JP2007076225A - Inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method which is suitable for various kinds of recording mediums, enhances the wetting property to the recording mediums, can obtain an image of a high density, is excellent in beading resistance and color bleeding resistance, and has a high printing quality. <P>SOLUTION: The inkjet recording method is as follows. An ink for inkjet recording comprises at least a coloring agent, water and a high molecular compound having a plurality of side chains on a hydrophilic principal chain, and capable of being crosslinked by the irradiation of an active energy ray. The ink for inkjet recording is discharged on the recording medium heated in advance. After the ink for inkjet recording is irradiated with the active energy ray, the ink for inkjet recording is dried. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet recording method using an inkjet ink containing a polymer compound that can be cross-linked by irradiation with active energy rays.

  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-jet ink suitable for each purpose is used.

  In particular, in recent years, the recording speed has been greatly improved, and an ink jet printer having performance capable of withstanding light printing applications has also been developed. However, in order to bring out the performance of an ink jet printer, an ink jet dedicated paper having an ink absorbing ability is required.

  When recording on coated paper, art paper, or plastic film that does not absorb ink at all, different color ink liquids mix on the recording medium and cause color turbidity. In the ink jet recording method, it has been a problem in providing diversity to recording media.

  In response to the above problems, a hot melt ink composition made of a solid wax or the like at room temperature is used, liquefied by heating or the like, sprayed with some energy applied, cooled and solidified while adhering to the recording medium, and recorded A hot melt type ink jet recording method for forming dots has been proposed (see Patent Documents 1 and 2). Since this hot melt ink is solid at room temperature, it does not get dirty during handling, and since there is substantially no ink evaporation during melting, nozzle clogging does not occur. Furthermore, it is said to be an ink composition that provides good print quality regardless of paper quality because it solidifies immediately after adhesion and has little color bleeding. However, an image recorded by such a method has problems such as deterioration of quality due to the rising of the dots and lack of scratching performance because the ink dots are in the form of soft wax.

  On the other hand, an inkjet ink that is cured by irradiation with active energy rays has been disclosed (see Patent Document 3). In addition, a so-called non-aqueous ink containing a pigment as a coloring material, a triacrylate or higher polyacrylate as a polymerizable material, and having a ketone or alcohol as a main solvent has been proposed (see Patent Document 4). . Further, an ink using a water-based ultraviolet polymerization monomer has been proposed (see Patent Document 5).

  In these methods, since the ink itself is cured by the curing component, recording is possible even on a non-absorbent recording medium, but since a large amount of the curing component other than the coloring material is contained and they do not volatilize. However, the recorded image surface is raised by ink dots, and there is a problem in that the image quality, particularly glossiness, is unnatural. Furthermore, with the conventionally known curing components, there are safety concerns, and even if safety is cleared, there is a limit to the range of compounds that are compatible with it, and it is possible to design freely both in terms of compounds and physical properties. There was a problem that it was not possible.

The inventors of the present invention can solve the above problems by including in the ink a polymer compound having a plurality of side chains in the hydrophilic main chain and capable of crosslinking between the side chains by irradiation with active energy rays. However, as a result of further studies on technical improvements, it has been found that, depending on the recording medium, the ink wettability is poor and an inkjet recording image may not be obtained satisfactorily. In particular, a plastic film that has not been surface-treated has poor wettability, and a satisfactory image cannot be obtained at a high density.
US Pat. No. 4,391,369 U.S. Pat. No. 4,484,948 U.S. Pat. No. 4,228,438 Japanese Patent Publication No. 5-64667 JP-A-7-224241

  The present invention has been made in view of the above problems, and has an object of having printability on various types of recording media, improving wettability to the recording media, and obtaining high-density images. An object of the present invention is to provide an ink jet recording method having excellent beading resistance and color bleed resistance and high print quality.

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

  (1) For an inkjet comprising 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 irradiation with active energy rays An ink jet recording method comprising ejecting ink onto a preheated recording medium and irradiating the ink jet ink with active energy rays.

  (2) The inkjet recording method described in (1) above, wherein the recording medium is a plastic film, resin-coated paper, or synthetic paper.

  (3) The ink jet recording method as described in (2) above, wherein the plastic film is a polyvinyl chloride film.

  (4) The inkjet recording method according to any one of (1) to (3), wherein the temperature of the preheated recording medium is 40 ° C. or higher and 100 ° C. or lower.

  (5) The content of the polymer compound in the inkjet ink is 0.8% by mass or more and 5.0% by mass or less, and any one of (1) to (4) above The ink jet recording method described in 1.

  (6) The hydrophilic main chain is a saponified product of polyvinyl acetate, the saponification degree is 77% or more and 99% or less, and the polymerization degree is 200 or more and 4000 or less. The inkjet recording method according to any one of (5) to (5).

  (7) The inkjet recording method described in any one of (1) to (6) above, which contains a water-soluble photopolymerization initiator.

  (8) Any one of (1) to (7), wherein the inkjet ink is ejected onto the preheated recording medium, irradiated with active energy rays, and then dried in a drying step. The ink jet recording method described in 1.

  The present invention has printability on various types of recording media, improves wettability to the recording media, provides a high-density image, has excellent beading resistance, color bleed resistance, and high print quality. An ink jet recording method could be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the present inventor has a plurality of side chains in at least a colorant, water, and a hydrophilic main chain, and irradiates active energy rays between the side chains. Various types of ink-jet recording methods comprising discharging an ink-jet ink containing a crosslinkable polymer compound onto a preheated recording medium and irradiating the ink-jet ink with active energy rays. The ink-jet recording method has high print quality, has good printability on recording media, has improved wettability to recording media, and can obtain high-density images, has excellent beading resistance and color bleed resistance. It is up to the headline and the present invention.

  Details of the present invention will be described below.

<Inkjet ink>
First, the details of the inkjet ink (hereinafter also simply referred to as ink) used in the inkjet recording method of the present invention will be described.

