JP5878097B2 - Inkjet recording method - Google Patents

Description

  The present invention relates to an inkjet recording method and printed matter, and more particularly to a technique for forming an image by ejecting a plurality of colors of ink.

As an image recording method for forming an image on a recording medium such as paper based on an image data signal, there are an electrophotographic method, a sublimation type and a melt type thermal transfer method, an ink jet method and the like.
The ink jet method is an inexpensive printing apparatus and does not require a plate at the time of printing, and the ink composition is ejected only on the required image portion to form an image directly on a recording medium. It can be used efficiently, and the running cost is low especially for small lot production. Furthermore, it has low noise and is excellent as an image recording method, and has attracted attention in recent years.
In particular, an ink composition for ink jet recording (a radiation curable ink composition for ink jet recording) that can be cured by irradiation with radiation such as ultraviolet rays is cured by irradiation with radiation such as ultraviolet rays, and most of the components of the ink composition are cured. It is an excellent method in that it can be printed on various recording media because it is excellent in drying properties and hard to blur images as compared with solvent-based ink compositions.

Further, as conventional ink jet recording apparatuses and ink compositions, those described in Patent Documents 1 to 3 are known.
Patent Document 1 contains at least a coloring material, water, and a polymer compound having a plurality of side chains in a hydrophilic main chain and capable of crosslinking between side chains by irradiation with active energy rays. An ink jet recording apparatus comprising: an ink jet ink to perform; an active energy ray irradiating means; an ink jet head for forming an image with the ink jet ink; and a scanning means for scanning the ink jet head relative to a recording medium. The active energy ray irradiating means has an irradiating light source having a main emission wavelength in a wavelength region of 300 to 400 nm.
In Patent Document 2, the following general formula (I):
_{^{CH 2 = CR 1 -COOR 2 -O}} -CH = CH-R 3 ··· (I)
Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a divalent organic residue having 2 to 20 carbon atoms, and R ³ is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. Group.)
An ultraviolet curable ink-jet ink composition comprising: a monomer A represented by: a (meth) acrylated amine compound; a hindered amine compound other than the (meth) acrylated amine compound; and a photopolymerization initiator. Has been.
Patent Document 3 includes (A) N-vinyl lactams, (B) other polymerizable compounds, (C) a polymerization initiator, (D) a basic compound, and (E) an oxidation potential of 1.0 V ( vs. SCE) or more of an oil-soluble dye, wherein the monofunctional polymerizable compound is 65% by weight or more of the total amount of (A) N-vinyl lactams and (B) other polymerizable compounds. An ink composition is described.
In Patent Document 4, a nozzle row group is configured by arranging a plurality of nozzle rows each having a plurality of nozzle openings perforated at a constant nozzle pitch to form a nozzle row group, and an ink type is set for each nozzle row. In the ink jet type recording head configured to discharge the nozzle array, the nozzle array group is formed in N strips in which the positions of the nozzle openings are shifted by 1 / N (N is a natural number of 4 or more) pitch in the nozzle array direction. An ink jet recording head characterized by comprising a high-resolution nozzle array group is described.

JP 2007-118409 A JP 2012-92291 A JP 2010-77228 A JP 2002-67317 A

  An object of the present invention is to provide an ink jet recording method which is excellent in image quality obtained even after long-term storage and excellent in curability even when ink jet recording with a high ink jet head scanning speed is performed (during high production). Is to provide.

The above object has been achieved by the means described in <1> or <17> below. It is shown below with <2>-<16> which are preferable embodiments.
<1> Preparation step for preparing an ink jet recording apparatus provided with an ink jet head, a discharge step for discharging an ink composition from the ink jet head of the ink jet recording apparatus onto a recording medium, and applying active energy from an active energy applying means A curing step of curing the ejected ink composition, and the ink composition contains 0.05% by mass or more of (Component A) N-oxyl compound based on the total amount of the ink composition, (Component B) A radically polymerizable ink composition containing 40% by mass or more of a polyfunctional monomer with respect to the total amount of the ink composition, and (Component C) containing a photopolymerization initiator. An inkjet recording method, wherein the scan speed is 0.9 m / s or more;
<2> The inkjet recording method according to <1>, wherein the ink composition contains 2 to 40% by mass of (Component D) N-vinyl lactam based on the total amount of the ink composition.
<3> The inkjet recording method according to <1> or <2>, wherein the component B is a polyfunctional (meth) acrylate monomer,
<4> The ink jet recording method according to any one of the above <1> to <3>, wherein the ink composition contains a (component E) sensitizer.
<5> The inkjet recording method according to any one of <1> to <4>, wherein Component A is a compound having a 2,2,6,6-tetramethylpiperidinyl-N-oxyl group. ,
<6> The inkjet recording method according to any one of <1> to <5>, wherein Component A is 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl. ,
<7> The inkjet recording method according to any one of <1> to <6>, wherein the content of component B is 40 to 85% by mass relative to the total amount of the ink composition;
<8> The inkjet recording method according to any one of the above <1> to <7>, wherein the ink composition is supplied from an oxygen-impermeable ink pack having no gas-liquid interface inside.
<9> The ink jet recording method according to any one of <1> to <7>, wherein the ink composition contains a phthalocyanine pigment.
<10> The ink jet recording method according to any one of <1> to <8>, wherein the ink composition is a cyan ink composition.
<11> The ink jet recording method according to any one of <1> to <10>, wherein the ink composition does not substantially contain a silicone-based surfactant and a fluorine-based surfactant.

<12> The inkjet recording apparatus is
Ink composition of at least four colors of cyan, magenta, yellow and black, in which nozzles for discharging curable ink that is cured by application of active energy are arranged in a first direction at a predetermined pitch P. Each of the nozzle rows for each of the N colors (N ≧ 4), and each nozzle row includes an inkjet head in which the nozzles are shifted in the first direction;
Active energy applying means for applying the active energy to ink droplets ejected from the nozzles and ejected onto the recording surface of a recording medium;
Holding means for arranging and holding the ink jet head and the active energy applying means along a second direction orthogonal to the first direction;
Scanning means for relatively scanning the holding means and the recording medium in the second direction;
Moving means for relatively moving the holding means and the recording medium in the first direction for each scanning by the scanning means;
Control means for forming an image on the recording surface of the recording medium while causing the inkjet head and the active energy applying means held by the holding means to scan each area of the recording medium a predetermined number of times. An inkjet recording method according to any one of <1> to <11>, wherein the inkjet recording apparatus includes:
<13> The inkjet recording method according to any one of <1> to <12>, wherein the ejection frequency of the inkjet head is 10 kHz or more,
<14> The inkjet recording according to <12>, wherein the nozzle of the black ink is disposed on the most upstream side of the relative movement of the recording medium relative to the inkjet head in the first direction among the nozzle rows of the inkjet head. Method,
<15> Each of the three color ink compositions of cyan, magenta and yellow contains (Component A) 0.05% by mass or more of hindered amine based on the total amount of the ink composition, and (Component B) a polyfunctional monomer. The inkjet recording method according to <12> or <14>, wherein the ink composition is a radical polymerizable ink composition containing 40% by mass or more based on the total amount of the ink composition and containing (Component C) a photopolymerization initiator,
<16> Each of the four ink compositions of cyan, magenta, yellow and black contains (Component A) 0.05% by mass or more of (hindered amine) based on the total amount of the ink composition, and (Component B) polyfunctional The inkjet recording method according to <15>, wherein the monomer is a radical polymerizable ink composition containing 40% by mass or more based on the total amount of the ink composition and containing (Component C) a photopolymerization initiator;
<17> Printed matter obtained by the inkjet recording method according to any one of <1> to <16>.

  According to the present invention, there is provided an inkjet recording method that is excellent in image quality obtained even after long-term storage and excellent in curability even when inkjet recording with a high inkjet head scanning speed is performed (during high production). Could be provided.

It is an expansion schematic diagram which shows an example of the inkjet head used suitably for this invention. It is an expansion schematic diagram which shows another example of the inkjet head used suitably for this invention. It is explanatory drawing for demonstrating the outline | summary of a structure of an example of the inkjet recording device used suitably for this invention. 1 is a system configuration diagram of an example of an ink jet recording apparatus preferably used in the present invention. It is an expansion schematic diagram which shows another example of the inkjet head used suitably for this invention. It is a flowchart which shows an example of the inkjet recording method of this invention. It is an external appearance perspective view of another example of the inkjet recording device used suitably for this invention. It is explanatory drawing which shows typically the recording-medium conveyance path in the inkjet recording device shown in FIG. It is a plane perspective view which shows arrangement | positioning of the inkjet head in the inkjet recording device shown in FIG. 7, a temporary curing light source, and a main curing light source. 1 is a block diagram illustrating an example of the configuration of an ink supply system of an inkjet recording apparatus that is preferably used in the present invention. It is a block diagram which shows an example of a structure of the inkjet recording device used suitably for this invention.

Hereinafter, the present invention will be described in detail.
In addition, in this specification, description of "xx-yy" represents the numerical range containing xx and yy.
“(Meth) acrylate” and the like are synonymous with “acrylate and / or methacrylate” and the like.
In the present invention, “mass%” and “wt%” are synonymous, and “part by mass” and “part by weight” are synonymous.

(Inkjet recording method)
The ink jet recording method of the present invention comprises a preparation step of preparing an ink jet recording apparatus provided with an ink jet head, a discharge step of discharging an ink composition from the ink jet head of the ink jet recording apparatus onto a recording medium, and an active energy applying means. A curing step of curing the discharged ink composition by applying active energy from the ink composition, and the ink composition comprises (Component A) N-oxyl compound in an amount of 0.05 mass with respect to the total amount of the ink composition. % Or more, (Component B) a radically polymerizable ink composition containing 40% by mass or more of the polyfunctional monomer based on the total amount of the ink composition, and (Component C) containing a photopolymerization initiator. The scanning speed of the inkjet head in the process is 0.9 m / s or more.

In recent years, with the increase in production of inkjet printers, it has been required to increase the shuttle scan speed.
In order to form an image by ejecting an ink composition at a desired location, inkjet requires precise adjustment of shuttle scan speed, slow distance, and ink ejection speed.
As a result of detailed investigations by the present inventors, in particular, with respect to the aspect of achieving high productivity by increasing the scanning speed of the inkjet head, it is greatly influenced by variations in physical properties centered on the viscosity of the ink composition, The results have been found to have a big impact on image quality. Accordingly, the viscosity variation allowable range of the ink composition becomes smaller as the production of the ink jet printer increases. In other words, the present inventor states that a technique for suppressing the viscosity fluctuation of the ink composition, which has been allowed in a printer with a conventional productivity (in particular, meaning that the carriage speed is slow), is essential in an ink jet printer that is highly produced. Etc. found. For example, in an inkjet printer PX-G5000 (manufactured by Seiko Epson Corporation), which is a conventional inkjet recording apparatus as described in Patent Document 2, the scan speed of the inkjet head is less than 0.9 m / s.
As a result of further detailed studies by the present inventors, it was found that (Component A) N-oxyl compound was contained in an amount of 0.05% by mass or more based on the total amount of the ink composition, and (Component B) a polyfunctional monomer was used as the ink composition By including 40% by mass or more with respect to the total amount, the detailed mechanism is unknown, but even when the scan speed of the inkjet head is 0.9 m / s or more, it is particularly non-oxygen permeable after long-term storage. It has been found that the image quality obtained is excellent even after long-term storage in an ink pack, and that the curability is excellent even during high production.
The present invention will be described in detail below in the order of the ink composition and each step.

<Ink composition>
In the inkjet recording method of the present invention, (Component A) N-oxyl compound is contained in an amount of 0.05% by mass or more based on the total amount of the ink composition, and (Component B) a polyfunctional monomer is 40% based on the total amount of the ink composition. At least one radical polymerizable ink composition (hereinafter also simply referred to as “ink”) containing at least mass% and containing (Component C) a photopolymerization initiator is used.
The radical polymerizable ink composition is preferably a cyan ink composition.
In the ink jet recording method of the present invention, at least a three-color ink composition of cyan, magenta and yellow is used, and each of the three color ink compositions of cyan, magenta and yellow contains (Component A) a hindered amine. 0.05% by mass or more with respect to the total amount of the ink composition, (Component B) a polyfunctional monomer with 40% by mass or more with respect to the total amount of the ink composition, and (Component C) a photopolymerization initiator. It is preferably a radically polymerizable ink composition, and at least four ink compositions of cyan, magenta, yellow and black are used, and all of the four ink compositions of cyan, magenta, yellow and black are (Component A) 0.05% by mass or more of hindered amine based on the total amount of the ink composition, (Component B) a polyfunctional monomer Containing more than 40% by weight, based on the ink composition total amount, and more preferably (Component C) a radically polymerizable ink composition containing a photopolymerization initiator. The image quality of the printed matter after long-term storage is excellent when it is in the above embodiment.
Furthermore, in the ink jet recording method of the present invention, any ink composition to be used contains (Component A) N-oxyl compound in an amount of 0.05% by mass or more based on the total amount of the ink composition, and (Component B) A radically polymerizable ink composition containing a functional monomer in an amount of 40% by mass or more based on the total amount of the ink composition and containing (Component C) a photopolymerization initiator is particularly preferable. The image quality of the printed matter after long-term storage is excellent when it is in the above embodiment.

The ink composition that can be used in the present invention is an oil-based ink composition that can be cured by active energy. “Activity energy” is an active energy ray that can give energy for generating an initiation species in the ink composition by irradiation, and includes α rays, γ rays, X rays, ultraviolet rays, visible rays, electron rays, and the like. . Of these, ultraviolet rays and electron beams are preferred from the viewpoint of curing sensitivity and device availability, and ultraviolet rays are particularly preferred. As a more preferable light source, there is a light emitting diode (LED) light source because it does not generate heat due to exposure, has a wide base material application range, does not generate ozone, and does not require an inexpensive and excessive cooling device.
Further, the ink composition that can be used in the present invention is an active energy curable ink composition, and does not contain a highly volatile solvent and is solvent-free in order to cure the ink composition after it is applied on a recording medium. Preferably there is. This is because if a highly volatile solvent remains in the cured ink image, the solvent resistance deteriorates, and the problem of VOC (Volatile Organic Compound) of the remaining solvent arises. The content of the solvent with respect to the total mass of the ink composition is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, and no content. Is most preferred.
Hereinafter, components contained in the ink composition will be described.

