JP2007031469A - Inkjet ink, ink set for the inkjet ink and ink jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide inkjet ink having printing fitness to various recording media, improved in intermittent jetting stability, excellent in feathering resistance, bead resistance and bleed resistance, having strong adhesiveness to the recording media and high printing quality, an ink set for the inkjet ink and an inkjet recording method using the same. <P>SOLUTION: The inkjet ink contains at least a colorant, water and a high molecular compound having two or more side chains in a hydrophilic main chain and crosslinkable by irradiating active energy rays. The hydrophilic main chain of the high molecular compound is a saponified product of polyvinyl acetate and has 77-99% degree of saponification and ≥200 to <500 degree of polymerization. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  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 dedicated paper having ink absorbability is required.

  When recording on coated paper or art paper that does not absorb much ink, or on plastic film that does not absorb ink at all, different color ink liquids mix on the recording medium and cause color turbidity. There is a problem, and it has been a problem to give diversity to the recording medium by inkjet recording.

  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 recording 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 continuing investigations regarding technical improvements, it has been found that the intermittent emission stability may be deteriorated in the ink jet recording system by including a polymer compound in the ink.
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 its purpose is to have printability on various recording media, improved intermittent emission stability, and excellent feathering resistance, beading resistance, and bleed resistance. Another object of the present invention is to provide an ink jet ink, an ink jet ink set, and an ink jet recording method using them, which have high adhesion to a recording medium and high print quality.

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

(1)
An inkjet ink 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 ink, wherein the hydrophilic main chain of the polymer compound is a saponified product of polyvinyl acetate and the degree of polymerization is 200 or more and less than 500.

(2)
The inkjet ink as described in (1) above, wherein the modification rate of the side chain with respect to the hydrophilic main chain is 0.8 mol% or more and 4.0 mol% or less.

(3)
The ink-jet ink according to item (1) or (2), wherein the addition amount of the polymer compound is 0.8% or more and 5.0% or less.

(4)
The inkjet ink according to any one of (1) to (3), further comprising a water-soluble photopolymerization initiator.

(5)
An inkjet ink comprising two or more inkjet inks, wherein at least one of the inkjet inks is the inkjet ink according to any one of (1) to (4). set.

(6)
An ink jet recording method comprising: discharging the ink jet ink according to any one of (1) to (4) onto a recording medium, irradiating the ink jet ink with active energy rays, and drying the ink. .

(7)
An ink jet recording method comprising: discharging an ink jet ink constituting the ink jet ink set according to the item (5) onto a recording medium, irradiating the ink jet ink with active energy rays, and drying the ink.

(8)
The inkjet recording method according to item (6) or (7), wherein the recording medium is plain paper.

(9)
The ink jet recording method according to item (6) or (7), wherein the recording medium is art paper or coated paper.

(10)
The inkjet recording method according to (6) or (7), wherein the recording medium is a non-absorbent recording medium.

  According to the present invention, printing on various recording media is suitable, intermittent emission stability is improved, feathering resistance and bleed resistance are excellent for plain paper, and bead is used for art paper and coated paper. It is possible to provide an ink jet ink, an ink jet ink set, and an ink jet recording method using the same, which have high printing quality and have excellent printing resistance and bleeding resistance and high adhesion to a recording medium.

  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 coloring material, water, and a hydrophilic main chain, and can be cross-linked between side chains by irradiating active energy rays. Various recordings using an ink-jet ink comprising a high molecular compound, the hydrophilic main chain of the high molecular compound being a saponified product of polyvinyl acetate, and a polymerization degree of 200 or more and less than 500 It has the ability to print on media, has improved intermittent emission stability, has excellent feathering resistance and bleeding resistance on plain paper, and has excellent beading resistance and bleeding resistance on art paper and coated paper. Further, the present inventors have found that an inkjet ink having high adhesion to a recording medium and high printing quality can be realized.

  Details of the present invention will be described below.

<Inkjet ink>
First, each component of the inkjet ink of the present invention (hereinafter also simply referred to as ink) will be described.

[Active energy ray crosslinkable polymer compound]
The ink-jet ink of the present invention comprises 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. By including a molecular compound, it is possible to provide stable printability to various types of recording media, and the formed images are excellent in feathering resistance, beading resistance, bleed resistance, and output properties, and adhere to recording media. Ink jet ink with high quality and high print quality could be obtained.

  Polymer compounds having a plurality of side chains in the hydrophilic main chain and capable of crosslinking between side chains by irradiation with active energy rays include saponified polyvinyl acetate, polyvinyl acetal, polyethylene oxide, polyalkylene Oxides, polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose and the like are known. In the present invention, the hydrophilic main chain is a saponified product of polyvinyl acetate, and the degree of polymerization. Is 200 or more and less than 500.

  By using a saponified product of polyvinyl acetate as the hydrophilic main chain, the ease of introduction of the side chain is improved and the handleability is also improved. Further, by setting the degree of polymerization to 200 or more and less than 500, it is possible to effectively prevent clogging of the head due to increase in viscosity when added to the ink and drying when not emitted, and as a result, excellent Intermittent emission stability can be realized.

  If the degree of polymerization is less than 200, the viscosity increase due to crosslinking is reduced, and the bleed resistance described later may be insufficient. On the other hand, when the polymerization degree is 500 or more, the viscosity when added to the ink is increased, and the emission stability may be deteriorated.

  In addition, a modifying group such as a photodimerization type, a photodecomposition type, a photopolymerization type, a photomodification type, and a photodepolymerization type can be introduced into the side chain. From the viewpoint of reaction efficiency with the color material to be combined, the side chain Are preferably nonionic, anionic, and amphoteric (betaine compounds). Particularly, when combined with an anionic dye or an anionic pigment as a coloring material, it is preferably nonionic or anionic, particularly preferably nonionic. It is.

  The modification rate of the side chain with respect to the hydrophilic main chain is preferably 0.8 mol% or more and 4.0 mol% or less, and more preferably 1.5 mol% or more and 3.0 mol% or less. More preferable from the viewpoint of reactivity. If the modification rate of the side chain with respect to the hydrophilic main chain is 0.8 mol% or more, it has sufficient crosslinkability, and the objective effect of the present invention can be remarkably obtained. On the other hand, if it is 4.0 mol% or less, the crosslinking density is appropriate, so that a flexible image film can be easily obtained and the film strength is particularly good.

  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 inkjet ink of the present invention, when using a polymer compound having a photopolymerizable modifying group, it is preferable to use a known photopolymerization initiator, and it is particularly preferable to use a water-soluble photopolymerization initiator.

