JP5665010B2 - Inkjet recording method and inkjet recording apparatus - Google Patents

Description

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

Conventionally, various recording methods are used as an image recording method for forming an image on a recording medium such as paper based on an image data signal. Among these, the ink jet recording method is an inexpensive apparatus that ejects ink only to a required image portion and directly forms an image on a recording medium. Therefore, the ink can be used efficiently and the running cost is low. Furthermore, the ink jet recording method is excellent as an image recording method because of low noise.
For example, Patent Document 1 discloses an ink jet recording method in which printing is performed by attaching a reaction liquid containing a reactant and a photopolymerization initiator and an ink composition containing an acrylate monomer and an acrylate oligomer to a recording medium. ing. Patent Document 2 discloses an ink jet recording in which a water-soluble reaction liquid is attached to a recording medium, an oil-soluble photocurable ink composition is attached to the recording medium, and then a photocurable reaction is performed. A method is disclosed.

Japanese Patent No. 3642152 JP 2008-284826 A

  However, the acrylate monomer and acrylate oligomer used in Patent Document 1 may be separated due to poor solubility in water.

  In the recording method described in Patent Document 2, since the water-soluble reaction liquid and the oil-soluble ink are used, the ink aggregates when contacted, but the spots are generated and the printed spots are conspicuous after curing. there were. In addition, since the swell of the printed portion is conspicuous, there is a problem that the print density is uneven (density spots) or that the print density is uniform even if the print density is uniform.

  In addition, when water-based ink compositions are used in the ink jet recording method, there are many types of printing paper that are generally used, from those with high ink permeability to those with low ink permeability. Some printing papers have density spots, and some have low printing density.

  Therefore, in order to solve these problems, the present invention is excellent in quick-drying after printing, and there is no occurrence of density spots (print spots) of printed images on various printing papers having different ink permeability. One of the objects is to provide an ink jet recording method and an ink jet recording apparatus which have high printing density and few paper sheets such as curling and cockling.

  The inventors of the present application have made extensive studies to solve the above problems. The inventors of the present application focused on the behavior of an aqueous photocurable ink composition (hereinafter also simply referred to as “photocurable ink composition”) on a recording medium in the process of inkjet recording.

  In a conventional ink jet recording method, an ink composition is ejected from a recording head (hereinafter also simply referred to as “head”) and landed on a recording medium to form an image. When the water-based photocurable ink composition is used, after the ink composition has landed on the recording medium, image formation is completed by irradiating at least the landed portion with an active energy ray such as ultraviolet rays and curing. . Here, there were differences in printing density, color bleed, and the like due to differences in ink permeability of the recording medium. In particular, a recording medium having a high ink permeability tends to have a low printing density, and a recording medium having a low ink permeability tends to cause color bleeding and density spots. Further, particularly in the case of thin paper (printing paper with a small basis weight, such as plain paper or high-quality paper), there is a problem that curling and cockling are likely to occur.

  Therefore, the inventors of the present application have intensively studied a method for solving the different problems due to the difference in permeability of the ink to the recording medium and obtaining the same print density and image quality. As a result, an aqueous photocurable ink composition is ejected from a head and landed on a recording medium on which an aqueous liquid containing a saccharide and a cationic water-soluble polymer is previously applied, and then irradiated with ultraviolet rays of a predetermined wavelength. The present inventors have found that the above problems can be solved and have completed the present invention.

That is, the present invention is as follows.
[1]
A coating step of applying a flocculant, a water-soluble organic solvent, a saccharide, and water at least on a recording medium; a colorant; an amphiphilic photopolymerizable compound; a photopolymerization initiator; a polar solvent; An aqueous photocurable ink composition containing at least water is discharged from a recording head to land the ink composition on a recording medium after the coating step, and an aqueous photocuring after the discharging step. And a curing step of curing the ink composition by light irradiation.
[2]
The inkjet recording method according to [1], wherein the flocculant is a cationic water-soluble polymer.
[3]
The inkjet recording method according to [1] or [2], wherein the amphiphilic photopolymerizable compound is a compound having at least one radical polymerizable group, hydrophilic group, and hydrophobic group.
[4]
The inkjet recording method according to any one of [1] to [3], wherein the amphiphilic photopolymerizable compound is an amphiphilic urethane acrylate.
[5]
The inkjet recording method according to [4], wherein the amphiphilic urethane acrylate is emulsified by forming a micelle structure in the aqueous photocurable ink composition.
[6]
The inkjet recording method according to any one of [1] to [5], wherein the photopolymerization initiator has a peak wavelength in a range of 380 to 410 nm.
[7]
The inkjet recording method according to any one of [1] to [6], wherein the photopolymerization initiator is an acylphosphine oxide photopolymerization initiator.
[8]
The inkjet recording method according to any one of [1] to [7], wherein the penetrant is a glycol ether.
[9]
A recorded matter on which an image is formed by the inkjet recording method according to any one of [1] to [8].
[10]
An inkjet recording apparatus for carrying out the inkjet recording method according to any one of [1] to [8], wherein the aggregation liquid contains at least an aggregating agent, a water-soluble organic solvent, a saccharide, and water in the aggregation liquid tank. And at least a part of the roller are in contact with each other, and when the roller rotates, the aggregation liquid application means for applying the aggregation liquid onto the recording medium, a colorant, an amphiphilic photopolymerizable compound, and photopolymerization By ejecting an aqueous photocurable ink composition containing at least an initiator, a polar solvent, and water from a recording head, the aqueous photocurable ink composition is attached onto the recording medium on which the aggregation liquid has been applied. An ink discharge means for causing the light-curable ink composition to be irradiated with light to cure the water-based photocurable ink composition. Ink jet recording apparatus.
[11]
The ink jet recording apparatus according to [10], wherein the light irradiation unit includes a light emitting diode irradiation lamp.

1 is a schematic configuration diagram illustrating an inkjet recording apparatus according to an embodiment of the present invention.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not restrict | limited to the following embodiment, A various deformation | transformation can be implemented within the range of the summary.

[Inkjet recording method]
One embodiment of the present invention relates to an inkjet recording method, and includes an aggregation liquid application step, a water-based photocurable ink composition discharge step, and a curing step, which will be described later. A predetermined aggregating liquid is applied on the recording medium in advance, and then the aqueous photocurable ink composition is ejected from the head to land the photocurable ink composition on the recording medium. The solid component (pigment etc.) in the ink composition can be instantly aggregated. Furthermore, by irradiating and curing an active energy ray such as ultraviolet rays, there is no difference in printing density and color bleeding due to the difference in ink permeability of the recording medium. In particular, a recording density similar to that of a recording medium having a low ink permeability can be obtained even on a recording medium having a high ink permeability, and color bleed and density spots are also observed on a recording medium having a low ink permeability. It is suppressed. Furthermore, when an aqueous liquid (aggregation liquid) containing a saccharide and a cationic water-soluble polymer is applied in advance, paper wrinkles such as curling and cockling are suppressed.

[Coating liquid application process]
The method for applying the aggregated liquid to the surface of the recording medium is not particularly limited. For example, the aggregated liquid in the aggregated liquid tank is in contact with at least a part of the roller, and the roller rotates so that the aggregated liquid is recorded on the recording medium. Examples of the method include a method of coating on top, coating by an inkjet method (discharge of aggregating liquid from the head), coating by a roll coater, coating by a ringer roll, coating by a bar coater, coating by spraying, and brush coating. Among these, from the viewpoint of more effectively and reliably achieving the effects of the present embodiment, the agglomerated liquid in the agglomerated liquid tank and at least a part of the roller are in contact with each other, and the roller rotates so that the agglomerated liquid is transferred onto the recording medium. The method of apply | coating to is preferable.

  A suitable liquid amount of the aggregation liquid to be applied will be described later.

[Aggregating liquid]
The aggregating liquid is composed of at least an aggregating agent, water, and a water-soluble organic solvent, and further contains a surfactant for the purpose of controlling wettability and permeability to a recording medium, and also prevents curling and cockling after printing. In order to suppress, it contains a saccharide that easily forms a hydrogen bond with the hydrophilic group of the cellulose fiber of paper. Saccharides can also be used to adjust the viscosity of the aggregate liquid depending on the application method used in the application process of the aggregate liquid. The aggregating liquid is applied on the recording medium in advance, and the photocurable ink composition of the present embodiment is ejected from the head and brought into contact with the aggregating agent in the aggregating liquid applied on the recording medium. Aggregates instantly.

