection stability can be realized.

  A radiation curable ink composition such as the ink composition of the present invention generally has a higher viscosity than a water-based ink composition usually used in an ink composition for ink jet recording, and therefore has a large viscosity fluctuation due to temperature fluctuations during ejection. Viscosity fluctuation of the ink composition has a great influence on the change of the droplet size and the change of the droplet discharge speed, and thus causes the image quality deterioration. Therefore, it is necessary to keep the temperature of the ink composition during ejection as constant as possible. Therefore, in the present invention, the temperature control range of the ink composition is preferably set to ± 5 ° C. of the set temperature, more preferably ± 2 ° C. of the set temperature, and further preferably set temperature ± 1 ° C. .

Next, (b ¹ ) a step of curing the ink composition by irradiating the discharged ink composition with active radiation will be described.

  The ink composition ejected on the recording medium is cured by irradiation with actinic radiation. This is because the polymerization initiator contained in the ink composition of the present invention is decomposed by irradiation with actinic radiation to generate a starting species such as a cation and an acid, and the polymerization reaction of the polymerizable compound is a function of the starting species. This is because it is created and promoted. At this time, if a sensitizer is present together with the polymerization initiator in the ink composition, the sensitizer in the system absorbs actinic radiation to be in an excited state, and promotes decomposition of the polymerization initiator by contacting with the polymerization initiator. And a more sensitive curing reaction can be achieved.

  Here, α rays, γ rays, electron beams, X rays, ultraviolet rays, visible light, infrared rays, or the like can be used as the active radiation used. Although the peak wavelength of actinic radiation depends on the absorption characteristics of the sensitizer, for example, it is preferably 200 to 600 nm, more preferably 300 to 450 nm, still more preferably 320 to 420 nm, and activity. It is particularly preferable that the radiation is ultraviolet rays having a peak wavelength in the range of 340 to 400 nm.

In addition, the polymerization initiation system of the ink composition of the present invention has sufficient sensitivity even with a low output actinic radiation. Therefore, it is appropriate to cure the exposed surface with an illuminance of 10 to 4,000 mW / cm ² , more preferably 20 to 2,500 mW / cm ² .
The ink composition of the present invention is appropriately irradiated with such actinic radiation for 0.01 to 120 seconds, more preferably for 0.1 to 90 seconds.

The ink composition of the present invention is an ink composition having excellent curability and adhesion to various light sources. Examples of various light sources (active radiation sources) include a mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a light emitting diode (LED), and a laser diode (LD).
In the present invention, it is preferable that the mercury lamp, the ultra-high pressure mercury lamp, the metal halide lamp, and the LED, which are typical ultraviolet light sources, are all excellent in curability and adhesion.

There is no restriction | limiting in particular as a mercury lamp, A well-known mercury lamp can be used, A low pressure mercury lamp, a high pressure mercury lamp, the mercury lamp with which the fluorescent substance was apply | coated, a high pressure mercury lamp etc. can be illustrated.
There is no restriction | limiting in particular as an ultrahigh pressure mercury lamp, A well-known ultrahigh pressure mercury lamp can be used, The ultrahigh pressure mercury lamp shown in FIG.1 and FIG.2 can illustrate preferably.
FIG. 1 is a schematic perspective view showing a preferred example of an ultrahigh pressure mercury lamp that can be used in the present invention.
FIG. 2 is a conceptual cross-sectional view showing the ultrahigh pressure mercury lamp unit 61 in FIG.
The super high pressure mercury lamp shown in FIG. 1 has 4 × 6 super high pressure mercury lamp units 61 shown in FIG. A light guide unit 62, a light diffusion plate 63, and an optical shutter 64 are provided on the exit side of the ultrahigh pressure mercury lamp unit 61.
The light guide unit 62 and the light diffusion plate 63 can be appropriately selected from known materials and shapes, and may be selected in consideration of the size of the image to be formed (image forming region) and the like.

