JP2007144685A - Inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method which enables recording on various recording mediums even with an active energy beam of a relatively low illuminance and which prevents feathering, bleeding, etc. and causes little damage to the recording mediums. <P>SOLUTION: The inkjet recording method uses an inkjet ink containing at least a coloring agent, water and a polymeric compound having a plurality of side chains in a hydrophilic main chain and being crosslinkable between the side chains by irradiation with the active energy beam and employs a recording head having at least one nozzle which is selectively controllable as to discharge of an ink droplet. The active energy beam of which the maximum illuminance at 200-400 nm is 0.1-50 mW/cm<SP>2</SP>is used, and an inert gas is substituted for a curing atmosphere after an impact of ink. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording method.

  The ink jet recording method is capable of recording high-definition images with a relatively simple apparatus, and has been rapidly developed in various fields. In addition, there are various uses, and a recording medium or ink suitable for each purpose is used.

  In particular, in recent years, the recording speed has been greatly improved, and printers having performance capable of withstanding light printing applications have been developed.

  However, in order to bring out the performance of the ink jet printer, an ink jet special paper provided with ink absorbability is required.

  When recording on coated paper, art paper, or plastic film that does not absorb ink very much, problems such as so-called bleed that cause different color ink liquids to mix on the recording medium and cause color turbidity Therefore, there has been a problem in providing a variety of recording media to the ink jet.

  In order to solve the above problem, an inkjet ink that is cured by exposure to ultraviolet rays is disclosed (see Patent Document 1). In addition, a so-called non-aqueous ink containing a pigment essential, a tri- or higher functional polyacrylate as a polymerizable material, and a ketone or alcohol as a main solvent has been proposed (see Patent Document 2). . An ink using an aqueous ultraviolet polymerization monomer has been proposed (see Patent Document 3).

  In these methods, since the ink itself is cured with a curing component, recording is possible even on a non-absorbing medium. However, since the curing component other than the colorant is contained in a large amount and does not volatilize, the recording surface is reduced. The ink dots swelled up, causing unnaturalness in image quality, especially gloss.

In addition, conventionally known UV inkjet inks require active energy rays with high illuminance, and heat generated at that time causes film shrinkage, paper burning, and the like.
U.S. Pat. No. 4,228,438 Japanese Patent Publication No. 5-64667 JP-A-7-224241

  An object of the present invention is to provide an ink jet recording method capable of recording on various recording media even with an active energy ray of relatively low illuminance, preventing feathering, bleeding, etc., and causing little damage to the recording media. That is.

  The above object of the present invention is achieved by the following configurations.

1. Select using an ink-jet ink containing at least a colorant, water, and a polymer compound that has a plurality of side chains in the hydrophilic main chain and that can be crosslinked between the side chains by irradiating active energy rays. In an inkjet recording method using a recording head having at least one nozzle capable of controlling the ejection of ink droplets, an active energy ray having a maximum illuminance at 200 to 400 nm of 0.1 to 50 mW / cm ² is used, and the ink An ink jet recording method comprising replacing a curing atmosphere after landing with an inert gas.

  2. 2. The ink jet recording method according to 1, wherein the active energy ray is irradiated within 1 second after ink landing.

  3. The polymer compound contained in the inkjet ink has a hydrophilic main chain of saponified polyvinyl acetate, a polymerization degree of 200 to 1000, and a saponification degree of 70 to 99%. 1 or 2 The ink jet recording method described in 1.

  4). The inkjet recording according to any one of 1 to 3, wherein the polymer compound contained in the inkjet ink has a side chain modification ratio of 0.6 to 4 mol% with respect to the hydrophilic main chain. Method.

  According to the present invention, there is provided an ink jet recording method capable of recording on various recording media even with relatively low illuminance active energy rays, preventing feathering, bleeding, etc., and reducing damage to the recording media. be able to.

As a result of intensive studies, the present inventor has at least a colorant, water, and a polymer compound having a plurality of side chains in a hydrophilic main chain and capable of crosslinking between side chains by irradiating active energy rays. In an inkjet recording method using a recording head having at least one nozzle capable of selectively controlling the ejection of ink droplets, the maximum illuminance at 200 to 400 nm is 0.1 to 50 mW / cm ² . The inkjet recording method that uses active energy rays and replaces the curing atmosphere after ink landing with an inert gas enables recording on various recording media even with relatively low illuminance active energy rays. It has been found that an ink jet recording method can be obtained in which bleeding and the like are prevented and damage to the recording medium is small.

  Hereinafter, the present invention will be described in detail.

(Active energy ray crosslinkable polymer compound)
The polymer compound having a plurality of side chains in the hydrophilic main chain according to the present invention and capable of crosslinking between the side chains by irradiating with active energy rays is a saponified product of polyvinyl acetate, polyvinyl acetal, polyethylene Oxide, polyalkylene oxide, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, or a derivative of the hydrophilic resin, and at least one hydrophilic selected from the group consisting of these copolymers In the resin, a modified group such as a photodimerization type, a photodecomposition type, a photopolymerization type, a photomodification type, or a photodepolymerization type is introduced into the side chain. Photopolymerizable crosslinkable groups are desirable from the viewpoints of sensitivity and performance of the generated image.

  There is a preferable combination between the ionicity of the color material used in the inkjet ink (hereinafter also simply referred to as ink) and the ionicity of the side chain of the polymer compound. It was found that by selecting an anionic property for the color material and combining a nonionic or anionic property for the side chain, the color material is excellent in terms of image fastness, ink storage stability, and continuous emission. The side chain is most preferably nonionic. The reason is not clear, but in the case of the combination of the above ions, the decomposition of the ink composition, the association between the ink compositions, and the like are reduced, which may affect the above effect.

  What the partial structure of the hydrophilic principal chain and side chain of the active energy ray crosslinkable polymer compound according to the present invention is represented by the following general formula (A) is preferable.