(Flocculant)
In the present embodiment, by using the aggregating agent described later, the ink solid component, that is, the pigment and the photopolymerizable compound contained in the photocurable ink composition can be rapidly and sufficiently aggregated.

  Although it does not specifically limit as an aggregating agent, For example, cationic water-soluble polymers, such as polyallylamine or its derivative (s), a quaternary ammonium salt polymer, a quaternary sulfonium salt polymer, and a polyvalent metal salt are mentioned. Among these, the aggregation liquid containing a cationic water-soluble polymer such as polyallylamine or a derivative thereof and a quaternary ammonium salt polymer or a quaternary sulfonium salt polymer is uniformly coated on a recording medium such as paper, Because it tends to remain on the surface of the recording medium, it is easy to agglomerate efficiently, and it is easy to adjust the viscosity to be suitable for application with a roller, etc. Curling and cockling after printing are less likely to occur. Accordingly, cationic water-soluble polymers are preferred.

The cationic water-soluble polymer is preferably a cationic polymer having a weight average molecular weight of 5,000 to 500,000 having a structure having a charged group that is soluble in water and has a positive charge in water.
In addition, the weight average molecular weight in this specification is the average of the molecular weight by a weight fraction, is calculated | required by the following numerical formula, and is measured by the gel permeation chromatography (GPC) method.

(There are Ni molecules of molecular weight MI in the polymer.)

  Examples of the cationic polymer include compounds represented by the following general formula (I), general formula (II), and general formula (III).

In the above formula, X ⁻ represents a chloride ion, a bromide ion, an iodide ion, a nitrate ion, a phosphate ion, a sulfate ion, or an acetate ion. Moreover, n is a natural number of 100 to 10,000, for example.

  In addition to these, a copolymer of allylamine and diallylamine, or a copolymer of diallylmethylammonium chloride and sulfur dioxide can also be used as polyallylamine or a derivative thereof.

  Furthermore, specifically, polyallylamine hydrochloride, polydiallylamine hydrochloride, polydiallylmethylamine hydrochloride, allylamine hydrochloride-diallylamine hydrochloride copolymer, diallylamine hydrochloride-maleic acid copolymer, polydiallylmethylammonium chloride, Examples include diallylmethylammonium chloride-acrylamide copolymer, methyldiallylamine hydrochloride copolymer, methyldiallylamineamide sulfate polymer, diallyldimethylammonium chloride polymer, diallyldimethylammonium chloride-acrylamide copolymer.

  The content of polyallylamine or a derivative thereof is preferably 0.1 to 30% by mass with respect to the total amount of the aggregate liquid. Furthermore, it is preferable that it is 0.5-20 mass%. If the content of polyallylamine or a derivative thereof is less than 0.1% by mass, it is difficult to agglomerate even when it comes into contact with the ink of this embodiment. It may be difficult to apply.

  Next, although it does not specifically limit as a quaternary ammonium salt polymer, For example, the polymer which is soluble in water and has one or more quaternary ammonium salts in the chain | strand which makes the repeating unit of a polymer is mentioned.

  Specific examples of the quaternary ammonium salt polymer include, but are not limited to, poly (2-hydroxy-3-methacryloxypropyltrimethylammonium chloride), poly (2-hydroxy-3-methacryloxypropyltriethylammonium chloride), poly ( 2-hydroxy-3-acryloxypropyltrimethylammonium chloride), poly (2-hydroxy-3-acryloxypropyltriethylammonium chloride), poly (2-methacryloxyethyltrimethylammonium chloride), poly (2-methacryloxyethyltriethyl) Ammonium chloride), poly (2-acryloxyethyltrimethylammonium chloride), poly (2-acryloxyethyltriethylammonium chloride), poly (dimethyl) Salt of polyaminoethyl methacrylate), salt of poly (diethylaminoethyl methacrylate), salt of poly (diethylaminoethyl acrylate), salt of poly (dimethylaminoethyl methacrylate), salt of poly (dimethylaminoethyl acrylate), poly (4- Vinyl-N-methylpyridinium chloride), N, N-dimethyl substituted 3,5-methylpiperidinium chloride resin, poly (dimethyldiallylammonium chloride), and poly (diethyldiallylammonium chloride) polyethyleneimine hydrochloride.

  The content of the quaternary ammonium salt polymer is preferably 0.1 to 30% by mass with respect to the total amount of the aggregate liquid. Furthermore, it is preferable that it is 0.5-20 mass%. If the content of the quaternary ammonium salt polymer is less than 0.1% by mass, it is difficult to aggregate even if it comes into contact with the ink of this embodiment, and if it exceeds 30% by mass, the viscosity of the aggregate liquid becomes too high and the recording medium is recorded. May be difficult to apply.

  Said flocculant may be used individually by 1 type, and 2 or more types may be mixed and used for it.

In the present embodiment, a polyvalent metal salt can also be used. The polyvalent metal salt is a compound that is composed of divalent or higher polyvalent metal ions and anions that bind to these polyvalent metal ions, and is soluble in water. Specific examples of the polyvalent metal ion are not particularly limited, but divalent metal ions such as Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Zn ²⁺ , and Ba ²⁺ , and Al ³⁺ , Fe ³⁺ , and Cr ^3+. And trivalent metal ions. Specific examples of the anion include, but are not limited to, SO ₄ ²⁻ , Cl ⁻ , NO ₃ ⁻ , I ⁻ , Br ⁻ , ClO ₃ ⁻ , and CH ₃ COO ⁻ .

Among these, a metal salt composed of Ca ²⁺ or Mg ²⁺ is preferable from the viewpoint of the pH of the aggregate liquid and the image quality.

  The content of the polyvalent metal salt may be appropriately determined as long as the excellent image quality and the effect of preventing clogging can be obtained, but is preferably 0.1 to 40% by mass with respect to the total amount of the aggregate liquid. Yes, more preferably 5 to 25% by mass.

  In a preferred embodiment, the polyvalent metal salt is a compound composed of divalent or higher polyvalent metal ions and nitrate ions or carboxylate ions that bind to the polyvalent metal ions, and is soluble in water. Here, the carboxylate ion is preferably a compound derived from a saturated aliphatic monocarboxylic acid having 1 to 6 carbon atoms or a carbocyclic monocarboxylic acid having 7 to 11 carbon atoms. Although it does not specifically limit as a C1-C6 saturated aliphatic monocarboxylic acid, For example, formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, and hexanoic acid are mentioned. Among these, formic acid or acetic acid is preferable.

  The hydrogen atom in the saturated aliphatic hydrocarbon group of the above monocarboxylic acid may be substituted with a hydroxyl group, and examples of such carboxylic acid include, but are not particularly limited to, lactic acid. Moreover, although it does not specifically limit as an example of a C7-C11 carbocyclic monocarboxylic acid, A benzoic acid and a naphthoic acid are mentioned, Preferably it is a benzoic acid.

  The solvent used in the aggregation liquid of the present invention preferably contains water and a water-soluble organic solvent, and may further contain other components as desired.

(Water-soluble organic solvent)
Examples of the water-soluble organic solvent include water-soluble high-boiling organic solvents and low-boiling organic solvents. Since the aggregation liquid in the embodiment of the present invention contains a high-boiling organic solvent having a boiling point of 180 ° C. or higher, drying in the storage tank of the aggregation liquid can be avoided and the viscosity at the time of application can be stabilized. It can be stably applied onto a recording medium.
On the other hand, when it is necessary to dry the solvent component of the aggregate liquid within the time until the photocurable ink composition is landed, the aggregate liquid and the photocurable ink composition are brought into contact with each other to be aggregated. When it is necessary to cure by irradiating with ultraviolet rays after that, and then drying the solvent component in the aggregation liquid and the photocurable ink composition in a short time, the aggregation liquid in the present embodiment contains a low boiling point organic solvent. Can do.

  Specific examples of the water-soluble organic solvent having a boiling point of 180 ° C. or higher that can be used in the present invention include ethylene glycol, propylene glycol, diethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, tripropylene glycol, polyethylene glycol having a molecular weight of 2,000 or less, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, glycerin , Mesoerythritol, pentaerythritol, and the like.