  As a water-soluble photopolymerization initiator applicable to the ink jet ink of the present invention, a compound represented by the following general formula (7) is preferable from the viewpoint of compatibility with a polymer compound and sensitivity.

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

  The photopolymerization initiator is preferably grafted to the side chain with respect to the hydrophilic main chain of the polymer compound according to the present invention.

  In such an active energy ray cross-linking type polymer compound, the main chain having a certain degree of polymerization is cross-linked through a cross-linking bond between the side chains, and therefore the monomer is subjected to a general chain reaction. The effect of increasing the molecular weight per photon is remarkably large as compared with the conventionally known active energy ray-curable resin produced by polymerizing. On the other hand, in the conventionally known active energy ray-curable resins, the number of crosslinking points cannot be controlled, so the film physical properties after curing cannot be controlled to desired conditions, and as a result, a hard and brittle image It tends to be a film.

  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, so that the physical properties of the ink film can be controlled according to the purpose. In particular, the molecular weight (degree of polymerization) of the hydrophilic main chain also affects the strength of the film after crosslinking, but when it is placed in the ink, it also greatly affects the viscosity increase when the ink is dried at the head. As described above, by setting the molecular weight (degree of polymerization) to an appropriate range (in the present invention, the degree of polymerization is 200 or more and less than 500), the viscosity during drying is suppressed and the stability of intermittent emission is improved. Can do well. In this range, beading resistance and color bleed resistance described later are sufficient.

  Furthermore, the ink using the conventionally known active energy ray-curable resin is a component in which almost all of the ink other than the color material is involved in the curing. Therefore, the dots after curing rise and the image quality represented by gloss is significantly deteriorated. On the other hand, the polymer compound according to the present invention requires only a small amount of ink used in the ink and has a large amount of dry components, so that the image quality after drying is improved and the fixing property is also good.

  The hydrophilic main chain according to the present invention has a plurality of side chains, and the amount of the polymer compound that can be cross-linked between the side chains by irradiating active energy rays in the ink is 0.8% or more, It is preferably 5.0% or less.

  If the addition amount is within this range, the crosslinking efficiency is improved, and the ink is ejected from the head and adhered to the base material, and then crosslinked, so that the viscosity of the ink after crosslinking is rapidly increased and the beading resistance and color bleed resistance are increased. Will improve. If the addition amount is less than 0.8%, the object effect of the present invention obtained due to insufficient crosslinkability becomes small, and if it exceeds 5.0%, the ink viscosity increases and affects the emission stability. There is.

[Colorant]
As the color material used in the ink jet ink of the present invention, it is preferable to use a dye or a pigment.

(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. Basic Yellow>
1, 2, 11, 13, 15, 19, 21, 28, 29, 32, 36, 40, 41, 45, 51, 63, 67, 70, 73, 91,
<C. I. Basic Orange>
2, 21, 22,
<C. I. Basic Red>
1, 2, 12, 13, 14, 15, 18, 23, 24, 27, 29, 35, 36, 39, 46, 51, 52, 69, 70, 73, 82, 109,
<C. I. Basic Violet>
1, 3, 7, 10, 11, 15, 16, 21, 27, 39,
<C. I. Basic Blue>
1, 3, 7, 9, 21, 22, 26, 41, 45, 47, 52, 54, 65, 69, 75, 77, 92, 100, 105, 117, 124, 129, 147, 151,
<C. I. Basic Green>
1, 4,
<C. I. Basic Brown>
1,
<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.

[Chelating dye, silver dye bleach dye]
In addition, chelate dyes and azo dyes used for silver dye bleach (silver dye bleaching) photosensitive materials (for example, Cibachrome manufactured by Ciba Geigy) can be used.

  Chelating dyes are described, for example, in British Patent No. 1,077,484. As for azo dyes for silver dye bleaching photosensitive materials, for example, British Patent Nos. 1,039,458, 1,004,957, 1,077,628, U.S. Pat. 612,448.

(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 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 polycyclic pigments, dye lakes such as basic dye lakes, and acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and 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.

  In the present invention, methods for obtaining pigment particles having a polar group on the surface include, for example, WO 97/48769, JP-A-10-110129, JP-A-11-246807, JP-A-11-57458, 11-189739, JP-A-11-323232, JP-A-2000-265094, and the like, by causing the surface of the pigment particles to have an appropriate oxidizing agent, at least a part of the pigment surface has a sulfonic acid group or The method of introduce | transducing polar groups, such as the salt, 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, amidosulfuric acid, etc. in sulfolane or N-methyl-2-pyrrolidone. can do. In these reactions, the pigment dispersion can be obtained by removing and purifying the substance that has been excessively oxidized and becomes water-soluble. 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 of adsorbing the pigment derivative described in JP-A-11-49974, JP-A-2000-273383, JP-A-2000-303014, etc. on the pigment particle surface by a treatment such as milling, and the like. Examples include a method of dissolving the pigment described in 2002-179777, 2002-201401, etc. together with a pigment derivative in a solvent and then crystallization in a poor solvent, and any method can easily polarize the surface. Pigment particles having groups can be obtained.

  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 (eg, lithium, sodium, potassium, magnesium, calcium, aluminum, nickel, ammonium) and organic salts (eg, triethylammonium, diethylammonium, pyridinium, triethanolammonium, etc.). A counter salt having a monovalent valence is preferable.

  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.

[Method for producing pigment dispersion]
Next, the pigment dispersion method according to the present invention will be described.

  In the present invention, a pigment is dissolved in an acidic solvent or an alkaline aprotic polar solvent in a reaction vessel, and if necessary, a solution containing a polymer compound, and if necessary, a polymer compound and a pigment derivative having a polar group are contained. After stirring and mixing the pigment insoluble medium, the pigment particles can be crystallized to obtain a pigment dispersion.

  The stirring means of the reaction vessel to be used is not particularly limited, and a normal impeller can be used. Examples include a paddle wing, a curved paddle wing, a tilted paddle wing, a propeller wing, a turbine wing, a bull margin wing, an icari wing, a spiral shaft wing, a spiral wing, a dissolver wing, and a homomixer wing. Of these, it is preferable to use an axial flow type stirring blade that can generate a strong flow in the axial direction by thrust in the rotational axis direction.

The mixing of the pigment solution is preferably substantially turbulent in order to achieve more uniform mixing. Turbulence is defined by the Reynolds (Re) number. The Reynolds number is the typical length of an object in the flow, D, velocity U, density ρ, viscosity η,
Re = DUρ / η
Is defined by a dimensionless number.