Formula (A) Poly - {(X 1) m - [B- (Y _{1) n] p}}
In the formula, Poly represents a hydrophilic main chain. Saponified product of polyvinyl acetate, polyvinyl acetal, polyethylene oxide, polyalkylene oxide, polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, or a derivative of the hydrophilic resin, and copolymers thereof Is preferred.

{} Represents a side chain. In the side chain, X ₁ represents a (p + 1) -valent linking group. p represents a positive integer, preferably an integer of 1 to 5. Specifically, when p = 1, X ₁ represents a divalent linking group. For example, an alkylene group, an arylene group, a heteroarylene group, an ether group, a thioether group, an imino group, an ester group, an amide group, a sulfonyl group Groups and the like, and these may be combined to form one divalent or higher group. Moreover, when p = 2 or more, a plurality of B and Y described later may be the same or different.

X ₁ is preferably an alkylene oxide or a divalent or higher linking group in which an aromatic group is combined at least.

  B represents a crosslinking group. Specifically, it is a group containing a double bond or a triple bond, and represents, for example, an acryl group, a methacryl group, a vinyl group, an allyl group, a diazo group, or an azide group. An acrylic group and a methacryl group are preferable.

Y ₁ represents a hydrogen atom or a substituent. Specific examples of the substituent include a halogen atom (eg, fluorine atom, chlorine atom, etc.), an alkyl group (eg, methyl, ethyl, butyl, pentyl, 2-methoxyethyl, trifluoromethyl, 2-ethylhexyl, cyclohexyl, etc. ), Aryl groups (eg, phenyl, p-tolyl, naphthyl, etc.), acyl groups (eg, acetyl, propionyl, benzoyl, etc.), alkoxy groups (eg, methoxy, ethoxy, butoxy, etc.), alkoxycarbonyl groups (eg, methoxy Carbonyl, i-propoxycarbonyl, etc.), acyloxy groups (eg, acetyloxy, ethylcarbonyloxy, etc.), carbamoyl groups (eg, methylcarbamoyl, ethylcarbamoyl, butylcarbamoyl, phenylcarbamoyl, etc.), sulfamoyl groups (eg, sulfamoyl groups) Famoyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl etc.), alkylthio group (eg methylthio, ethylthio, octylthio etc.), arylthio group (eg phenylthio, p-tolylthio etc.), alkylureido group (eg , Methylureido, ethylureido, methoxyethylureido, dimethylureido, etc.), arylureido groups (eg, phenylureido etc.), alkylsulfonamide groups (eg, methanesulfonamide, ethanesulfonamide, butanesulfonamide, trifluoromethylsulfone) Amide, 2,2,2-trifluoroethylsulfonamide, etc.), arylsulfonamide groups (eg, phenylsulfonamide, tolylsulfonamide, etc.), alkylaminosulfonylamino (Eg, methylaminosulfonylamino, ethylaminosulfonylamino, etc.), arylaminosulfonylamino groups (eg, phenylaminosulfonylamino, etc.), hydroxy groups, heterocyclic groups (eg, pyridyl, pyrazolyl, imidazolyl, furyl, thienyl, etc.) And these may further have a substituent.

  m represents 0 or 1.

  n represents 0 or 1.

  In the hydrophilic main chain, a saponified product of polyvinyl acetate is preferable from the viewpoint of ease of introduction of side chains and handling, and the degree of polymerization is preferably 300 to 4000, more preferably 200 to 1000 from the viewpoint of handling. The saponification degree is preferably 70 to 99%. The modification rate of the side chain with respect to the main chain is preferably 0.3 to 4 mol%, and more preferably 0.6 to 4 mol% from the viewpoint of reactivity. If it is less than 0.3 mol%, the crosslinkability is insufficient and the effect of the present invention is reduced. If it is more than 4 mol%, the crosslink density is increased and the film is hard and brittle, and the strength of the film is lowered.

  In the active energy ray crosslinkable polymer compound according to the present invention, a more preferable structure is represented by the following general formula (1) in the photosensitive resin and polyvinyl alcohol structure described in JP-A-56-67309. The side chain of 2-azido-5-nitrophenylcarbonyloxyethylene structure (nonionic) or the side of 4-azido-3-nitrophenylcarbonyloxyethylene structure (nonionic) represented by the following general formula (2) It is a resin composition having a chain.

  A side chain of a modifying group (anionic) represented by the following general formula (3) is also preferably used.

  In the formula, R represents an alkylene group or an aromatic ring. A benzene ring is preferred.

  As the photopolymerization type modifying group, for example, a resin (nonionic) represented by the following general formula (4) shown in JP-A Nos. 2000-181062 and 2004-189841 is preferable from the viewpoint of reactivity. .

In the formula, R ₂ represents Me or H, n represents 1 or 2, X represents — (CH ₂ ) _m —COO— or —O—, Y represents an aromatic ring or a single bond, and m represents 0 to 6 Represents an integer.

  Moreover, it is also preferable to use the photopolymerization type | mold modified group (nonionic property) represented by following General formula (5) described in Unexamined-Japanese-Patent No. 2004-161942 for a conventionally well-known water-soluble resin.

In the formula, R ₃ represents Me or H, and R ₄ represents a linear or branched alkylene group having 2 to 10 carbon atoms.

  Furthermore, modified groups (nonionic) represented by the following general formulas (6) to (8) are also preferably used.

  Such an active energy ray-crosslinking resin is preferably contained in an amount of 0.5 to 5.0% by mass with respect to the total mass of the ink. The presence of 0.5% by mass or more improves the cross-linking efficiency, and beading and color bleeding are more preferable due to a rapid increase in ink viscosity after cross-linking. In the case of 5.0% by mass or less, it is difficult to adversely affect the physical properties of the ink and the state in the ink head, which is preferable from the viewpoints of light emission properties and ink storage stability.