(Component A) N-oxyl compound At least one ink composition in the ink jet recording method of the present invention contains 0.05% by mass or more of (Component A) N-oxyl compound based on the total amount of the ink composition.
In the ink jet recording method of the present invention, it is particularly preferable that any ink composition used contains (Component A) N-oxyl compound in an amount of 0.05% by mass or more based on the total amount of the ink composition. The image quality of the printed matter after long-term storage is excellent when it is in the above embodiment.
The N-oxyl compound is not particularly limited as long as it is a compound having an N-oxyl group (> N—O ^● ), and a known compound can be used.
The N-oxyl compound is preferably an N-oxyl compound obtained by N-oxylating a hindered amine compound from the viewpoint of the stability of the compound itself.
Examples of N-oxyl compounds obtained by N-oxylating a hindered amine compound include TEMPO (2,2,6,6-tetramethylpiperidinyl-N-oxyl) and HO-TEMPO (4-hydroxy-2, 2,6,6-tetramethylpiperidinyl-N-oxyl) is preferred.
The N-oxyl compound is preferably an N-oxyl compound having an aliphatic cyclic structure from the viewpoint of compatibility with other components of the ink.
Further, the N-oxyl compound is preferably an N-oxyl compound having a hydroxy group from the viewpoint of compatibility with other components of the ink and stability in the ink composition.
In the present invention, component A is preferably a compound represented by the following formula (A-1).

（式（Ａ−１）中、Ｗは炭素数４又は５の環状アルキレン鎖を示し、該環状アルキレン鎖は置換基を有してもよい。）

(In formula (A-1), W represents a cyclic alkylene chain having 4 or 5 carbon atoms, and the cyclic alkylene chain may have a substituent.)

  The compound represented by the formula (A-1) is more preferably a compound represented by the formula (A-2).

（式（Ａ−２）中、Ｒ¹¹〜Ｒ¹⁶はそれぞれ独立に、水素原子、ハロゲン原子、又は１価の有機基を表すか、あるいは、Ｒ¹¹及びＲ¹²、Ｒ¹³及びＲ¹⁴、Ｒ¹⁵及びＲ¹⁶はこれらが結合する炭素と共に１個のカルボニル基を形成してもよい。）

(In the formula (A-2), R ^{11 to} R ¹⁶ each independently represents a hydrogen atom, a halogen atom, or a monovalent organic group, or R ¹¹ and R ¹² , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ may form one carbonyl group together with the carbon to which they are attached.)

In the formula (A-2), when R ^{11 to} R ¹⁶ are monovalent organic groups, the monovalent organic group includes a hydroxyl group, —NR ¹ R ² (R ¹ and R ² are each independently Represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.), An alkyl group, an aryl group, an alkoxy group, an aryloxy group, —O (C═O) R ³ , —NH (C═O) R ⁴ ( R ³ and R ⁴ each independently represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 20 carbon atoms), a carbamoyl group, a carboxy group, a cyano group, a maleimide group or a phosphoryl group. preferable.

The alkyl group is preferably an alkyl group having 1 to 16 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Further, the alkyl group may be linear or branched and may have a cyclic structure.
The aryl group is preferably an aryl group having 6 to 20 carbon atoms, and more preferably an aryl group having 6 to 10 carbon atoms.
The alkoxy group is preferably an alkoxy group having 1 to 16 carbon atoms, and more preferably an alkoxy group having 1 to 10 carbon atoms.
The aryloxy group is preferably an aryloxy group having 6 to 20 carbon atoms, and more preferably an aryloxy group having 6 to 10 carbon atoms.

Further, when R ¹¹ to R ¹⁶ is a monovalent organic group, it may have one or more substituents. Moreover, the substituent mentioned above may be further substituted by another substituent.
Examples of the substituent include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, alkoxy groups such as methoxy group, ethoxy group and tert-butoxy group, aryloxy groups such as phenoxy group and p-tolyloxy group. , Alkoxycarbonyl groups such as methoxycarbonyl group, butoxycarbonyl group, phenoxycarbonyl group or aryloxycarbonyl group, acetoxy group, propionyloxy group, acyloxy group such as benzoyloxy group, acetyl group, benzoyl group, isobutyryl group, acryloyl group, Acyl groups such as methacryloyl group and methoxalyl group, alkylsulfanyl groups such as methylsulfanyl group and tert-butylsulfanyl group, arylsulfanyl groups such as phenylsulfanyl group and p-tolylsulfanyl group, Group, alkylamino group such as cyclohexylamino group, dimethylamino group, diethylamino group, morpholino group, dialkylamino group such as piperidino group, arylamino group such as phenylamino group, p-tolylamino group, methyl group, ethyl group, In addition to alkyl groups such as tert-butyl group and dodecyl group, phenyl groups, p-tolyl groups, xylyl groups, cumenyl groups, naphthyl groups, anthryl groups, phenanthryl groups, etc., hydroxy groups, carboxy groups, formyl groups , Mercapto group, sulfo group, mesyl group, p-toluenesulfonyl group, amino group, nitro group, cyano group, trifluoromethyl group, trichloromethyl group, trimethylsilyl group, phosphono group, trimethylammonium group, dimethylsulfonium group, triphenyl Phenacylphosphonium group And the like.

In formula (A-2), R ¹¹ , R ¹² , R ¹⁵ and R ¹⁶ are preferably hydrogen atoms.
In formula (A-2), R ¹³ and R ¹⁴ are a hydrogen atom, a hydroxyl group, —NR ¹ R ² (R ¹ and R ² each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms). ), An alkyl group (1 to 10 carbon atoms), an aryl group (6 to 10 carbon atoms), an alkoxy group (1 to 10 carbon atoms), an aryloxy group, —O (C═O) R ³ , —NH ( C═O) R ⁴ (R ³ and R ⁴ each independently represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 20 carbon atoms), or R ¹³ and R ¹⁴ are It is preferable to form one carbonyl group together with the carbon to which they are bonded, R ¹³ is a hydroxy group or an alkoxy group, R ¹⁴ is more preferably a hydrogen atom, and R ¹³ is a hydroxy group. And R ¹⁴ is particularly preferably a hydrogen atom.

  Although the compound preferable as a component A is illustrated below, this invention is not limited to these.

R represents a linear alkyl group having 1 to 10 carbon atoms, and the alkyl group may be linear or branched.
Among the compounds (A-1-1) to (A-1-10), (A-1-1), (A-1-2), (A-1-4), (A-1-5). It is preferable that (A-1-1), (A-1-2), and (A-1-4) are more preferable, and (A-1-2) is particularly preferable.

Component A may be used alone or in combination of two or more.
The content of Component A is 0.05% by mass or more with respect to the total amount of the ink composition, preferably 0.05 to 5% by mass, more preferably 0.05 to 2% by mass, It is still more preferable that it is 0.08-1.0 mass%, and it is especially preferable that it is 0.15-0.5 mass%.

(Component B) Multifunctional monomer At least one ink composition in the ink jet recording method of the present invention comprises (Component B) a polyfunctional monomer (also referred to as “polyfunctional polymerizable compound”) with respect to the total amount of the ink composition. Contains 40% by mass or more. Here, the polyfunctional monomer refers to a monomer having two or more functions.
In the ink jet recording method of the present invention, it is particularly preferable that any ink composition to be used contains (Component B) a polyfunctional monomer in an amount of 40% by mass or more based on the total amount of the ink composition. The image quality of the printed matter after long-term storage is excellent when it is in the above embodiment.
The monomer in the present invention is a polymerizable compound having a molecular weight of 1,000 or less, and is preferably a polymerizable compound having a molecular weight of 200 to 750.
The polyfunctional monomer that can be used in the present invention is not particularly limited, and a known polyfunctional monomer can be used, but a polyfunctional radical polymerizable monomer is preferable. Preferred examples of the polyfunctional radical polymerizable monomer include polyfunctional (meth) acrylate monomers and polyfunctional vinyl ether compounds.
The polyfunctional monomer that can be used in the present invention is preferably a compound having two or more ethylenically unsaturated groups, and preferably contains at least a polyfunctional (meth) acrylate monomer as the polyfunctional monomer. More preferably, the polyfunctional (meth) acrylate monomer is contained in an amount of 30% by mass or more based on the total amount of the ink composition, and the polyfunctional (meth) acrylate monomer is particularly preferably contained in an amount of 40% by mass or more based on the total amount of the ink composition. preferable. It is excellent in sclerosis | hardenability at the time of high production as it is the said aspect.
Moreover, it is preferable that the polyfunctional monomer which can be used for this invention contains a polyfunctional vinyl ether compound at least as a polyfunctional monomer. It is excellent in sclerosis | hardenability at the time of high production as it is the said aspect.

(Component B-1) Polyfunctional (meth) acrylate monomer The ink composition used in the present invention may contain (Component B-1) a polyfunctional (meth) acrylate monomer as the (Component B) polyfunctional monomer. preferable.
The polyfunctional (meth) acrylate monomer that can be used in the present invention is a polyfunctional monomer having two or more groups selected from the group consisting of an acryloxy group and a methacryloxy group. By containing a polyfunctional (meth) acrylate monomer, an ink composition having excellent curability and high cured film strength can be obtained.
In the present invention, the ink composition particularly preferably contains a polyfunctional acrylate monomer as Component B-1.

Specific examples of Component B-1 include bis (4-acryloxypolyethoxyphenyl) propane, neopentyl glycol di (meth) acrylate, ethoxylated (2) neopentyl glycol di (meth) acrylate (neopentyl glycol ethylene oxide) 2 mol adduct diacrylated compound), propoxylation (2) neopentylglycol di (meth) acrylate (nepentylglycol propylene oxide 2 mol adduct diacrylated), 1,6-hexanediol di (Meth) acrylate, 1,9-nonanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol Cold di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, penta Erythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, tetramethylolmethanetri (meth) acrylate , Modified glycerin tri (meth) acrylate, modified bisphenol A di (meth) acrylate, bisphenol A Examples include dioxide (PO) adduct di (meth) acrylate, bisphenol A ethylene oxide (EO) adduct di (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, and the like. It is done.
Can be mentioned.

It is also preferable to contain a poly (meth) acrylate having an alkylene oxide group as component B-1. Here, “poly (meth) acrylate” means that the molecule has two or more (meth) acrylic acid ester residues, and preferably has 2 to 4 residues. More preferably, it has a (meth) acrylic acid ester residue. Moreover, as an alkylene oxide, ethylene oxide and / or propylene oxide are preferable. The added mole number of the alkylene oxide group is preferably 1 to 10, and more preferably 1 to 6. This polyfunctional monomer can be obtained by adding an alkylene oxide to glycols to obtain a polyester of (meth) acrylic acid.
Specific examples of the (meth) acrylate having an alkylene oxide group include a PO adduct di (meth) acrylate of bisphenol A, an EO adduct di (meth) acrylate of bisphenol A, and propoxylated neopentyl glycol di (meth) acrylate. included.

Component B-1 preferably contains a polyfunctional (meth) acrylate monomer having an aliphatic cyclic structure.
The aliphatic cyclic structure is preferably an aliphatic cyclic structure in which two or more rings are condensed, and more preferably a tricyclodecane ring structure.
Examples of the polyfunctional (meth) acrylate monomer having an aliphatic cyclic structure include cyclohexanediol di (meth) acrylate, cyclohexanedidimaledi (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, and tricyclodecane. Examples include diol di (meth) acrylate, propylene oxide (PO) adduct di (meth) acrylate of hydrogenated bisphenol A, and ethylene oxide (EO) adduct di (meth) acrylate of hydrogenated bisphenol A. Among these, tricyclodecane dimethanol di (meth) acrylate is particularly preferable.

Component B-1 may be used alone or in combination of two or more.
The content of Component B-1 is preferably 30% by mass or more of the entire ink composition, more preferably 40% by mass or more, and further preferably 50% by mass or more. Moreover, it is preferable that it is 95 mass% or less, It is more preferable that it is 90 mass% or less, It is still more preferable that it is 85 mass% or less, It is especially preferable that it is 75 mass% or less. In the above embodiment, the image quality obtained is excellent even after long-term storage, and the curability is excellent even during high production.

(Component B-2) Polyfunctional vinyl ether compound The ink composition for inkjet recording of the present invention preferably contains (Component B-2) a polyfunctional vinyl ether compound as the (Component B) polyfunctional monomer.
The polyfunctional vinyl ether compound is not particularly limited as long as it is a compound having two or more vinyl ether groups (CH ₂ ═CH—O—) in the molecule, but it has a divinyl ether compound having an (poly) oxyalkylene skeleton and an alkylene skeleton. Vinyl ether compounds and vinyl ether compounds having a cycloalkane skeleton are preferred.
Examples of the divinyl ether compound having a (poly) oxyalkylene skeleton include ethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol glycol divinyl ether, polypropylene glycol glycol divinyl ether, butylene glycol divinyl ether, and polybutylene glycol divinyl ether. Can be mentioned.
Examples of the divinyl ether compound having an alkylene skeleton include 1,6-hexanediol divinyl ether, 1,9-nonanediol divinyl ether, 1,10-decanediol divinyl ether, neopentyl glycol divinyl ether, and neopentyl hydroxypivalate. Examples include glycol divinyl ether.
Examples of the divinyl ether compound having a cycloalkane skeleton include 1,4-cyclohexanediol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, tricyclodecanediol divinyl ether, tricyclodecane dimethanol divinyl ether, and pentacyclopentadecane. Examples include dimethanol divinyl ether and pentacyclopentadecanediol divinyl ether.
Examples of the trivinyl ether compound include trimethylolpropane trivinyl ether.

Among these, a divinyl ether compound is preferable, a divinyl ether having an alkylene skeleton and a divinyl ether compound having a (poly) oxyalkylene skeleton are more preferable, a divinyl ether compound having a polyoxyalkylene skeleton is more preferable, and triethylene glycol divinyl ether Is particularly preferred.
As the oxyalkylene group, an oxyalkylene group having 2 to 6 carbon atoms is preferable, an oxyalkylene group having 2 to 4 carbon atoms is more preferable, and an oxyethylene group and an oxypropylene group are preferable.
In the divinyl ether compound having a polyoxyalkylene skeleton, the number of repeating oxyalkylene groups is preferably 1 to 10, preferably 2 to 8, and more preferably 2 to 6. Moreover, it is preferable that molecular weight is 100-1,000, It is more preferable that it is 150-800, It is still more preferable that it is 180-600.

Component B-2 may be used alone or in combination of two or more.
The content of Component B-2 is preferably 1 to 50% by mass of the total ink composition, more preferably 3 to 30% by mass, and still more preferably 5 to 20% by mass.

Component B may be used alone or in combination of two or more.
The content of component B is 40% by mass or more, more preferably 50% by mass or more, and still more preferably 52% by mass or more with respect to the total amount of the ink composition. Moreover, it is preferable that it is 95 mass% or less, It is more preferable that it is 90 mass% or less, It is still more preferable that it is 85 mass% or less, It is especially preferable that it is 75 mass% or less. In the above embodiment, the image quality obtained is excellent even after long-term storage, and the curability is excellent even during high production.