  Generally, when Re <2300, it is called laminar flow, 2300 <Re <3000 is called a transition region, and when Re> 3000, it is called turbulent flow. Substantially turbulent refers to Re> 3000, preferably Re> 5000, more preferably Re> 10000. In this invention, it is preferable to mix by Reynolds number 3000 or more, and 5000 or more are still more preferable.

  The pigment solution is preferably added to a place where there is no stagnation due to the flow of the liquid, and more preferably added to the liquid near the stirring blade. The number of nozzles for adding the pigment solution may be one, but it is preferable that a plurality of nozzles are present.

  In the present invention, the mixing device may be a dynamic mixing device having a stirrer inside or a static mixing device having no stirrer. In the case of a static mixing apparatus, all the supply pipes and the axes of the pipes for discharging the deposited pigment are all gathered at the same point, and there is no stirrer inside the pipe. For example, it may be T-shaped or Y-shaped. In both the dynamic mixing device and the static mixing device, the number of the pigment solution, the pigment derivative solution, and the nozzle for introducing the aqueous medium may be one or one, but it is preferable that there are a plurality or a plurality of nozzles. preferable.

  The temperature at which the solution of the dissolved pigment is added to the aqueous medium in which the pigment derivative having a polar group is dissolved or dispersed is not particularly limited, but preferably ranges from 0 ° C to 80 ° C. If it is less than 0 ° C., water in the hydrophilic medium may freeze, and if it exceeds 80 ° C., the growth of pigment particles is remarkably accelerated and the desired particle size cannot be obtained.

  In the present invention, desalting is preferably performed simultaneously with crystallization.

  In the present invention, desalting is a method for producing a pigment dispersion using a polymer compound, a pigment derivative having a polar group, and a pigment. In the method for producing a pigment dispersion, a salt such as sodium produced during or after the production of the pigment dispersion, an acidic solvent, The process of removing an alkaline aprotic polar solvent is shown. As the desalting method, various methods such as a centrifugal separation method, a flotation separation method, a sedimentation separation method, an ultrafiltration method, and an electrodialysis method are preferably used. In the present invention, a more preferable method is an ultrafiltration method.

  In the present invention, the desalting degree is preferably 5,000 μm / cm or less, more preferably 3,000 μm / cm or less, and still more preferably 1,000 μm / cm or less as the conductivity of the solution.

  In the present invention, a pigment dispersion having a desired small particle diameter can be obtained by crystallization, desalting, and concentration. However, if this is still insufficient, a mechanical dispersion means may be used as appropriate. good. As the mechanical dispersion means, for example, various methods such as a disper, a sand mill, a homogenizer, a ball mill, and a paint shaker are preferably used. In the present invention, a more preferable method includes a sand mill.

[Surfactant applicable to pigment dispersion]
If the pigment dispersion obtained in the present invention is used, the dispersion stability is considerably improved as compared with the conventional one, but if it is still insufficient, a surfactant and a polymer dispersant may be contained as necessary. . The type of surfactant (pigment dispersant) and polymer dispersant is not particularly limited. Examples of the pigment dispersant include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, and sulfosuccinates. , Naphthalene sulfonate, alkyl phosphate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide, etc. As the polymer dispersant, a water-soluble resin is preferably used from the viewpoint of ejection stability. For example, styrene, styrene derivatives, vinyl naphthalene derivatives, acrylic acid, acrylic acid derivatives , Malein , Maleic acid derivatives, 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, More specifically, styrene-acrylic acid-alkyl acrylate ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid. -Acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, etc. .

  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.

[Pigment particle diameter]
The particle size of the pigment particles includes the particle size (primary particle size) obtained by directly observing the particles with an electron microscope, and the dispersed particle size (secondary particle size) using a particle size measuring device utilizing light scattering. There is a viscosity-converted particle size obtained from the intrinsic viscosity.

  The primary particle diameter of the pigment in the ink of the present invention is preferably 10 nm or more and 1000 nm or less, more preferably 10 nm or more and 70 nm, from the viewpoint of light resistance and dispersion stability. If it is smaller than 10 nm, the light resistance will not deteriorate, and if it exceeds 100 nm, it will cause clogging of the head due to aggregation. Here, in order to obtain primary particles, the major axis of 1000 pigment particles is measured with a transmission electron microscope, and the average value (number average) can be obtained.

[DBP oil absorption, nitrogen adsorption specific surface area of carbon black]
When carbon black is used as a coloring material of the ink-jet ink of the present invention, DBP oil absorption of carbon black is preferably at least 70cm ^3/100 g, is more preferably 80 cm ^3/100 g or more.

  The DBP oil absorption amount of carbon black here is a characteristic value calculated based on the test method shown in JIS-K-6217 (1997).

When carbon black is used as the coloring material of the inkjet ink of the present invention, the nitrogen adsorption specific surface area of carbon black is preferably 100 m ² / g or more, more preferably 150 m ² / g or more, and still more preferably. 200 m ² / g or more.

  The nitrogen adsorption specific surface area of carbon black here is calculated based on the test method shown in JIS-K-6217 (1997).

[Inkjet ink set]
The ink-jet ink set of the present invention is composed of two or more ink-jet inks, and at least one of the ink-jet inks has a plurality of side chains in the hydrophilic main chain of the present invention. It is an ink-jet ink containing a polymer compound (polyvinyl acetate saponified product having a polymerization degree of 200 or more and less than 500) that can be crosslinked between side chains by irradiation.

  The ink-jet ink set of the present invention comprises the ink-jet ink described in claim 1, 2, 3 or 4, and preferably two or more inks are the ink-jet ink of the present invention, particularly preferably. The effects of the present invention are remarkably exhibited when all the inks are the ink-jet inks of the present invention.

  As the ink having different hues constituting the inkjet ink set of the present invention, it is preferable to use an ink set composed of inkjet inks of yellow, magenta, cyan, and black.

  Further, in addition to the four color inks, a light cyan ink, a light magenta ink, a dark yellow ink, and a light black ink (gray ink) may be used. It is also possible to use so-called special color inks such as blue, red, green, orange and violet.

(Dark ink)
In the ink-jet ink set of the present invention, it is desirable to use an ink-jet ink set composed of at least two inks of the same color having different densities in at least one color ink. Further, it is more preferable to use an ink jet ink set composed of at least two inks of the same color having different densities in two or more colors. In particular, at least two inks of the same color having different densities are used. It is preferable to use an ink-jet ink set composed of ink.