[Active energy ray crosslinkable polymer compound]
The ink-jet ink of the present invention is characterized by containing a polymer compound having a plurality of side chains in the hydrophilic main chain and capable of crosslinking between the side chains by irradiation with active energy rays.

  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.

  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 saponification is preferably 77% or more and 99% or less, and the degree of polymerization thereof. Is preferably 200 or more and 4000 or less, and more preferably 200 or more and 2000 or less from the viewpoint of handling. The modification rate of the side chain with respect to the main chain is preferably 0.3 mol% or more and 4 mol% or less, and more preferably 0.8 mol% or more and 4 mol% or less from the viewpoint of reactivity. When it is less than 0.3 mol%, the crosslinkability is insufficient, and the effect of the present invention is reduced.

  As the photodimerization-type modifying group, those in which a diazo group, a cinnamoyl group, a stilbazonium group, a stilquinolium group or the like is introduced are preferable. For example, a photosensitive resin described in JP-A-60-129742 (Composition).

  The photosensitive resin described in JP-A-60-129742 is a compound represented by the following general formula (1) in which a stilbazonium group is introduced into a polyvinyl alcohol structure.

In the formula, R ₁ represents an alkyl group having 1 to 4 carbon atoms, and A ⁻ represents a counter anion.

  The photosensitive resin described in JP-A-56-67309 includes a 2-azido-5-nitrophenylcarbonyloxyethylene structure represented by the following general formula (2) in the polyvinyl alcohol structure, or the following general formula. This is a resin composition represented by (3) and having a 4-azido-3-nitrophenylcarbonyloxyethylene structure.

  Further, a modifying group represented by the following general formula (4) 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 represented by the following general formula (5) shown in JP-A Nos. 2000-181062 and 2004-189841 is preferable from the viewpoint of reactivity.

In the formula, R ₂ represents a methyl group or a hydrogen atom, n represents 1 or 2, X represents — (CH ₂ ) _m —COO— or —O—, and Y represents an aromatic ring or a single bond. And m represents an integer from 0 to 6.

  Moreover, it is also preferable to use the photopolymerization type | mold modified group represented by following General formula (6) described in Unexamined-Japanese-Patent No. 2004-161942 for a conventionally well-known water-soluble resin.

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

  In the ink according to the present invention, the active energy ray-crosslinking polymer compound according to the present invention is preferably contained in an amount of 0.8% by mass to 5.0% by mass with respect to the total mass of the ink. The presence of 0.8% by mass or more improves 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 polymer compound according to the present invention, the main chain having a certain degree of polymerization is cross-linked through a cross-linking bond between the side chains, and therefore through a general chain reaction. The effect of increasing the molecular weight per photon is remarkably large for the active energy ray-curable resin that polymerizes. On the other hand, in the conventionally known active energy ray curable resins, the number of crosslinking points cannot be controlled, so that the physical properties of the cured film cannot be controlled, and the film tends to be hard and brittle.

  In the polymer compound according to 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, the conventionally known active energy ray-curable ink is used in the present invention, because almost all of the ink other than the colorant is curable, so that the dots after curing rise and the image quality typified by gloss is inferior. The required amount of the resin is small, 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 ink according to 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.

  Although there is no restriction | limiting in particular about the photoinitiator and photosensitizer which are applied, A water-soluble photoinitiator 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, from the viewpoint of compatibility with the resin, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (n = 1, HMPK) represented by the following general formula (7), The ethylene oxide adduct (n = 2 to 5) is more preferable.

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

  Other photopolymerization initiators include benzophenones such as benzophenone, hydroxybenzophenone, bis-N, N-dimethylaminobenzophenone, bis-N, N-diethylaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone. Thioxanthones such as thioxatone, 2,4-diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone, and isopropoxychlorothioxanthone. Anthraquinones such as ethyl anthraquinone, benzanthraquinone, aminoanthraquinone and chloroanthraquinone. Acetophenones. Benzoin ethers such as benzoin methyl ether. 2,4,6-trihalomethyltriazines, 1-hydroxycyclohexyl phenyl ketone, 2- (o-chlorophenyl) -4,5-diphenylimidazole 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- (2,4-dimethoxyphenyl) -4,5 -2,4,5-triarylimidazole dimer of diphenylimidazole dimer, benzyldimethyl ketal, 2-benzyl-2-dimethyl Amino-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, phenanthrenequinone, 9,10-phenanthrenequinone, Benzoins such as methylbenzoin and ethylbenzoin, 9-phenylacridine, acridine derivatives such as 1,7-bis (9,9′-acridinyl) heptane, bisacylphosphine oxide, and mixtures thereof are preferably used. 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 and their irradiation methods]
The ink jet recording method of the present invention includes an ink jet recording medium containing a polymer compound having a plurality of side chains in the hydrophilic main chain and capable of crosslinking between side chains by irradiating active energy rays. After recording an image by ejecting recording ink, the active energy ray is irradiated onto the recorded image to cure the polymer compound, and then dried to form an image.

(Active energy irradiation method)
The ink according to the present invention has a water-soluble polymer having a plurality of side chains in the hydrophilic main chain and capable of crosslinking between the side chains by irradiating active energy rays. After spraying, curing is performed by irradiation with active energy rays.

  Hereinafter, a method for irradiating an inkjet ink with an active energy ray will be described.

<Active energy rays>
Examples of the active energy rays in the present invention include electron beams, ultraviolet rays, α rays, β rays, γ rays, X-rays, etc., but they are dangerous to the human body and easy to handle. Electron beams and ultraviolet rays that are widely used are preferred. In the present invention, ultraviolet rays are particularly preferable.

  When using an electron beam, the amount of the electron beam to be irradiated is preferably in the range of 0.1 to 30 Mrad. If it is less than 0.1 Mrad, a sufficient irradiation effect cannot be obtained, and if it exceeds 30 Mrad, the support or the like may be deteriorated.

  When ultraviolet rays are used, the light source is, for example, 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 having an operating pressure of several hundred Pa to 1 MPa. A conventionally well-known thing, such as LED, is used.