(Component C) Photopolymerization Initiator At least one ink composition in the ink jet recording method of the invention contains (Component C) a photopolymerization initiator.
In the ink jet recording method of the present invention, any ink composition to be used preferably contains (Component C) a photopolymerization initiator.
Examples of the photopolymerization initiator include a radical photopolymerization initiator and a cationic photopolymerization initiator, but it is more preferable to contain a radical photopolymerization initiator.
A known photopolymerization initiator can be used as the photopolymerization initiator. The photopolymerization initiator that can be used in the present invention may be used alone or in combination of two or more. Moreover, you may use together a radical photoinitiator and a cationic photoinitiator.
The photopolymerization initiator that can be used in the present invention is a compound that absorbs active energy and generates a polymerization initiating species. Examples of active energy rays include γ rays, β rays, electron beams, ultraviolet rays, visible rays, and infrared rays.

Examples of the photopolymerization initiator that can be used in the present invention include (a) aromatic ketones, (b) acylphosphine compounds, (c) aromatic onium salt compounds, (d) organic peroxides, and (e) thio compounds. (F) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) carbon halogen bond And (m) an alkylamine compound. These polymerization initiators may use the above compounds (a) to (m) alone or in combination. Details of the polymerization initiator are known to those skilled in the art, and are described, for example, in JP-A-2009-185186.
Although the photoinitiator in this invention is used suitably by 1 type single or 2 or more types of combined use, It is preferable to use 2 or more types together, It is more preferable to use 3 or more types together, 3 to 5 types combined use More preferably.

  As Component C, it is preferable to use at least one compound selected from the group consisting of a bisacylphosphine compound, a monoacylphosphine compound, an α-hydroxyketone compound, and an α-aminoketone compound. More preferably, at least two compounds selected from the group consisting of a monoacylphosphine compound, an α-hydroxyketone compound, and an α-aminoketone compound are used, and a bisacylphosphine compound and a monoacylphosphine compound are used in combination. It is particularly preferred.

Preferred examples of the bisacylphosphine compound and the monoacylphosphine compound include bisacylphosphine oxide compounds and monoacylphosphine compounds described in paragraphs 0080 to 0098 of JP-A-2009-096985.
Of these, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide is preferable as the bisacylphosphine oxide compound.
As the monoacylphosphine oxide compound, 2,4,6-trimethylbenzoyldiphenylphosphine oxide is preferable.

Examples of α-hydroxyketone compounds include 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one and 2-hydroxy-2-methyl-1-phenyl. Propan-1-one, 1-hydroxycyclohexyl phenyl ketone and the like can be mentioned.
Examples of the α-aminoketone compound include 2-methyl-1-phenyl-2-morpholinopropan-1-one, 2-methyl-1- [4- (hexyl) phenyl] -2-morpholinopropan-1-one, 2-ethyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one and the like can be mentioned.

  The content of Component C in the ink composition of the present invention is preferably 0.1 to 20.0% by mass, and 0.5 to 18.0% by mass with respect to the total mass of the ink composition. It is more preferable that it is 1.0-15.0 mass%. When the content of component C is in the above range, the curability is excellent and it is appropriate from the viewpoint of reducing surface stickiness.

(Component D) N-vinyl lactams The at least one ink composition in the ink jet recording method of the invention preferably contains (Component D) N-vinyl lactams.
In the ink jet recording method of the present invention, it is more preferable that any ink composition to be used contains (Component D) N-vinyl lactams.
When (Component D) N-vinyl lactam is contained, it is more excellent in curability.
As N-vinyl lactam, the compound represented by Formula (d) is preferable.

In formula (d), n represents an integer of 2 to 6, and n is 3 to 5 from the viewpoints of flexibility after the ink composition is cured, adhesion to a recording medium, and availability of raw materials. It is preferably an integer, more preferably n is 3 or 5, and particularly preferably n is 5, that is, N-vinylcaprolactam. N-vinylcaprolactam is preferable since it is excellent in safety, is generally available and can be obtained at a relatively low price, and provides particularly good ink curability and good adhesion of a cured film to a recording medium.
In the N-vinyllactam, a hydrogen atom on the lactam ring may be substituted with a substituent such as an alkyl group or an aryl group, or a lactam ring and a saturated or unsaturated ring structure may be linked. Good.
The compound represented by Formula (d) may be used individually by 1 type, or may use 2 or more types together.

The content of N-vinyl lactams is preferably 5 to 40% by mass, and more preferably 10 to 35% by mass, based on the entire ink composition.
N-vinyl lactams are preferably used when the ink composition is a colored ink composition.

(Component E) Sensitizer The at least one ink composition in the ink jet recording method of the invention preferably contains (Component E) a sensitizer.
In the ink jet recording method of the present invention, it is more preferable that any ink composition to be used contains (Component E) a sensitizer.
(Component E) A sensitizer is a compound that absorbs a specific active energy ray and accelerates the decomposition of the photopolymerization initiator, and is excellent in curability by containing a sensitizer.
Examples of the sensitizer include polynuclear aromatics (eg, pyrene, perylene, triphenylene, 2-ethyl-9,10-dimethoxyanthracene), 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 (eg , Acridine orange, chloroflavin, acriflavine, etc.), anthraquinones (eg, anthraquinone, etc.), squaliums (eg, squalium), coumarins (eg, 7-diethylamino-4-methylcoumarin, etc.), thioxanthate Class (e.g., 2,4-diethyl thioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone, etc.), a thiochromanone compound (e.g., a thiochromanone etc.) are preferred.
) And the like.
Among these, thioxanthones are preferable, and 2-isopropylthioxanthone and / or 4-isopropylthioxanthone are more preferable. The sensitizer may be used alone or in combination of two or more. Good.
The content of the sensitizer is preferably from 0.1 to 10% by mass, more preferably from 0.2 to 5% by mass, based on the entire ink composition.

(Component F) Oligomer The at least one ink composition in the ink jet recording method of the invention preferably contains (Component F) an oligomer.
In the ink jet recording method of the present invention, it is more preferable that any ink composition to be used contains (Component F) oligomer.
Here, the oligomer is a polyfunctional oligomer which is a compound having a molecular weight exceeding 1,000, preferably contains a plurality of ethylenically unsaturated groups, and contains 2 to 4 ethylenically unsaturated groups. Is more preferable. The radical polymerizable oligomer preferably has an ethylenically unsaturated group at the molecular end or molecular side chain of an addition polymer having a finite number of structural units (generally 5 to 100), and has a weight average molecular weight of 1. It is preferably more than 1,000 and 10,000 or less, more preferably more than 1,000 and 5,000 or less.
The molecular weight measurement method of the oligomer includes (1) end group determination method, (2) bundled property utilization method, (3) light scattering method, (4) ultracentrifugation method, (5) viscosity method, (6) A gel permeation chromatography (GPC) method and the like can be mentioned. Among them, a gel permeation chromatography (GPC) method is preferable. Specifically, for example, GPC analysis can be performed under the following conditions, and measurement can be suitably performed.
1) Equipment: HLC-8220GPC manufactured by Tosoh Corporation
2) Column (manufacturer, column property): TSK gel SuperAWM-H 3 linked (6.0 mm ID × 15 cm × 3), manufactured by Tosoh Corporation, fine particle gel 3 based on hydrophilic vinyl polymer ) Solvent: Tetrahydrofuran 4) Flow rate: 0.5 mL / min
5) Sample concentration: 0.1% by mass
6) Injection volume: 60 μL
7) Temperature: 40 ° C
8) Detector: Differential refractometer (RI)

The oligomer is preferably a radically polymerizable oligomer.
The radical polymerizable oligomer preferably has a (meth) acryloxy group, and more preferably has two or more (meth) acryloxy groups.
As the radically polymerizable oligomer, any monomer may be used as its constituent unit, for example, olefin (ethylene oligomer, propylene oligomer butene oligomer, etc.), vinyl (styrene oligomer, vinyl alcohol oligomer, vinyl pyrrolidone oligomer acrylate). Oligomer, methacrylate oligomer, etc.), diene (butadiene oligomer, chloroprene rubber, pentadiene oligomer, etc.), ring-opening polymerization (di-, tri-, tetraethylene glycol, polyethylene glycol, polyethylimine, etc.), polyaddition (oligo) Ester acrylate, polyamide oligomer, polyisocyanate oligomer), addition condensation oligomer (phenol resin, amino resin, xylene resin, ketone resin, etc.) That. Among these, urethane (meth) acrylate, polyester (meth) acrylate, and epoxy (meth) acrylate are preferable, and urethane (meth) acrylate is more preferable.

Preferred examples of the urethane (meth) acrylate include aliphatic urethane (meth) acrylates and aromatic urethane (meth) acrylates, and more preferred are aliphatic urethane (meth) acrylates.
The urethane (meth) acrylate is preferably a bifunctional to tetrafunctional urethane (meth) acrylate, and more preferably a bifunctional urethane (meth) acrylate.
By containing urethane (meth) acrylate, an ink composition having excellent adhesion to a recording medium and excellent curability can be obtained.
Regarding the oligomer, the oligomer handbook (supervised by Junji Furukawa, Chemical Industry Daily Co., Ltd.) can also be referred to.

Examples of commercially available radical polymerizable oligomers include urethane (meth) acrylates such as R1204, R1211, R1213, R1217, R1218, R1301, R1302, R1303, R1304, R1306, and R1308 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. , R1901, R1150, etc., and EBECRYL series (for example, EBECRYL230, 270, 4858, 8402, 8804, 8807, 8803, 9260, 1290, 1290K, 5129, 4842, 8210, 210, 4827, manufactured by Daicel Cytec Co., Ltd. 6700, 4450, 220), NK Oligos U-4HA, U-6HA, U-15HA, U-108A, U200AX, etc. manufactured by Shin-Nakamura Chemical Co., Ltd., Aronix M-110 manufactured by Toagosei Co., Ltd. , M-1200, M-1210, M-1310, M-1600, M-1960, it includes the CN964 A85 such as manufactured by Sartomer Japan (Ltd.).
Examples of the polyester (meth) acrylate include EBECRYL series (for example, EBECRYL770, IRR467, 81, 84, 83, 80, 675, 800, 810, 812, 1657, 1810, IRR302, 450, manufactured by Daicel Cytec Co., Ltd. 670, 830, 870, 1830, 1870, 2870, IRR267, 813, IRR483, 811 etc.), Aronix M-6100, M-6200, M-6250, M-6500, M-7100, manufactured by Toagosei Co., Ltd. M-8030, M-8060, M-8100, M-8530, M-8560, M-9050, etc. are mentioned.
Moreover, as epoxy (meth) acrylate, for example, EBECRYL series (for example, EBECRYL600, 860, 2958, 3411, 3600, 3605, 3700, 3701, 3703, 3702, 3708, RDX63182, 6040, etc. manufactured by Daicel Cytec Co., Ltd. ) And the like.

Moreover, an oligomer may be used individually by 1 type and may use 2 or more types together.
The content of the oligomer is preferably 0.1% by weight or more and less than 10% by weight, more preferably 0.5 to 8% by weight, and more preferably 1 to 7% by weight with respect to the total weight of the ink composition. It is particularly preferred that

(Component G) Other monofunctional polymerizable monomer In the ink jet recording method of the present invention, at least one kind of the ink composition may contain (Component G) other monofunctional polymerizable monomer other than Component D. .
The other monofunctional polymerizable monomer is preferably a monofunctional radical polymerizable monomer.
Other monofunctional polymerizable monomers that can be used in the present invention are not particularly limited as long as they do not depart from the gist of the present invention, and known radically polymerizable compounds can be used.
Examples of other monofunctional polymerizable monomers include, for example, JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, JP-A-10-863, JP-A-9-80675, and the like. A photocurable material using the photopolymerizable composition described in 1) is known.

Other monofunctional polymerizable monomers that can be used in the present invention include ethylenically unsaturated groups selected from the group consisting of vinyl groups, acrylate groups, methacrylate groups, acrylamide groups, methacrylamide groups, and N-vinyl groups. Preferred examples include monofunctional radically polymerizable monomers. Among these, monofunctional (meth) acrylate monomers are preferable.
As the monofunctional (meth) acrylate monomer, for example, a radical polymerizable monomer described in JP-A 2009-22214, a polymerizable compound described in JP-A 2009-209289, and JP-A 2009-191183 are described. Of ethylenically unsaturated compounds.

Examples of monofunctional (meth) acrylate monomers include phenoxyethyl (meth) acrylate, cyclic trimethylolpropane formal (meth) acrylate, isobornyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, norbornyl (meth) acrylate, cyclohexyl (Meth) acrylate, cyclopentyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, cyclodecyl (meth) acrylate, dicyclodecyl (meth) acrylate, 3,3,5-trimethylcyclohexyl (meth) acrylate, 4-t-butylcyclohexyl (meth) acrylate, acryloylmorpholine, N-phthalimidoethyl (meth) acrylate, pentamethyl Peridyl (meth) acrylate, tetramethylpiperidyl (meth) acrylate, 5- (meth) acryloyloxymethyl-5-ethyl-1,3-dioxacyclohexane, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) Acrylate, 2-butoxyethyl (meth) acrylate, carbitol (meth) acrylate, methyl (meth) acrylate, n-butyl (meth) acrylate, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, 2- (2 -Butoxyethoxy) ethyl (meth) acrylate, dimethylaminomethyl (meth) acrylate and the like.
Among these, phenoxyethyl (meth) acrylate, cyclic trimethylolpropane formal (meth) acrylate, and isobornyl (meth) acrylate are preferable.

Component G may be used alone or in combination of two or more.
The content of component G is preferably less than the content of component B, preferably less than 40% by mass, more preferably less than 10% by weight, and still more preferably less than 5% by weight.

(Component H) Other Polymerization Inhibitor The at least one ink composition in the ink jet recording method of the present invention may contain (Component H) other polymerization inhibitor other than Component B.
Other polymerization inhibitors include nitroso polymerization inhibitors, phosphite ester polymerization inhibitors, hydroquinone, methoxyhydroquinone, benzoquinone, p-methoxyphenol, hindered amines and the like.
Specific examples of the nitroso polymerization inhibitor preferably used in the present invention are shown below, but are not limited thereto.