  In the active energy ray cross-linking resin according to the present invention, the main chain originally having a certain degree of polymerization is cross-linked via a cross-linking bond between side chains, and thus polymerized via a general chain reaction. The effect of increasing the molecular weight per photon is significantly greater than the active energy ray-curable resin. On the other hand, in the conventionally known active energy ray curable resins, the number of crosslinking points cannot be controlled, so the physical properties of the cured film cannot be controlled, and the film tends to be hard and brittle.

  In the resin used in the present invention, the number of crosslinking points can be completely controlled by the length of the hydrophilic main chain and the amount of side chains introduced, and the physical properties of the ink film can be controlled according to the purpose.

  Furthermore, almost all of the conventionally known active energy ray-curable inks other than the colorant are curable, so that the dots after curing are raised and inferior in image quality typified by gloss, are used in the present invention. The resin requires only a small amount, and since there are many dry components, the image quality after drying is improved and the fixing property is also good.

(Photopolymerization initiator, sensitizer)
In the present invention, it is also preferable to add a photopolymerization initiator or a sensitizer. These compounds may be dissolved or dispersed in a solvent, or may be chemically bonded to the photosensitive resin.

  There is no restriction | limiting in particular about the photoinitiator and photosensitizer which are applied, A conventionally well-known thing can be used.

  Although there is no restriction | limiting in particular about the photoinitiator and photosensitizer which are applied, A water-soluble thing is preferable from a viewpoint of mixability and reaction efficiency. In particular, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (HMPK), thioxanthone ammonium salt (QTX), and benzophenone ammonium salt (ABQ) are preferable from the viewpoint of miscibility with an aqueous solvent.

  Furthermore, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (n = 1, HMPK) represented by the following general formula (9) from the viewpoint of compatibility with the resin, An ethylene oxide adduct (n = 2 to 5) is more preferable.

  In the formula, n represents an integer of 1 to 5.

  Others include benzophenones such as benzophenone, hydroxybenzophenone, bis-N, N-dimethylaminobenzophenone, bis-N, N-diethylaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone; thioxatone, 2, 4 -Thioxanthones such as diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone, isopropoxychlorothioxanthone; anthraquinones such as ethyl anthraquinone, benzanthraquinone, aminoanthraquinone, chloroanthraquinone; benzoin ethers such as acetophenone; , 6-Trihalomethyltriazines; 1-hydroxycyclohexyl phenyl ketone, 2- (o-chlorophenyl) -4,5-diph Nilimidazole dimer, 2- (o-chlorophenyl) -4,5-di (m-methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-phenylimidazole dimer, 2 -(O-methoxyphenyl) -4,5-phenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer, 2, -di (p-methoxyphenyl) -5 Phenylimidazole dimer, 2,4,5-triarylimidazole dimer of 2- (2,4-dimethoxyphenyl) -4,5-diphenylimidazole dimer, benzyldimethyl ketal, 2-benzyl-2- Dimethylamino-1- (4-morpholinophenyl) butan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1 Propanone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one Benzoins such as phenanthrenequinone, 9,10-phenanthrenequinone, methylbenzoin, ethylbenzoin; acridine derivatives such as 9-phenylacridine, 1,7-bis (9,9'-acridinyl) heptane, bisacylphosphine Oxides, and mixtures thereof are preferably used, and the above may be used alone or in combination.

  In addition to these photopolymerization initiators, accelerators and the like can also be added. Examples of these include ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, ethanolamine, diethanolamine, triethanolamine and the like.

  Even if these photoinitiators are grafted to the side chain with respect to the hydrophilic main chain.

(Active energy rays, irradiation method)
Examples of the active energy ray in the present invention include electron beam, ultraviolet ray, α ray, β ray, γ ray, X ray, etc., but it is dangerous to human body, easy to handle, and industrially uses it. UV is popular.

  When using ultraviolet rays, the light source is a low pressure, medium pressure, high pressure mercury lamp, metal halide lamp, xenon lamp having a light emission wavelength in the ultraviolet region, cold cathode tube, hot cathode tube, LED, for example, having an operating pressure of 0.1 kPa to 1 MPa. A conventionally well-known thing is used.

In the present invention, irradiation conditions with a maximum illuminance of 0.1 to 50 mW / cm ² in a wavelength region of 200 to 450 nm are used. If the illuminance is greater than 50 mW / cm ² , the amount of heat generated at the same time increases the damage to the recording medium, which is not preferable.

  Further, by reducing the maximum illuminance, the light source can be reduced in size, which is preferable for reducing the load on the apparatus.

  In the present invention, the curing atmosphere during irradiation with active energy rays is replaced with an inert gas. The inert gas may be anything that is conventionally known, and examples thereof include nitrogen gas, carbon dioxide gas, and argon gas. Substitution with an inert gas refers to controlling the oxygen concentration in the curing atmosphere to 0.01 to 1%.

(Light irradiation conditions after ink landing)
As the irradiation condition of the active energy ray, the active energy ray is preferably irradiated within 1.0 second after the ink landing, and more preferably 0.001 to 0.5 second. In order to form a high-definition image, it is particularly important that the irradiation timing is as early as possible.

(Installation of lamp)
As a method for irradiating active energy rays, a basic method is disclosed in Japanese Patent Application Laid-Open No. 60-132767. According to this, the light source is provided on both sides of the head unit, and the head and the light source are scanned by the shuttle method. Irradiation is performed after a certain period of time after ink landing. Further, the curing is completed by another light source that is not driven. In US Pat. No. 6,145,979, as an irradiation method, a method using an optical fiber or a method of applying a collimated light source to a mirror surface provided on the side of the head unit and irradiating the recording unit with UV light is disclosed. Yes. Any of these irradiation methods can be used in the present invention.