  This is because by using a low-density ink jet ink, it is possible to reduce graininess and form a high-quality image without so-called “roughness”. In particular, it is preferable to use at least two inks having different densities in magenta ink or cyan ink having high human visibility.

  The density ratio of the ink jet ink sets having different densities may be any value. However, in order to achieve smooth gradation reproduction, the ratio of the high density ink to the low density ink (color material density / high density of the low density ink) The color material density of the density ink is preferably between 0.1 and 1.0, more preferably between 0.2 and 0.5, and between 0.25 and 0.4. It is particularly preferred.

(Water-soluble organic solvent)
In the inkjet ink of the present invention, it is preferable to use a water-soluble organic solvent. Examples of the water-soluble organic solvent that can be used in the present invention include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl). Alcohol), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol Etc.), polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether, ethylene glycol) Ether monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl 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, etc.), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, mole) Phosphorus, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N , N-dimethylacetamide, etc.), heterocyclic rings (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides ( For example, dimethyl sulfoxide etc.), sulfones (for example, sulfolane etc.), urea, acetonitrile, acetone etc. are mentioned. Preferable water-soluble organic solvents include polyhydric alcohols. Furthermore, it is particularly preferable to use a polyhydric alcohol and a polyhydric alcohol ether in combination.

  The water-soluble organic solvent may be used alone or in combination. The total amount of the water-soluble organic solvent added to the ink is 5 to 60% by mass, preferably 10 to 35% by mass.

(Organic / inorganic ratio of water-soluble organic solvent)
In the ink of the present invention, the content of the water-soluble organic solvent having an inorganic / organic ratio of 0.5 to 2.4 is preferably 5 to 15% by mass.

  The inorganic / organic ratio of the water-soluble organic solvent referred to in the present invention is defined in “Organic Conceptual Diagram” by Yoshio Koda, Sankyo Publishing 1985, and the calculation method is also described in the Sankyo Publication 1985. It can be calculated by the method.

  Examples of the water-soluble organic solvent of the present invention include the following.

Inorganic / organic ratio Glycerin 5.0
Ethylene glycol 5.0
Propylene glycol 3.3
Diethylene glycol 2.8
1,2 pentanediol 2.0
Dipropylene glycol 1.8
Ethylene glycol monomethyl ether 2.0
Ethylene glycol monoethyl ether 1.5
Diethylene glycol monobutyl ether 0.9
Triethylene glycol monobutyl ether 0.8
[Other additives for inkjet ink]
In the ink of the present invention, if necessary, various known additives such as ejection stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other performance improvement purposes, for example, , Viscosity modifier, Surface tension modifier, Specific resistance modifier, Film forming agent, Dispersant, Surfactant, Ultraviolet absorber, Antioxidant, Anti-fading agent, Antifungal agent, Rust inhibitor, etc. For example, polystyrene, polyacrylates, polymethacrylates, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or a copolymer thereof, urea resin, or melamine Organic latex such as resin, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil and other oil droplets, ON or nonionic surfactants, UV absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192, JP-A-57-87989, 60-72785, 61-146591, anti-fading agents described in JP-A-1-95091 and 3-13376, JP-A-59-42993, 59-52689, 62- 280069, 61-242871, and JP-A-4-219266, etc., optical brighteners, pH adjusters such as sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, etc. Can be mentioned.

(Aqueous polymer)
In the inkjet ink of the present invention, an aqueous polymer can also be used. Preferred examples of the aqueous polymer include natural polymers, and specific examples thereof include proteins such as glue, gelatin, casein, or albumin, natural rubbers such as gum arabic or tragacanth, glucosides such as saponin, Examples include alginic acid and alginic acid propylene glycol ester, alginic acid derivatives such as triethanolamine alginate, or ammonium alginate, and cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, or ethylhydroxylcellulose.

  Further, preferred examples of the aqueous polymer include synthetic polymers such as polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic. Acrylic resin such as acid ester copolymer or acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, Styrene acrylic resin such as styrene-α-methylstyrene-acrylic acid copolymer or styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride Copolymer, vinyl naphthalene-a Crylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-crotonic acid copolymer Examples include polymers, vinyl acetate copolymers such as vinyl acetate-acrylic acid copolymers, and salts thereof. Among these, polyvinylpyrrolidones are particularly preferable examples.

  The molecular weight of the polymer is preferably 1,000 or more and 200,000 or less. Furthermore, 3,000 or more and 20,000 or less are more preferable. If it is less than 1,000, the effect of suppressing the growth and aggregation of pigment particles is reduced, and if it exceeds 200,000, problems such as an increase in viscosity and poor dissolution tend to occur.

  The addition amount of the polymer is preferably 10% by mass or more and 1,000% by mass or less with respect to the color material. Furthermore, 50 mass% or more and 200 mass% or less are more preferable. If it is less than 10% by mass, the effect of suppressing the growth and aggregation of the pigment particles is reduced, and if it exceeds 1000% by mass, problems such as an increase in viscosity and poor dissolution tend to occur.

(Wetting agent)
A wetting agent can also be used in the inkjet ink of the present invention. Examples of the wetting agent include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, diethylene glycol diethyl ether, diethylene glycol mono n-butyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene Polyhydric alcohols such as glycol monobutyl ether, methyl carbitol, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, diethyl carbitol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether and ethers thereof , Acetates, N-methyl- - pyrrolidone, 1,3-dimethylimidazolidinone, can be used triethanolamine, formamide, nitrogen-containing compounds such as dimethyl formamide, dimethyl monkey sulfoxide one or two or more kinds. Although there is no restriction | limiting in particular in the compounding quantity of these wetting agents, Preferably 0.1-50 mass% can be mix | blended in the said ink, More preferably, 0.1-30 mass% can be mix | blended.

(Defoamer)
In the inkjet ink of the present invention, an antifoaming agent can be added, and a commercially available product can be used without particular limitation as the antifoaming agent. Examples of such commercially available products include KF96, 66, 69, KS68, 604, 607A, 602, 603, KM73, 73A, 73E, 72, 72A, 72C, 72F, 82F, 70, 71 manufactured by Shin-Etsu Silicone. 75, 80, 83A, 85, 89, 90, 68-1F, 68-2F (trade name), and the like. Although there is no restriction | limiting in particular in the compounding quantity of these compounds, It is preferable to mix | blend 0.001-2 mass% in the ink of this invention. If the compounding amount of the compound is less than 0.001% by mass, bubbles are likely to be generated at the time of preparing the ink, and it is difficult to remove small bubbles in the ink. During printing, repellency may occur in the ink and the print quality may be deteriorated.