Examples of commercially available nitroso polymerization inhibitors include FIRSTCURE ST-1 (manufactured by Chem First).
Phosphite ester polymerization inhibitors include triphenyl phosphite, tris (nonylphenyl phosphite), triethyl phosphite, tris (2-ethylhexyl) phosphite, tridecyl phosphite, tris (tridecyl) phosphite, diphenyl Mono (2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl mono (tridecyl) phosphite, dilauryl hydrogen phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite, Tetra (tridecyl) -4,4'-isopropylidene diphenyl diphosphite, trilauryl trithiophosphite, bis (tridecyl) pentaerythritol diphosphite And wite, tristearyl phosphite, distearyl pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, and tris (2,4-di-t-butylphenyl) phosphite.
Among them, cuperon Al (tris (N-nitroso-N-phenylhydroxylamine) aluminum salt, FIRSTCURE ST-1) and / or methoxyhydroquinone is preferable.
The content of the other polymerization inhibitor in the ink composition used in the present invention is preferably 0.5% by mass or less, more preferably 0.01 to 0.5% by mass, and More preferably, it is 05-0.2 mass%. Within the above numerical range, polymerization at the time of preparation and storage of the ink composition can be suppressed, and clogging of the ink jet nozzle can be prevented.

(Component I) Colorant When at least the ink composition in the ink jet recording method of the present invention is a colored ink composition, it preferably contains a colorant. Among these, it is particularly preferable to contain a phthalocyanine pigment as a colorant. The effect of this invention can be exhibited more as it is the said aspect.
The colorant that can be used in the present invention is not particularly limited, but pigments and oil-soluble dyes that are excellent in weather resistance and excellent in color reproducibility are preferable, and are arbitrarily selected from known colorants such as soluble dyes. Can be used. From the viewpoint of not reducing the sensitivity of the curing reaction by actinic radiation, it is preferable to select a compound that does not function as a polymerization inhibitor in the polymerization reaction, which is a curing reaction, as the colorant that can be suitably used in the present invention.

Although it does not necessarily limit as a pigment which can be used for this invention, For example, the organic or inorganic pigment of the following number described in a color index can be used.
Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 42, 43, 48: 1, 48: 2, 48: 3, 48: 4, 48: 5, 49: 1, 53. : 1, 57: 1, 57: 2, 58: 4, 63: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 88, 104, 108, 112, 122, 123, 144 , 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13, 16, 20, 36,
Pigment Blue 1,15,15: 1,15: 2,15: 3,15: 4,15: 6,16,17-1,22,27,28,29,36,60 as a blue or cyan pigment ,
As a green pigment, Pigment Green 7, 26, 36, 50,
As yellow pigments, Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 120, 137 , 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193,
As the black pigment, Pigment Black 7, 28, 26,
As a white pigment, Pigment White 6, 18, 21
Etc. can be used according to the purpose.
Among them, C.I. I. Preferred examples include phthalocyanine pigments such as CI Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17: 1.

Below, the oil-soluble dye which can be used by this invention is demonstrated.
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.

  Among 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; and quinone dyes such as naphthoquinone dyes and anthraquinone dyes. And dyes and acridinone dyes.

  Of the oil-soluble dyes usable in the present invention, any magenta dye can be used. For example, aryl or hetaryl 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; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes and 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 applicable to 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; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, xanthene dyes Phthalocyanine dyes; anthraquinone dyes; for example, aryl or heteryl azo dyes having phenols, naphthols and anilines as coupling components; indigo / thioindigo dyes;

  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, and organic cations such as pyridinium and quaternary ammonium salts may be used, and furthermore, polymer cations having such a partial structure may be used.

Although not limited to the following, preferred specific examples 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; and the like.
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.
In the present invention, the oil-soluble dye may be used alone or in combination of several kinds.

Moreover, when using an oil-soluble dye as a colorant, other water-soluble dyes, disperse dyes, pigments, and other colorants can be used in combination as long as the effects of the present invention are not impaired.
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;

  It is preferable that the colorant that can be used in the present invention is appropriately dispersed in the ink composition after being added to the ink composition. For dispersing the colorant, for example, a dispersion device such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, or a paint shaker can be used.

In preparing the ink composition, the colorant may be blended directly with each component, but in order to improve dispersibility, it is added in advance to a dispersion medium such as a solvent or a radical polymerizable compound used in the present invention. It can also be blended after being uniformly dispersed or dissolved.
In the present invention, in order to avoid the problem of deterioration of solvent resistance when the solvent remains in the cured image and the problem of VOC (Volatile Organic Compound) of the remaining solvent, the colorant is a radical polymerizable compound. It is preferable to add and mix in advance in such a dispersion medium. In consideration of only dispersibility, it is preferable to select a monomer having a low viscosity as the polymerizable compound used for adding the colorant.

  These colorants may be used by appropriately selecting one type or two or more types according to the purpose of use of the ink composition.

When using a colorant such as a pigment that remains solid in the ink composition, the average particle diameter of the colorant particles is preferably 0.005 to 0.5 μm, more preferably 0.01 to It is preferable to set the colorant, the dispersant, the dispersion medium, the dispersion conditions, and the filtration conditions so as to be 0.45 μm, more preferably 0.015 to 0.4 μm. This particle size control is preferable because clogging of the head nozzle can be suppressed and ink storage stability, ink transparency, and curing sensitivity can be maintained.
In the present invention, the content of the colorant in the ink composition is appropriately selected depending on the color and purpose of use, but is preferably 0.01 to 30% by mass with respect to the mass of the entire ink composition.

(Component J) Dispersant The ink composition that can be used in the present invention preferably contains (Component J) a dispersant. In particular, when the ink composition of the present invention is used as a colored ink composition, it is preferable to contain (Component J) a dispersant for the purpose of improving the dispersibility of the colorant.
As the dispersant, a polymer dispersant is preferable. The “polymer dispersant” in the present invention means a dispersant having a mass average molecular weight of 1,000 or more.

Examples of the polymer dispersant include DISPERBYK-101, DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-111, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-166, DISPERBYK-166, and DISPERBYK-166. , DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-182 (manufactured by BYK Chemie); EFKA7462, EFKA7500, EFKA7570, EFKA7575, EFKA7580 (manufactured by Efka Additive); Disperse Aid 6, Disperse Aid 8, Disperse Aid 15, Disperse Aid 9100 (manufactured by Sannopco); Solsperse (SOLSPERSE) 3000 Various Solsperse dispersants (manufactured by Noveon) such as 5000, 9000, 12000, 13240, 13940, 17000, 22000, 24000, 26000, 28000, 32000, 36000, 39000, 41000, 71000; Adeka Pluronic L31, F38, L42, L44 , L61, L64, F68, L72, P95, F77, P84, F87, P94, L101, P103, F108, L121, -123 (manufactured by ADEKA Corporation), Ionette S-20 (manufactured by Sanyo Chemical Industries, Ltd.); Disparon KS-860, 873SN, 874 (polymer dispersing agent), # 2150 (aliphatic polycarboxylic acid), # 7004 (polyether ester type) (manufactured by Enomoto Kasei Co., Ltd.).
The content of the dispersant in the ink composition is appropriately selected depending on the purpose of use, but is preferably 0.05 to 15% by mass with respect to the mass of the entire ink composition.

(Component K) Surfactant A surfactant may be added to the ink composition that can be used in the present invention in order to impart stable ejection properties for a long time.
However, it is preferable that the ink composition of the present invention does not substantially contain a silicone-based surfactant and a fluorine-based surfactant from the viewpoint of suppressing glossiness and stripe unevenness. The term “substantially free of surfactant” refers to 0 to 0.03% by weight, preferably 0 to 0.005% by weight, based on the total weight of the ink composition.
Examples of surfactants other than silicone surfactants and fluorine surfactants include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts.

<Other ingredients>
In the ink composition of the present invention, a co-sensitizer, an ultraviolet absorber, an antioxidant, an anti-fading agent, a conductive salt, a solvent, a polymer compound, a basic compound, in addition to the above components, as necessary , Leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, rubber resins, waxes and the like may be included. As these other components, known components can be used, for example, those described in JP-A-2009-22214.

<Ink physical properties>
The ink composition that can be used in the present invention has a viscosity at 25 ° C. of preferably 40 mPa · s or less, more preferably 5 to 40 mPa · s, and more preferably 7 to 30 mPa · s in consideration of dischargeability. More preferably. Moreover, it is preferable that the viscosity in discharge temperature (Preferably 25-80 degreeC, More preferably, 25-50 degreeC) is 3-15 mPa * s, and it is more preferable that it is 3-13 mPa * s. It is preferable that the composition ratio of the ink composition is appropriately adjusted so that the viscosity is in the above range. By setting the viscosity at room temperature (25 ° C.) high, even when a porous recording medium is used, ink penetration into the recording medium can be avoided and uncured monomers can be reduced, which is preferable. . Furthermore, it is preferable because ink bleeding at the time of ink droplet landing can be suppressed, and as a result, the image quality is improved.
In the present invention, the viscosity of the ink composition is preferably measured using a B-type viscometer: Brookfield LVDV-I (manufactured by Brookfield) at 25 ° C. and a rotor rotation speed of 20 rpm.

The surface tension at 25 ° C. of the ink composition that can be used in the present invention is preferably 40 mN / m or less, more preferably 35 mN / m or less, and more preferably 30 mN / m or less from the viewpoint of wettability. More preferably. Further, from the viewpoint of bleeding and penetration, it is preferably 20 mN / m or more, and more preferably 23 mN / m or more.
In addition, as a method for measuring the surface tension of the ink composition at 25 ° C., a known method can be used, but it is preferable to measure by a hanging ring method or a Wilhelmy method. In the present invention, the surface tension is measured at a liquid temperature of 25 ° C. by the Wilhelmy method using a commonly used surface tension meter (for example, Kyowa Interface Science Co., Ltd., surface tension meter CBVP-Z). Preferably it is done.

<Preparation process>
The inkjet recording method of the present invention includes a preparation step of preparing an inkjet recording apparatus provided with an inkjet head.
The ink jet recording apparatus that can be used in the present invention is not particularly limited, and a known ink jet recording apparatus can be used. However, the following specific ink jet recording apparatus is preferable.
As an ink jet recording apparatus that can be used in the present invention, nozzles that discharge curable ink that is cured by application of active energy are nozzle rows arranged at a predetermined pitch P in the first direction, and at least cyan. , Magenta, yellow, and black, each of which has a nozzle row for each of N colors (N ≧ 4), and the nozzle rows are arranged with the nozzles shifted in the first direction. The ink jet head, the active energy applying means for applying the active energy to the ink droplets ejected from the nozzles and ejected onto the recording surface of the recording medium, and the ink jet head and the active energy applying means. A holding unit arranged and held along a second direction orthogonal to the direction of 1, the holding unit and the recording medium; Scanning means for relatively scanning in the second direction, moving means for relatively moving the holding means and the recording medium in the first direction for each scanning by the scanning means, and the holding means Control means for forming an image on the recording surface of the recording medium while causing the inkjet head and the active energy applying means held by the head to scan each region of the recording medium a predetermined number of times. An inkjet recording apparatus is preferable.
Hereinafter, an ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention will be described. The color inks such as cyan, magenta, yellow, and black will be described later.

-Inkjet head-
An ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention is a nozzle row in which nozzles that discharge curable ink that is cured by application of active energy are arranged at a predetermined pitch P in the first direction. And N (N ≧ 4) nozzle rows for each of the colors ejecting at least four inks of cyan, magenta, yellow, and black, respectively, each nozzle row in the first direction An ink jet head in which nozzles are arranged to be shifted by P / N is provided.
The first direction is preferably a recording medium conveyance direction (sub-scanning direction).
The inkjet head has a nozzle row for each of N (N ≧ 4) inks that eject at least four inks of cyan, magenta, yellow, and black, respectively, and includes at least cyan, magenta, yellow, and black. It is preferable to have a nozzle row for each of N (N ≧ 5) colors that respectively eject four color inks and at least one light ink, and at least cyan, magenta, yellow, black, light cyan, and It is more preferable to have a nozzle row for each of N (N ≧ 6) colors that respectively eject light magenta ink.

Each nozzle row of the inkjet head is a nozzle row in which nozzles that discharge curable ink that is cured by application of active energy are arranged at a predetermined pitch P in the first direction.
The pitch P is not particularly limited and may be any desired pitch, but is preferably 50 dpi or more (about 508 μm or less) and 600 dpi or less (about 42 μm or more).
Moreover, it is preferable that the nozzle rows of the inkjet head are arranged such that the nozzles are shifted in the first direction, and the nozzles are shifted by P / N in the first direction.
The method of shifting each nozzle row is not particularly limited as long as each nozzle row is shifted, and each nozzle may be shifted stepwise, or even if the shift between adjacent nozzle rows is P / N. , May be an integer multiple of P / N, or may be an arbitrary deviation. For example, in the case of a four-color nozzle row, a shifting method as shown in FIG. 1 or FIG. 2 can be mentioned. In particular, when the nozzles are shifted by P / N, it is preferable to shift the adjacent nozzle rows so that the deviation of the adjacent nozzle rows is not P / N as much as possible. It is particularly preferable that the shift is any (2 × P / N) or more.
In the first direction, each nozzle row of the inkjet head has a black ink nozzle row, a yellow ink nozzle row, and a cyan ink nozzle row in the case of four colors from the most upstream side of the recording medium relative to the inkjet head in the first direction. The magenta ink nozzle rows are preferably arranged in a shifted order. In the case of four colors and a total of six colors of light cyan and light magenta, the nozzle row for black ink, the nozzle row for yellow ink, the nozzle row for light magenta ink, the nozzle row for cyan ink, the nozzle row for light cyan ink, and for magenta ink It is preferable that the nozzle rows are arranged in a shifted order.

In addition, each nozzle row of the ink jet head preferably has an ink nozzle with the lowest curing sensitivity arranged on the most upstream side of the relative movement of the recording medium with respect to the ink jet head in the first direction. It is more preferable that the recording medium is disposed from upstream to downstream relative to the nozzle inkjet head in order from the ink. In the above aspect, since the ink of the nozzles arranged on the upstream side of the relative movement of the recording medium is arranged in a layer closer to the recording surface of the recording medium so that an image is formed on the recording surface of the recording medium. An ink having a low curing sensitivity can be arranged in a layer closest to the recording surface, so that the state of the surface layer can be kept constant, and uneven gloss can be reduced.
Of the four color inks, the ink with the lowest curing sensitivity is often a black ink, and the ink with the second lowest curing sensitivity is often a yellow ink.
The inkjet head has nozzle rows that discharge light cyan and light magenta inks as light ink, and each nozzle row of the inkjet head is arranged with the nozzles shifted by P / 6 in the first direction, In addition, a light cyan or light magenta nozzle may be disposed between the cyan nozzle and the magenta nozzle, between the magenta nozzle and the yellow nozzle, or between the yellow nozzle and the cyan nozzle. preferable.