  Also preferred is a method in which the irradiation of active energy rays is divided into two stages, and the active energy rays are first irradiated by the above-described method between 0.001 and 1.0 seconds after ink landing, and further the active energy rays are irradiated. It is one of. By dividing the irradiation of the active energy ray into two stages, it is possible to further suppress the shrinkage of the recording material that occurs during ink curing.

(Colorant)
As the colorant used in the ink-jet ink according to the present invention, various dyes or pigments known in ink-jet can be used, but anionic property is preferable in combination with the ionicity of the side chain of the active energy ray-crosslinking resin. .

<dye>
There is no restriction | limiting in particular as dye which can be used by this invention, Water-soluble dyes, such as an acid dye, a direct dye, and a reactive dye, a disperse dye, etc. are mentioned, An anionic dye is preferable.

<Water-soluble dye>
Examples of the anionic water-soluble dye that can be used in the present invention include azo dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, phthalocyanine dyes, triphenylmethane dyes, diphenylmethane dyes, and the like. The specific compound is shown below. However, it is not limited to these exemplified compounds.

<C. I. Acid Yellow>
1, 3, 11, 17, 18, 19, 23, 25, 36, 38, 40, 42, 44, 49, 59, 61, 65, 67, 72, 73, 79, 99, 104, 110, 114, 116, 118, 121, 127, 129, 135, 137, 141, 143, 151, 155, 158, 159, 169, 176, 184, 193, 200, 204, 207, 215, 219, 220, 230, 232, 235, 241, 242, 246,
<C. I. Acid Orange>
3, 7, 8, 10, 19, 24, 51, 56, 67, 74, 80, 86, 87, 88, 89, 94, 95, 107, 108, 116, 122, 127, 140, 142, 144, 149, 152, 156, 162, 166, 168,
<C. I. Acid Red>
88, 97, 106, 111, 114, 118, 119, 127, 131, 138, 143, 145, 151, 183, 195, 198, 211, 215, 217, 225, 226, 249, 251, 254, 256, 257, 260, 261, 265, 266, 274, 276, 277, 289, 296, 299, 315, 318, 336, 337, 357, 359, 361, 362, 364, 366, 399, 407, 415,
<C. I. Acid Violet>
17, 19, 21, 42, 43, 47, 48, 49, 54, 66, 78, 90, 97, 102, 109, 126,
<C. I. Acid Blue>
1, 7, 9, 15, 23, 25, 40, 62, 72, 74, 80, 83, 90, 92, 103, 104, 112, 113, 114, 120, 127, 128, 129, 138, 140, 142, 156, 158, 171, 182, 185, 193, 199, 201, 203, 204, 205, 207, 209, 220, 221, 224, 225, 229, 230, 239, 249, 258, 260, 264, 278, 279, 280, 284, 290, 296, 298, 300, 317, 324, 333, 335, 338, 342, 350,
<C. I. Acid Green>
9, 12, 16, 19, 20, 25, 27, 28, 40, 43, 56, 73, 81, 84, 104, 108, 109,
<C. I. Acid Brown>
2, 4, 13, 14, 19, 28, 44, 123, 224, 226, 227, 248, 282, 283, 289, 294, 297, 298, 301, 355, 357, 413,
<C. I. Acid Black>
1, 2, 3, 24, 26, 31, 50, 52, 58, 60, 63, 107, 109, 112, 119, 132, 140, 155, 172, 187, 188, 194, 207, 222,
<C. I. Direct yellow>
8, 9, 10, 11, 12, 22, 27, 28, 39, 44, 50, 58, 79, 86, 87, 98, 105, 106, 130, 132, 137, 142, 147, 153,
<C. I. Direct orange>
6, 26, 27, 34, 39, 40, 46, 102, 105, 107, 118,
<C. I. Direct Red>
2, 4, 9, 23, 24, 31, 54, 62, 69, 79, 80, 81, 83, 84, 89, 95, 212, 224, 225, 226, 227, 239, 242, 243, 254,
<C. I. Direct Violet>
9, 35, 51, 66, 94, 95,
<C. I. Direct Blue>
1, 15, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 160, 168, 189, 192, 193, 199, 200, 201, 202, 203, 218, 225, 229, 237, 244, 248, 251, 270, 273, 274, 290, 291,
<C. I. Direct Green>
26, 28, 59, 80, 85,
<C. I. Direct Brown>
44, 106, 115, 195, 209, 210, 222, 223,
<C. I. Direct Black>
17, 19, 22, 32, 51, 62, 108, 112, 113, 117, 118, 132, 146, 154, 159, 169,
<C. I. Reactive Yellow>
2, 3, 7, 15, 17, 18, 22, 23, 24, 25, 27, 37, 39, 42, 57, 69, 76, 81, 84, 85, 86, 87, 92, 95, 102, 105, 111, 125, 135, 136, 137, 142, 143, 145, 151, 160, 161, 165, 167, 168, 175, 176,
<C. I. Reactive Orange>
1, 4, 5, 7, 11, 12, 13, 15, 16, 20, 30, 35, 56, 64, 67, 69, 70, 72, 74, 82, 84, 86, 87, 91, 92, 93, 95, 107,
<C. I. Reactive Red>
2, 3, 5, 8, 11, 21, 22, 23, 24, 28, 29, 31, 33, 35, 43, 45, 49, 55, 56, 58, 65, 66, 78, 83, 84, 106, 111, 112, 113, 114, 116, 120, 123, 124, 128, 130, 136, 141, 147, 158, 159, 171, 174, 180, 183, 184, 187, 190, 193, 194, 195, 198, 218, 220, 222, 223, 228, 235,
<C. I. Reactive Violet>
1, 2, 4, 5, 6, 22, 23, 33, 36, 38,
<C. I. Reactive Blue>
2, 3, 4, 5, 7, 13, 14, 15, 19, 21, 25, 27, 28, 29, 38, 39, 41, 49, 50, 52, 63, 69, 71, 72, 77, 79, 89, 104, 109, 112, 113, 114, 116, 119, 120, 122, 137, 140, 143, 147, 160, 161, 162, 163, 168, 171, 176, 182, 184, 191, 194, 195, 198, 203, 204, 207, 209, 211, 214, 220, 221, 222, 231, 235, 236,
<C. I. Reactive Green>
8, 12, 15, 19, 21,
<C. I. Reactive Brown>
2, 7, 9, 10, 11, 17, 18, 19, 21, 23, 31, 37, 43, 46,
<C. I. Reactive Black>
5, 8, 13, 14, 31, 34, 39,
<C. I. Food Black>
1, 2,
Etc.