<Light irradiation conditions after image recording>
As the irradiation condition of the active energy ray, it is preferable that the active energy ray is irradiated for 0.001 to 1.0 seconds after the ink has landed on the recording medium, and more preferably 0.001 to 0.00. 5 seconds. In order to form a high-definition image, it is particularly important that the irradiation timing is as early as possible.

<Irradiation method of active energy rays>
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 ink jet recording 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. Furthermore, there is a method in which 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 irradiating a recording unit with ultraviolet rays by applying a collimated light source to a mirror surface provided on the side surface of the head unit is disclosed. . Any of these irradiation methods can be used in the image recording method of 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 within 0.001 to 2.0 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.

[Color material]
As the color material used in the ink jet ink of the present invention, a dye or a pigment can be used.

[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.

  Specific examples of dyes applicable to the ink jet ink of the present invention are listed below, but the present invention is not limited to these exemplified dyes.

(Water-soluble dye)
Examples of water-soluble dyes that can be used in the present invention include azo dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, phthalocyanine dyes, triphenylmethane dyes, and diphenylmethane dyes.

<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.

  Furthermore, examples of the dye include a compound represented by the following general formula (8) or a compound represented by the general formula (9).

In the general formula (8), R ₁ represents a hydrogen atom or a substitutable substituent, and is preferably a hydrogen atom or a phenylcarbonyl group. R ₂ may be different and represents a hydrogen atom or a substitutable substituent, and is preferably a hydrogen atom. R ₃ represents a hydrogen atom or a substitutable substituent, and is preferably a hydrogen atom or an alkyl group. R ₄ represents a hydrogen atom or a substitutable substituent, preferably a hydrogen atom or an aryloxy group. R ₅ may be different and represents a hydrogen atom or a substitutable substituent, and is preferably a sulfonic acid group. n represents an integer of 1 to 4, and m represents an integer of 1 to 5.

In the general formula (9), X represents a phenyl group or a naphthyl group, may be substituted with a substitutable substituent, and is preferably substituted with a sulfonic acid group or a carboxyl group. Y represents hydrogen ion, sodium ion, potassium ion, lithium ion, ammonium ion or alkylammonium ion. R ₆ may be different and represents a hydrogen atom or a substituent that can be substituted on the naphthalene ring. q represents 1 or 2. p represents an integer of 1 to 4. However, q + p = 5. Z represents a substitutable substituent, and represents a carbonyl group, a sulfonyl group or a group represented by the following general formula (10), and particularly preferably a group represented by the following general formula (10).

In the general formula (10), W ₁ and W ₂ each independently represent a halogen atom, amino group, hydroxyl group, alkylamino group or arylamino group, preferably a halogen atom, hydroxyl group or alkylamino group.

(Disperse dye)
As the disperse dye, various disperse dyes such as azo disperse dyes, quinone disperse dyes, anthraquinone disperse dyes, quinophthalone disperse dyes can be used, and specific compounds thereof are listed below.

<C. I. Disperse Yellow>
3, 4, 5, 7, 9, 13, 23, 24, 30, 33, 34, 42, 44, 49, 50, 51, 54, 56, 58, 60, 63, 64, 66, 68, 71, 74, 76, 79, 82, 83, 85, 86, 88, 90, 91, 93, 98, 99, 100, 104, 108, 114, 116, 118, 119, 122, 124, 126, 135, 140, 141, 149, 160, 162, 163, 164, 165, 179, 180, 182, 183, 184, 186, 192, 198, 199, 202, 204, 210, 211, 215, 216, 218, 224, 227, 231, 232,
<C. I. Disperse Orange>
1, 3, 5, 7, 11, 13, 17, 20, 21, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 47, 48, 49, 50, 53, 54, 55, 56, 57, 58, 59, 61, 66, 71, 73, 76, 78, 80, 89, 90, 91, 93, 96, 97, 119, 127, 130, 139, 142,
<C. I. Disperse Red>
1, 4, 5, 7, 11, 12, 13, 15, 17, 27, 43, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 65, 72, 73, 74, 75, 76, 78, 81, 82, 86, 88, 90, 91, 92, 93, 96, 103, 105, 106, 107, 108, 110, 111, 113, 117, 118, 121, 122, 126, 127, 128, 131, 132, 134, 135, 137, 143, 145, 146, 151, 152, 153, 154, 157, 159, 164, 167, 169, 177, 179, 181, 183, 184, 185, 188, 189, 190, 191, 192, 200, 201, 202, 203, 205, 206, 207, 210, 221, 224, 225, 227, 229, 23 , 240,257,258,277,278,279,281,288,298,302,303,310,311,312,320,324,328,
<C. I. Disperse Violet>
1, 4, 8, 23, 26, 27, 28, 31, 33, 35, 36, 38, 40, 43, 46, 48, 50, 51, 52, 56, 57, 59, 61, 63, 69, 77,
<C. I. Disperse Green>
9,
<C. I. Disperse Brown>
1, 2, 4, 9, 13, 19,
<C. I. Disperse Blue>
3, 7, 9, 14, 16, 19, 20, 26, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 71, 72, 73, 75, 79, 81, 82, 83, 87, 91, 93, 94, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128, 130, 139, 141, 142, 143, 146, 148, 149, 153, 154, 158, 165, 167, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259, 267, 268, 270, 284, 285, 287, 288, 291, 293, 295, 297, 301, 315, 3 0,333,
<C. I. Disperse Black>
1, 3, 10, 24
Etc.

  These dyes listed above are described in “Dyeing Note 21st Edition” (published by Color Dyeing Co., Ltd.) and the like.

[Pigment]
Examples of the pigment that can be used in the present invention include conventionally known organic or inorganic pigments. For example, azo pigments such as azo lake pigments, 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. Polycyclic pigments, dye lakes such as basic dye type lakes and acid dye type lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, daylight fluorescent pigments, and inorganic pigments such as carbon black .

  Hereinafter, specific examples of the pigment applicable to the ink-jet ink of the present invention will be listed, but the present invention is not limited only to these exemplified pigments.