The ultrahigh pressure mercury lamp unit 61 shown in FIG. 2 includes a cathode discharge electrode and an anode discharge electrode 65, a reflecting mirror 66, and a glass tube 67 in which rare gas and mercury are enclosed. A cooling fan 69 is provided on a surface different from the light emitting portion 68.
Ultra high pressure mercury lamp units are on the market, and can be obtained from, for example, USHIO INC., GS Yuasa Lighting Co., Ltd., Phoenix Electric Co., Ltd., etc. An extra high pressure mercury lamp unit is described in Japanese Patent Application Laid-Open No. 2007-296735.

There is no restriction | limiting in particular as a metal halide lamp, A well-known metal halide lamp can be used, What used halogen compounds, such as sodium iodide and a scandium iodide, can be illustrated.
Moreover, various LED and LD can be used as a light emitting diode (LED) and a laser diode (LD), and when an ultraviolet light source is especially required, ultraviolet LED and ultraviolet LD can be used conveniently. For example, Nichia Corporation has introduced a purple LED whose main emission spectrum has a wavelength between 365 nm and 420 nm. When even shorter wavelengths are required, US Pat. No. 6,084,250 discloses an LED that can emit actinic radiation centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands. The actinic radiation source particularly preferred in the present invention is a UV-LED, particularly preferably a UV-LED having a peak wavelength at 350 to 420 nm.
Incidentally, it is preferable that maximum illumination intensity of the LED on a recording medium is 10 to 2,000 mW / cm ^2, more preferably 20 to 1,000 mW / cm ^2, is 50 to 800 mW / cm ² It is particularly preferred.

  Actinic radiation irradiation conditions and a basic irradiation method are disclosed in JP-A-60-132767. Specifically, the light source is provided on both sides of the head unit including the ink composition discharge device, and the head unit and the light source are scanned by a so-called shuttle method. Irradiation with actinic radiation is performed for a certain period of time (preferably 0.01 to 0.5 seconds, more preferably 0.01 to 0.3 seconds, still more preferably 0.01 to 0.15 seconds) after the ink composition has landed. ). In this way, by controlling the time from landing to irradiation of the ink composition to an extremely short time, it is possible to prevent the ink composition that has landed on the recording medium from spreading before curing. In addition, since the ink composition can be exposed to a porous recording medium before the ink composition penetrates to a deep part where the light source does not reach, it is preferable because residual unreacted monomers can be suppressed.

  Further, the curing may be completed by another light source that is not driven. International Publication No. 99/54415 pamphlet discloses a method using an optical fiber or a method of irradiating a recording unit with UV light by applying a collimated light source to a mirror surface provided on the side of the head unit as an irradiation method. Such a curing method can also be applied to the ink jet recording method of the present invention.

By adopting the ink jet recording method as described above, the dot diameter of the landed ink composition can be kept constant even on various recording media having different surface wettability, and the image quality is improved. In addition, in order to obtain a color image, it is preferable to superimpose in order from the color with the lowest brightness. By superimposing the ink compositions in order of low lightness, it becomes easy for the irradiation rays to reach the lower ink composition, and good curing sensitivity, reduction of residual monomers, and improvement in adhesion can be expected. In addition, irradiation can be performed by discharging all colors and collectively exposing, but exposure for each color is preferable from the viewpoint of promoting curing.
Thus, the ink composition of the present invention can form an image on the surface of a recording medium by being cured with high sensitivity by irradiation with actinic radiation.
In the ink jet recording method of the present invention, the ink composition of the present invention is preferably used as a yellow ink composition.

The ink set of the present invention is an ink set containing at least one ink composition of the present invention.
The ink composition of the present invention is preferably used as an ink set composed of a plurality of ink compositions for inkjet recording. In this case, in addition to the ink composition, an ink composition exhibiting each color of cyan, magenta, and black An ink set is preferably used in combination, and it is preferable to use an ink composition exhibiting a white color as necessary.