  Although it does not specifically limit as a low boiling point organic solvent, For example, methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, sec-butanol, tert-butanol, iso-butanol, and n-pentanol are mentioned. It is done.

  The total content of the water-soluble organic solvents including these water-soluble high-boiling organic solvents is preferably about 5 to 50% by mass, more preferably 10 to 30% by mass, based on the total amount of the aggregate liquid. It is.

  The aggregate solution of the present invention further comprises 2-pyrrolidone, N-methylpyrrolidone, ε-caprolactam, dimethyl sulfoxide, sulfolane, morpholine, N-ethylmorpholine, 1,3-dimethyl-2-imidazolidinone, and the like. One or more polar solvents selected from can be added. By adding a polar solvent, the above-mentioned flocculant is easily dissolved, and the flocculant is easily applied uniformly to a recording medium such as plain paper, high-quality paper, and printing paper.

  A water-soluble solvent may be used individually by 1 type, and 2 or more types may be mixed and used for it.

(Penetration agent)
The flocculant of the present invention preferably further contains a penetrant for the purpose of promoting the penetration of the aqueous solvent into a recording medium such as plain paper, fine paper, and printing paper. By using the penetrant, saccharides described later can be uniformly present in the recording medium, and paper wrinkles such as curling and cockling that occur when the aqueous solvent is dried can be suppressed. As such a penetrant, polyhydric alcohol alkyl ethers (also referred to as glycol ethers) are preferably used.

  Examples of the alkyl ether of polyhydric alcohol include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, Ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol Mono-t-butyl ether, -Methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether , Dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, and the like.

  The penetrant used is appropriately selected from these. In particular, in the embodiment of the present invention, it is preferable to use at least one selected from propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether as the penetrant.

  The content of these penetrants is preferably 1 to 10% by mass with respect to the total amount of the aggregate liquid. By setting the content of the penetrant to 1% by mass or more, an effect of improving the permeability of the flocculant to a recording medium such as plain paper, high-quality paper, and printing paper can be obtained. This is not preferable because the recording medium tends to swell.

(Sugar)
The flocculant of the present invention further contains a saccharide. Saccharides penetrate into paper permeable recording media such as plain paper, fine paper, and printing paper together with water and water-soluble organic solvents, forming hydrogen bonds with the hydrophilic groups of cellulose that form paper fibers. By doing so, it is possible to suppress the occurrence of paper jams such as curling and cockling. It can also be used to adjust the viscosity of the aggregating liquid according to the coating method used in the aggregating liquid coating process.

  Examples of the saccharide include monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Specifically, glucose, mantose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glycitol, sorbitol, maltose, cellobiose, and lactose. , Sucrose, trehalose, maltotriose and the like. In particular, one or more selected from the group consisting of lactose, maltose, cellobiose, and trehalose having a structure similar to that of cellulose is preferable. In addition, these saccharides may be used individually by 1 type, and may use 2 or more types together. The saccharide content is preferably 1 to 40% by mass, more preferably 5 to 30% by mass, based on the total amount of the aggregate liquid. When the saccharide content is less than 1% by mass, it is difficult to obtain the effect of suppressing paper koji, and when it exceeds 40% by mass, it becomes a viscous liquid with viscosity, which is not preferable.

(Surfactant)
The surfactant reduces the surface tension of the aggregate liquid to improve the wettability to the recording medium, and also improves the permeability to the recording medium such as plain paper, high-quality paper, and printing paper. Use for. As the surfactant, a nonionic surfactant or a cationic surfactant is used. Specific examples of the cationic surfactant include primary fatty amine salt, secondary fatty amine salt, tertiary fatty amine salt, tetraalkylammonium salt, trialkylbenzylammonium salt, alkylbiridinium salt, 2-alkyl- 1-alkyl-1-hydroxyethylimidazolinium salt, N, N-dialkylmorpholinium salt, polyethylene polyamine fatty acid amide salt, salt of urea condensate of polyethylene polyamine fatty acid amide, urea condensate of polyethylene polyamine fatty acid amide Quaternary ammonium salts such as quaternary ammonium salts can be mentioned.

  Specific examples of the nonionic surfactant include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, Ether compounds such as polyoxyethylene alkyl ether and polyoxyalkylene alkyl ether, and polyoxyethylene oleic acid, polyoxyethylene oleic acid ester, polyoxyethylene distearic acid ester, sorbitan laurate, sorbitan monostearate, sorbitan mono Oleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate What ester compounds and the like.

  In particular, the aggregating liquid according to the embodiment of the present invention desirably contains an acetylene glycol surfactant and / or an acetylene alcohol surfactant as a surfactant. As a result, the wettability of the aggregating liquid to the recording medium is improved and the recording medium such as plain paper, high-quality paper, and printing paper is likely to penetrate. Furthermore, there is an advantage that the generation of bubbles is small.

  As preferred specific examples of the acetylene glycol surfactant used in the present invention, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3, 6-diol, 3,5-dimethyl-1-hexyn-3-ol, and the like. Specific examples of commercial products marketed as acetylene glycol surfactants include Surfynol 104, 82, 465, 485, 104PG50, and TG (all available from trade names, Air Products and Chemicals. Inc.). ), And Olfin STG and Olphine E1010 (trade names, manufactured by Nissin Chemical Co., Ltd.).

  Examples of the acetylene alcohol surfactant include Surfynol 61 (trade name, available from Air Products and Chemicals. Inc.). These acetylene glycol surfactants and / or acetylene alcohol surfactants are preferably in the range of 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total amount of the aggregate liquid. It is preferable to use so that it may become a range.

  In addition to the above surfactants, in order to optimize the wettability of the aggregating liquid to the recording medium (the aggregating liquid is uniformly wetted to the recording medium), a silicone-based surfactant, a fluorine-based surfactant Surfactants can also be used.

  These surfactants may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  By adding the above surfactant, the surface tension of the aggregate liquid is preferably adjusted to 20 to 50 mPa · s, more preferably 20 to 40 mPa · s. By adjusting the surface tension within this range, it is possible to obtain optimum wettability and permeability for various recording media.

(water)
Although it does not specifically limit as water, The thing which does not contain cation ions, such as a calcium ion and magnesium ion, and anion ions, such as a sulfate ion, is used. For example, ion-exchange water, distilled water, and pure water are mentioned. The water content is preferably 10 to 95% by mass, more preferably 10 to 60% by mass, based on the total amount of the aggregate liquid.

(Other components that can be included in the aggregate)
The aggregating liquid in the present embodiment may contain a pH adjuster, an antifungal agent, an antirust agent and the like in addition to the above-described components.

[Discharge process of photocurable ink composition]
In the discharging step of the photocurable ink composition, the photocurable ink composition containing at least a polar solvent, a colorant, an amphiphilic photopolymerizable compound, a photopolymerization initiator, and water is discharged from the recording head. Thus, the ink composition is landed on the recording medium after the aggregation liquid coating step. The ink composition instantaneously aggregates on the recording medium coated with the aggregation liquid, and solid components such as a colorant and an amphiphilic photopolymerizable compound remain on the surface of the recording medium. .

[Water-based photocurable ink composition]
The aqueous photocurable ink composition contains at least a polar solvent, a colorant, an amphiphilic photopolymerizable compound, a photopolymerization initiator, and water.

(Amphiphilic photopolymerizable compound)
An amphiphilic photopolymerizable compound is a compound having one or more hydrophilic structural sites, one or more photopolymerization reaction sites, and one or more hydrophobic structural sites in one molecule. The hydrophilic structural portion is composed of a group exhibiting hydrophilicity, for example, a hydroxyl group, a polyethylene oxide group, a sulfonic acid group and a salt thereof, a sulfinic acid group and a salt thereof, a carboxylic acid group and a salt thereof, a phosphinic acid group and a salt thereof. , Phosphate ester group, amino group, amide group and the like. The photopolymerization reaction site consists of a group having an unsaturated double bond capable of photoradical polymerization, such as acryloyl group, methacryloyl group, acrylamide group, methacrylamide group, allyl group, vinyl ether group, vinyl thioether group, vinyl amino group. More preferred are acryloyl group, acrylamide group, methacryloyl group and methacrylamide group, and more preferred are acryloyl group and acrylamide group, from the viewpoint that photoradical polymerization reactivity is particularly high. The hydrophobic structure site is composed of a hydrophobic group, and examples thereof include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, a fluoroalkyl group, and a polysiloxane structure. Examples of the aliphatic hydrocarbon group include an alkyl group, an alkenyl group, and an alkynyl group, and examples of the aromatic hydrocarbon group include an aryl group and an aralkyl group.