  Examples of magenta or red pigments 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 orange or yellow pigments 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. Pigment yellow 138, pigment yellow 180, and the like.

  Examples of green or cyan pigments 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 15: 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Examples of the pigment for black include carbon black.

(Self-dispersing pigment)
In the inkjet ink of the present invention, a self-dispersing pigment can also be used as the pigment. The self-dispersing pigment refers to a pigment that can be dispersed without a dispersant, and particularly preferably pigment particles having a polar group on the surface.

  Pigment particles having a polar group on the surface are pigments directly modified with a polar group on the surface of the pigment particle, or organic substances having an organic pigment mother nucleus and having a polar group bonded directly or via a joint , Referred to as pigment derivative).

  Examples of the 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 sulfonic acid group.

(Method for producing pigment dispersion)
As a method for dispersing the pigment, for example, various dispersing machines 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. It is also preferable to use a centrifugal separator or a filter for the purpose of removing the coarse particles of the pigment dispersion.

(Surfactant applicable to pigment dispersion)
In preparing the pigment dispersion, if necessary, a surfactant or a polymer dispersant may be contained as a pigment dispersant. The type of surfactant and polymer dispersant is not particularly limited. Examples of the surfactant include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, and naphthalene sulfonates. , Alkyl phosphate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide and the like As the polymer dispersant, a water-soluble resin is preferably used from the viewpoint of ejection stability. For example, styrene, a styrene derivative, a vinyl naphthalene derivative, acrylic acid, an acrylic acid derivative, maleic acid, maleic acid. acid Examples include conductors, itaconic acid, itaconic acid derivatives, fumaric acid, block copolymers composed of two or more monomers selected from fumaric acid derivatives, random copolymers, and salts thereof. Styrene-acrylic acid-alkyl acrylate ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-alkyl acrylate copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid-acrylic acid Examples thereof include an alkyl ester copolymer, a styrene-methacrylic acid copolymer, a styrene-maleic acid half ester copolymer, a vinyl naphthalene-acrylic acid copolymer, and a vinyl naphthalene-maleic acid copolymer.
The amount of each polymer dispersant added to the total amount of the ink is preferably 0.1 to 10% by mass, more preferably 0.3 to 5% by mass. Two or more of these polymer dispersants can be used in combination.

(Particle size of pigment particles)
The average particle diameter of the pigment particles used in the inkjet ink of the present invention is preferably 500 nm or less, more preferably 200 nm or less, preferably 10 nm or more and 200 nm or less, and more preferably 10 nm or more and 150 nm or less. 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 determined 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.

(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]
Surfactants preferably used in the ink according to the present invention include alkyl sulfates, alkyl ester sulfates, dialkyl sulfosuccinates, alkyl naphthalene sulfonates, alkyl phosphates, polyoxyalkylene alkyl ether phosphates, Anionic surfactants such as fatty acid salts, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyalkylene alkyl phenyl ethers, acetylene glycols, polyoxyethylene-polyoxypropylene block copolymers, glycerin esters, Activators such as sorbitan esters, polyoxyethylene fatty acid amides, amine oxides, and cationic surfactants such as alkylamine salts and quaternary ammonium salts.

  These surfactants can also be used as pigment dispersants, and anionic and nonionic surfactants can be particularly preferably used.

[Various additives]
The ink according to the present invention can contain other conventionally known additives. For example, optical brighteners, antifoaming agents, lubricants, preservatives, thickeners, antistatic agents, matting agents, water-soluble polyvalent metal salts, acid bases, pH adjusters such as buffer solutions, antioxidants, surface tension It is a regulator, a non-resistance modifier, a rust inhibitor, an inorganic pigment, and the like.

"recoding media"
As a recording medium applicable to the ink jet recording method of the present invention, various media can be used, and examples thereof include paper, plastic, metal, cloth, and rubber. Of these, paper and plastic films are preferred as ink jet recording media generally used for forming images. The effects of the present invention can be exhibited without any difficulty. In particular, in sign applications such as indoor and outdoor signboards, application to plastic films, resin-coated paper, and synthetic paper is preferable from the viewpoint of water resistance.

  As the paper, plain paper, non-coated paper, coated paper and the like can be used. In addition, any commonly used plastic film can be used. For example, there are a polyester film, a polyolefin film, a polyvinyl chloride film, a polyvinylidene chloride film, etc., and a polyvinyl chloride film is particularly preferable. The resin-coated paper is a paper base having both sides coated with a resin, and a well-known resin-coated paper is a photographic resin-coated paper having both sides coated with polyethylene resin. Synthetic paper includes YUPO paper manufactured by YUPO Corporation, and Toyobo's Crisper.

  For outdoor sign use, it is particularly preferable to use a polyvinyl chloride film. Polyvinyl chloride has a high flexibility of the base material and can be easily attached to a bent surface.

  Some recording media have a problem of poor wettability with water-based ink. In particular, wettability of water-based ink is poor with respect to plastic film, resin-coated paper, and synthetic paper. In the present invention, the surface condition of the recording medium is changed by heating the recording medium in advance, and the wettability with respect to the water-based ink is improved.

  The effect of improving the wettability to a recording medium by heating according to the present invention is significant for plastic films, resin-coated paper, and synthetic paper. In particular, the effect of improving wettability with a vinyl chloride film is great.

<Preliminary heating of recording medium>
The inkjet recording method of the present invention is characterized in that the recording medium is heated before printing the inkjet ink. By heating, wettability with water-based ink is improved, and good printability is obtained. The heating is preferably performed so that the temperature of the recording medium is 40 ° C. or higher and 100 ° C. or lower. When the temperature is lower than 40 ° C., improvement in wettability with water-based ink is insufficient, and when the temperature exceeds 100 ° C., the recording medium may be deformed by heat. A particularly preferable heating temperature of the recording medium is 40 ° C. or higher and 70 ° C. or lower. The recording medium is heated before the inkjet ink is printed, but may be continuously applied after printing.