The inkjet head may have a white ink nozzle row and / or a clear ink nozzle row. Since white ink and clear ink have little influence on the gloss unevenness of the image, the white ink nozzle row and / or the clear ink nozzle row together with the other nozzle rows in the first direction. The nozzles may be arranged in a shifted manner or not.
In addition, the white ink nozzle row and / or the clear ink nozzle row has N pieces of ink for ejecting ink of each color of cyan, magenta, yellow, and black (preferably, light cyan and / or light magenta), respectively. It is preferable that one type is arranged on each side in the second direction of the nozzle row for each color. Specifically, for example, the arrangement shown in FIG.
In the inkjet recording method of the present invention, the clear ink may be used in the same manner as the colored ink, or may be used for forming an undercoat layer or an overcoat layer.

  The number of nozzles arranged at a predetermined pitch P of the nozzle row in the inkjet is not particularly limited as long as it is 2 or more, but is preferably 4 or more and 1,024 or less, and more preferably 8 or more and 512 or less. More preferred.

Examples of the ink jet recording apparatus that can be used in the present invention include an apparatus including an ink supply system and a temperature sensor.
The ink supply system includes, for example, an original tank containing ink, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head. The piezo-type ink jet head is preferably 1 to 100 pL, more preferably 3 to 42 pL, and still more preferably 8 to 30 pL, preferably 300 × 300 to 4,000 × 4,000 dpi, more preferably 400. It can drive so that it can discharge with the resolution of * 400-1600 * 1,600 dpi. In the present invention, dpi represents the number of dots per 2.54 cm.

The ink jet head used in the ink jet recording method of the present invention is preferably an ink jet head having a non-liquid repellent treatment nozzle plate.
As the nozzle plate having the nozzle rows arranged at the pitch P, known ones can be used. For example, US Pat. No. 7,011,396, US Patent Application Publication No. 2009/02900000 Etc. can be preferably used. Such a nozzle plate is mounted on, for example, an on-demand inkjet head using a piezo drive system manufactured by FUJIFILM Dimatix. Specific examples thereof include S-class and Q-class Sapphire.

  More preferably, at least a part of the surface on the side facing the recording medium is subjected to non-liquid repellent treatment (ink affinity treatment). As the non-liquid repellent treatment method, a known method can be used and is not limited. For example, (1) a method of thermally oxidizing the surface of a nozzle plate made of silicon to form a silicon oxide film, and (2) silicon or Examples thereof include a method of oxidatively forming an oxide film other than silicon, a method of forming by sputtering, and (3) a method of forming a metal film. For details of these methods, reference can be made to US Patent Application Publication No. 2010/0141709.

  In the present invention, since it is preferable to set the ejected ink to a constant temperature, an image forming apparatus capable of performing heat insulation and heating is preferably used from the ink supply tank to the inkjet head portion. The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors in each piping portion and perform heating control according to the ink flow rate and the environmental temperature. The temperature sensor can be provided in the vicinity of 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 heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

-Active energy application means-
An ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention includes active energy applying means for applying the active energy to ink droplets ejected from the nozzles and ejected onto the recording surface of a recording medium. Yes.
It is preferable that the active energy applying unit applies the active energy to the extent that the ink droplets deposited on the recording surface of the recording medium are incompletely cured in one scan by the scanning unit. Glossiness can be increased in the above embodiment.
The ink jet recording apparatus used in the present invention includes a second active energy applying unit that fully cures the ink droplet by further applying the active energy to the ink droplet to which the active energy is applied by the active energy applying unit. It is preferable. In the above embodiment, the ink can be appropriately cured.

  As the active energy source in the active energy applying means, a mercury lamp, a gas / solid laser or the like is mainly used, and as a light source used for curing the ultraviolet light curable ink jet recording ink, a mercury lamp, a metal halide, etc. Lamps are widely known. However, from the viewpoint of environmental protection, mercury-free is strongly desired, and replacement with a GaN-based semiconductor ultraviolet light-emitting device is very useful industrially and environmentally. Furthermore, LED (UV-LED) and LD (UV-LD) are small, have a long lifetime, high efficiency, and low cost, and are expected as light sources for photo-curable ink jets.

For curing the ink in the present invention, it is preferable to use an ultraviolet light emitting diode (UV-LED) as a radiation source for irradiating ultraviolet rays, and light emission that generates ultraviolet rays having an emission peak wavelength in the range of 300 to 420 nm. More preferably, a diode is used.
As a UV-LED, for example, Nichia Corporation has launched a purple LED whose main emission spectrum has a wavelength between 365 nm and 420 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands.
From the viewpoint of curability, the emission peak wavelength of ultraviolet light in the active energy application means is preferably 300 to 420 nm, more preferably 350 to 420 nm, and more preferably 380 to 420 nm, depending on the absorption characteristics of the sensitizer. Further preferred.

The active energy application conditions and the basic application method can be exemplified by those disclosed in JP-A-60-132767. Specifically, it is preferable that 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.
In this way, by using a small and light UV-LED as an active energy source provided in the operating part, the inkjet recording apparatus can be reduced in size and energy can be saved, and an image can be formed with high productivity. it can. Moreover, since UV-LED is excellent in the variability of exposure conditions, suitable exposure conditions can be set according to ink, and an image can be formed with high productivity.

  Further, the curing may be completed by another light source that is not driven. In WO 99/54415, 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 surface of the head unit is disclosed as an application method. Such a curing method can also be applied to the ink jet recording method of the present invention.

-Holding means-
The ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention is configured to hold the ink jet head and the active energy applying unit arranged and held along a second direction orthogonal to the first direction. Means.
The second direction is preferably an inkjet head scanning direction (main scanning direction) orthogonal to the recording medium conveyance direction. The second direction is preferably substantially parallel to the recording surface of the recording medium.
The holding unit is not particularly limited, and may be, for example, a member that includes both an inkjet head and an active energy application unit, or a mechanism that drives both the inkjet head and the active energy application unit.
The holding unit is not particularly limited as long as it is a unit that holds the arrangement of the inkjet head and the active energy applying unit as described above, but holds at least one inkjet head and at least two active energy applying units. Preferably, it is a means for holding the active energy applying means on both sides in the second direction of the inkjet head. In the above embodiment, it is easy to incompletely cure the ink.

Further, it is preferable that the holding unit holds the second active energy applying unit on the downstream side of the relative movement of the recording medium. In the above embodiment, the ink can be cured completely appropriately.
The maximum illuminance on the surface of the recording medium in the second active energy applying means is preferably larger than the maximum illuminance on the surface of the recording medium in the (first) active energy applying means. Further, the integrated light amount on the surface of the recording medium in the second active energy applying unit is preferably larger than the integrated light amount on the surface of the recording medium in the (first) active energy applying unit.

-Scanning means and moving means-
An ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention includes a scanning unit that relatively scans the holding unit and the recording medium in the second direction, and each scan by the scanning unit. Moving means for relatively moving the holding means and the recording medium in the first direction;
The scanning means and moving means are not particularly limited, and known means can be used.
Examples of the scanning unit include a guide rail, a driving mechanism, a driving motor, and a control circuit.
Examples of the moving means include a nip roller, a platen, a drive mechanism, a drive motor, and a control circuit.

-Control means-
The ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention is configured such that the ink jet head held by the holding means and the active energy applying means are relative to each region of the recording medium a predetermined number of times. And control means for forming an image on the recording surface of the recording medium while scanning.
There is no restriction | limiting in particular as a control means, A well-known means can be used, For example, control apparatuses, such as a computer provided with the central processing unit (CPU), are mentioned.
Examples of the control device include a recording medium conveyance control unit, a carriage drive control unit, a light source control unit, an image processing unit, and an ejection control unit, and each of these units includes a hardware circuit or software, or a combination thereof. Can be mentioned.

-Other means-
The ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention may include known means other than those described above, if necessary. For example, an input panel such as an operation panel for operating the ink jet recording apparatus or an interface for inputting an image to be formed, a display apparatus for displaying a current state of the ink jet recording apparatus, an input operation, an input image, or the like.

An ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention will be further described with reference to the drawings.
FIG. 3 is an explanatory diagram for explaining an outline of the configuration of the inkjet recording apparatus 100. FIG. 4 is a system configuration diagram of the inkjet recording apparatus 100.

  The inkjet recording apparatus 100 includes an inkjet head 110, curing light sources 116R and 116L, a carriage 118 (an example of a holding unit) on which the inkjet head 110 and the curing light sources 116R and 116L are mounted, and the carriage 118 in the main scanning direction (second direction). A carriage scanning mechanism 130 (an example of a scanning unit) configured to be able to scan along a guide 119 extended in a sub-scanning direction (first scanning direction) orthogonal to the main scanning direction. A recording medium transport mechanism 132 (an example of a moving unit) configured to be movable in an image input interface 134 for acquiring image data via a wired or wireless communication interface, and desired input image data. The image processing unit 136 that performs the image processing, and the inkjet recording apparatus 10 The a control unit 138 and the like for generally controlling.

FIG. 5 is an enlarged schematic diagram of the inkjet head 110. The inkjet head 110 includes six heads 112K, 112C, 112M, 112Y, 112LC, and 112LM (an example of a nozzle array). The six heads 112K, 112C, 112M, 112Y, 112LC, and 112LM are black inks (black inks, K inks) that are ultraviolet curable inks (UV curable inks, examples of curable inks that are cured by application of active energy), A plurality of nozzles 114K, 114C, 114M, 114Y for ejecting cyan ink (C ink), magenta ink (M ink), yellow ink (Y ink), light cyan ink (LC ink), and light magenta ink (LM ink) , 114LC and 114LM, respectively. Here, the LC ink is the same color system as the C ink, and is an ink (light ink) having a lower colorant concentration than the C ink. Similarly, the LM ink is an ink (light ink) having the same color as the M ink and having a lower colorant concentration than the M ink.
Here, among the six colors of inks of K ink, C ink, M ink, Y ink, LC ink, and LM ink, K ink with respect to the wavelength of ultraviolet rays (for example, 385 nm) irradiated from the curing light sources 116R and 116L. Has the lowest curing sensitivity, and Y ink has the second lowest curing sensitivity. Further, the curing sensitivity is low in the order of LM ink, C ink, LC ink, and M ink.

  Here, the curing sensitivity refers to the amount of energy required for complete curing when irradiating ultraviolet rays to cure the ink droplet, and the smaller the energy amount, the higher the sensitivity. Therefore, the lowest curing sensitivity means that the amount of energy required for complete curing is the largest.

The plurality of nozzles 114K of the head 112K are arranged in a line at equal intervals along the sub-scanning direction. Similarly, the plurality of nozzles 114C of the head 112C, the plurality of nozzles 114M of the head 112M, the plurality of nozzles 114Y of the head 112Y, the plurality of nozzles 114LC of the head 112LC, and the plurality of nozzles 114LM of the head 112LM are each along the sub-scanning direction. They are arranged in a line at equal intervals. Here, the pitch of the nozzles 114 of each color head 112 is all 100 dpi.
Each color head 112 is arranged in the order of 112LM, 112K, 112C, 112M, 112Y, 112LC from the left in the main scanning direction.
In the sub-scanning direction, the nozzle 114K is disposed on the uppermost stream side in the recording medium conveyance direction, and is arranged at equal intervals in the order of 114K, 114Y, 114LM, 114C, 114LC, 114M (600 dpi (254 μm ÷ 6) toward the downstream side. = The color heads 112 are arranged so as to be arranged at intervals of about 42 μm). Here, it is sufficient that the nozzle arranged on the most upstream side among the nozzles (effective nozzles) used for printing is the nozzle 114K, and the nozzles (invalid nozzles) not used for printing are upstream of the nozzle 114K. It may be arranged on the side.

  In this way, the color heads 112 are arranged so as to be shifted by P / N in the sub-scanning direction, where P is the nozzle pitch and N is the number of heads (number of nozzle rows). Note that shifting in the sub-scanning direction means that, among the nozzles 114 of each color head 112, the nozzle on the upstream side in the recording medium conveyance direction (No. 1 nozzle) is arranged before and after the No. 1 nozzle of the reference ink. . The first nozzle is not limited to the nozzle 114 provided on each color head 112 that is most upstream in the recording medium transport direction, but is the most used nozzle that is used for ejection in the drawing mode and contributes to drawing. A nozzle located on the upstream side.

  The inkjet head 110 is reciprocally scanned in the main scanning direction by scanning the carriage 118 and discharges ink from the nozzles 114 of the respective color heads 112 according to the control of the control unit 138, whereby the ink of each color is applied to the recording surface of the recording medium 120. Ink droplets are ejected.

  Each time the inkjet head 110 is scanned in the main scanning direction, the recording medium 120 is transported (scanned) by a predetermined amount in the sub-scanning direction by the recording medium transport mechanism 132. In this specification, the upper side in FIG. 3 is referred to as the upstream side in the conveyance direction of the recording medium 120, and the lower side in FIG. 3 is referred to as the downstream side in the conveyance direction of the recording medium 120.

  Curing light sources 116R and 116L (an example of active energy application means) each include a plurality of UV-LEDs. In the curing light sources 116 </ b> R and 116 </ b> L, the control unit 138 turns off the UV-LED located on the upstream side of the main scanning of the carriage 118 and turns on the UV-LED located on the downstream side. In this lit UV-LED, the ink droplets of the respective color inks ejected from the respective color heads 112 onto the recording medium 120 are irradiated with ultraviolet rays to be incompletely cured (semi-cured).

  That is, when ink is ejected from the nozzles 114 of the respective color heads 112 while the carriage 118 moves in the right direction in FIG. 3, the ink droplets are irradiated with ultraviolet rays by the UV-LED of the curing light source 116L located on the downstream side of scanning. To do. In addition, when ink is ejected from the nozzles 114 of the respective color heads 112 while the carriage 118 moves in the left direction in FIG. 3, the ink droplets are irradiated with ultraviolet rays by the UV-LED of the curing light source 116R located on the downstream side of scanning. To do.

The ink droplets ejected onto the recording medium 120 are not completely cured by a single UV irradiation by the curing light sources 116R and 116L, but are in a semi-cured state. Here, the semi-cured state refers to a cured state from when the ink starts to be cured until it reaches the main cured state. Thereafter, the semi-cured ink droplets are further irradiated with ultraviolet rays from a main curing light source (not shown) arranged on the downstream side in the transport direction of the recording medium 120 to be in a main curing state. Is recorded. Note that the fully cured state refers to a state where ink droplets are cured to such an extent that the image does not deteriorate even when the recording medium 120 is handled. That is, the main curing does not necessarily mean that the curing reaction has been completed.
Note that the irradiation light amount of the curing light sources 116R and 116L and the irradiation light amount of the main curing light source can be set separately. As described above, the glossiness of the recorded image can be increased by reducing the amount of irradiation light during semi-curing.