  Among these, from the viewpoint of obtaining sufficient hydrophobicity, at least one selected from the group consisting of an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, a fluoroalkyl group, and a polysiloxane structure Are preferred. More preferred are an aliphatic hydrocarbon group having 4 or more carbon atoms, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, a fluoroalkyl group, and a polysiloxane structure. More preferably, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, isodecyl group, lauryl group, stearyl group, octyl group, isooctyl group, benzyl group, cyclohexyl group, phenyl group, biphenyl group, naphthyl group , Isophorone group, isobornyl group, dicyclopentanyl group, dicyclopentenyl group, fluoroalkyl group, polysiloxane structure and the like.

  The content of the amphiphilic photopolymerizable compound is preferably 5 to 50% by mass and more preferably 10 to 30% by mass with respect to the total amount of the photocurable ink composition. When the amount of the amphiphilic photopolymerizable compound is less than 5% by mass, the photopolymerization by ultraviolet irradiation is slow, and when it exceeds 50% by mass, the viscosity of the ink composition tends to increase, and the ejection from the recording head is difficult. It tends to be difficult to do.

  Examples of the amphiphilic photopolymerizable compound include monomers as monomers and oligomers having dimers to quantifiers or molecular weights of up to several thousand.

  The amphiphilic photopolymerizable compound is preferably a monofunctional or bifunctional or higher functional oligomer.

  Although it does not specifically limit as an oligomer more than monofunctional or bifunctional, For example, an amphiphilic urethane acrylate, an amphiphilic polyester acrylate, an amphiphilic epoxy acrylate etc. are mentioned.

  In particular, amphiphilic urethane acrylate is preferably used. Since such an amphiphilic urethane acrylate can suppress the thickening of the photocurable ink composition, a self-emulsifying form that forms a micelle structure in the photocurable ink composition is preferable. The amphiphilic urethane acrylate in this case can be referred to as a urethane acrylate emulsion.

  A photocurable ink composition containing an amphiphilic urethane acrylate instantly aggregates on a paper permeable recording medium such as plain paper, high-quality paper, and printing paper that has been previously coated with an aggregating liquid. The amphiphilic urethane acrylate in the photocurable ink composition remaining on the surface of the recording medium can be cured by irradiation with ultraviolet rays. The resulting cured coating film can form a cured coating film having excellent adhesion, flexibility and toughness with the recording medium. The cured coating film is excellent in abrasion resistance and has good adhesion to plastics such as polyvinyl chloride, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, acrylonitrile / butadiene / styrene (ABS) and polystyrene. Moreover, it is excellent in storage stability.

  The amphiphilic urethane acrylate may be monofunctional or bifunctional or higher.

  The content of the amphiphilic urethane acrylate is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, based on the total amount of the photocurable ink composition. When the amount of the amphiphilic photopolymerizable compound is less than 5% by mass, the photopolymerization by ultraviolet irradiation is slow, and when it exceeds 50% by mass, the viscosity of the ink composition tends to increase, and the ejection from the recording head is difficult. It tends to be difficult to do.

  Examples of commercially available amphiphilic photopolymerizable compounds include EM-90 (urethane acrylate emulsion, manufactured by Arakawa Chemical Industries, Ltd.).

(Photopolymerization initiator)
A known radical photopolymerization initiator is used as the photopolymerization initiator. The radical photopolymerization initiator causes radical photopolymerization of an amphiphilic photopolymerizable compound when irradiated with active energy rays such as ultraviolet rays.

  Specific examples of the photo radical polymerization initiator include acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, benzophenone, 2-chlorobenzophenone, p, p′-dichlorobenzophenone, p, p′-bisdiethylaminobenzophenone. Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-propyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzyl methyl ketal, 2,2-dimethoxy-1,2- Diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] Nyl} 2-methylpropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-dimethylamino-2- (4-methylbenzyl) -1- ( 4-morpholin-4-yl-phenyl) butan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2, 6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] 2-morpholinopropan-1-one, thioxanthone, 2-chlorothioxanthone, 2 -Hydroxy-2-methyl-1-phenyl-1-one, 1- (4-isopropylphenyl) -2 Hydroxy-2-methylpropan-methylbenzoyl fill formate, azo-bis-isobutyronitrile Lilo nitrile, benzoyl peroxide, di -tert- butyl peroxide, and the like.

  Examples of commercially available photo radical polymerization initiators include IRGACURE 651 (2,2-dimethoxy-1,2-diphenylethane-1-one), IRGACURE 184 (1-hydroxy-cyclohexyl-phenyl-ketone), DAROCUR 1173. (2-hydroxy-2-methyl-1-phenyl-propan-1-one), IRGACURE 2959 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane- 1-one), IRGACURE 127 (2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one}, IRGACURE 907 (2-Methyl-1- (4-methylthiophenyl) -2-morphol Linopropan-1-one), IRGACURE 369 (2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1), IRGACURE 379 (2- (dimethylamino) -2-[(4- Methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone), DAROCUR TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide), IRGACURE 819 (bis (2, 4,6-trimethylbenzoyl) -phenylphosphine oxide), IRGACURE 784 (bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole-1-) Yl) -phenyl) titanium), IRGACURE OXE 01 (1.2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)]), IRGACURE OXE 02 (ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime)), IRGACURE 754 (oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2- (Mixture of (2-hydroxyethoxy) ethyl ester) (manufactured by Ciba Japan KK), DETX-S (2,4-diethylthioxanthone) (Nippon Kayaku Co., Ltd. )), Lucirin TPO, LR8883, LR8970 (above, manufactured by BASF), Ubekrill P36 (manufactured by UCB), etc. And the like.

  In particular, in the embodiment of the present invention in which a pigment is used as a colorant, it is possible to sufficiently cure to the deep part of the coating film by using ultraviolet rays on the long wavelength side of 360 to 410 nm, so that it absorbs in this wavelength region. A certain acylphosphine oxide compound is preferably used. Specifically, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (DAROCUR TPO: manufactured by Ciba Japan KK), bis (2,4,6-trimethylbenzoyl) -phenylphosphine Oxide (IRGACURE 819: manufactured by Ciba Japan KK).

  A radical photopolymerization initiator may be used individually by 1 type, and may be used in combination of 2 or more type. The radical photopolymerization initiator is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass, based on the total amount of the photocurable ink composition. When it is within the above range, good curability can be obtained.

(Polar solvent)
Said radical photopolymerization initiator can be mixed in water by using together with a polar solvent in the embodiment of the present invention. Examples of the polar solvent include 2-pyrrolidone, N-methylpyrrolidone, ε-caprolactam, dimethyl sulfoxide, sulfolane, morpholine, N-ethylmorpholine, and 1,3-dimethyl-2-imidazolidinone. In particular, 2-pyrrolidone is preferable because of its excellent effect.

  The content of these polar solvents is preferably 1% by mass to 20% by mass and more preferably 1% by mass to 10% by mass with respect to the total amount of the photocurable ink composition. If the content of the polar solvent is less than 1% by mass, it becomes difficult to mix the radical photopolymerization initiator and water, and if it exceeds 20% by mass, the curability is affected.

(Coloring agent)
Since ultraviolet rays are used for curing the photocurable ink composition of the present invention, the colorant is preferably a pigment that does not fade due to ultraviolet irradiation.

  As the pigment, both inorganic pigments and organic pigments can be used. The colorant is preferably contained in an amount of 1 to 10% by mass and more preferably 1 to 5% by mass with respect to the total amount of the photocurable ink composition.

  As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, iron oxide, and titanium oxide can be used.

  Organic pigments include insoluble azo pigments, condensed azo pigments, azo lakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Polycyclic pigments, dye chelates (for example, basic dye chelates, acid dye chelates, etc.), dye rakes (basic dye rakes, acid dye rakes), nitro pigments, nitroso pigments, aniline black, daytime A photofluorescent pigment is mentioned. The said pigment may be used individually by 1 type, and may use 2 or more types together.