<Pigment>
As the pigment that can be used in the present invention, conventionally known organic and inorganic pigments can be used, but they are anionic pigments. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Examples include cyclic pigments, dye lakes such as acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, and inorganic pigments such as carbon black.

  Specific organic pigments are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. And CI Pigment Yellow 138.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

<Dispersant>
As the water-soluble polymer dispersant for stably dispersing the pigment in the ink, the following water-soluble resin can be used, which is preferable from the viewpoint of ejection stability.

  As the water-soluble resin, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid copolymer, styrene-maleic acid-acrylic acid alkyl ester copolymer are preferably used. Polymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer It is a water-soluble resin such as.

  As content with respect to the ink whole quantity of water-soluble resin, 0.1-10 mass% is preferable, More preferably, it is 0.3-5 mass%.

  Two or more of these water-soluble resins can be used in combination.

<Anionic pigment>
The form of the anionic pigment used in the present invention is preferably a pigment in which the pigment is dispersed with an anionic polymer dispersant or an anion-modified self-dispersing pigment from the viewpoint of dispersion stability.

  The anionic polymer dispersant refers to a dispersant having an anionic group obtained by neutralizing an acidic group in a molecule with a basic compound. Examples of the basic compound used at this time include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and amines such as ammonia, alkylamine, and alkanolamine. In the present invention, amines are particularly preferable. .

  The anionic polymer dispersant preferably used in the present invention is not particularly limited as long as the molecular weight is 1000 or more. For example, polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer Polymers, acrylic resins such as potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer Styrene-acrylic resin such as polymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer , Styrene-maleic acid copolymer, styrene-maleic anhydride Acid copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid ester copolymer Copolymers, vinyl acetate copolymers such as vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic acid copolymer, and copolymers or resins such as salts thereof, for example, carboxylic acid, sulfonic acid or phosphonic acid Including homopolymers, copolymers and terpolymers having the following functionalities: Monomers that give acid functionality are, for example, acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, mesaconic acid, fumaric acid, citraconic acid, vinyl acetic acid, acryloxypropionic acid, vinyl sulfonic acid, Styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, allylsulfonic acid, allylphosphonic acid, vinylphosphonic acid and vinylsulfonic acid.

  The anion-modified self-dispersing pigment preferably used in the present invention refers to a pigment having an anionic group on the surface and capable of being dispersed without a dispersant. An anionic self-dispersing pigment refers to a pigment in which an acidic group is modified on the pigment, and this is neutralized with a basic compound to form an anionic group that can be dispersed in water without a dispersant.

  The pigment particle having an acidic group on the surface means a pigment directly modified with an acidic group on the surface of the pigment particle, or an organic substance having an organic pigment mother nucleus and having an acidic group bonded directly or through a joint. .

  Examples of the acidic group (also referred to as polar group) include a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a boric acid group, and a hydroxyl group, preferably a sulfonic acid group and a carboxylic acid group, and more preferably a sulfone group. It is an acid group.

  Acid group modifiers include sulfuric acid, fuming sulfuric acid, sulfur trioxide, chlorosulfuric acid, fluorosulfuric acid, amidosulfuric acid, sulfonated pyridine salt, sulfamic acid and other treatments containing sulfur atoms, and the pigment particle surface is oxidized. Carboxylating agents such as sodium hypochlorite and potassium hypochlorite that introduce carboxylic acid groups can be mentioned. Among them, a sulfonating agent such as sulfur trioxide, sulfonated pyridine salt or sulfamic acid, or a carboxylating agent is preferable. Examples of basic compounds that neutralize acidic groups include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and amines such as ammonia, alkylamines, and alkanolamines. In the present invention, amines are used. Is particularly preferred.

  Examples of a method for obtaining pigment particles having a polar group on the surface include, for example, International Publication No. 97/48769 Pamphlet, JP-A Nos. 10-110129, 11-246807, 11-57458, and 11-189739. No. 11-323232, JP-A 2000-265094, etc., the surface of the pigment particles is oxidized with an appropriate oxidizing agent, so that at least a part of the pigment surface has a polarity such as a sulfonic acid group or a salt thereof. The method of introduce | transducing group is mentioned. Specifically, it is prepared by oxidizing carbon black with concentrated nitric acid, or in the case of color pigments by oxidizing with sulfamic acid, sulfonated pyridine salt, amide sulfuric acid, etc. in sulfolane or N-methyl-2-pyrrolidone. can do. A pigment dispersion can be obtained by removing and purifying a substance that has been excessively oxidized and becomes water-soluble by these reactions. Moreover, when a sulfonic acid group is introduced onto the surface by oxidation, the acidic group may be neutralized with a basic compound as necessary.

  Other methods include a method in which the pigment derivatives described in JP-A-11-49974, JP-A-2000-273383, JP-A-2000-303014, etc. are adsorbed on the surface of pigment particles by a treatment such as milling. 179977, 2002-201401, the pigment is combined with a pigment derivative in a solvent and then crystallized in a poor solvent, and any method can be used to easily polar groups on the surface. Pigment particles having can be obtained.