(Surfactant)
Surfactants preferably used in the inkjet ink of the present invention include alkyl sulfates, alkyl ester sulfates, dialkyl sulfosuccinates, alkyl naphthalene sulfonates, alkyl phosphates, and 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 , Surfactants such as sorbitan esters, polyoxyethylene fatty acid amides and amine oxides, and cationic surfactants such as alkylamine salts and quaternary ammonium salts.

[Preparation of ink]
There is no particular limitation on the preparation of the ink-jet ink of the present invention. However, when an ink containing a dispersion such as a pigment, a disperse dye, inorganic fine particles, or resin fine particles is prepared, no aggregation or sedimentation occurs in the preparation process. Thus, it is preferable to prepare the ink. If necessary, a preparation method such as adjusting the order of addition of the dispersion, solvent, water, photosensitive resin and other additives, and the addition rate can be taken. In addition, for the purpose of stabilizing the dispersion and redispersing the agglomeration generated during the blending of the ink during or after the blending, a dispersion process using a bead mill or ultrasonic waves, a heating process, or the like may be performed.

"recoding media"
As the recording medium applicable in the ink jet recording method of the present invention, various papers, various films, various cloths, various woods, various ink jet recording media, and the like can be used, and the recording medium is plain paper, art paper, coated paper. It is preferable that the recording medium is an absorptive recording medium, a low-absorbing recording medium, or a non-absorbing recording medium.

[Various papers]
The various paper, coated paper, there is a non-coated paper, as the coated paper, the coating amount per 1m ² is one side 20g before and after of art paper, coating amount per 1m ² of the front and rear single-sided 10g Court paper, 1m coating amount per ² is one side 5g before and after of lightweight coated paper, Binurikoshi, mat coated paper matte finish, Darukoto paper of dull finish, can be mentioned, such as 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 the “Latest Paper Processing Handbook” edited by the Paper Processing Handbook Editorial Committee, published by Tech Times, “Printing Engineering Handbook” edited by the Japan Printing Society.

The plain paper referred to in the present invention belongs to a part of non-coated paper, special printing paper and information paper, and includes 80 to 200 μm non-coated 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. In addition, as the coated paper, the coating amount per 1m ² is one side 20g before and after of art paper, coating amount per 1m ² is one side 10g before and after the coated paper, the coating amount per 1m ² is one side 5g of before and after Lightweight coated paper, finely coated paper, matte-finished matte-coated paper, dull-finished dull-coated paper, newsprint paper, and the like.

  Examples of plain paper, art paper, and coated paper that can be used in the ink jet recording method of the present invention include high-quality paper and color high-quality paper, recycled paper, copy paper / colored paper, OCR paper, carbonless paper / colored paper, YUPO Synthetic paper such as 60, 80, 110 microns, YUPO COAT 70, 90 microns, etc., single-sided art paper 68 kg, coated paper 90 kg, foam mat paper 70, 90, 110 kg, expanded 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 Fine Paper, OK Map Paper, OK Ishikari, Cucumber, OK Foam, OKH, NIP-N (Shin Oji Paper), gold , Toko, export quality paper, special demand quality paper, book paper, book paper L, light cream book paper, small textbook paper, continuous slip paper, high quality NIP paper, silver ring, gold yang, gold yang (W), bridge, Capital, Silver Ring Books, Harp, Harp Cream, SK Color, Securities Paper, Opera Cream, Opera, KYP Medical Record, Silvia HN, Excellent Foam, NPI Form DX (above, Nippon Paper Industries), Pearl, Kinryo, Usscream Fine Paper , Special book paper, super book paper, book paper, diamond form, inkjet form (Mitsubishi Paper), carpet V, carpet SW, white elephant, high-grade publication paper, cream carpet, cream white elephant, securities / voucher Paper, book paper, map paper, copy paper, HNF (Hokuetsu Paper), phone book cover, book paper, cream paper, cream paper Raichu Rough, Cream Shirai Dairafu, DSK (above, Daishowa Paper), Sendai MP fine paper, Nishiki River, Thunderbird fine, hanging paper, colored paper base, dictionary paper, cream book, white book, cream fine paper, map Paper, continuous slip paper (above, Chuetsu Pulp), OP gold cherry (chuetsu), gold sand, reference book paper, replacement paper (white), form printing paper, KRF, white foam, color foam, (K) NIP, fine PPC, Kishu Inkjet Paper (Made by Kishu Paper), Taiou, Bright Foam, Kant, Kant White, Dante, CM Paper, Dante Comic, Heine, Bunko Paper, Heine S, New AD Paper, Utrillo Excel, Excel Super A , Kant Excel, Excel Super B, Dante Excel, Heine Excel, Excel Super C, Excels Super D, AD Excel, Excel Super E, New Bright Foam, New Bright NIP (made by Daio Paper Co., Ltd.), Sun Ring, Moon Ring, Cloud Pass, Galaxy, Baiyun, Weiss, Moon Ring Ace, Baiyun Ace, Kumo Ace ( (Nippon Paper Industry), Taiou, Bright Foam, Brightnip (Nagoya Pulp), Peony A, Gold Pigeon, Special Peony, White Peony A, White Peony C, Silver Pigeon, Super White Peony A, Light Cream White Peony, Special Medium Paper, White Pigeon, Super Medium 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 (Honshu Paper), Starlinden (A / AW), Star Elm, Star Maple, Star Laurel, Star Poplar, MOP, Star Cherry I, Cherry I Sueー, Cherry II Super, Star Cherry III, Star Cherry IV, Cherry III Super, Cherry IV Super (Maruzumi Paper), SHF (Toyo Pulp), TRP (Tokai Pulp) It is done.

  Typical printing papers include Mitsubishi Paper's Tokuhishi Art and Oji Paper's OK Top Coat N.

[Non-absorbent recording medium]
As the non-absorbable recording medium, all commonly used various 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 or YUPO paper that is synthetic paper can also be used.

[Various fabrics]
As the various fabrics, for example, any fabric using natural fibers, chemically synthesized fibers, and recycled fibers can be used.

[Inkjet recording medium]
In the present invention, various ink jet recording media can be applied. In these, a non-absorbent support or paper is used as a substrate, and an ink receiving layer is formed on the surface thereof. Examples of the ink receiving layer include a coating layer, a swelling layer, and a fine void layer.