  More specifically, as an inorganic pigment used for black, the following carbon black, for example, No. manufactured by Mitsubishi Chemical Corporation is used. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, or No2200B, etc .; Columbia-made Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc .; 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc .; or Color Black FW1, Color Black FW2, Bck, Col Black FW2, Cck W200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, and Special Black 4 and the like.

  Examples of the yellow organic pigment include CIPigment Yellow 1, CIPigment Yellow 2, CIPigment Yellow 3, CIPigment Yellow 4, CIPigment Yellow 5, CIPigment Yellow 6, CIPigment Yellow 7, CIPigment Yellow 10, CIPigment Yellow Yellow 11, CIPigment Yellow 12, CIPigment Yellow 13, CIPigment Yellow 14, CIPigment Yellow 16, CIPigment Yellow 17, CIPigment Yellow 24, CIPigment Yellow 34, CIPigment Yellow 35, CIPigment Yellow 37, CIPigment Yellow 53, CIPigment Yellow 55, CIPigment Yellow 65, CIPigment Yellow 73, CIPigment Yellow 74, CIPigment Yellow 75, CIPigment Yellow 81, CIPigment Yellow 83, CIPigment Yellow 93, CIPigment Yellow 94, CIPigment Yellow 95, CIPigment Yellow 97, CIPigment Yellow 98, CIPigment Yellow 99, CIPigment Yellow 108, CIPigment Yellow 109, CIPigment Yellow 110, CIPigment Yellow 113, CIPigment Yellow 114, CIPigment Yellow 117, CIPigment Yellow 120, CIPigment Yellow 124, CIPigment Yellow 128, CIPi gment Yellow 129, CIPigment Yellow 133, CIPigment Yellow 138, CIPigment Yellow 139, CIPigment Yellow 147, CIPigment Yellow 151, CIPigment Yellow 153, CIPigment Yellow 154, CIPigment Yellow 167, CIPigment Yellow 172, CI Pigment Yellow 180.

  Examples of the magenta organic pigment include CIPigment Red 1, CIPigment Red 2, CIPigment Red 3, CIPigment Red 4, CIPigment Red 5, CIPigment Red 6, CIPigment Red 7, CIPigment Red 8, CIPigment Red Red 9, CIPigment Red 10, CIPigment Red 11, CIPigment Red 12, CIPigment Red 14, CIPigment Red 15, CIPigment Red 16, CIPigment Red 17, CIPigment Red 18, CIPigment Red 19, CIPigment Red 21, CIPigment Red 22, CIPigment Red 23, CIPigment Red 30, CIPigment Red 31, CIPigment Red 32, CIPigment Red 38, CIPigment Red 40, CIPigment Red 41, CIPigment Red 42, CIPigment Red 48 (Ca), CIPigment Red 48 (Mn), CIPigment Red 57 (Ca), CIPigment Red 57: 1, CIPigment Red 88, CIPigment Red 112, CIPigment Red 114, CI Pigment Red 122, CIPigment Red 123, CIPigment Red 144, CIPigment Red 146, CIPigment Red 149, CIPigment Red 150, CIPigment Red 166, CIPigment Red 168, CIPigment Red 170, CIPigment Red 171, CI Pigment Red 175, CIPigment Red 176, CIPigment Red 177, CIPigment Red 178, CIPigment Red 179, CIPigment Red 184, CIPigment Red 185, CIPigment Red 187, CIPigment Red 202, CIPigment Red 209, CIPigment Red 219, CIPigment Red 224, CIPigment Red 245, or CIPigment Violet 19, CIPigment Violet 23, CIPigment Violet 32, CIPigment Violet 33, CIPigment Violet 36, CIPigment Violet 38, CIPigment Violet 43, CI Pigment Violet 50.

  Examples of cyan organic pigments include CIPigment Blue 1, CIPigment Blue 2, CIPigment Blue 3, CIPigment Blue 15, CIPigment Blue 15: 1, CIPigment Blue 15: 2, CIPigment Blue 15: 3, CI Pigment Blue 15:34, CIPigment Blue 15: 4, CIPigment Blue 16, CIPigment Blue 18, CIPigment Blue 22, CIPigment Blue 25, CIPigment Blue 60, CIPigment Blue 65, CIPigment Blue 66, CIVat Blue 4, CIVat Blue 60.

  Examples of organic pigments other than magenta, cyan, and yellow include CIPigment Green 7, CIPigment Green 10, CIPigment Brawn 3, CIPigment Brawn 5, CIPigment Brawn 25, CIPigment Brawn 26, CIPigment Orange 1, CIPigment Orange 2, CIPigment Orange 5, CIPigment Orange 7, CIPigment Orange 13, CIPigment Orange 14, CIPigment Orange 15, CIPigment Orange 16, CIPigment Orange 24, CIPigment Orange 34, CIPigment Orange 36, CIPigment Orange 38, CIPigment Orange 40, CIPigment Orange 43, CIPigment Orange 63.

  When using said pigment, the average particle diameter has preferable 500 nm or less, More preferably, it is 200 nm or less, Furthermore, 50-100 nm is preferable. When the average particle diameter is within the above range, the reliability such as ejection stability and dispersion stability in the photocurable ink composition is further improved, and an image with excellent image quality can be formed. Here, the average particle diameter in the present specification is measured by a dynamic light scattering method.

  According to a preferred embodiment of the present invention, the pigment is preferably added to the ink as a pigment dispersion in which the pigment is dispersed in an aqueous medium with a dispersant. As the dispersant used for preparing the pigment dispersion, a dispersant generally used for preparing the pigment dispersion, for example, a polymer dispersant or a surfactant can be used. It is obvious to those skilled in the art that the surfactant contained in the pigment dispersion will function as a surfactant for the photocurable ink composition.

  Preferred examples of the polymer dispersant include natural polymers, and specific examples thereof include proteins such as glue, gelatin, casein, and albumin; natural rubbers such as gum arabic and tragacanth; glucosides such as saponin; Examples include alginic acid derivatives such as alginic acid and propylene glycol alginate, triethanolamine alginate, and ammonium alginate; cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and ethylhydroxycellulose.

  Preferred examples of the polymer dispersant include synthetic polymers such as polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic. Acrylic resins such as acid ester copolymers and acrylic acid-acrylic acid ester copolymers; styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene -Styrene-acrylic resins such as α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer; styrene-maleic acid copolymer, styrene-maleic anhydride copolymer Polymer, vinyl naphthalene-acrylic acid copolymer, vinyl Lunaphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleic ester copolymer, vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic Examples thereof include vinyl acetate copolymers such as acid copolymers, and salts thereof.

  Among these, a copolymer of a monomer having a hydrophobic group and a monomer having a hydrophilic group, and a polymer comprising a monomer having both a hydrophobic group and a hydrophilic group in the molecular structure are particularly preferable.

  The addition amount of the dispersant is about 0.1 to 20% by mass, preferably about 0.1 to 10% by mass, with respect to the total amount of the photocurable ink composition.

  The pigment dispersion is a suitable dispersing machine (for example, ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill, ultrasonic homogenizer, jet mill, ang mill, etc.). To obtain a uniform pigment dispersion.

  The photocurable ink composition according to the present invention can be produced by dispersing and mixing the above components by an appropriate method. Specifically, while stirring the pigment dispersion in a suitable disperser, water, a water-soluble organic solvent, a penetrating agent, a surfactant, a sugar, and other components were added and dissolved in advance. The ink solvent is gradually dropped and stirred thoroughly. After sufficiently stirring, filtration is performed to remove coarse particles and foreign matters that cause clogging, thereby obtaining a desired photocurable ink composition.

[Curing process]
The curing step is a step of curing the photocurable ink composition by irradiating light of a specific wavelength after the discharging step.

  After the aggregating liquid is applied on the recording medium, the photocurable ink composition is discharged, and the agglomerates formed by contacting the aggregating agent in the recording medium with the ink composition landed on the recording medium are specified. By irradiating with light in the wavelength region, a photocuring reaction (photoradical polymerization) is caused to produce a cured coating film. The light in the specific wavelength region is preferably an ultraviolet (UV) ray region. The specific wavelength region (ultraviolet region) is preferably in the range of 360 to 410 nm, and more preferably in the range of 380 to 400 nm. In the embodiment of the present invention, when the wavelength region is within the above range, the curability is further improved.