[Data processing method]
As shown in FIG. 5, since the positions of the respective color heads 112 (nozzles 114 thereof) in the sub-scanning direction are shifted from each other, the halftone data at the shifted positions is cut out for each raster as the halftone image data. Then, the ink is transferred to each color head 112 and ejected.

  Halftoned image data is generated on the RIP software in the same manner as usual, input to the inkjet recording apparatus 100 via the image input interface 134, and sent to the image processing unit 136. Each color, for example, LM, K, C, M, Y, and LC, is sent to and stored in the image processing unit 136 by shifting one dot at a time in the sub-scanning direction from the upper end of the image.

  The image processing unit 136 sends image data from a point shifted in the sub-scanning direction close to the shift amount to the control unit 138 from a certain reference color data according to the shift amount of each color head 112. Data from a point shifted in the sub-scanning direction from the reference color data is transferred to the control unit 138 according to the shifted arrangement. As a result, while the RIP software performs normal halftone processing, the ink jet recording apparatus 100 performs output in accordance with the shift position of each color head 112, so that the effect of shifting the arrangement of each color head 112 is small as a completed image. Processing is performed.

  In the embodiment shown in FIG. 4, halftoned image data is input from the image input interface 134, but an RGB image or the like is input and converted into dot data for printing in the image processing unit 136. May be.

  Since each color head 112 is arranged in the order of 112K, 112Y, 112LM, 112C, 112LC, and 112M in the sub-scanning direction, the K ink having the lowest curing sensitivity first lands on the surface of the recording medium 120 and then 2 Second, Y ink with low curing sensitivity lands. Hereinafter, the LM ink, the C ink, the LC ink, and the M ink are landed in the order of low curing sensitivity. Accordingly, the K ink, Y ink, LM ink, C ink, LC ink, and M ink are arranged in this order from the surface of the recording medium toward the upper layer.

  As described above, in the inkjet recording method of the present invention, the nozzles are shifted in the order of the ink having the lower curing sensitivity (step S1 in FIG. 6), and the ink having the lower curing sensitivity is disposed in the lower layer and the ink having the higher curing sensitivity is disposed in the upper layer. It is preferable to form an image (step S2 in FIG. 6) (the ink of the nozzles arranged upstream in the recording medium conveyance direction is arranged in the lower layer). Thereby, the state of a surface layer can always be made constant and gloss unevenness can be reduced more.

  In addition, the UV curable ink forms a three-dimensional shape on the surface without penetrating into the inside of the recording medium at the time of curing, and thus 4C (cyan ink, magenta ink, yellow ink, black ink) that requires a large amount of ink to be ejected. ), The uneven glossiness becomes prominent. The light ink is hardly used in the high density image portion composed of the four types of ink.

  Therefore, in the embodiment shown in FIG. 3, as the arrangement of the color heads 112 in the sub-scanning direction, the light ink nozzles are arranged between the Y ink, C ink, and M ink nozzles that are dark ink. By disposing in this way, droplet ejection interference between dark inks can be reduced, and uneven gloss can be avoided.

  In the nozzle order in the sub-scanning direction, it is preferable that the color nozzles 114 are arranged at 600 dpi in the interval 100 dpi between the nozzles 114 of the color heads 112. Thereby, in the ink jet recording apparatus in which the light source for semi-curing and the light source for main curing are separated, it is possible to form an image with high glossiness and inconspicuous gloss unevenness by reducing the illuminance of the semi-curing light source.

  In this way, the position of each color head 112 in the sub-scanning direction is shifted in the upstream direction of the recording medium conveyance direction in consideration of the ink curing sensitivity, and the light ink nozzles are arranged between the dark ink nozzles. By inserting the gap, the space between the dark ink dots is opened when forming a high-density image, so that the amount of light from the semi-curing light source can be further reduced, and it is possible to simultaneously increase gloss and avoid uneven gloss.

  In this embodiment, two colors of ink, LC ink and LM ink, are used as the light ink, but the light ink is not limited to two colors. Light black ink (LK ink) that is the same color as K ink and has a lower colorant concentration than K ink, or light yellow ink (LY ink) that is the same color as Y ink and has a lower colorant concentration than Y ink It is also possible to adopt a configuration of one to four colors using Also in this case, as the arrangement of the color heads 112 in the sub-scanning direction, the light ink nozzles are arranged between the K ink, Y ink, C ink, and M ink nozzles, which are dark inks. Drop interference can be reduced.

  In this embodiment, the position of each color head 112 in the sub-scanning direction is shifted to the upstream side in the recording medium conveyance direction as the nozzle of the low sensitivity ink. However, the ink nozzle having the lowest curing sensitivity is arranged on the most upstream side. If the ink having the lowest curing sensitivity is arranged in the layer closest to the recording medium, there is a certain effect for avoiding uneven glossiness even if the arrangement order of the other inks is different.

  For example, when the six color inks are used, the ink nozzle 114K having the lowest curing sensitivity is arranged on the most upstream side in the conveyance direction of the recording medium 120, and the K ink first hits the surface of the recording medium 120 (ie, It is sufficient to land on the layer closest to the recording surface of the recording medium 120). The other nozzles may be in the order of 114K, 114C, 114LM, 114M, 114LC, 114Y or the order of 114K, 114M, 114LC, 114Y, 114LM, 114C toward the downstream side.

Further, other ink jet recording apparatuses that can be suitably used in the ink jet recording method of the present invention will be described with reference to the drawings, but it goes without saying that the present embodiment is not limited thereto.
FIG. 7 is an external perspective view of another ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention. The ink jet recording apparatus 10 is a wide format printer that forms a color image on a recording medium 12 using ultraviolet curable ink (UV curable ink). A wide format printer is an apparatus suitable for recording a wide drawing range, such as a large poster or a commercial wall advertisement. Here, the one corresponding to A3 Nobi or higher is called “wide format”.

  The ink jet recording apparatus 10 includes an apparatus main body 20 and support legs 22 that support the apparatus main body 20. The apparatus main body 20 includes a drop-on-demand type ink jet head 24 that ejects ink toward a recording medium (medium) 12, a platen 26 that supports the recording medium 12, a guide mechanism 28 as a head moving unit, and a carriage 30. (An example of scanning means) is provided.

  The guide mechanism 28 is above the platen 26 and is perpendicular to the conveyance direction (X direction, first direction) of the recording medium 12 and parallel to the medium support surface of the platen 26 (Y direction, second direction). ) To extend along. The carriage 30 is supported so as to reciprocate in the Y direction along the guide mechanism 28. An ink jet head 24 is mounted on the carriage 30, and temporary curing light sources 32 </ b> A and 32 </ b> B that irradiate ink on the recording medium 12 with ultraviolet rays and main curing light sources 34 </ b> A and 34 </ b> B are mounted.

The temporary curing light sources 32A and 32B emit ultraviolet rays for temporarily curing (semi-curing) the ink so that the adjacent droplets do not coalesce after the ink droplets ejected from the inkjet head 24 land on the recording medium 12. A light source for irradiation. The main curing light sources 34 </ b> A and 34 </ b> B are light sources that irradiate with ultraviolet rays for performing additional exposure after temporary curing and finally completely curing (main curing) the ink.
The term “semi-cured” in the present invention refers to a state from when the ink composition starts to fully cured.
Further, “completely cured” in the present invention refers to a state in which the inside and the surface of the ink composition are completely cured. Specifically, it is possible to determine whether or not the ink composition has been transferred to the permeation medium by pressing the permeation medium such as plain paper. That is, the case where no transfer is performed is called a completely cured state.

  The inkjet head 24, the temporary curing light sources 32 </ b> A and 32 </ b> B, and the main curing light sources 34 </ b> A and 34 </ b> B disposed on the carriage 30 move integrally with the carriage 30 along the guide mechanism 28.

  As will be described later, the recording medium 12 is not limited to any material such as paper, non-woven fabric, vinyl chloride, synthetic chemical fiber, polyethylene resin, polyester resin, and tarpaulin, and may be a permeable medium or a non-permeable medium. Instead, various media can be used. The recording medium 12 is fed in a roll paper state (see FIG. 8) from the back side of the apparatus, and after printing is wound up by a winding roller (not shown in FIG. 7, reference numeral 44 in FIG. 8) on the front side of the apparatus. (Example of moving means). Ink droplets are ejected from the inkjet head 24 to the recording medium 12 conveyed on the platen 26, and the temporary curing light sources 32A and 32B and the main curing light sources 34A and 34B are applied to the ink droplets attached on the recording medium 12. Ultraviolet rays are irradiated.

  In FIG. 7, a mounting portion 38 for the ink cartridge 36 is provided on the left front surface of the apparatus main body 20. The ink cartridge 36 is a replaceable ink supply source (ink tank) that stores ultraviolet curable ink. The ink cartridge 36 is provided corresponding to each color ink used in the inkjet recording apparatus 10 of this example. Each color-specific ink cartridge 36 is connected to the inkjet head 24 by an ink supply path (not shown) formed independently. When the remaining amount of ink for each color is low, the ink cartridge 36 is replaced.

  Although not shown, a maintenance unit for the inkjet head 24 is provided on the right side of the apparatus main body 20 toward the front. The maintenance unit is provided with a cap for keeping the ink-jet head 24 moisturized during non-printing and a wiping member (blade, web, etc.) for cleaning the nozzle surface (ink ejection surface) of the ink-jet head 24. . The cap for capping the nozzle surface of the inkjet head 24 is provided with an ink receiver for receiving ink droplets discharged from the nozzle for maintenance.

[Description of recording medium transport path]
FIG. 8 is an explanatory diagram schematically showing a recording medium conveyance path in the inkjet recording apparatus 10. As shown in FIG. 8, the platen 26 is formed in an inverted bowl shape, and its upper surface serves as a support surface of the recording medium 12 (referred to as “medium support surface”). A pair of nip rollers 40 that are recording medium conveying means for intermittently conveying the recording medium 12 are disposed on the upstream side in the recording medium conveying direction (X direction) in the vicinity of the platen 26. The nip roller 40 moves the recording medium 12 on the platen 26 in the X direction.

  The recording medium 12 sent out from a supply-side roll (referred to as a “feed-out supply roll”) 42 that constitutes a roll-to-roll type medium conveying means is fed to the entrance of the printing unit (upstream of the platen 26 in the recording medium conveying direction). Are intermittently conveyed in the X direction by a pair of nip rollers 40 provided on the side). The recording medium 12 that has reached the printing unit immediately below the ink jet head 24 is printed by the ink jet head 24 and is taken up by the take-up roller 44 after printing. A guide 46 for the recording medium 12 is provided on the downstream side of the printing unit in the recording medium conveyance direction.

  A temperature adjusting unit 50 for adjusting the temperature of the recording medium 12 during printing is provided on the back surface (the surface opposite to the surface supporting the recording medium 12) of the platen 26 at a position facing the inkjet head 24 in the printing unit. Is provided. When the recording medium 12 at the time of printing is adjusted to a predetermined temperature, the physical properties such as the viscosity of the ink droplets that have landed on the recording medium 12 and the surface tension become the desired values, and the desired dot diameter is set. Can be obtained. In addition, as needed, the pre temperature control part 52 may be provided in the upstream of the temperature control part 50, and the after temperature control part 54 may be provided in the downstream of the temperature control part 50.

[Description of inkjet head]
FIG. 9 is a plan perspective view showing an example of the arrangement of the inkjet head 24, the temporary curing light sources 32A and 32B, and the main curing light sources 34A and 34B arranged on the carriage 30. FIG.

  The inkjet head 24 includes nozzle rows 61CL, 61W, 61LM, 61K for ejecting ink for each color of CL (clear), W (white), LM, K, C, M, Y, LC. 61C, 61M, 61Y, 61LC, 61CL, 61W. In FIG. 9, the nozzle rows are indicated by dotted lines and are shown in a simplified manner, and the displacement of each nozzle row and the individual illustration of the nozzles are omitted. In the following description, the nozzle rows 61CL, 61W, 61LM, 61K, 61C, 61M, 61Y, 61LC, 61CL, and 61W may be collectively referred to as the nozzle row with reference numeral 61.

  The types of ink colors (number of colors) and color combinations are not limited to those shown in FIG. For example, a form in which the LC and LM nozzle arrays are omitted, a form in which the CL and W nozzle arrays are omitted, and a form in which a nozzle array for ejecting special color ink is added are possible. Further, there is no particular limitation on the arrangement order of the nozzle rows for each color in the Y direction.

  By forming a head module for each color nozzle row 61 and arranging them, it is possible to form an inkjet head 24 capable of color drawing. For example, the head modules 24CL, 24W, 24LM, 24K, 24C, 24M, 24Y, and 24LC having nozzle arrays 61CL, 61W, 61LM, 61K, 61C, 61M, 61Y, and 61LC, respectively, are arranged in the Y direction of the carriage 30. It is also possible to arrange them at regular intervals.

  Each of the color-specific head modules 24CL, 24W, 24LM, 24K, 24C, 24M, 24Y, and 24LC may be interpreted as an “inkjet head”. Alternatively, a configuration in which an ink flow path is formed separately for each color inside one inkjet head 24 and a nozzle array that discharges a plurality of colors of ink with one head is also possible.

  Each nozzle row 61 has a plurality of nozzles arranged in a line (linearly) along the X direction at regular intervals. In the inkjet head 24 of this example, the arrangement pitch (nozzle pitch) of the nozzles constituting each nozzle row 61 is 254 μm (100 dpi), the number of nozzles constituting one nozzle row 61 is 256 nozzles, and the total length of the nozzle row 61 Lw (corresponding to “nozzle row length”, sometimes referred to as “nozzle row width”) is approximately 65 mm (254 μm × 255 = 64.8 mm).

  The nozzle arrays 61LM, 61K, 61C, 61M, 61Y, and 61LC are arranged such that each nozzle is shifted in the X direction (not shown), and the K ink having the lowest curing sensitivity is ejected from the upstream side in the media conveyance direction. Are arranged in the order of the nozzle row 61 </ b> K that performs, and the nozzle row 61 </ b> Y that discharges Y ink having the second lowest curing sensitivity. Further, LM ink and LC ink nozzles which are light inks are arranged between nozzles of Y ink, C ink and M ink which are dark inks (see FIG. 5). Note that dark ink with lower curing sensitivity may be arranged on the upstream side in the media conveyance direction.

  Further, the discharge frequency is 15 kHz, and three types of discharge droplet amounts of 10 pl, 20 pl, and 30 pl can be distinguished by changing the drive waveform. That is, it is possible to form three sizes of dots, small dots, medium dots, and large dots.