  The method for heating the recording medium is not particularly limited, and examples thereof include radiant heat heating such as a heating fan, a surface heater, a heating roller, a heating belt, a halogen heater, and a far-infrared heater. be able to.

  According to the ink jet recording method of the present invention, the wettability to the recording medium is improved by heating, and the formed ink dots are spread and spread on the recording medium. However, with conventional water-based inks, ink dots that have once spread and spread may shrink during drying, and as a result, the dots become smaller and a sufficient image density may not be obtained. In the ink jet recording method of the present invention, the active energy ray cross-linking resin rapidly increases the ink viscosity after cross-linking, and as a result, suppresses dot shrinkage at the time of drying, and as a result, the dot diameter does not shrink. A density image is obtained.

  Hereinafter, a method for heating a recording medium applicable to the ink jet recording method of the present invention will be described with reference to the drawings. However, the present invention is not limited to these exemplified methods.

  FIG. 1 is a schematic diagram illustrating an example of a method for heating a recording medium using a drying fan as preheating means.

  In FIG. 1, an image printing unit 1 includes an image recording head 2 that ejects ink for inkjet and an irradiation light source 3 that irradiates active energy rays to ink containing a polymer compound on a carriage 4. A heating fan 8 is installed on the downstream side of the image printing unit, and the recording medium P conveyed thereby is heated in the range of 40 to 100 ° C. Reference numeral 7 denotes a conveyance roller for conveying the recording medium P from right to left in the figure, and 6 is a guide roller for holding the recording medium P to be conveyed.

  A heating fan 8 shown in FIG. 1 is provided with heat generating means such as a heating wire, a heater, and the like, and air is introduced into the recording medium to blow it onto the recording medium as hot air to heat the recording medium to a predetermined temperature. .

  FIG. 2 is a schematic view showing an example of a method for heating a recording medium using a surface heater as preheating means.

  In FIG. 2, the image printing unit 1 has a configuration similar to that in FIG. 1, and the recording medium P is heated by installing a surface heater 9 on the back side of the recording medium P downstream thereof.

  The surface heater 9 is a heating member in which a heating element made of nichrome wire is laid flat and covered with an aluminum plate or the like. The surface heater 9 takes advantage of the characteristics of the aluminum plate and is in contact with the recording medium as a curved surface. May be better.

  FIG. 3 is a schematic view showing an example of a method for heating a recording medium using radiant heat heating means as preheating means.

  In FIG. 3, the image printing unit 1 has the same configuration as that in FIG. 1, and a radiant heat heating means including a heat source 10 and a reflector 11 is arranged on the upper portion of the recording medium P in the downstream portion thereof. The recording medium is heated to a predetermined temperature by the generated radiant heat.

  As the heat source, for example, a halogen lamp, a far infrared heater or the like can be used.

  In FIG. 3, the heat source 10 and the reflection plate 11 are arranged on the top of the recording medium P. However, heating may be performed by arranging the heat source 10 and the reflection plate 11 on the back of the recording medium P.

  FIG. 4 is a schematic diagram showing an example of a method for heating a recording medium using a heating roller as preheating means.

  In FIG. 4, the image printing unit 1 has the same configuration as that in FIG. 1, and a heating roller is disposed downstream thereof to heat the recording medium P to a predetermined temperature.

  4A, when the recording medium P is conveyed linearly, a heating roller 14 provided with heating means 13 is disposed inside the recording medium on the back surface side, and pressure is applied to the front surface side of the recording medium. A roller 12 is provided for effective heating.

  FIG. 4B shows a heating method in the case where the recording medium conveyance path has a bent portion. At this time, the recording medium P is held and heated only by the heating roller 14.

  As the heating roller 14, the heating means 13 is included in a hollow cored bar. The pipe-shaped metal core is mainly composed of metal, and examples of the metal constituting the metal core include metals such as iron, aluminum, and copper, and alloys thereof.

  Further, as the heating means 13 held inside, a heating element such as a halogen lamp, an electromagnetic induction coil, or a nichrome wire can be used. Further, the roller pair of the heating roller and the pressure roller may be one set or may be configured by arranging a plurality of sets in parallel.

  FIG. 5 is a schematic view showing an example of a method for heating a recording medium using a heating belt as preheating means.

  In FIG. 5, the image printing unit 1 has the same configuration as that in FIG. 1, and a heating belt B is disposed downstream thereof to heat the recording medium P to a predetermined temperature. The heating method using an endless belt can increase the contact time with the recording medium, and can perform effective heating.

  The heating belt B heats the recording medium P via the heated endless belt 16 while holding and transporting the endless belt 16 by the heating roller 14 and the support roller 15 similar to those in FIG. 4.

  The material of the endless belt 16 is not particularly limited, but is preferably made of a material having flexibility and high thermal conductivity, such as a metal plate or plastic. As an endless belt, for example, a metal belt using a nickel electroformed belt as a base, or a heat-resistant resin belt using polyimide, polyamide, or the like is coated on the outside (outer peripheral surface) with insulating silicon rubber. Examples of the release layer include those having a surface subjected to fluororesin (PFA) coating.

  FIG. 6 is a schematic diagram illustrating an example of a method for heating a recording medium in which a surface heater is disposed in the vicinity of the printing unit as preheating means.

  6 is a method of heating the recording medium P by installing a surface heater 9 on the back side of the recording medium P in the vicinity of the image printing unit 1 as compared to FIG.

  FIG. 7 is a schematic diagram showing an example of a method for heating a recording medium using a heating roller and a surface heater in combination as preheating means.

  In FIG. 7, the surface heater 9 is further installed on the back side of the recording medium P in the vicinity of the image printing unit 1 to heat the recording medium P in the method using the heating roller as the preheating means shown in FIG. Is the method.

  FIG. 8 is a schematic view showing an example of a method for heating a recording medium in which radiant heat heating means is arranged in the vicinity of the printing unit as preheating means.