The amount of light irradiation is preferably 10 to 20,000 mJ / cm ² , more preferably 50 to 15,000 mJ / cm ² . When the irradiation amount is within the above range, the curing reaction can be sufficiently performed.

  For example, mercury lamps and metal halide lamps are widely known as light emitting light sources in the above wavelength range. On the other hand, from the viewpoint of environmental protection, since mercury-free is strongly desired, replacement of GaN-based semiconductors with ultraviolet light-emitting devices is progressing. Light emitting diodes (LEDs) and laser diodes (LDs) are being used as light sources for photo-curing inkjet recording because of their small size, high efficiency, and long life. For the reasons described above, a light emitting diode (LED) having a peak wavelength in the range of 360 to 400 nm is preferable.

[Recording medium]
Examples of the recording medium include an absorptive or non-absorbable recording medium. The ink jet recording method of the embodiment of the present invention has various absorption performances from a non-absorbable recording medium in which the water-soluble ink composition is difficult to penetrate to an absorbent recording medium in which the water-soluble ink composition is easily penetrated. Can be widely applied to recording media having However, when a non-absorbing non-recording medium is used, it may be necessary to provide a drying step after applying the aggregating liquid, or to provide a drying step after irradiating and curing with ultraviolet rays.

  The absorbent recording medium is not particularly limited. For example, plain paper such as electrophotographic paper having high water-based ink permeability, ink jet paper (an ink absorbing layer composed of silica particles or alumina particles, or polyvinyl alcohol). Art paper and coats used for general offset printing with relatively low permeability of water-based ink from (PVA) and inkjet pyrrole (PVP) and other ink-absorbing layers composed of hydrophilic polymers such as polyvinylpyrrolidone (PVP). Examples thereof include paper and cast paper.

  The non-absorbable recording medium is not particularly limited. For example, a plastic film or plate such as polyvinyl chloride, polyethylene, polypropylene, or polyethylene terephthalate, a metal plate such as iron, silver, copper, or aluminum, or Examples thereof include metal plates produced by vapor deposition of these various metals, plastic films, and plates made of alloys such as stainless steel and brass.

[Inkjet recording apparatus]
An ink jet recording apparatus for carrying out the ink jet recording method of one embodiment of the present invention will be described below with reference to the drawings. In addition, about the content which overlaps with description of an inkjet recording method, description here is abbreviate | omitted.

  FIG. 1 is a schematic configuration diagram of an ink jet recording apparatus. The ink jet recording apparatus 1 includes a recording medium mounting unit 11 on which a recording medium 10 is mounted, a paper feeding roller 12, a platen 13, a conveying roller 14, a conveying belt 15, an aggregating liquid tank 16, and an aggregating liquid. The replenishing tank 17, the aggregation liquid supply rollers 18 and 19, the aggregation liquid application roller 20, the squeegee 21, the recording head 22, the ultraviolet irradiation lamps 23 and 25, the driving means 30, and the control means 31 are provided.

  The paper feed roller 12 separates the recording medium 10 placed on the recording medium placement unit 11 one by one and sends it to the platen 13. The paper feed roller 12 is, for example, a D-type paper feed roller. In the D-type paper feeding roller, the recording medium 10 is not conveyed on the D-shaped flat surface portion, but is conveyed on the curved surface portion.

  In FIG. 1, a single-sheet recording medium 10 is illustrated, but roll paper may be used. In that case, a circular paper feed roller may be used as the paper feed roller 12 for continuous paper feed.

  The platen 13 supports the recording medium 10 from below and regulates the positional relationship between the recording medium 10 and the aggregation liquid application roller 20. On the platen 13, the recording medium 10 is applied with the aggregation liquid by the aggregation liquid application roller 20 and sent to the conveyance belt 15.

  The conveyor belt 15 is stretched between two rotatable conveyor rollers 14, and is configured to be able to go around as the conveyor rollers 14 rotate. The conveyor belt 15 is a belt that combines the conveyance of the recording medium 10 and the platen. The surface of the conveyance belt 15 is charged upstream in the conveyance direction, and conveys the recording medium 10 by electrostatic adsorption. The surface of the transport belt 15 is neutralized downstream in the transport direction, so that the recording medium 10 from the transport belt 15 can be easily separated.

  The flocculated liquid tank 16 contains the flocculated liquid therein. The aggregation liquid is for aggregating ink solids contained in the photocurable ink composition ejected from the recording head 22 to increase the reactivity of the photocurable reaction of the photocurable ink composition. The aggregating liquid contains at least an aggregating agent, a water-soluble organic solvent, a saccharide, and water. The aggregate liquid replenishment tank 17 supplies the aggregate liquid to the aggregate liquid tank 16 through a supply pipe. For example, the aggregate liquid is supplied from the aggregate liquid replenishment tank 17 so that the amount of the aggregate liquid in the aggregate liquid tank 16 becomes a constant amount.

  In FIG. 1, the flocculating liquid replenishing tank 17 is illustrated above the flocculating liquid tank 16, but the flocculating liquid replenishing tank 17 may be disposed at the same height as or below the flocculating liquid tank 16. In that case, the coagulating liquid replenishing tank 17 can supply the coagulating liquid to the coagulating liquid tank 16 through the supply pipe by the action of the coagulating liquid transfer pump (not shown).

  The aggregate liquid supply roller 18 is rotatably supported in a state where at least a part of the peripheral surface is immersed in the liquid surface of the aggregate liquid in the aggregate liquid tank 16. The aggregate liquid supply roller 19 is rotatably supported in contact with the aggregate liquid supply roller 18. The aggregate liquid application roller 20 is rotatably supported in contact with the aggregate liquid supply roller 19. The rotation axes of the aggregate liquid supply rollers 18 and 19 and the aggregate liquid application roller 20 are arranged in parallel. Accordingly, the aggregating liquid supply rollers 18 and 19 are configured to rotate in accordance with the rotation of the aggregating liquid application roller 20, and further, the aggregating liquid application roller 19 passes through the aggregating liquid supply roller 19. The aggregate liquid is supplied to the peripheral surface of 20. The aggregate liquid supply rollers 18 and 19 and the aggregate liquid application roller 20 are examples of the aggregate liquid application unit of the present invention.

  The squeegee 21 is provided so as to be able to contact the aggregate liquid supply roller 19 or the aggregate liquid application roller 20 in order to adjust the amount of the aggregate liquid held on the surface of the aggregate liquid supply roller 19 or the aggregate liquid application roller 20. FIG. 1 illustrates an example in which the squeegee 21 is in contact with the aggregate liquid supply roller 19.

  The recording head (ink discharge means) 22 discharges and attaches an aqueous photocurable ink composition containing ink solids in a dissolved state or a dispersed state to the recording medium 10 to which the aggregate liquid is applied. The aqueous photocurable ink composition contains at least a colorant, an amphiphilic photopolymerizable compound, a photopolymerization initiator, a polar solvent, and water. For example, when inks for cyan, magenta, yellow, and black are required, a photocurable ink composition is prepared for each color. The recording head 22 may be a headset in which a plurality of heads for discharging the photocurable ink composition of each color are arranged along the conveyance direction of the recording medium 10. In addition, the recording head 22 may include a plurality of nozzles for discharging the photocurable ink composition of each color in a direction orthogonal to the conveyance direction of the recording medium 10.

  The ultraviolet irradiation lamps (light irradiation means) 23 and 25 irradiate the photocurable ink composition attached to the recording medium 10 with ultraviolet rays to cure the photocurable ink composition. The ultraviolet irradiation lamp 25 is disposed on the downstream side of the ultraviolet irradiation lamp 23. For example, the widths of the ultraviolet irradiation lamps 23 and 25 in the direction orthogonal to the conveyance direction of the recording medium 10 are equal to or larger than the width of the recording medium 10. As a result, the recording medium 10 passes through the irradiation areas of the ultraviolet irradiation lamps 23 and 25 so that the entire area of the recording medium 10 is irradiated with ultraviolet rays.