  In the inkjet recording method of the present invention, the order of the respective colored ink compositions to be ejected is not particularly limited, but it is preferably applied to the recording medium from a colored ink composition having low brightness, and yellow, cyan, When magenta and black ink compositions are used, they are preferably applied onto the recording medium in the order of yellow → cyan → magenta → black. In addition, when white is added to this, it is preferable to apply it on the recording medium in the order of white → yellow → cyan → magenta → black. Further, the present invention is not limited to this, and the ink set of the present invention including at least a total of seven colors of light cyan, light magenta, cyan, magenta, black, and white ink compositions can be preferably used. In this case, it is preferable to apply the recording material in the order of white → light cyan → light magenta → yellow → cyan → magenta → black.

In the present invention, the recording medium is not particularly limited, and a known recording medium can be used as a support or a recording material. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, polyvinyl chloride, cellulose diacetate, cellulose triacetate) Cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film on which the above-mentioned metal is laminated or deposited. In addition, as the recording medium in the present invention, a non-absorbable recording medium can be preferably used.
As the recording medium, polyvinyl chloride is particularly preferably used.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not restrict | limited to these. Unless otherwise specified, “part” represents “part by weight” and “%” represents “% by weight”.

(Preparation of pigment dispersion)
Cyan, magenta, yellow, black, and white pigment dispersions were prepared through a preliminary dispersion step and a main dispersion step.
Predispersing step: The components shown in Table 1 were mixed and stirred with a stirrer for 1 hour.
Main dispersion step: The mixture after stirring was dispersed by bead mill dispersion to obtain a pigment dispersion. Dispersion conditions were as follows: zirconia beads having a diameter of 0.65 mm were filled at a filling rate of 70%, the peripheral speed was 9 m / s, and the dispersion time was 2 to 8 hours.

The pigments, dispersants and polymerizable compounds used in Table 1 are as follows.
Cyan pigment A: C.I. I. Pigment Blue 15: 3 (PB15: 3, IRGALITE BLUE GLO; manufactured by Ciba Specialty Chemicals)
-Magenta pigment A: quinacridone (CINQUASIA MAGENTA RT-355D; manufactured by Ciba Specialty Chemicals)
Yellow pigment A: C.I. I. Pigment Yellow 185 (PY185, Palitol Yellow D1155; manufactured by BASF)
Black pigment A: carbon black (SPECIAL BLACK 250; manufactured by Degussa)
White pigment A: Titanium dioxide (CR60-2; manufactured by Ishihara Sangyo Co., Ltd.)
Oxetane compound A: OXT-221 (oxetane compound, manufactured by Toagosei Co., Ltd.)
Polymer dispersing agent A: BYK168 (manufactured by Big Chemie)
Polymer dispersing agent B: Solsperse 36000 (manufactured by Noveon)
-Dispersing aid A: Solsperse 22000 (Noveon)

(Preparation of ink composition)
The components shown in Tables 2 to 9 (units are parts by weight) were stirred, mixed and dissolved to obtain ink compositions.

The photoacid generator, sensitizer, oxetane compound, and epoxy compound used in Tables 2 to 9 are as follows.
Photoacid generator A: the following compound

Sensitizer A: Dibutoxyanthracene (manufactured by Kawasaki Kasei Kogyo Co., Ltd.)
Oxetane compound A: OXT-221 (oxetane compound, manufactured by Toagosei Co., Ltd.)
Epoxy compound A: Syna-Epoxy 30 (monofunctional epoxy compound, manufactured by Cinacia, corresponding to formula (1), the following compound)

Epoxy compound B: limonene dioxide (bifunctional epoxy compound, manufactured by Arkema)
Epoxy compound C: Epolide GT401 (tetrafunctional epoxy compound, ε-caprolactone-modified tetra (3,4-epoxycyclohexylmethyl) butanetetracarboxylate, manufactured by Daicel Chemical Industries, Ltd.)
Epoxy compound D: triglycidyl isocyanurate (trifunctional epoxy compound, manufactured by Tokyo Chemical Industry Co., Ltd.)
Epoxy compound E: Neopentyl glycol diglycidyl ether (bifunctional epoxy compound, manufactured by Tokyo Chemical Industry Co., Ltd.)