  In the present invention, the polar group may be free or in a salt state, or may have a counter salt. Examples of the counter salt include inorganic salts (lithium, sodium, potassium, magnesium, calcium, aluminum, nickel, ammonium) and organic salts (triethylammonium, diethylammonium, pyridinium, triethanolammonium, etc.), preferably 1 A counter salt having a valence.

  The average particle size of the pigment dispersion used in the inkjet ink according to the present invention is preferably 500 nm or less, more preferably 200 nm or less, preferably 10 to 200 nm, and more preferably 10 to 150 nm. If the average particle size of the pigment dispersion exceeds 500 nm, the dispersion becomes unstable. In addition, even when the average particle size of the pigment dispersion is less than 10 nm, the stability of the pigment dispersion tends to deteriorate, and the storage stability of the ink tends to deteriorate.

  The particle size of the pigment dispersion can be measured by a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method or the like. It is also possible to obtain a particle image with a transmission electron microscope on at least 100 particles and perform statistical processing on the image using image analysis software such as Image-Pro (manufactured by Media Cybernetics). Is possible.

  Various methods 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, and a paint shaker can be used as a pigment dispersion method.

  The content of the colorant that can be dispersed or dissolved in water used in the inkjet ink according to the present invention is preferably 1 to 10% by mass with respect to the total mass of the ink.

(Water-soluble solvent)
As the solvent according to the present invention, an aqueous liquid medium is preferably used, and as the aqueous liquid medium, a mixed solvent such as water and a water-soluble organic solvent is more preferably used. Examples of water-soluble organic solvents that are preferably used include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol), polyhydric alcohols (eg, ethylene glycol, diethylene glycol, Triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), polyhydric alcohol ethers (eg, ethylene glycol monomethyl ether, ethylene Glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Nomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol Monophenyl ether, propylene glycol monophenyl ether), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetra) , Tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2 -Pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone), sulfoxides (for example, dimethyl sulfoxide) and the like.

(Surfactant)
Examples of the surfactant preferably used in the ink according to the present invention include nonionic interfaces such as polyoxyethylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, acetylene glycols, and polyoxyethylene-polyoxypropylene block copolymers. Activators such as activators, glycerin esters, sorbitan esters, polyoxyethylene fatty acid amides, and amine oxides.

  These surfactants can also be used as pigment dispersants.

  The fact that the surfactant has a charge not only reduces the reaction efficiency by acting on the polymer compound crosslinkable between the side chains according to the present invention, but also inhibits ink storage stability for the same reason. Unfavorable above.

  Such a problem is remarkable when the polymer compound used in the present invention is used, and is a problem that has not existed before.

  On the other hand, the nonionic surfactant improves the reaction efficiency and the storage stability of the ink with a specific use amount. This effect is remarkable when the polymer compound used in the present invention is used, and the preferred amount used is 0.1 to 3% by mass, more preferably 0.4 to 1.5% by mass in the ink.

(Various additives)
In the present invention, other conventionally known additives can be contained. For example, fluorescent brighteners, antifoaming agents, lubricants, preservatives, thickeners, antistatic agents, matting agents, water-soluble polyvalent metal salts, acid bases, pH adjusters such as buffers, antioxidants, surfaces These are tension modifiers, non-resistance modifiers, rust inhibitors, inorganic pigments, and the like.

(recoding media)
Examples of the recording medium used in the present invention include recording paper and various films.

<Recording sheet>
The paper, coated paper, there is a non-coated paper, the coated paper, 1 m ² per coated amount on one side 20g around the art paper, 1 m ² per coated amount on one side 10g before and after the coated paper Examples include a light-weight coated paper having a coating amount per 1 m ^{2 of about} 5 g on one side, a finely coated paper, a mat-like finished mat-coated paper, a dull-like finished dull-coated paper, and newsprint. Non-coated paper includes printing paper A using 100% chemical pulp, printing paper B using 70% or more chemical pulp, printing paper C using 40% or more and less than 70% chemical pulp, and printing using less than 40% chemical pulp. Examples thereof include paper D, gravure paper containing mechanical pulp and subjected to calendar treatment. Further details are described in detail in “Latest Paper Processing Handbook” edited by Paper Processing Handbook Editorial Committee, published by Tech Times, “Printing Engineering Handbook” edited by Japan Printing Society.