  As an ink ejection method of the inkjet head 24, a method (piezo jet method) in which ink droplets are ejected by deformation of a piezoelectric element (piezo actuator) is employed. In addition to a configuration using an electrostatic actuator (electrostatic actuator method) as a discharge energy generating element, a heating element (heating element) such as a heater is used to heat ink to generate bubbles and to eject ink droplets with that pressure. It is also possible to adopt a form (thermal jet system).

[About the layout of ultraviolet irradiation equipment]
As shown in FIG. 9, provisional curing light sources 32 </ b> A and 32 </ b> B are disposed on the left and right sides of the scanning direction (Y direction) of the inkjet head 24. Further, main curing light sources 34 </ b> A and 34 </ b> B are arranged on the downstream side in the recording medium conveyance direction (X direction) of the inkjet head 24.
The ink droplets ejected from the nozzles of the inkjet head 24 and landed on the recording medium 12 are immediately irradiated with ultraviolet rays for temporary curing by the temporary curing light source 32A (or 32B) passing thereover. Ink droplets on the recording medium 12 that have passed through the printing area of the inkjet head 24 as the recording medium 12 is intermittently conveyed are irradiated with ultraviolet rays for main curing by the main curing light sources 34A and 34B.
The temporary curing light sources 32A and 32B and the main curing light sources 34A and 34B may be constantly turned on during the printing operation of the inkjet recording apparatus 10, or may be appropriately turned on and off as necessary.

[Configuration example of temporary curing light source]
As shown in FIG. 9, each of the temporary curing light sources 32A and 32B has a structure in which a plurality of UV-LED elements 33 are arranged. The two temporary curing light sources 32A and 32B have a common configuration. In this example, as the temporary curing light sources 32A and 32B, the LED element array in which six UV-LED elements 33 are arranged in a line along the X direction is illustrated, but the number of LED elements and the array form thereof are shown in this example. It is not limited. For example, a configuration in which a plurality of LED elements are arranged in a matrix in the X / Y direction is also possible.
The six UV-LED elements 33 are arranged so that UV irradiation can be performed at once on a region having the same width as the nozzle row width Lw of the inkjet head 24.

[Configuration example of the main curing light source]
As shown in FIG. 9, each of the main curing light sources 34A and 34B has a structure in which a plurality of UV-LED elements 35 are arranged. The two main curing light sources 34A and 34B have a common configuration. In the example of FIG. 9, as the main curing light sources 34A and 34B, an LED element array (6 × 2) in which six UV-LED elements 35 in the Y direction and two in the X direction are arranged in a matrix is illustrated. Yes.

  The arrangement of the UV-LED elements 35 in the X direction is related to the swath width described later, and has a width corresponding to 1 / n (n is a positive integer) of the nozzle row width Lw in one scan of the carriage 30. It is determined so that UV irradiation can be performed at once. In the example of FIG. 9, the UV-LED elements 35 are arranged so that an area having a width of ½ (n = 2) of the nozzle row width Lw can be irradiated at once.

  In addition, the number of LED elements of the main curing light source and the arrangement form thereof are not limited to the example of FIG. Further, the light sources of the temporary curing light sources 32A and 32B and the main curing light sources 34A and 34B are not limited to the UV-LED elements 33 and 35, and a UV lamp or the like can also be used.

[About drawing mode]
The inkjet recording apparatus 10 configured as described above is applied with multi-pass drawing control, and the print resolution can be changed by changing the number of print passes. For example, three types of drawing modes, a high production mode, a standard mode, and a high image quality mode, are prepared, and the printing resolution is different in each mode. The drawing mode can be selected according to the printing purpose and application.

In the high production mode, printing is executed with a resolution of 600 dpi (main scanning direction) × 400 dpi (sub-scanning direction). In the high production mode, a resolution of 600 dpi is realized by two passes (two scans) in the main scanning direction. First, dots are formed with a resolution of 300 dpi in the first scan (the forward path of the carriage 30). In the second scan (return pass), dots are formed such that the middle of the dots formed in the first scan (forward pass) is interpolated at 300 dpi, and a resolution of 600 dpi is obtained in the main scan direction.
On the other hand, in the sub-scanning direction, the nozzle pitch is 100 dpi, and dots are formed at a resolution of 100 dpi in the sub-scanning direction by one main scanning (one pass). Therefore, a resolution of 400 dpi is realized by performing interpolation printing by four-pass printing (four scans).
In this specification, the product of the number of passes in the main scanning direction and the number of passes in the sub-scanning direction is referred to as the number of passes in the drawing mode. Therefore, the number of passes in the high production mode is main scanning 2-pass printing × sub-scanning 4-pass printing = 8 passes.

In the standard mode, printing is performed with a resolution of 600 dpi × 800 dpi. This resolution can be obtained by 2-pass printing in the main scanning direction and 8-pass printing in the sub-scanning direction. That is, the number of passes in the standard mode is main scanning 2-pass printing × sub-scanning 8-pass printing = 16 passes.
In the high image quality mode, printing is performed at a resolution of 1200 × 1200 dpi, and this resolution is obtained by 4 passes in the main scanning direction and 12 passes in the sub-scanning direction. That is, the number of passes in the high image quality mode is main scanning 4 pass printing × sub scanning 12 pass printing = 48 passes.

[Description of ink supply system]
FIG. 10 is a block diagram showing the configuration of the ink supply system of the inkjet recording apparatus 10. As shown in the figure, the ink stored in the ink cartridge 36 is sucked by the supply pump 70 and sent to the inkjet head 24 via the sub tank 72. The sub tank 72 is provided with a pressure adjusting unit 74 for adjusting the pressure of the ink inside.
The pressure adjusting unit 74 includes a pressure increasing / decreasing pump 77 communicating with the sub tank 72 via the valve 76, and a pressure gauge 78 provided between the valve 76 and the pressure increasing / decreasing pump 77.
During normal printing, the pressure increasing / decreasing pump 77 operates in the direction of sucking ink in the sub tank 72, and the internal pressure of the sub tank 72 and the internal pressure of the inkjet head 24 are maintained at negative pressure. On the other hand, at the time of maintenance of the ink jet head 24, the pressure increasing / decreasing pump 77 operates to pressurize the ink in the sub tank 72, and the inside of the sub tank 72 and the inside of the ink jet head 24 are forcibly pressurized. The ink inside is discharged through the nozzle. The ink forcibly discharged from the inkjet head 24 is stored in the ink receiver of the cap (not shown) described above.

[Description of control system of inkjet recording apparatus]
FIG. 11 is a block diagram showing the configuration of the inkjet recording apparatus 10. As shown in the figure, the inkjet recording apparatus 10 is provided with a control device 202 as control means. As the control device 202, for example, a computer having a central processing unit (CPU) can be used. The control device 202 corresponds to the control unit 138 shown in FIG. 4 and functions as a control device that controls the entire inkjet recording apparatus 10 according to a predetermined program and also functions as an arithmetic device that performs various calculations. The control device 202 includes a recording medium conveyance control unit 204, a carriage drive control unit 206, a light source control unit 208, an image processing unit 210, and an ejection control unit 212. Each of these units is realized by a hardware circuit, software, or a combination thereof.
The recording medium conveyance control unit 204 controls the conveyance driving unit 214 for conveying the recording medium 12 (see FIG. 7). The conveyance drive unit 214 corresponds to the recording medium conveyance mechanism 132 shown in FIG. 4, and includes a drive motor that drives the nip roller 40 shown in FIG. The recording medium 12 conveyed on the platen 26 (see FIG. 7) is intermittently fed in the sub-scanning direction in units of swath widths in accordance with the reciprocating scanning (movement of the printing pass) in the main scanning direction by the inkjet head 24.

A carriage drive control unit 206 shown in FIG. 11 controls a main scanning drive unit 216 for moving the carriage 30 (see FIG. 7) in the main scanning direction. The main scanning drive unit 216 corresponds to the carriage scanning mechanism 130 shown in FIG. 4 and includes a drive motor connected to the moving mechanism of the carriage 30 and its control circuit.
The light source control unit 208 adjusts the amount of light emitted from the UV-LED elements 33 of the temporary curing light sources 32A and 32B via the LED drive circuit 218, and the UV-LEDs of the main curing light sources 34A and 34B via the LED drive circuit 219. It is a control means for adjusting the light emission amount of the element 35.
The LED driving circuit 218 adjusts the light emission amount of the UV-LED element 33 by outputting a voltage having a voltage value corresponding to a command from the light source control unit 208. In addition, the LED drive circuit 219 adjusts the light emission amount of the UV-LED element 35 by outputting a voltage having a voltage value corresponding to a command from the light source control unit 208. The LED light emission amount may be adjusted by changing the duty ratio of the drive waveform using PWM (Pulse Width Modulation) instead of changing the voltage, or changing both the voltage value and the duty ratio. May be.

An input device 220 such as an operation panel and a display device 222 are connected to the control device 202.
The input device 220 is means for inputting a manual external operation signal to the control device 202. For example, various forms such as a keyboard, a mouse, a touch panel, and operation buttons can be adopted. Various forms such as a liquid crystal display, an organic EL display, and a CRT can be adopted for the display device 222. By operating the input device 220, the operator can select a drawing mode, input printing conditions, and input / edit attached information. Various information such as input contents and search results are displayed on the display device 222. It can be confirmed through the display.

Further, the ink jet recording apparatus 10 is provided with an information storage unit 224 that stores various types of information and an image input interface 226 for capturing image data for printing. As the image input interface, a serial interface or a parallel interface may be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted.
Image data input via the image input interface 226 is converted into print data (dot data) by the image processing unit 210. This dot data is generally generated by performing color conversion processing and halftone processing on multi-tone image data.

Various known means such as an error diffusion method, a dither method, a threshold matrix method, and a density pattern method can be applied as the halftone processing means. In the halftone process, generally, gradation image data having an M value (M ≧ 3) is converted into gradation image data having an N value (N <M). In the simplest example, it is converted into binary (dot on / off) dot image data, but in halftone processing, it corresponds to the dot size type (for example, three types such as large dot, medium dot, small dot). It is also possible to perform multi-level quantization.
The binary or multi-valued image data (dot data) obtained in this way controls the driving (ON) / non-driving (OFF) of each nozzle, and in the case of multiple values, controls the droplet amount (dot size). Used as ink ejection data (droplet ejection control data).

The ejection control unit 212 generates an ejection control signal for the head drive circuit 228 based on the dot data generated by the image processing unit 210. Further, the discharge control unit 212 includes a drive waveform generation unit (not shown). The drive waveform generation unit is a means for generating a drive voltage signal for driving an ejection energy generation element (in this example, a piezo element) corresponding to each nozzle of the inkjet head 24.
The waveform data of the drive voltage signal is stored in advance in the information storage unit 224, and waveform data to be used is output as necessary. The signal (drive waveform) output from the drive waveform generation unit is supplied to the head drive circuit 228. Note that the signal output from the drive waveform generation unit may be digital waveform data or an analog voltage signal.
A common driving voltage signal is applied to each ejection energy generating element of the inkjet head 24 via the head driving circuit 228, and the switching element is connected to the individual electrode of each energy generating element according to the ejection timing of each nozzle. By switching on / off (not shown), ink is ejected from the corresponding nozzle.

  The information storage unit 224 stores programs executed by the CPU of the control device 202, various data necessary for control, and the like. The information storage unit 224 stores resolution setting information according to the drawing mode, the number of passes (the number of scan repetitions), light emission amount information of the temporary curing light sources 32A and 32B, and the main curing light sources 34A and 34B.

  The encoder 230 is attached to the drive motor of the main scanning drive unit 216 and the drive motor of the transport drive unit 214, and outputs a pulse signal corresponding to the rotation amount and rotation speed of the drive motor. Is sent to the controller 202. Based on the pulse signal output from the encoder 230, the position of the carriage 30 and the position of the recording medium 12 (see FIG. 7) are grasped.

  The sensor 232 is attached to the carriage 30, and the width of the recording medium 12 is grasped based on the sensor signal obtained from the sensor 232.

  According to the inkjet recording apparatus 10 configured as described above, the heads of the respective color inks are shifted in the recording medium conveyance direction within the nozzle pitch, and the lower sensitivity ink heads are arranged on the upstream side in the recording medium conveyance direction. By arranging and recording the ink with higher sensitivity in the lower layer, it is possible to keep the state of the surface layer constant and reduce gloss unevenness.

  In the above-described embodiment, an example in which an image is formed using UV curable ink is described. However, the present invention can be applied to a case where curable ink that is cured by applying active energy is used. For example, an ink that is cured by X-ray, molecular beam, ion beam, or the like can be used.

<Discharge process>
The ink jet recording method of the present invention includes a discharge step of discharging an ink composition onto a recording medium from the ink jet head of the ink jet recording apparatus.
The ejection step is preferably a step of ejecting at least two of the ink compositions of four colors of cyan, magenta, yellow, and black from the inkjet head of the inkjet recording apparatus. More preferably, it is a step of discharging at least three of the ink compositions of four colors of cyan, magenta, yellow and black from the inkjet head, and at least cyan, magenta and yellow from the inkjet head of the inkjet recording apparatus. And a step of discharging the ink composition of four colors of black. The effect of this invention can be exhibited more as it is the said aspect.
In addition, the scanning speed of the inkjet head in the ejection step is 0.9 m / s or higher, and preferably 0.95 m / s or higher. Moreover, it is preferable that it is 3.5 m / s or less, It is more preferable that it is 3.0 m / s or less, It is still more preferable that it is 2.5 m / s or less. The effect of this invention can be exhibited more as it is the said aspect.

  In the present invention, the recording medium is not particularly limited, and a known recording medium can be used. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, 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 the ejection of the ink composition in the ejection step, the ink composition is preferably heated to 25 to 80 ° C., more preferably 25 to 50 ° C., and the viscosity of the ink composition is preferably 3 to 15 mPa · s. More preferably, it is carried out after lowering to 3 to 13 mPa · s. In particular, it is preferable to use an ink composition having a viscosity of 10 to 30 mPa · s at 25 ° C. as in the present invention since it can be discharged satisfactorily. By using this method, high ejection stability can be realized.
A radiation curable ink composition generally has a higher viscosity than a water-based ink composition that is generally 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, the temperature control range of the ink composition is preferably ± 5 ° C. of the set temperature, more preferably ± 2 ° C. of the set temperature, and still more preferably ± 1 ° C. of the set temperature.