Examples of the ultraviolet irradiation lamps (light irradiation means) 23 and 25 include a mercury lamp and a metal halide lamp. Alternatively, a light emitting diode (LED) or a laser diode (LD) may be used. Among these, a light emitting diode (LED) is preferable from the viewpoint of cost and versatility. The wavelength range of ultraviolet rays is, for example, 360 nm to 450 nm. The amount of light irradiation is preferably 10 to 20,000 mJ / cm ² , more preferably 50 to 15,000 mJ / cm ² .

  The drive means 30 drives the squeegee 21 to adjust the pressure of pushing the squeegee 21 against the aggregate liquid supply roller 19 or the aggregate liquid application roller 20. By reducing the pushing pressure of the squeegee 21, the amount of the aggregating liquid on the aggregating liquid supply roller 19 or the aggregating liquid application roller 20 can be increased, and by increasing the pushing pressure of the squeegee 21, the aggregating liquid supply roller. 19 or the amount of the aggregate liquid on the aggregate application roller 20 can be reduced. In this way, by adjusting the pushing pressure of the squeegee 21 by the driving means 30, the application amount of the aggregation liquid to the recording medium 10 is finally adjusted.

  The control means 31 is connected to the drive means 30 and sets the application amount of the aggregation liquid according to the printing conditions. The driving unit 30 controls the pushing pressure of the squeegee 21 based on the application amount set by the control unit 31. For example, the control means 31 sets the application amount of the aggregation liquid that differs depending on the monochrome mode or the color mode. Further, the control unit 31 calculates the amount of printing on the recording medium 10 and sets the application amount of the aggregation liquid that differs depending on the amount of printing. The control means 31 is also connected to, for example, the paper feed roller 12, the coagulating liquid application roller 20, the transport roller 14, the recording head 22, and the ultraviolet irradiation lamps 23 and 25, and controls the operation of the entire apparatus.

  Thus, according to an embodiment of the present invention, it is possible to provide an ink jet recording method that is excellent in the drying property of a coating film, suppresses the occurrence of printing spots, has a uniformly high printing density, and has little paper wrinkles. Can do.

  Furthermore, the recorded matter on which an image is formed by the above-described ink jet recording method has excellent quality such as generation of printing spots is suppressed, the printing density is uniformly high, and there are few paper wrinkles.

  Further, as described above, according to the embodiment of the present invention, it is possible to carry out an ink jet recording method that is excellent in the drying property of the coating film, suppresses the occurrence of printing spots, is uniformly high in printing density, and has little paper wrinkles. An ink jet recording apparatus can be provided.

  Hereinafter, the embodiments of the present invention will be described more specifically with reference to examples and comparative examples. However, the embodiments of the present invention are not limited to these examples.

[Use ingredients]
The components used in the following examples and comparative examples are as follows.

[Water-based photocurable ink composition]
(Pigment)
・ C. I. Pigment Yellow 73 (abbreviated as Yellow 73 in Table 1)
・ C. I. Pigment Red 122 (abbreviated as Red 122 in Table 1)
・ C. I. Pigment Blue 15: 3 (abbreviated as Blue 15: 3 in Table 1)
Carbon black MA7 (Mitsubishi Chemical Corporation, abbreviated as Bk MA7 in Table 1)
(Dispersant)
Solsperse 27000 (manufactured by LUBRIZOL, abbreviated as SOL27000 in Table 1)
(solvent)
2-pyrrolidone triethylene glycol (abbreviated as TEG in Table 1)
Triethylene glycol monobutyl ether (abbreviated as TEGBE in Table 1)
(Surfactant)
・ Orphine E1010 (ethylene oxide (10 mol) adduct of acetylenic diol, manufactured by NISSIN CHEMICAL INDUSTRY CO., LTD.)
(Photopolymerizable compound)
Amphiphilic urethane acrylate (EM90, manufactured by Arakawa Chemical Industries, abbreviated as EM90 in Table 1)
Trimethylolpropane triacrylate (abbreviated as TMPTA in Table 1)
Polyethylene glycol diacrylate (PEG600 diacrylate, manufactured by DAICEL-CYTEC Company LTD., Abbreviated as PEGDA in Table 1)
(Photopolymerization initiator)
DAROCUR TPO (acylphosphine oxide photoinitiator, manufactured by Ciba Japan KK, abbreviated as TPO in Table 1)
(PH adjuster)
10% aqueous potassium hydroxide solution (abbreviated as 10% KOHaq in Table 1)
(water)
・ Ion exchange water

[Aggregating liquid]
(Flocculant)
-Diallyldimethylammonium chloride polymer PAS-H-5L (molecular weight 4000, solid content 20%, manufactured by Nittobo)
(solvent)
Triethylene glycol monobutyl ether (abbreviated as TEGBE in Table 1)
Triethylene glycol (abbreviated as TEG in Table 1)
Propylene glycol (abbreviated as PG in Table 1)
・ Glycerin (pH adjuster)
Triethanolamine (abbreviated as TEA in Table 1)
(Surfactant)
・ Orphine E1010 (ethylene oxide (10 mol) adduct of acetylenic diol, manufactured by NISSIN CHEMICAL INDUSTRY CO., LTD.)
(water)
・ Ion exchange water

[Preparation of ink (ink 1 to ink 12)]
A water-based photocurable ink composition (inks 1 to 12) was prepared by the following method.
In the pigment dispersion, 25 g of Solsperse 27000 (manufactured by LUBRIZOL) was dissolved in 850 g of ion-exchanged water, and 100 g of the pigment described in Table 1 was added thereto and mixed. This mixed solution was dispersed for 5 hours under conditions of 70% bead filling and 5,000 rpm using Eiger Motor Mill Model M250 (trade name, manufactured by Eiger Japan), and pigmented with ion-exchanged water. The concentration was adjusted to 15% by mass.

  The preparation of the photocurable ink composition will be described by taking ink 1 as an example. 10 g of 2-pyrrolidone (abbreviated as pyrrolidone in Table 1), 5 g of propylene glycol (abbreviated as PG in Table 1), 3 g of triethylene glycol (abbreviated as TEG in Table 1), triethylene glycol monobutyl ether (abbreviated as TEGBE in Table 1) ) 1 g, cellobiose (sugar) 5 g, orphine E1010 1 g, and ion-exchanged water 47.8 g were mixed and dissolved. To this, 0.5 g of photoinitiator DAROCUR TPO (acylphosphine oxide photoinitiator, manufactured by Ciba Japan K.K., abbreviated as TPO in Table 1) was added and mixed. Furthermore, 10 g of amphiphilic urethane acrylate (EM90, manufactured by Arakawa Chemical Industries, Ltd., abbreviated as EM90 in Table 1) was added and mixed and stirred to prepare a liquid mixture. C. obtained by the above method. I. Pigment Yellow 73 (abbreviated as Yellow 73 in Table 1) 26.7 g of the pigment dispersion was placed in a stirrer and the liquid mixture was gradually added and mixed to obtain the desired ink 1.

  Based on the composition shown in Table 1 below, inks 2 to 12 were prepared according to the method for preparing the ink 1 described above.

  In addition, the composition described in Table 1 below is shown in mass%.

[Preparation of Aggregate (Aggregate 1)]
The aggregating liquid was prepared according to the composition shown in Table 2 below. The composition (unit: mass%) described in Table 2 was blended, and this was stirred with a stirrer to obtain a common aggregate liquid 1 between the examples and the comparative examples.

  The blank part in Table 2 means no addition. In addition, the composition described in Table 2 is expressed by mass%.

[Measurement and evaluation method]
For the photocurable ink composition obtained in the following Examples and Comparative Examples, or the coating film obtained from the ink composition, the printability, curability, presence or absence of printing spots, and printing density are as follows: It evaluated as follows.

[Evaluation 1: Printability]
The aggregating liquid is applied to fine paper (gold rhombus) by the aggregating liquid application means of the ink jet recording apparatus of the present invention, and ink sets 1 to 3 are applied to the application surface on each of the headsets having a nozzle arrangement structure of 180 lines per line and 8 lines. One row is filled with yellow (Y), magenta (M), cyan (C), and black (Bk), and a 100% duty solid image is formed at a resolution of 720 dpi × 720 dpi at 7 pL per dot. The recording apparatus was irradiated with 5000 mJ / cm ² of 395 nm ultraviolet light with the ultraviolet irradiation mechanism of the recording apparatus to obtain a printed matter.