  FIG. 8 is a method for heating the recording medium P with respect to FIG. 3 by installing a radiant heat heating means comprising a heat source 10 and a reflecting plate 11 on the back side of the recording medium P in the vicinity of the image printing unit 1.

  FIG. 9 is a schematic diagram illustrating an example of a method for heating a recording medium in which a heating belt is disposed in the vicinity of the printing unit as preheating means.

  9A is a system composed of a heating roller 14, a support roller 15 and an endless belt 16 similar to FIG. 5. In FIG. 9B, the endless belt 16 is held by a pair of support rollers 15. FIG. In this method, a surface heater 9 is arranged on the inner surface side to heat the endless belt.

<< Drying process >>
In the ink jet recording method of the present invention, it is preferable that the recording medium is heated in advance by each of the preheating means described above, then ink jet ink is ejected, irradiated with active energy rays, and then dried using a drying step. .

  The drying means that can be applied to the drying step according to the present invention is not particularly limited, but the same heating means as that applied by the preliminary heating means can be appropriately selected and used.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<< Synthesis of polymer compounds >>
[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 each put in a reaction vessel and stirred in a hot water bath at 80 ° C. for 8 hours.

  Next, 45 g of a polyvinyl acetate saponified product having a polymerization degree of 300 and a saponification degree of 88% was dispersed in 225 g of ion-exchanged water, and then 4.5 g of phosphoric acid was added to this solution and p- (3- (Methacryloxy-2-hydroxypropyloxy) benzaldehyde was added under the condition 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 resulting solution to room temperature, 30 g of basic ion exchange resin was added and stirred for 1 hour. Next, the ion exchange resin was filtered, and Irgacure 2959 (manufactured by Ciba Specialty Chemicals) was mixed here as a photopolymerization initiator at a ratio of 0.1 g with respect to 100 g of a 15% aqueous solution. Dilution was performed to obtain a 10% aqueous solution of polymer compound 1.

[Synthesis of Polymer Compound 2]
A 10% aqueous solution of polymer compound 2 was obtained in the same manner as in the synthesis of polymer compound 1 except that the polymerization degree of the polyvinyl acetate saponified product was changed to 180.

[Synthesis of Polymer Compound 3]
A 5% aqueous solution of polymer compound 3 was obtained in the same manner as in the synthesis of polymer compound 1, except that the polymerization degree of polyvinyl acetate saponified product was changed to 4500.

[Synthesis of Polymer Compound 4]
After 100 g of polyacrylic acid (weight average molecular weight 800,000) was dissolved by heating in 750 g of methanol, 16 g of 4-hydroxybutyl acrylate glycidyl ether and 11 g of pyridine were added as a catalyst, and the mixture was stirred for 24 hours while maintaining at 60 ° C. The temperature of the system was raised to 95 ° C., and methanol was distilled off while adding water dropwise, followed by an ion exchange resin (Mitsubishi Chemical: PK-216H) treatment to remove pyridine and an aqueous solution with a nonvolatile content of 15%. Got. Here, as a photopolymerization initiator, Irgacure 2959 (manufactured by Ciba Specialty Chemicals), which is a compound represented by the general formula (7) and n = 1, is mixed at a ratio of 0.1 g with respect to 100 g of 15% aqueous solution. Then, it was diluted with ion exchange water to obtain 10% of the polymer compound 4.

<Preparation of ink>
(Preparation of pigment dispersion)
(Preparation of magenta pigment dispersion)
The following additives were mixed and dispersed using a sand grinder filled with 50% by volume of 0.5 mm zirconia beads to prepare a magenta pigment dispersion having a magenta pigment content of 10%. The average particle size of the magenta pigment particles contained in this magenta pigment dispersion was 83 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

C. I. Pigment Red 122 10 parts Jonkrill 61 (acrylic styrene resin dispersant, manufactured by Johnson) 3 parts Glycerin 15 parts Ion-exchanged water 72 parts (Preparation of 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 size of the carbon black particles contained in the obtained black pigment dispersion was 153 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

[Preparation of ink set 1]
Ink set 1 consisting of magenta ink 1 and black ink 1 was prepared according to the following method.

(Preparation of magenta ink 1)
Magenta pigment dispersion 30 parts 10% aqueous solution of polymer compound 1 20 parts 1,2-hexanediol 7 parts Ethylene glycol 15 parts Diethylene glycol monobutyl ether 2 parts Olphine E1010 (manufactured by Nisshin Chemical Co., Ltd.) 0.2 parts Magenta ink 1 was obtained by adding exchange water to make the total amount 100 parts.

(Preparation of black ink 1)
A black ink 1 was prepared in the same manner as in the preparation of the magenta ink 1 except that the magenta pigment dispersion was changed to a black pigment dispersion.

[Preparation of ink set 2]
A magenta ink prepared in the same manner as the ink set 1 except that the 10% aqueous solution of the polymer compound 1 used for the preparation of the magenta ink 1 and the black ink 1 was changed to a 10% aqueous solution of the polymer compound 2. 2 and black ink 2 were obtained.

[Preparation of ink set 3]
Ink set 3 consisting of magenta ink 3 and black ink 3 was prepared according to the following method.

(Preparation of magenta ink 3)
Magenta pigment dispersion 30 parts 5% aqueous solution of polymer compound 3 40 parts 1,2-hexanediol 7 parts Ethylene glycol 15 parts Diethylene glycol monobutyl ether 2 parts Olphine E1010 (manufactured by Nissin Chemical Co., Ltd.) 0.2 parts Magenta ink 3 was obtained by adding exchange water to make the total amount 100 parts.

(Preparation of black ink 3)
A black ink 3 was prepared in the same manner as in the preparation of the magenta ink 3 except that the magenta pigment dispersion was changed to a black pigment dispersion.

[Preparation of ink set 4]
In the preparation of the ink set 1, the magenta ink 4 and the black prepared in the same manner except that the solid content of the polymer compound 1 used for the preparation of the magenta ink 1 and the black ink 1 was changed to 0.5% by mass. Ink set 4 comprising ink 4 was obtained.
Ink set 4 was obtained.