  The plain paper is 80 to 200 μm uncoated paper belonging to a part of uncoated paper, special printing paper and information paper. The plain paper used in the present invention includes, for example, high-grade printing paper, intermediate-grade printing paper, low-grade printing paper, thin-like printing paper, fine-coating printing paper, special printing paper such as fine-quality printing paper, foam paper, PPC paper, and others There are information sheets and the like. Specifically, there are the following sheets and various modified / processed sheets using these sheets, but the present invention is not particularly limited thereto. High quality paper and colored high quality paper, recycled paper, copy paper / colored paper, OCR paper, carbonless paper / colored paper, synthetic paper such as YUPO 60, 80, 110 microns, YUPO COAT 70, 90 microns, etc. Coated paper 90kg, Foam mat paper 70, 90, 110kg, Foamed PET 38 microns, Mitsuori-kun (above, Kobayashi recording paper), OK fine paper, New OK fine paper, Sunflower, Phoenix, OK Royal White, Export fine paper ( NPP, NCP, NWP, Royal White) OK Book Paper, OK Cream Book Paper, Cream Premium Paper, OK Map Paper, OK Ishikari, Cucumber, OK Foam, OKH, NIP-N (above, Shin Oji Paper), Gold Wang, Toko, export quality paper, special demand quality paper, book paper, book paper L, light cream book paper, elementary textbook Paper, continuous slip paper, high quality NIP paper, silver ring, gold yang, gold yang (W), bridge, capital, silver ring book, harp, harp cream, SK color, securities paper, opera cream, opera, KYP medical record, silvia HN, Excellent Foam, NPI Foam DX (Nippon Paper), Pearl, Kinryo, Uscream fine paper, Special Book Paper, Super Book Paper, Book Paper, Diamond Foam, Inkjet Foam (Mitsubishi Paper), Carpet V, carpet SW, white elephant, luxury publication paper, cream carpet, cream white elephant, securities / voucher paper, book paper, map paper, copy paper, HNF (above, Hokuetsu), phone book cover, Book paper, cream shirairai, cream shirairaifu, cream shirairaifu, DSK (above, Daishowa Paper), Sendai MP fine paper, Jiang, Thunderbird quality, hanging paper, colored paper base, dictionary paper, cream book, white book, cream quality paper, map paper, continuous slip paper (above, Chuetsu Pulp), OP gold cherry (Chuetsu), gold sand, reference book paper, Replacement certificate paper (white), form printing paper, KRF, white foam, color foam, (K) NIP, fine PPC, Kishu inkjet paper (above, made by Kishu Paper), Taiou, Bright Foam, Kant, Kant White, Dante , CM paper, Dante comic, Heine, paperback book paper, Heine S, New AD paper, Utrilo Excel, Excel Super A, Kant Excel, Excel Super B, Dante Excel, Heine Excel, Excel Super C, Excel Super D, AD Excel, Excel Super E, New Bright Foam, New Bright NI P (above, made by Daio Paper), Sun Ring, Moon Ring, Cloud Pass, Galaxy, Baiyun, Wyeth, Moon Ring Ace, Baiyun Ace, Cloud Pass Ace (above, Nippon Paper Industries), Taiou, Bright Foam, Bright Nip (Nagoya Pulp), Peony A, Golden Pigeon, Special Peony, White Peony A, White Peony C, Silver Pigeon, Super White Peony A, Light Cream White Peony, Special Medium Quality Paper, White Pigeon, Super Medium Quality Paper, Blue Pigeon, Red Pigeon, Gold Pigeon M Snow Vision, Snow Vision, Gold Pigeon Snow Vision, White Pigeon M, Super DX, Hamanasu O, Red Pigeon M, HK Super Printing Paper (Made by Honshu Paper), Stalinden (A・ AW), Star Elm, Star Maple, Star Laurel, Star Poplar, MOP, Star Cherry I, Cherry I Super, Cherry II Super, Star Cherry III, Star Cherry IV, Cherry III Super, Cheri -IV Super (above, made by Maruzumi Paper), SHF (above, made by Toyo Pulp), TRP (above, made by Tokai Pulp), etc.

<Various films>
As the various films, all commonly used films can be used. For example, there are a polyester film, a polyolefin film, a polyvinyl chloride film, a polyvinylidene chloride film, and the like. Resin-coated paper that is photographic printing paper, YUPO paper that is synthetic paper, and the like can also be used.

  Hereinafter, although an example is given and explained, the present invention is not limited to these examples. In the examples, “%” represents mass% unless otherwise specified.

Example 1
<Synthesis of Polymer Compound 1>
56 g of glycidyl methacrylate, 48 g of p-hydroxybenzaldehyde, 2 g of pyridine, and 1 g of N-nitroso-phenylhydroxyamine ammonium salt were put in a reaction vessel and stirred in a hot water bath at 80 ° C. for 8 hours.

  Next, 20 g of a polyvinyl acetate saponified product having a polymerization degree of 300 and a saponification rate of 88% and 25 g of polyvinyl acetate saponified product having a polymerization degree of 500 and a saponification rate of 99% were dispersed in 225 g of ion-exchanged water. 0.5 g and p- (3-methacryloxy-2-hydroxypropyloxy) benzaldehyde obtained by the above reaction were added so that the modification rate was 3 mol% with respect to the saponified polyvinyl acetate, and the mixture was stirred at 90 ° C. for 6 hours. . After cooling the obtained solution to room temperature, 30 g of basic ion exchange resin was added and stirred for 1 hour. Thereafter, the ion exchange resin is filtered off, and Irgacure 2959 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator is mixed at a ratio of 2.0 g with respect to 100 g of a 15% aqueous solution. To obtain a 10% aqueous solution of polymer compound 1.

[Preparation of inkjet ink]
(Preparation of pigment dispersion)
Magenta and black color pigment dispersions were prepared as follows.

<Magenta pigment dispersion>
A magenta self-dispersion cabo-jet 260 manufactured by Cabot was diluted with ion-exchanged water to prepare a magenta pigment dispersion having a magenta pigment content of 10%. The average particle diameter of the magenta pigment particles contained in the obtained magenta pigment dispersion was 180 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

<Black pigment dispersion>
A carbon black self-dispersion cabo-jet 300 manufactured by Cabot was diluted with ion-exchanged water to prepare a black pigment dispersion having a carbon black content of 10%. The average particle diameter of the carbon black particles contained in the obtained black pigment dispersion was 111 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

(Preparation of ink)
Magenta ink 1 and black ink 1 were prepared as follows.

<Preparation of magenta ink 1>
Magenta pigment dispersion 5 parts Polymer compound 1 25 parts 2-Pyrrolidone 16 parts Ethylene glycol 24 parts Diethylene glycol monobutyl ether 2 parts Orphine e1010 (manufactured by Nissin Chemical Co., Ltd.) 0.6 parts As a result, magenta ink 1 was obtained.

<Preparation of black ink 1>
In the preparation of magenta ink 1, the magenta pigment dispersion was replaced with a black pigment dispersion to obtain black ink 1.

(Preparation of ink set 1)
An ink set 1 composed of magenta ink 1 and black ink 1 was prepared.