(Inkjet recording device)
The prepared ink composition for five colors is an ink jet printer (Toshiba Tech Co., Ltd. head mounted = droplet ejection frequency: 6.2 KHz, number of nozzles: 636, nozzle density: 300 npi (nozzle / inch, the same applies hereinafter), drop Size: 6 pl to 42 pl. Two sets of variable heads arranged in 7 stages and 600 npi in a full line array were mounted on 5 sets).
The recording medium (PVC: polyvinyl chloride) can be moved directly under the head, and the head is fixed to the machine in the order of white, yellow, cyan, magenta, black from the upstream of the recording medium conveyance direction. .
An ultraviolet light source was installed downstream of the black ink head. The ultraviolet light source has a structure that can be attached and detached, and the curability and adhesion of the ink composition to several light sources were evaluated. There are four types of installed light sources: metal halide lamps, mercury lamps, ultra-high pressure mercury lamps, and ultraviolet LEDs. Note that the exposure energy was changed in three stages by changing the conveyance speed of the recording medium directly under the lamp.

(Metal halide lamp)
As a metal halide lamp, Vzero-085 (made by Integration Technology) equipped with a D bulb was used. The irradiation energy by the metal halide lamp can be adjusted to 300 to 900 mJ / cm ² by changing the conveying speed. Specifically, 300 mJ / cm ² (stage 1), 600 mJ / cm ² (stage 2), and 900 mJ / cm ² (stage 3).

(Mercury lamp)
As the mercury lamp, Vzero-085 (manufactured by Integration Technology) equipped with an H bulb was used. The irradiation energy by the mercury lamp can be adjusted to 250 to 750 mJ / cm ² by changing the conveying speed. Specifically, they are 250 mJ / cm ² (stage 1), 500 mJ / cm ² (stage 2), and 750 mJ / cm ² (stage 3).

(Ultra high pressure mercury lamp)
As the ultra high pressure mercury lamp, the ultra high pressure mercury lamp shown in FIGS. 1 and 2 was used.
Irradiation energy by the ultra high pressure mercury lamp can be adjusted to 120 to 360 mJ / cm ² by changing the conveying speed. Specifically, 120 mJ / cm ² (stage 1), 240 mJ / cm ² (stage 2), 360 mJ / cm ² (stage 3).

(Ultraviolet LED)
As the ultraviolet LED, a commercially available unit (manufactured by ITEC System) equipped with an ultraviolet LED chip (emission wavelength 365 nm) was used. The irradiation energy by the ultraviolet LED can be adjusted to 50 to 150 mJ / cm ² by changing the conveying speed. Specifically, they are 50 mJ / cm ² (stage 1), 100 mJ / cm ² (stage 2), and 150 mJ / cm ² (stage 3).

Example 1
Each ink composition (cyan, magenta, yellow, black, and white) shown in Table 2 was used as ink set 1, and ink set 1 was filled in the ink jet printer. Primary colors (cyan, magenta, yellow, black) Or white), and a primary color solid image is printed by applying an ink composition droplet of 12 picoliters per pixel at a pixel density of 600 × 600 dpi. A cured film was prepared using various types of ultraviolet light sources. The cured film produced was evaluated for curability and adhesion according to the following evaluation criteria. The evaluation results are as shown in Table 10.

(Examples 2 to 4 and Comparative Examples 1 to 3)
The ink compositions (cyan, magenta, yellow, black, and white) shown in Tables 3 to 9 were set as ink sets 2 to 8, respectively.
With the combination of ink sets shown in Table 10, the curability and adhesion of a cured film produced in the same manner as in Example 1 were evaluated according to the following evaluation criteria. The evaluation results are as shown in Table 10.