[Preparation of ink set 5]
In the preparation of the ink set 1, the magenta ink 5 and the black ink prepared in the same manner except that the solid content of the polymer compound 1 used for the preparation of the magenta ink 1 and the black ink 1 was changed to 6.0% by mass. Ink set 5 composed of ink 5 was obtained.

[Preparation of ink set 6]
Ink set 6 composed of magenta ink 6 and black ink 6 was prepared according to the following method.

(Preparation of magenta ink 6)
1,4-Butadiol diepoxyacrylate (BASF, LR8765) 10 parts Irgacure 651 (Ciba Specialty Chemicals photopolymerization initiator) 0.4 part Magenta pigment dispersion 30 parts Neugen ET150 10% aqueous solution ( (Made by Daiichi Kogyo Seiyaku Co., Ltd.) 7 parts Diethylene glycol 15 parts The above was finished to 100 parts with ion-exchanged water to prepare magenta ink 6.

(Preparation of black ink 6)
A black ink 6 was prepared in the same manner as in the preparation of the magenta ink 6 except that the magenta pigment dispersion was changed to a black pigment dispersion.

[Preparation of ink set 7]
In the preparation of the ink set 1, in place of the 10% aqueous solution of the polymer compound 1 used for the preparation of the magenta ink 1 and the black ink 1, a compound in which R is represented by a p-phenylene group in the general formula (4) ( From magenta ink 7 and black ink 7 prepared in the same manner except for RSP manufactured by Toyo Gosei Kogyo, main chain PVA polymerization degree 1700, saponification degree 88%, modification rate 0.9 mol%, solid content concentration 10%) An ink set 7 was obtained.

[Preparation of ink set 8]
In the preparation of the ink set 1, in place of the 10% aqueous solution of the polymer compound 1 used in the preparation of the magenta ink 1 and the black ink 1, the polyvinyl alcohol (degree of polymerization 2000, saponification degree 88%) was replaced with a 10% aqueous solution. An ink set 8 composed of magenta ink 8 and black ink 8 prepared in the same manner was obtained.

<< Heat treatment, image formation and evaluation >>
As shown in Table 1, the following evaluations were made by combining the ink set, the recording medium, the heating temperature, and the heating method.

  The details of each recording medium described in abbreviations in Table 1 are as follows.

<Polymer compound>
RSP: a compound in which R is a p-phenylene group in the general formula (4) (RSP manufactured by Toyo Gosei Kogyo, main chain PVA polymerization degree 1700, saponification degree 88%, modification rate 0.9 mol%, solid content concentration 10 %)
<recoding media>
PVC: Polyvinyl chloride (manufactured by MACTAC, JT5929P)
PET: White polyethylene terephthalate film Synthetic paper: YUPO FPG (manufactured by YUPO Corporation)
RC: Resin-coated paper for photography (polyolefin resin layer is coated on both sides of base paper with basis weight of 170 g / m ² )
<Heating method>
Method 1: Consisting of the configuration shown in FIG. 1, a drying fan with a built-in heating wire as a preheating means is arranged downstream of the image printing unit, and the temperature shown in Table 1 is reached 0.5 seconds before printing. Thus, the recording medium was preheated.

  Method 2: Consists of the configuration shown in FIG. 2, a heating element of nichrome wire is laid flat on the back side of the recording medium P downstream of the image printing unit as a preheating means, and the surface of the aluminum plate is covered. A surface heater was installed, and the recording medium was preheated to reach the temperature shown in Table 1 0.5 seconds before printing.

  Method 3: Consists of the configuration shown in FIG. 3, and a radiant heat heating means using a far infrared heater as a heat source as a preheating means is arranged downstream of the image printing section, and is shown in Table 1 0.5 seconds before printing. The recording medium was preheated so that the temperature of

  Method 4: Consists of the configuration shown in FIG. 4, a heating roller incorporating a halogen lamp is installed as a preheating means downstream of the image printing unit, and the temperature shown in Table 1 is reached 0.5 seconds before printing. Thus, the recording medium was preheated.

  Method 5: With the configuration shown in FIG. 5, a heating belt comprising a heating roller incorporating a halogen lamp as a preheating means, a support roller, and an endless belt is installed on the downstream side of the image printing unit. The recording medium was preheated to the temperature shown in Table 1 5 seconds ago.

  Method 6: A surface heater having the structure shown in FIG. 6 and having a nichrome wire heating element laid flat on the back side of the recording medium P at the bottom of the printing unit as a preheating means and covering the surface of the aluminum plate The recording medium was preheated so that the temperature shown in Table 1 was reached 0.2 seconds before printing.

  Method 7: Consists of the configuration shown in FIG. 8, and radiant heat heating means using a far-infrared heater as a heat source is arranged on the back side of the recording medium P at the lower part of the printing unit, and Table 1 shows 0.2 seconds before printing. The recording medium was preheated so as to reach the described temperature.

  Method 8: Heating comprising the configuration described in a) of FIG. 9 and comprising a heating roller having a halogen lamp built in as a preheating means, a support roller, and an endless belt on the back side of the recording medium P at the bottom of the printing unit A belt was installed, and the recording medium was preheated to reach the temperature shown in Table 1 0.2 seconds before printing.

[Evaluation of beading resistance]
Using a piezo head having a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle count of 128, and a nozzle density of 180 dpi, the maximum recording density of 720 × 720 dpi (dpi in the present invention represents the number of todds per 2.54 cm). Using a demand-type inkjet printer, magenta ink is continuously ejected onto a recording medium preheated at the heating method and heating temperature shown in Table 1 to print a 10 cm × 10 cm magenta solid image. 0.1 seconds after landing, a 120 W / cm metal halide lamp (MAL 400NL manufactured by Nippon Battery Co., Ltd., power supply power 3 kW · hr) was irradiated and dried.

  The obtained magenta solid image was visually observed, and beading resistance was evaluated according to the following criteria.