[Formation and evaluation of inkjet images]
(Inkjet image formation)
It has a piezo head having a nozzle diameter of 25 μm, a driving frequency of 12 kHz, a nozzle number of 128, a nozzle density of 150 dpi (hereinafter, dpi represents the number of dots per inch (2.54 cm)), and a maximum recording density of 1440 × 720 dpi. An on-demand type ink jet printer was filled with the ink set 1 prepared above, and after forming an image on the recording medium shown in Table 1 in a curing atmosphere in which the oxygen concentration was reduced by replacing the inert gas shown in Table 1, Using a low-pressure mercury lamp manufactured by Harrison Toshiba Lighting Co., Ltd., GLQ60OUS / T1, irradiates ultraviolet rays 0.2 seconds after ink landing under the conditions of an illuminance of 40 mW / cm ² at a main emission wavelength of 254 nm and an integrated irradiation energy of 100 mJ / cm ² did.

(Evaluation of inkjet image)
<Fine line quality>
A black thin line having a width of 250 μm and a length of 5 cm was printed and visually observed, and feathering was evaluated according to the following criteria.

◎: Thin lines are reproduced without blurring due to bleeding ○: Lines are not thickened due to bleeding, but less than 5 spots, ink bleeding in the direction orthogonal to the straight line is observed Δ: Lines due to bleeding The ink bleed in the orthogonal direction is observed with a straight line of less than 10 points, but the line is slightly thickened due to the bleed, and the bleed in the direction orthogonal to the straight line is observed at 10 or more points. The line is severely thickened, and more than 20 spots are observed in the direction orthogonal to the straight line. Of these, x and xx are levels that are problematic as products.

<Bleed>
A black fine line of 250 μm was printed on a magenta solid and evaluated according to the following.

◎: The boundary between the fine line and the solid is clear. ○: The boundary is slightly blurred, but there is no problem in practical use. △: The boundary is blurred, but practically acceptable. X: Obvious blurring is observed at the boundary, the line width is about 1.5 times, and this is a quality that is a practical problem. XX: The boundary between the fine line and the solid part is unclear. Quality and extremely low bleed resistance <Recording medium damage>
The damage of the recording medium after irradiation with the active energy ray was evaluated. ◎: No change ○: There is a slight deformation of the recording medium, but there is no practical problem. Δ: There is a slight deformation of the recording medium, but there is no practical problem.

×: The recording medium is deformed or partially burned and melted, etc., and is not allowed. Xx: The recording medium is deformed and melted completely different from the original, and is not allowed at all.

  The evaluation results are shown in Table 2.

  From the table, images created by the inkjet recording method of the present invention can be recorded on various recording media even with a relatively low illuminance active energy ray, preventing feathering, bleeding, etc. You can see that there is little damage. The image of the comparative example has a high oxygen concentration in the curing atmosphere at the time of active energy ray irradiation, and the above effect cannot be obtained.

Example 2
In Example 1, the radiation source and irradiation conditions were changed as described below, and the other images were formed and evaluated in the same manner.

Irradiation was performed 0.2 seconds after landing of the ink using a cold cathode tube manufactured by Highbeck under the irradiation conditions of an illuminance of 20 mW / cm ² at an emission main wavelength of 365 nm and an integrated irradiation energy of 50 mJ / cm ² .

  Table 3 shows the evaluation results.

  From the table, images created by the inkjet recording method of the present invention can be recorded on various recording media even with a relatively low illuminance active energy ray, preventing feathering, bleeding, etc. You can see that there is little damage. The image of the comparative example has a high oxygen concentration in the curing atmosphere at the time of active energy ray irradiation, and the above effect cannot be obtained.

Example 3
In Example 1, the radiation source and irradiation conditions were changed as described below, and the other images were formed and evaluated in the same manner.

Using a special order black light manufactured by Nippon Electric Co., Ltd., irradiation was performed 2 seconds after ink landing under irradiation conditions of an illuminance of 15 mW / cm ² at an emission main wavelength of 365 nm and an integrated irradiation energy of 70 mJ / cm ² .

  Table 4 shows the evaluation results.

  From the table, images created by the inkjet recording method of the present invention can be recorded on various recording media even with a relatively low illuminance active energy ray, preventing feathering, bleeding, etc. You can see that there is little damage. The image of the comparative example has a high oxygen concentration in the curing atmosphere at the time of active energy ray irradiation, and the above effect cannot be obtained.

Example 4
In Example 1, the radiation source and irradiation conditions were changed as described below, and the other images were formed and evaluated in the same manner.

Irradiation was performed 2 seconds after the landing of the ink using an I-Graphics high-pressure mercury lamp under irradiation conditions of an illuminance of 100 mW / cm ² at an emission main wavelength of 365 nm and an integrated irradiation energy of 200 mJ / cm ² .

  The evaluation results are shown in Table 5.

  From the table, it can be seen that the maximum illuminance of the used radiation source is high and the damage to the recording medium is large in this example.

Claims (4)

Select using an ink-jet ink containing at least a colorant, water, and a polymer compound that has a plurality of side chains in the hydrophilic main chain and that can be crosslinked between the side chains by irradiating active energy rays. In an inkjet recording method using a recording head having at least one nozzle capable of controlling the ejection of ink droplets, an active energy ray having a maximum illuminance at 200 to 400 nm of 0.1 to 50 mW / cm ² is used, and the ink An ink jet recording method comprising replacing a curing atmosphere after landing with an inert gas. 2. The ink jet recording method according to claim 1, wherein the active energy ray is irradiated within 1 second after ink landing. The polymer compound contained in the inkjet ink has a hydrophilic main chain of saponified polyvinyl acetate, a polymerization degree of 200 to 1000, and a saponification degree of 70 to 99%. Or the inkjet recording method of 2. The polymer compound contained in the inkjet ink has a side chain modification rate of 0.6 to 4 mol% with respect to the hydrophilic main chain. Inkjet recording method.