  An ink jet recording medium provided with the fine void layer using RC paper in which both surfaces of a paper substrate are coated with an olefin resin as a non-absorbing support is preferably used in terms of photographic images. The swelling layer, which is an ink receiving layer, absorbs ink when the ink receiving layer made of a water-soluble polymer swells. The fine void layer is composed of inorganic or organic fine particles having a secondary particle size of about 20 to 200 nm and a binder, and fine voids of about 100 nm absorb ink.

<Inkjet recording method>
In the inkjet image recording method of the present invention, a polymer compound having a plurality of side chains in the hydrophilic main chain of the present invention and capable of crosslinking between the side chains by irradiation with active energy rays (polyvinyl acetate ken Ink jet ink or ink jet ink set having a polymerization degree of 200 or more and less than 500) is ejected onto a recording medium, and the ink is cured by irradiation with active energy rays.

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

[Active energy ray irradiation]
(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 ink landing)
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 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 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 inkjet 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.

(Printer parts)
As a member used in the ink jet printer used in the ink jet recording method of the present invention, in order to prevent irradiation of the head surface due to irregular reflection of actinic rays, for example, ultraviolet rays, a material having a low transmittance or reflectance with respect to active energy rays is preferable. .

  The irradiation unit preferably has a shutter mounted. For example, when ultraviolet rays are used, the ratio of illuminance when opening and closing the shutter is preferably shutter open / shutter close = 10 or more, more preferably 100 or more. Preferably it is 10,000 or more.

  Next, an inkjet printer used in the inkjet image recording method of the present invention will be described.

〔inkjet printer〕
As an ink jet printer that can be used in the present invention, for example, image formation is arranged horizontally, and the back surface of the recording medium in a predetermined range on the upper surface (the surface opposite to the image forming surface side) is driven by the suction device. Equipped with a platen that is sucked and supported by a recording head, a recording head that discharges ink from a nozzle outlet toward a recording medium, and an irradiation unit that includes these recording head and actinic rays, and moves in the scanning direction during image formation A carriage, a drive circuit board mounted on the carriage and for driving the carriage, a guide member extending along the scanning direction to guide the movement of the carriage, and extending along the scanning direction; In the longitudinal direction, the linear scale on which the optical pattern is arranged and the optical pattern that is mounted on the carriage and arranged on the linear scale are read. It is constituted by a linear encoder sensor that outputs a clock signal.

  The recording head is arranged so that the image forming surface of the recording medium conveyed on the platen and the nozzle surface on which the ejection port of the recording head is formed face each other during image recording. Each head is supplied with ink from a recording ink cartridge and a colorless ink cartridge through a piping tube. A plurality of heads are provided as necessary. For example, when using cyan, magenta, and black / dark inks, yellow ink, and colorless ink, eight recording heads are provided. Irradiation means having an actinic ray is provided on both sides of the recording head.

(Recording head)
The recording head (ink jet print head) to be used may be an on-demand system or a continuous system. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, a thermal type) Examples thereof include an ink jet type, a bubble jet (registered trademark) type, an electrostatic suction type (for example, an electric field control type, a slit jet type, etc.), and a discharge type (for example, a spark jet type). The electro-mechanical conversion method is preferable, but any discharge method may be 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.

<< 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 compounds 2 to 8]
In the synthesis of polymer compound 1, the polymerization degree and saponification degree of polyvinyl acetate saponified product were changed as shown in Table 1, and the amount of p- (3-methacryloxy-2-hydroxypropyloxy) benzaldehyde was changed. Then, 10% aqueous solutions of polymer compounds 2 to 8 having the modification rate of the main chain PVA described in Table 1 were synthesized.

<Preparation of ink set>
Ink sets 1 to 14 using dyes as coloring materials were prepared as follows.

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

(Preparation of magenta ink 1)
C. I. Acid Red 35 5 parts 10% aqueous solution of polymer compound 1 20 parts Glycerol 7 parts Diethylene glycol 15 parts Diethylene glycol monobutyl ether 2 parts Olfine e1010 (manufactured by Nissin Chemical Co., Ltd.) 0.2 parts As a result, magenta ink 1 was obtained.

(Preparation of black ink 1)
In the preparation of the magenta ink 1, the C.I. I. Instead of Acid Red 35, C.I. I. A black ink 1 was obtained in the same manner except that Direct Black 19 was used.

[Preparation of ink set 2]
The ink set 1 was prepared in the same manner as in the ink set 1 except that a 10% aqueous solution of the polymer compound 2 having a main chain PVA modification rate of 0.5 mol% was used instead of the 10% aqueous solution of the polymer compound 1. Set 2 was obtained.

[Preparation of ink set 3]
The ink set 1 was prepared in the same manner as in the ink set 1 except that a 10% aqueous solution of the polymer compound 3 having a main chain PVA modification rate of 4.5 mol% was used instead of the 10% aqueous solution of the polymer compound 1. Set 3 was obtained.

[Preparation of ink set 4]
In the preparation of the ink set 1, instead of the 10% aqueous solution of the polymer compound 1, a 10% aqueous solution of the polymer compound 4 having a main chain PVA modification rate of 1.0 mol% was used, and the solid content addition amount was 3 mass. Ink set 4 was obtained in the same manner except that it was changed to%.

[Preparation of ink set 5]
Ink set 5 was obtained in the same manner as in the preparation of ink set 1 except that the solid content addition amount of polymer compound 1 was changed to 0.5% by mass.

[Preparation of ink set 6]
Ink set 6 was obtained in the same manner as in the preparation of ink set 1 except that the solid content addition amount of polymer compound 1 was changed to 5.5% by mass.

[Preparation of ink set 7]
In the preparation of the ink set 1, the ink set 7 was prepared in the same manner except that a 10% aqueous solution of the polymer compound 5 having a polymerization degree of the main chain PVA of 200 was used instead of the 10% aqueous solution of the polymer compound 1. Obtained.

[Preparation of ink set 8]
In the preparation of the ink set 1, the ink set 8 was prepared in the same manner except that a 10% aqueous solution of the polymer compound 6 having a main chain PVA polymerization degree of 450 was used instead of the 10% aqueous solution of the polymer compound 1. Obtained.

[Preparation of ink set 9]
In the preparation of the ink set 1, instead of the 10% aqueous solution of the polymer compound 1, a 10% aqueous solution of the polymer compound 7 having a polymerization degree of the main chain PVA of 1000 and a modification rate of 2.5 mol% was used. Similarly, an ink set 9 was obtained.

[Preparation of ink set 10]
In the preparation of the ink set 1, instead of the 10% aqueous solution of the polymer compound 1, the same was performed except that the polymerization rate of the main chain PVA was changed to 180% and the modification rate was 3 mol%. Thus, an ink set 10 was obtained.