A: Extremely uniform image. O: When observed in detail, there are less than 5 spotted noise parts. Δ: When observed in detail, there are more than 5 spotted noise parts. There are 10 or more clear madara noises and less than 20 xx: There are 20 or more clear madara noises. In the above evaluation, the rank is x and xx is a level where there is a problem as a product. .

[Evaluation of color bleed resistance]
Using a piezo-type head having a nozzle diameter of 25 μm, a driving frequency of 12 kHz, a nozzle number of 128, and a nozzle density of 180 dpi, an on-demand type ink jet printer having a maximum recording density of 720 × 720 dpi is used. A black fine line having a width of 100 μm was printed on the magenta solid image on the recording medium preheated in step 1. In addition, after each ink was continuously ejected and landed, a 120 W / cm metal halide lamp (MAL 400NL, manufactured by Nihon Battery Co., Ltd., power supply power 3 kW · hr) was irradiated and then dried.

  The images obtained as described above were visually observed, and color bleed resistance was evaluated according to the following criteria.

A: The boundary line between the black thin line image and the magenta solid image is clear. O: Bleeding is slightly observed at the boundary, but the quality is good. Δ: Bleeding is observed at the boundary. Practical quality is acceptable. ×: Obvious blurring is observed at the boundary and the line width is about 1.5 times, which is a practical problem. ××: Black thin line image and magenta solid The border of the image area is unclear and the color bleed resistance is extremely poor.
Using a piezo head having a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle count of 128, and a nozzle density of 180 dpi, the maximum recording density of 720 × 720 dpi (dpi in the present invention represents the number of todds per 2.54 cm). Using a demand-type inkjet printer, black ink is continuously ejected onto a recording medium preheated at the heating method and heating temperature shown in Table 1, and a black solid image of 10 cm × 10 cm is printed. 0.1 seconds after the landing, the sample was irradiated with a 120 W / cm metal halide lamp (MAL 400NL manufactured by Nippon Battery Co., Ltd., power supply power 3 kW · hr) and dried.

  The obtained black solid image was visually observed, and glossiness was evaluated according to the following criteria.

A: There is almost no difference in glossiness between the image recording area and the non-printed area. ○: The glossiness between the image recording area and the non-printed area is slightly recognizable, but the glossiness is good. Δ: Image recording A slight gloss difference is recognized between the area and the unprinted area, and the glossiness of the image recording surface is slightly higher than that of the unprinted area, but the quality is within the acceptable range for practical use. ×: In the image recording area and the unprinted area Clear gloss difference is recognized, and the glossiness of the image recording surface is higher than that of the unprinted area, which is a quality that is a problem in practical use. XX: A significant gloss difference is observed between the image recording area and the unprinted area. The glossiness of the recording surface is remarkably high compared to the unprinted area, and the quality is not practical. [Evaluation of image density]
The black density of the black solid image created by the glossiness evaluation was measured with a reflection densitometer (X-rite 938) manufactured by X-Rite, and the image density was evaluated according to the following criteria.

◎: Black density is 1.5 or more ○: Black density is 1.4 or more, less than 1.5 △: Black density is 1.2 or more, less than 1.4 ×: Black density is 0.8 or more, 1.2 Less than xx: Table 1 shows the results obtained when the black density was less than 0.8.

  As is clear from the results shown in Table 1, the image of the present invention formed by pre-printing the recording medium using an ink set containing the polymer compound defined in the present invention is a comparative example. On the other hand, it can be seen that the color bleed resistance, beading resistance and glossiness are excellent, and the obtained image density is high.

It is the schematic which shows an example of the heating method of the recording medium which used the drying fan as a preheating means. It is the schematic which shows an example of the heating method of the recording medium which used the surface heater as a preheating means. It is the schematic which shows an example of the heating method of the recording medium which used the radiant heat heating means as a preheating means. It is the schematic which shows an example of the heating method of the recording medium which used the heating roller as a preheating means. It is the schematic which shows an example of the heating method of the recording medium which used the heating belt as a preheating means. It is the schematic which shows an example of the heating method of the recording medium which has arrange | positioned the surface heater as a preheating means in the printing part vicinity. It is the schematic which shows an example of the heating method of the recording medium which used the heating roller and the surface heater together as a preheating means. It is the schematic which shows an example of the heating method of the recording medium which has arrange | positioned the radiant heat heating means to the printing part vicinity as a preheating means. It is the schematic which shows an example of the heating method of the recording medium which has arrange | positioned the heating belt as a preheating means in the printing part vicinity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image printing part 2 Image recording head 3 Irradiation light source 4 Carriage 5 Scanning guide 6 Guide roller 7 Conveyance roller 8 Heating fan 9 Surface heater 10 Heat source 11 Reflecting plate 12 Pressure roller 13 Heating means 14 Heating roller 15 Support roller 16 Endless belt B Heating belt P Recording medium

Claims (8)

An inkjet ink containing 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 irradiation with active energy rays, An ink jet recording method comprising discharging onto a preheated recording medium and irradiating the ink jet ink with active energy rays. The inkjet recording method according to claim 1, wherein the recording medium is a plastic film, resin-coated paper, or synthetic paper. The inkjet recording method according to claim 2, wherein the plastic film is a polyvinyl chloride film. The inkjet recording method according to any one of claims 1 to 3, wherein the temperature of the preheated recording medium is 40 ° C or higher and 100 ° C or lower. 5. The inkjet recording method according to claim 1, wherein the content of the polymer compound in the inkjet ink is 0.8% by mass or more and 5.0% by mass or less. . The hydrophilic main chain is a saponified product of polyvinyl acetate, the saponification degree is 77% or more and 99% or less, and the polymerization degree is 200 or more and 4000 or less. The inkjet recording method according to any one of the above. The ink jet recording method according to claim 1, further comprising a water-soluble photopolymerization initiator. The inkjet recording method according to claim 1, wherein the inkjet ink is ejected onto the preheated recording medium, irradiated with an active energy ray, and then dried in a drying step. .

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