At this time, the state of the printing part on the recording medium was visually observed and evaluated in the following two stages.
Evaluation A: The ink was uniformly applied, the image was clear, and the edge was sharp.
Evaluation B: The image lacked sharpness and the edge was not sharp due to the occurrence of ink repellency or printing spots in which high density portions were locally present.

[Evaluation 2: Scratch resistance]
The aggregating liquid is applied to fine paper (gold rhombus) by the aggregating liquid application means of the ink jet recording apparatus of the present invention, and ink sets 1 to 3 are applied to the application surface on each of the headsets having a nozzle arrangement structure of 180 lines per line and 8 lines. One row is filled with yellow (Y), magenta (M), cyan (C), and black (Bk), and an image is formed at a resolution of 720 dpi × 720 dpi at 7 pL per dot. The printed matter was obtained by irradiating 5000 mJ / cm ² with 395 nm ultraviolet light by an irradiation mechanism. After leaving the obtained printed matter in an atmosphere of 25 ° C. and 40% humidity for 1 hour, the printed portion was rubbed with a yellow aqueous fluorescent pen ZEBRA PEN2 (trade name) manufactured by Zebra under a load of 9.8 N / mm ² , The state of the image was visually observed and evaluated according to the following criteria.
Evaluation A: It was the same state as before rubbing.
Evaluation B: An intermediate state between evaluations A and C. The printed part is slightly stained by rubbing, but the image can be recognized.
Evaluation C: The printed part was soiled by rubbing, and the image was unclear.

[Evaluation 3: Printing density]
The aggregate liquid is applied to high-quality paper (gold rhombus) by the aggregate liquid application means of the ink jet recording apparatus of the present invention, and ink sets 1 to 3 are applied on the application surface to each of the headsets having a nozzle arrangement structure of 180 rows and 8 rows. The rows are filled with yellow (Y), magenta (M), cyan (C), and black (Bk), and a 100% duty solid image is formed at a resolution of 720 dpi vertical by 720 dpi horizontal by 7 pL per dot. The printed matter was obtained by irradiating 5000 mJ / cm ² of 395 nm ultraviolet light with the ultraviolet irradiation mechanism of the recording apparatus. Here, the evaluation criteria are as follows.
Evaluation A: It was uniform and the density was 1.5 or higher, which was a high value.
Evaluation B: There were density spots.
Evaluation C: It was uniform but the density was lower than 1.5.
The evaluation results are shown in Table 3 below.

  In Example 1, the ink aggregated on the high-quality paper (gold rhombus) at the same time as the landing, and the printed surface after irradiation with ultraviolet rays was completely dried. The obtained printed image was clear and free of density spots and repellency, and the edge portion of the image was sharp and clear. The print density was also high. In addition, even when solid printing was performed on the entire surface, curling and cockling were few and generation of paper wrinkles due to printing was suppressed. Further, the scratch resistance was good with no change before and after the evaluation test.

  In Comparative Example 1, spots and density spots where ink was repelled were found in the obtained printed image. Further, there was stickiness in the printed portion, and in the evaluation of scratch resistance, the printed portion was soiled by rubbing and the image became unclear.

  In Comparative Example 2, the image of the obtained printed matter was free from density spots and repellency, and the edge portion of the image was sharp and clear, but the printed portion was soiled by rubbing in the scratch resistance evaluation. The image became unclear. There was no stickiness in the printed part. The printing density was lower than that in Example 1.

  In Comparative Example 3, compared with Example 1, the printing density was lowered and the scratch resistance was also lowered.

The state of occurrence of paper wrinkles after printing was compared between Example 1 and the case where Aggregate 2 containing no cellobiose (saccharide) was used for the agglomerate of Example 1. Printing is performed by applying Aggregate 1 or Aggregate 2 to high-quality paper (gold rhombus) with the Aggregate application means of the ink jet recording apparatus of the present invention, and ink set 1 is arranged on the application surface in 1 row 180 dpi, 8 rows nozzle arrangement. A headset with a structure filled with yellow (Y), magenta (M), cyan (C), and black (Bk) in each row, with a resolution of 720 dpi x 720 dpi horizontal, 7 pL per dot, 100% duty solid An image was formed and further irradiated with 5000 mJ / cm ² of 395 nm ultraviolet light by the ultraviolet irradiation mechanism of the recording apparatus. As a result, compared with Example 1, when the coagulating liquid 2 containing no cellobiose (saccharide) was used for the coagulating liquid of Example 1, curling and cockling were large.

  From the above results, it was found that according to the recording method of the present invention, a sharp and clear image having a high printing density and no printing spots such as density spots and repellency can be obtained. It was also found that a printed matter with less paper wrinkles such as curling and cockling can be obtained. It was also found to be excellent in scratch resistance.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet recording apparatus, 10 ... Recording medium, 11 ... Recording medium mounting part, 12 ... Paper feed roller, 13 ... Platen, 14 ... Conveying roller, 15 ... Conveying belt, 16 ... Aggregating liquid tank, 17 ... Aggregating liquid tank Liquid replenishment tanks 18, 19 ... Aggregated liquid supply rollers 19, 19, 20 ... Aggregated liquid application rollers, 21 ... Squeegee, 22 ... Recording head, 23 ... UV irradiation lamp, 24 ... Heater, 25 ... Infrared lamp, 30 ... Drive means 31 ... Control means.

Claims (11)

A coating step of coating a flocculant, a water-soluble organic solvent, a saccharide, and an aggregating liquid containing at least water on a recording medium;
A recording medium after the coating step by discharging an aqueous photocurable ink composition containing at least a colorant, an amphiphilic photopolymerizable compound, a photopolymerization initiator, a polar solvent, and water from a recording head An ejection step for landing the ink composition on the surface;
A curing step of curing the aqueous photocurable ink composition after the ejection step by light irradiation;
Including
The amphiphilic photopolymerizable compound is a monofunctional or bifunctional or higher oligomer as a photopolymerizable compound, and is contained in the aqueous photocurable ink composition in a self-emulsifying form ,
The content of the saccharide with respect to the aggregate liquid is 1 to 40% by mass.
Inkjet recording method.   The inkjet recording method according to claim 1, wherein the aggregating agent is a cationic water-soluble polymer.   The inkjet recording method according to claim 1, wherein the amphiphilic photopolymerizable compound is a compound having one or more radically polymerizable groups, hydrophilic groups, and hydrophobic groups.   The inkjet recording according to any one of claims 1 to 3, wherein the amphiphilic photopolymerizable compound is at least one of an amphiphilic urethane acrylate, an amphiphilic polyester acrylate, and an amphiphilic epoxy acrylate. Method.   The inkjet recording method according to any one of claims 1 to 4, wherein the amphiphilic photopolymerizable compound is an amphiphilic urethane acrylate. The inkjet recording method according to any one of claims 1 to 5 , wherein the photopolymerization initiator has a peak wavelength in a range of 380 to 410 nm. The photopolymerization initiator is an acyl phosphine oxide-based photopolymerization initiator, an ink jet recording method according to any one of claims 1-6. The aggregating agent comprises an osmotic agent, said osmotic agent is a glycol ether, an ink jet recording method according to any one of claims 1-7. The inkjet recording method according to any one of claims 1 to 8 , wherein in the discharging step, a water-based photocurable ink composition (excluding an ink composition having a water content of less than 10% by weight) is discharged. An inkjet recording apparatus for carrying out the inkjet recording method according to any one of claims 1 to 9 ,
Coagulant aggregating liquid tank, a water-soluble organic solvent, at least seen including sugars, and water, and aggregating agent amount contained on the aggregation solution of the saccharide is 1 to 40 wt%, and at least a portion of the roller, but Aggregating liquid application means for applying the aggregating liquid onto the recording medium by contacting and rotating the roller;
By discharging an aqueous photocurable ink composition containing at least a colorant, an amphiphilic photopolymerizable compound, a photopolymerization initiator, a polar solvent, and water from a recording head, the coating liquid to which the aggregation liquid is applied is discharged. An ink discharge means for attaching the water-based photocurable ink composition on a recording medium;
Light irradiating means for irradiating the aqueous photocurable ink composition attached on the recording medium with light to cure the aqueous photocurable ink composition;
An ink jet recording apparatus. The inkjet recording apparatus according to claim 10 , wherein the light irradiation unit includes a light emitting diode irradiation lamp.