[Preparation of ink set 11]
An ink set 11 composed of a magenta ink 11 and a black ink 11 prepared according to the following procedure was prepared.

(Preparation of magenta ink 11)
1,4-butadiol diepoxyacrylate (BASF, LR8765) 10 parts Irgacure 651 (Ciba Specialty Chemicals photopolymerization initiator) 0.4 parts C.I. I. Acid Red 35 4 parts Neugen ET150 10% aqueous solution (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 11.

(Preparation of black ink 11)
In the preparation of the magenta ink 11, C.I. I. Instead of Acid Red 35, C.I. I. A black ink 11 was obtained in the same manner except that direct black 19 was used.

[Preparation of ink set 12]
Ink set 12 was obtained in the same manner as in the preparation of ink set 1 except that the same amount of water was used instead of the 10% aqueous solution of polymer compound 1.

[Preparation of ink set 13]
In the preparation of the ink set 1, the ink set 13 was prepared in the same manner except that a 10% polyvinyl alcohol aqueous solution (polymerization degree 300, saponification degree 88%) was used instead of the 10% aqueous solution of the polymer compound 1. Obtained.

[Preparation of ink set 14]
Ink set 14 was obtained in the same manner as in the preparation of ink set 1, except that instead of the 10% aqueous solution of polymer compound 1, the following change was made to Takelac W-6060 (manufactured by Takeda Pharmaceutical).

Takelac W-6060: Takeda Pharmaceutical Co., Ltd., urethane-based soap-free latex, solid content concentration 30%, Tg = 25 ° C., average particle size = 150 nm
[Preparation of ink sets 15 to 28]
In the preparation of the ink sets 1 to 14, ink sets 15 to 28 were obtained in the same manner except that the following magenta pigment dispersion and the following black pigment dispersion were used instead of the dye used as the colorant. .

(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 diameter of the magenta pigment particles contained in this magenta pigment dispersion was 81 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

C. I Pigment Red 122 12 parts Jonkrill 61 (acrylic styrene resin dispersant, manufactured by Johnson) 3 parts Glycerin 15 parts Ion-exchanged water 61 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 diameter of the carbon black particles contained in the obtained black pigment dispersion was 154 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

[Preparation of ink set 29]
Magenta ink 29 and black ink 29, which are solvent-based actinic ray curable inks, were prepared as described below, and ink set 29 was prepared.

(Preparation of magenta ink 29)
C. I. Pigment Red 122 10 parts Ajisper PB821 (manufactured by Ajinomoto Fine Techno) 3 parts Aronix M5700 (manufactured by Toagosei Co., Ltd.) 7 parts Ethylene oxide added 1,6 hexanediol acrylate 72 parts 3-methoxybutyl acrylate 8 parts Irgacure 369 (manufactured by Ciba Specialty Chemicals) 5 parts After mixing and stirring each of the above compositions, the resulting solution was filtered through a filter to prepare actinic ray curable magenta ink 29.

(Preparation of black ink 29)
Carbon black (manufactured by Mitsubishi Chemical Corporation, MA-7) 10 parts Azisper PB821 (manufactured by Ajinomoto Fine Techno) 3 parts Aronix M5700 (manufactured by Toagosei Co., Ltd.) 7 parts Ethylene oxide-added 1,6-hexanediol acrylate 72 parts 3-methoxybutyl acrylate 8 Part Irgacure 369 (manufactured by Ciba Specialty Chemicals) 5 parts After mixing and stirring each of the above compositions, the resulting solution was filtered through a filter to prepare actinic radiation curable black ink 29.

<< Formation and evaluation of inkjet image >>
(Evaluation of feathering resistance)
A piezo-type head having a nozzle diameter of 25 μm, a driving frequency of 12 kHz, a nozzle number of 128, a nozzle density of 180 dpi (dpi represents the number of dots per 2.54 cm (1 inch)), and a maximum recording density of 720 × 720 dpi on. Using a demand-type inkjet printer, print a black thin line 400 μm wide and 5 cm long on plain paper (Ricoh's full-color PPC paper type 6000), then visually observe it and evaluate the feathering resistance according to the following criteria. went.

  In addition, each ink was continuously ejected, and after landing for 0.1 seconds, 120 W / cm metal halide lamps (MAL 400NL power supply power 3 kW · hr, manufactured by Nihon Battery Co., Ltd.) disposed at both ends of the piezoelectric head were irradiated.

◎: Thin lines are reproduced without blurring due to bleeding ○: Lines are not thickened due to bleeding, but less than 5 spots, ink bleeding along the paper fiber is observed Δ: Lines are thickened due to bleeding No, but ink bleeding along the paper fiber is observed at 5 or more and less than 10 locations. X: The line is slightly thickened due to bleeding, and ink bleeding along the paper fiber is also observed at 10 or more and less than 20 locations. XX: Line thickening due to bleed is intense, and ink bleed along the paper fiber is observed at 20 or more locations. Of these, XX and XX are levels that are problematic as products.

(Evaluation of beading resistance)
Using an on-demand ink jet printer with a maximum recording density of 720 x 720 dpi, using a piezo-type head with a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle number of 128, and a nozzle density of 180 dpi, art paper (OK Koji Fuji manufactured by Oji Paper) A 5 cm × 5 cm magenta solid was printed and then visually observed, and beading resistance was evaluated according to the following criteria.

  In addition, each ink was continuously ejected, and 0.1 seconds after landing, 120 W / cm metal halide lamps (MAL 400NL manufactured by Nihon Battery Co., Ltd., power supply power 3 kW · hr) disposed at both ends of the piezoelectric head were irradiated.

◎: Uniform image ○: Mottled noise, which can be seen by looking closely, is present in less than 5 places. △: Mottled noise, which can be seen by looking closely, is present in 5 or more, and less than 10 places. There are 10 or more noises. XX: There are 20 or more mottled noises. Of these, XX and XX are levels that are problematic as products.

(Evaluation of color bleed resistance)
Using an on-demand ink jet printer with a maximum recording density of 720 x 720 dpi, using a piezo-type head with a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle number of 128, and a nozzle density of 180 dpi, art paper (OK Koji Fuji manufactured by Oji Paper) A black thin line with a width of 200 μm was printed on a magenta solid on plain paper (full color PPC paper type 6000 manufactured by Ricoh Co., Ltd.) and then visually observed, and bleed resistance was evaluated according to the following criteria.