<Curing process>
The ink jet recording method of the present invention includes a curing step of curing the ejected ink composition by applying active energy from the active energy applying unit.
The ink composition ejected on the recording medium is cured by applying active energy.
The maximum illuminance on the surface of the recording medium by the active energy applying means is preferably 10 to 3,000 mW / cm ² , more preferably 50 to 2,100 mW / cm ² from the viewpoint of image quality and productivity. 1,600 mW / cm ² is more preferable.
The energy imparted by the light emitting diode of the active energy imparting means, that is, the energy imparted to the ink composition on the recording medium by irradiation with ultraviolet rays (integrated light amount) is preferably 100 to 1,000 mJ / cm ² , and preferably 150 to 800 mJ. / Cm ² is more preferable, and 200 to 700 mJ / cm ² is still more preferable. Within the above range, both productivity and curability can be achieved.

In the inject recording method of the present invention, it is preferable to irradiate the active energy preferably for 0.1 to 2 seconds, more preferably 0.2 to 1.5 seconds, and still more preferably 0.3 to 1 second.
Irradiation with active energy 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. ) Is preferably performed. As described above, by controlling the time from the landing of the ink composition to the irradiation to an extremely short time, it is possible to prevent the ink composition that has landed on the recording medium from bleeding before being cured. Further, since the ink can be exposed to the porous recording medium before the ink penetrates to a deep part where the light source does not reach, the residual unreacted monomer can be suppressed.

  Moreover, the inkjet recording method of this invention may include processes other than the above as needed.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples. In the following description, “part” means “part by mass” unless otherwise specified, and “%” means “% by mass”.

<Preparation of each mill base>
Each component described in the following Table 1 to Table 4 is put into a disperser motor mill M50 (manufactured by Eiger) and dispersed using a zirconia bead having a diameter of 0.65 mm for 8 hours at a peripheral speed of 9 m / s. Each mill base was produced.

<Method for producing ink composition>
Each ink composition was obtained by mixing and stirring the materials described in Tables 1 to 4. In addition, the numerical value in a table | surface represents the compounding quantity (mass part) of each component. Stirring was performed using a mixer (Silverson L4R) at room temperature (25 ° C.) at 5,000 rpm for 20 minutes.

<Inkjet recording method>
-Device configuration-
As shown in FIG. 1, an apparatus including an ink jet head in which nozzle rows of the respective colors are arranged in a shifted manner was used. The details of each part are as follows.
Each of the yellow, magenta, cyan, and black color heads is a piezo ink jet head Q-class Sapphire QS-256 / 10 (manufactured by FUJIFILM DIMATIX, 256 nozzles (100 npi (nozzle per inch), minimum droplet amount 10 pL, 30 kHz) was used.
The light source is a temporary curing light source, as shown in FIG. 9 (however, the nozzle arrangement of each color in the inkjet head is as shown in FIG. 1), and is a light emitting diode (UV-LED, NC4U134 manufactured by Nichia Corporation). , comprising two light sources arranged a wavelength 385 nm), using what is intensity 780mW / cm ^2, light-emitting diodes as the curing light source (UV-LED, Nichia Corp. NC4U134, wavelength 385 nm) Were used, which had two light sources with an illuminance of 1,500 mW / cm ² .
The ink supply system consists of an ink pack, supply piping, deaeration filter SEPAREL EF-G2 (manufactured by DIC Corporation), an ink supply tank immediately before the inkjet head, a deaeration filter, and a piezo-type inkjet head. Then, the pressure was reduced to 0.5 atm.

-Image formation-
Image formation was performed using the apparatus configured as described above.
The drawing conditions were as follows.
Inkjet head scan speed: 1 m / s
Base material: UV gloss coat 157 (157 g / cm ² , UVGC760, gloss paper, manufactured by Sakurai Co., Ltd., thickness 150 μm)
Drawing mode: 1,200 dpi × 1,200 dpi, 12 passes Image: 300% gray with 4 colors (yellow, magenta, cyan, black) Relative relationship between head positions of each color: for each color head shown in FIG. Nozzle arrangement (In this embodiment, this mode is also referred to as “nozzle shifting”).

<Evaluation method>
-Image quality evaluation of printed matter after long-term storage in ink pack form-
A spout part is provided as an ink supply part, and an oxygen-impermeable ink pack (from the outside of the ink pack, a polyamide resin layer (15 μm) / adhesive layer (3 μm) / aluminum layer (10 μm) / adhesive layer (3 μm) / polyolefin An ink pack was prepared in a state where there was no gas-liquid interface inside the resin layer (an ink pack which was a resin layer (80 μm)). The ink pack was stored for 6 months at 30 ° C., mounted on a printer, and printed.
In the image quality evaluation, ISO 12642-2 Annex B (flash tone) was used as an output image, and drawing was performed in 900 * 800 dpi, 16-pass, bidirectional printing mode. Thereafter, the entire output product was synthesized and the roughness of the output image was visually evaluated in five stages.
5: Level that the image is smooth and does not feel rough 4: Level that the image is very slightly rough but satisfies the performance sufficiently for practical use 3: The image is slightly rough but satisfies the practical performance Level 2: It can be seen that the image is rough and the edge of the image is slightly blurred. Slightly problematic level for practical use 1: The image is noticeably rough and blurring is observed at the edge of the image. Unusable levels for practical use

-Evaluation of curability at high production-
4GC image data with C = 100, M = 100, Y = 100, and K = 100 was created in Photoshop, and this image was output by an actual printer. The printing conditions were 600 * 500 dpi, 10-pass, bidirectional printing mode, and output to coated paper (UV gloss coat 157, manufactured by Sakurai Co., Ltd.). The printed matter is cut to A4 size, coated paper of the same size is overlaid, and an acrylic plate (thickness 1 cm) is overlaid so that a uniform load is applied. Further, a 1 kg weight is placed on the acrylic plate, 40 ° C., 20 The time was accumulated, and the printed surface was visually evaluated in five stages.
5: There is no trace of coated paper on the printed surface.
4: The white background from the coated paper slightly facing the printing surface is transferred (less than 5%).
3: The white background of the coated paper facing the printing surface is transferred 5% or more and less than 30%.
2: The white background of the coated paper facing the printing surface is transferred 30% or more and less than 60%.
1: 60% or more of the white background of the coated paper facing the printing surface is transferred.

(Examples 1-10 and Comparative Examples 1-5)
Tables 1 to 4 show the results of image formation under the above conditions.
In the ink discharge, the discharge temperature was adjusted to optimize the viscosity during discharge. We also optimized the discharge waveform. As a result, it was confirmed that any of the inks can be discharged satisfactorily.
Further, in Example 6 in which the nozzles were not shifted in the system requirements, an apparatus including an inkjet head in which the arrangement of the nozzle rows of the respective colors was not shifted in the nozzle arrangement direction (the first direction) was used.

In addition, each component described in the said Table 1-Table 4 is as follows.
<Monomer>
NVC: N-vinylcaprolactam (V-CAP, manufactured by ISP)
PEA: Phenoxyethyl acrylate (SR339, manufactured by Sartomer Japan, Inc.)
CTFA: cyclic trimethylolpropane formal acrylate (SR531, manufactured by Sartomer Japan, Inc.)
-IBOA: Isobonyl acrylate (IBXA, manufactured by Osaka Organic Chemical Industry Co., Ltd.)
DPGDA: Dipropylene glycol diacrylate (SR508, manufactured by Sartomer Japan, Inc.)
・ RAPI-CURE DVE3: Triethylene glycol divinyl ether (manufactured by ISA)
・ 3-methylpentane diol diacrylate: 3-methylpentanediol diacrylate (SR341, manufactured by Sartomer Japan, Inc.)
SR-833: Tricyclodecane dimethanol diacrylate (manufactured by Sartomer Japan, Inc.)
EOTMPTA: ethoxylated (3) trimethylolpropane triacrylate (compound obtained by triacrylated trimethylolpropane ethylene oxide 3 mol adduct) (SR454 D NS, manufactured by Sartomer Japan, Inc.)
NPGPODA: propoxylation (2) neopentyl glycol diacrylate (compound obtained by diacrylate conversion of neopentyl glycol propylene oxide 2-mol adduct) (SR9003, manufactured by Sartomer Japan, Inc.)
-TMPTA: Trimethylolpropane triacrylate (SR351S, manufactured by Sartomer Japan, Inc.)

<Photopolymerization initiator>
IRGACURE 184: 1-hydroxycyclohexyl phenyl ketone (Ciba Japan Co., Ltd.)
TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (DAROCUR TPO, manufactured by Ciba Japan Co., Ltd.)
IRGACURE 819: Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (IRGACURE 819, manufactured by Ciba Japan Co., Ltd.)
-ITX: Isopropylthioxanthone (SPEEDCURE ITX, manufactured by LAMBSON)

<Polymerization inhibitor>
FIRSTCURE ST-1: Mixture of Tris (Tris (N-nitroso-N-phenylhydroxyamine) aluminum salt (10% by mass) and phenoxyethyl acrylate (90% by mass) (manufactured by Chem First)
・ MEHQ: Hydroquinone monomethylether (manufactured by Wako Pure Chemical Industries, Ltd.)
HO-TEMPO: 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl (manufactured by ADEKA)

<Pigment>
・ NOVOPERM YELLOW H2G (yellow pigment, manufactured by Clariant)
・ CINQUASIA MAGENTA RT-355-D (magenta pigment, manufactured by BASF Japan Ltd.)
・ IRGALITE BLUE GLVO (cyan pigment, manufactured by BASF Japan Ltd.)
SPECIAL BLACK 250 (Black pigment, manufactured by BASF Japan Ltd.)
<Dispersant>
・ SOLSPERSE 32000 (Noveon dispersant)
<Oligomer>
CN964A85 (aliphatic polyester urethane diacrylate oligomer (containing 15% tripropylene glycol diacrylate, manufactured by Sartomer Japan, Inc.)

10: inkjet recording apparatus, 12: recording medium, 20: apparatus main body, 22: support leg, 24: inkjet head, 26: platen, 28: guide mechanism, 30: carriage, 32A, 32B: temporary curing light source, 33, 35 : UV-LED element, 34A, 34B: main curing light source, 36: ink cartridge, 38: mounting portion, 40: nip roller, 42: feeding / feeding roll, 44: take-up roller, 46: guide, 50: temperature control portion, 52: Pre-temperature control unit, 54: After-temperature control unit, 61: Nozzle array, 70: Supply pump, 72: Sub tank, 74: Pressure adjustment unit, 76: Valve, 77: Pump for pressure increase / decrease, 78: Pressure gauge
100: inkjet recording apparatus, 110: inkjet head, 112: head, 114: nozzle, 116: curing light source, 118: carriage, 119: guide, 120: recording medium, 130: carriage scanning mechanism, 132: recording medium transport mechanism, 134: Image input interface, 136: Image processing unit, 138: Control unit,
202: control device, 204: recording medium conveyance control unit, 206: carriage drive control unit, 208: light source control unit, 210: image processing unit, 212: ejection control unit, 214: conveyance drive unit, 216: main scanning drive unit 218, 219: LED drive circuit, 220: input device, 222: display device, 224: information storage unit, 226: image input interface, 228: head drive circuit, 230: encoder, 232: sensor

Claims (13)

A preparation step of preparing an inkjet recording apparatus including an inkjet head;
An ejection step of ejecting an ink composition from an inkjet head of the inkjet recording apparatus onto a recording medium; and
A curing step of applying active energy from the active energy applying means and curing the ejected ink composition,
The inkjet recording apparatus is
Ink composition of at least four colors of cyan, magenta, yellow and black, in which nozzles for discharging curable ink that is cured by application of active energy are arranged in a first direction at a predetermined pitch P. Each of the nozzle rows for each of the N colors (N ≧ 4), and each nozzle row includes an inkjet head in which the nozzles are shifted in the first direction;
Active energy applying means for applying the active energy to ink droplets ejected from the nozzles and ejected onto the recording surface of a recording medium;
Holding means for arranging and holding the ink jet head and the active energy applying means along a second direction orthogonal to the first direction;
Scanning means for relatively scanning the holding means and the recording medium in the second direction;
Moving means for relatively moving the holding means and the recording medium in the first direction for each scanning by the scanning means;
Control means for forming an image on the recording surface of the recording medium while causing the inkjet head and the active energy applying means held by the holding means to scan each area of the recording medium a predetermined number of times. , An inkjet recording apparatus comprising:
In each nozzle row of the inkjet head, in the first direction, a black ink nozzle is arranged on the most upstream side of the relative movement of the recording medium with respect to the inkjet head,
Of the four ink compositions of cyan, magenta, yellow and black, at least two ink compositions contain (Component A) N-oxyl compound in an amount of 0.05% by mass or more based on the total amount of the ink composition. And (Component B) a radically polymerizable ink composition containing 40% by mass or more of the polyfunctional monomer based on the total amount of the ink composition, and (Component C) containing a photopolymerization initiator,
The inkjet recording method, wherein a scanning speed of the inkjet head in the ejection step is 0.9 m / s or more. 2. The ink jet recording method according to claim 1, wherein the ink composition containing Component A to Component C contains 2 to 40 mass% of (Component D) N-vinyl lactam based on the total amount of the ink composition.   The inkjet recording method according to claim 1, wherein Component B is a polyfunctional (meth) acrylate monomer. The ink jet recording method according to any one of claims 1 to 3, wherein the ink composition containing the component A to the component C contains a (component E) sensitizer.   The inkjet recording method according to claim 1, wherein Component A is a compound having a 2,2,6,6-tetramethylpiperidinyl-N-oxyl group.   The inkjet recording method according to any one of claims 1 to 5, wherein Component A is 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl.   The inkjet recording method according to any one of claims 1 to 6, wherein the content of Component B is 40 to 85 mass% with respect to the total amount of the ink composition. The ink jet recording method according to any one of claims 1 to 7, wherein the ink composition containing the components A to C is supplied from an oxygen-impermeable ink pack having no gas-liquid interface therein. The inkjet recording method according to any one of claims 1 to 8, wherein at least one of the ink compositions containing the component A to the component C contains a phthalocyanine pigment. The inkjet recording method according to any one of claims 1 to 9, wherein at least one of the ink compositions containing the component A to the component C is a cyan ink composition. The content of the silicone surfactant and the fluorine surfactant in the ink composition containing the components A to C is 0% by weight or more and 0.03% by weight or less based on the total weight of the ink composition. The inkjet recording method according to any one of claims 1 to 10. Ejection frequency of the ink jet head is 10kHz or more, the ink jet recording method according to any one of claims 1 to 11. Each of the four ink compositions of cyan, magenta, yellow and black contains (Component A) 0.05% by mass or more of hindered amine based on the total amount of the ink composition, and (Component B) a polyfunctional monomer as an ink. The inkjet recording method according to any one of claims 1 to 12 , which is a radically polymerizable ink composition containing 40% by mass or more based on the total amount of the composition and containing (Component C) a photopolymerization initiator. .

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