<Evaluation criteria for curability>
Curability was defined by the surface energy and the exposure energy at which film peeling did not occur. Presence or absence of surface stickiness was determined by pressing plain paper (copy paper C2 manufactured by Fuji Xerox Co., Ltd.) immediately after printing, and when there was transfer of the ink composition, and when there was no transfer, there was no stickiness. For film peeling, the cured film was scratched with a guitar pick (once), and when there was no film peeling, it was judged that there was no film peeling.
The exposure energy was changed in three stages for each exposure light source as described above, and evaluated according to the following criteria.
Evaluation was performed in the following five stages.
Excellent: No stickiness or film peeling was observed at the exposure energy of stage 1 for all colors.
Good: No stickiness and film peeling were observed at the exposure energy of stage 2 for all colors.
Conformity: No stickiness or film peeling was observed with the exposure energy of stage 3 for all colors.
Nonconformity: There were some colors in which no stickiness and film peeling were observed with the exposure energy of stage 3, but in some colors, there were stickiness or film peeling with the exposure energy of stage 3.
Defect: Stickiness or film peeling was observed at the exposure energy of stage 3 for all colors.

<Adhesion evaluation criteria>
The adhesion was defined by a cross-cut test of JIS standard (JIS-K5600). In addition, as for exposure energy, the cured film was produced only in stage 3 for each exposure light source.
Evaluation was performed in the following five stages.
Excellent: All colors were evaluated as “0” or “1” by JIS standard judgment.
Good: All colors were evaluated as “0”, “1”, or “2” in JIS standard judgment.
Conformity: All colors were evaluated as “0”, “1”, “2”, or “3” by JIS standard judgment.
Nonconformity: Evaluation of “0”, “1”, “2”, or “3” in JIS standard determination for some colors, but “4” or “5” in JIS standard determination for some colors There was a thing of evaluation.
Defect: All colors were evaluated as “4” or “5” by JIS standard judgment.

60: Super high pressure mercury lamp 61: Ultra high pressure mercury lamp unit 62: Light guide part 63: Light diffusion plate 64: Optical shutter 65: Cathode discharge electrode and anode discharge electrode 66: Reflective mirror 67: Glass tube 68: Light emission part 69: Cooling fan

Claims (7)

Epoxy compounds, and
Contains an oxetane compound,
The epoxy compound is a monofunctional epoxy compound represented by the formula (1), and, viewed contains a polyfunctional epoxy compound having three or more epoxy groups,
The polyfunctional epoxy compound having three or more epoxy groups is ε-caprolactone-modified tetra (3,4-epoxycyclohexylmethyl) butanetetracarboxylate, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, and isocyanuric acid An ink composition comprising a compound selected from the group consisting of triglycidyl .

(In the formula (1), R ^{1 to} R ⁶ each independently has a hydrogen atom, an alkyl group, —R ⁷ — (O—R ⁸ ) _n —R ⁹ , an alkoxy group, a hydroxyl group, or an ester bond. R ⁷ represents a single bond or an alkylene group, R ⁸ independently represents an alkylene group, R ⁹ represents a hydrogen atom, an alkyl group, an alkoxy group, or a hydroxyl group, n represents an integer of 1 or more, and at least one of R ^{1 to} R ⁶ is a monovalent organic group having an ester bond, and two or more of R ^{1 to} R ⁶ are bonded to form a ring. You may do it.)   The ink composition according to claim 1, wherein the total content of the epoxy compound is greater than the total content of the oxetane compound.   The ink composition according to claim 1, wherein the epoxy compound further comprises a polyfunctional epoxy compound having two epoxy groups.   The ink composition according to claim 1, wherein the total content Mmono of the monofunctional epoxy compound and the total content Mmulti of the polyfunctional epoxy compound satisfy a relationship of 3 × Mmono> Mmulti. The ink according to any one of claims 1 to 4, wherein the polyfunctional epoxy compound having three or more epoxy groups is ε-caprolactone-modified tetra (3,4-epoxycyclohexylmethyl) butanetetracarboxylate. Composition.   The ink composition according to claim 3, wherein the polyfunctional epoxy compound having two epoxy groups is an alicyclic epoxy compound. (A ¹⁾ onto a recording medium, a step of discharging the ink composition according to any one of claims 1 to 6 and,
(B ¹⁾ The ink composition discharged with actinic radiation is irradiated, the step of curing the ink composition, inkjet recording method comprising.

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