  In addition, each ink was continuously ejected, and 0.1 seconds after landing, 120 W / cm metal halide lamps (MAL 400NL manufactured by Nihon Battery Co., Ltd., power supply power 3 kW · hr) disposed at both ends of the piezoelectric head were irradiated.

◎: 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 (evaluation of scratch resistance)
In the same manner as the evaluation of beading resistance, a black fine line having a width of 100 μm was printed on art paper, and after 10 minutes, the black fine line image was rubbed with a finger five times, and the scratch resistance was evaluated according to the following criteria.

◎: No change in the printed image ○: Slight scratches are observed when observed in detail, but there is no problem in practical use △: A small amount of scratches is observed, but the quality is within the practically acceptable limit ×: Image density decreases with the occurrence of scratches, and is a quality that is a problem in practical use. XX: The formed black thin line image peels off from the recording paper, and is an unacceptable quality (evaluation of water resistance).
In the same manner as the evaluation of beading resistance, a black fine line with a width of 100 μm is printed on art paper, pure water is dropped after 10 minutes, and after 15 seconds, the black fine line image is rubbed 5 times with a finger, according to the following criteria. The water resistance was evaluated.

◎: No change in the printed image ○: Slight scratches are observed when observed in detail, but there is no problem in practical use △: A small amount of scratches is observed, but the quality is within the practically acceptable limit ×: Image density decreases with the occurrence of scratches, and this is a quality that is practically problematic. XX: The formed black thin line image peels off from the recording paper, and is an unacceptable quality (evaluation of glossiness)
Using an on-demand type ink jet printer with a maximum recording density of 720 × 720 dpi, using a piezo head with a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle number of 128, and a nozzle density of 180 dpi, art paper (Koji Fuji manufactured by Oji Paper) A black solid of 10 cm × 10 cm was printed, visually observed, and glossiness was evaluated according to the following criteria.

  In addition, each ink was continuously ejected, and after landing for 0.1 seconds, 120 W / cm metal halide lamps (MAL 400NL power supply power 3 kW · hr, manufactured by Nihon Battery Co., Ltd.) disposed at both ends of the piezoelectric head were irradiated.

◎: Natural difference between glossiness of recording surface and background is almost natural ○: Glossiness of recording surface and background is slightly different, but acceptable level Δ: Visual observation that glossiness of recording surface and background is slightly different X: The glossiness of the recording surface is remarkably higher than that of the background. X: It is possible to visually observe that the glossiness of the recording surface and the background is clearly different, and the glossiness of the recording surface is remarkably higher than that of the background. It is possible to visually observe that the glossiness of the recording media is clearly different, and the glossiness of the recording surface is significantly lower than that of the base (density measurement)
Using a piezo-type head with a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle count of 128, and a nozzle density of 180 dpi, using an on-demand type ink jet printer with a maximum recording density of 720 × 720 dpi, plain paper (full color PPC paper type manufactured by Ricoh) 6000) was printed with a black solid of 10 cm × 10 cm, and the black density was measured with a reflection densitometer of X-Rite, and evaluated according to the following criteria.

  In addition, each ink was continuously ejected, and after landing for 0.1 seconds, 120 W / cm metal halide lamps (MAL 400NL power supply power 3 kW · hr, manufactured by Nihon Battery Co., Ltd.) disposed at both ends of the piezoelectric head were irradiated.

◎: Black density 1.5 or more ○: Black density 1.4 or more, less than 1.5 △: Black density 1.2 or more, less than 1.4 ×: Black density 0.8 or more, less than 1.2 XX: Black density less than 0.8 (Evaluation of intermittent emission stability)
Using the above prepared ink sets 1 to 29, a piezo-type head having a nozzle diameter of 25 μm, a drive frequency of 12 kHz, a nozzle number of 128, and a nozzle density of 180 dpi, and using an on-demand type ink jet printer with a maximum recording density of 720 × 720 dpi, Intermittent operation of continuous discharge for 10 seconds → pause for a fixed time → continuous discharge was performed. At this time, since whether or not the discharge direction is disturbed at the beginning after the discharge pause is determined by the length of the pause time, the stability of intermittent discharge is measured by changing the length of the discharge pause time stepwise. The evaluation was based on the following criteria. The evaluation was performed at an environmental temperature of 23 ° C. and a humidity of 55% RH.

5: Stable discharge even when paused for 31 to 45 seconds 4: Stable discharge even after 21 to 30 seconds pause 3: Stable discharge even after 11 to 20 seconds pause 2: 6 to 10 seconds pause However, stable discharge was performed for only 1 to 5 seconds or less. Table 2 shows the results obtained as described above.

  As is apparent from the results shown in Table 2, the ink set of the present invention is formed without depending on the type of the recording medium, regardless of whether the color material is a dye-based ink or a pigment-based ink. It can be seen that the feathering resistance, beading resistance, bleed resistance, scratch resistance and water resistance of the obtained image are improved, the glossiness and the intermittent emission property are excellent, and a high image density can be obtained.

  Moreover, in the said evaluation, it replaced with art paper, As a result of having performed the same evaluation using the coated paper for printing (art post Yasutsubo: 256g made by Hokuetsu Paper Manufacturing Co., Ltd.) and a non-absorbent recording medium (polyester film), It was confirmed that the same effect as that obtained when the art paper described in 2 was used.

Claims (10)

An inkjet ink 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 ink, wherein the hydrophilic main chain of the polymer compound is a saponified product of polyvinyl acetate and the degree of polymerization is 200 or more and less than 500. The inkjet ink according to claim 1, wherein a modification rate of the side chain with respect to the hydrophilic main chain is 0.8 mol% or more and 4.0 mol% or less. The inkjet ink according to claim 1 or 2, wherein the addition amount of the polymer compound is 0.8% or more and 5.0% or less. The inkjet ink according to claim 1, further comprising a water-soluble photopolymerization initiator. An ink jet ink set comprising two or more ink jet inks, wherein at least one of the ink jet inks is the ink jet ink according to any one of claims 1 to 4. An ink jet recording method, comprising: discharging the ink jet ink according to claim 1 onto a recording medium, irradiating the ink jet ink with active energy rays, and drying the ink. An ink jet recording method comprising: discharging an ink jet ink constituting the ink jet ink set according to claim 5 onto a recording medium, irradiating the ink jet ink with active energy rays, and drying the ink. 8. The ink jet recording method according to claim 6, wherein the recording medium is plain paper. The ink jet recording method according to claim 6 or 7, wherein the recording medium is art paper or coated paper. The inkjet recording method according to claim 6 or 7, wherein the recording medium is a non-absorbable recording medium.