JP2007161887A - Ink jet ink, ink jet ink set and ink jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet ink which has printing suitability for various recording media, is excellent in color breeding resistance, beading resistance, and image weather resistance, and give images exhibiting excellent glosses, to provide an ink jet ink set, and to provide an ink jet recording method using the same. <P>SOLUTION: This ink jet ink is characterized by including at least water, active energy ray-reactive resin fine particles, and a polymer which has side chains on a hydrophilic main chain and can be cross-linked among the side chains by the irradiation of active energy rays. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet ink containing an active energy ray-reactive polymer compound, 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 no substantial amount of ink evaporated at the time of 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 in quality due to the rising of the dots and insufficient scratch resistance 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 a ketone or alcohol as a main solvent has been proposed (see Patent Document 4). An aqueous active energy ray-curable ink jet recording ink composition containing a polyurethane compound, a basic compound, a colorant, a water-soluble organic solvent and water containing a group having an active energy ray-curable unsaturated double bond Has been proposed (see Patent Document 5). Furthermore, a water-based inkjet ink comprising a self-dispersing pigment having one or more hydrophilic groups bonded to the surface of pigment particles, an ultraviolet curable monomer made of a vinyl compound, a photopolymerization initiator, and water ( Patent Document 6), and inkjet inks (see Patent Documents 7 and 8) containing active energy ray-reactive resin fine particles in an aqueous medium have been proposed.

Many of these proposed active energy ray reactive inks can be recorded on a non-absorbent recording medium because the ink itself is cured by a curing component, but an image forming portion and a non-image portion ( This results in an unnatural and uncomfortable image quality due to the difference in glossiness from the white background portion, and as a result, the image uniformity is impaired. In addition, some of these proposed active energy ray reactive inks have insufficient curability, and it has been found that some of the formed images cause color bleeding and beading, which requires immediate improvement. ing.
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 2002-80767 A JP 2002-275404 A JP 2001-115067 A JP 2001-311020 A

  The present invention has been made in view of the above problems, and its purpose is to have printability on various recording media, excellent color bleed resistance, beading resistance, image weather resistance, and excellent gloss. An object of the present invention is to provide an ink-jet ink, an ink-jet ink set, and an ink-jet recording method using the ink-jet ink that can obtain the image shown.

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

  1. It has a plurality of side chains in water, active energy ray-reactive resin fine particles, and a hydrophilic main chain, and contains a polymer compound that can be cross-linked between side chains by irradiating active energy rays. Inkjet ink.

  2. 2. The inkjet ink according to 1, wherein the hydrophilic main chain of the polymer compound capable of crosslinking between the side chains is a saponified product of polyvinyl acetate.

  3. 3. The inkjet ink according to 1 or 2, wherein a modification rate of the side chain with respect to the hydrophilic main chain of the polymer compound capable of cross-linking between the side chains is 0.8 to 4.0 mol%.

  4). 4. The inkjet ink according to any one of 1 to 3, wherein the hydrophilic main chain of the polymer compound capable of crosslinking between the side chains has a degree of polymerization of 200 to 500.

  5. The inkjet ink according to any one of claims 1 to 4, wherein the content of the polymer compound capable of crosslinking between the side chains is 0.8 to less than 5% by mass.

  6. 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 1 to 5.

  7. An ink jet recording method comprising discharging the ink jet ink according to any one of items 1 to 5 onto a recording medium, irradiating the ink jet ink with active energy rays, and drying the ink.

  8. An ink jet recording method comprising discharging an ink jet ink constituting the ink jet ink set described in 8.6 onto a recording medium, irradiating the ink jet ink with active energy rays, and then drying.

  9. 9. The inkjet recording method according to 7 or 8, wherein the recording medium is a coated paper for printing.

  10. 9. The ink jet recording method according to 7 or 8, wherein the recording medium is a non-absorbent recording medium.

  INDUSTRIAL APPLICABILITY According to the present invention, an inkjet ink, an inkjet ink set, and an ink jet ink set that have printability on various recording media, are excellent in color bleed resistance, beading resistance, image weather resistance, and are excellent in glossiness can be obtained. The ink jet recording method used could be provided.

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

  As one of the active energy ray reactive inks, an ink containing active energy ray reactive resin fine particles in an aqueous medium is known (Patent Documents 7 and 8). Although these inks exhibit fixability to various media, they have a drawback that the ink is not sufficiently thickened by irradiation with active energy rays and color bleeding and beading cannot be effectively prevented. For this reason, Patent Document 7 describes an embodiment in which pre-drying is performed before active energy ray irradiation. However, new problems such as deterioration of the emission property due to pre-drying around the print area are caused. It was a result.

  The present inventor has analyzed the above-mentioned problems of preventing color bleeding and beading. When resin fine particles are used as the active energy ray-reactive component, reactive groups are localized on the surface of the fine particles. It has been clarified that the establishment of collision between the sex groups is reduced and the reaction efficiency is lowered, and a sufficient thickening effect cannot be obtained unless the interparticle distance is brought close to some extent by pre-drying or the like.

  Based on the analysis results, various studies were conducted on the second reactive component that effectively increases the viscosity of the ink. As a result, water, active energy ray-reactive resin fine particles, and a hydrophilic main chain have a plurality of side chains. An inkjet ink comprising at least a polymer compound capable of crosslinking between side chains by irradiation with active energy rays, or an ink set including the inkjet ink, and an inkjet recording using the inkjet ink According to the method, it is possible to realize an ink jet ink, an ink jet ink set, and an ink jet recording method using them, which have printability on various recording media and can obtain an image excellent in color bleeding resistance, beading resistance and image gloss. It is up to the headline and the present invention.

  Hereinafter, the present invention will be described in detail.

  In the inkjet ink of the present invention (hereinafter, also simply referred to as ink), 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 (hereinafter, referred to as “ink”). It is also characterized by containing a crosslinkable polymer compound).

<Crosslinkable polymer compound>
Examples of the hydrophilic main chain of the crosslinkable polymer compound according to the present invention include saponified polyvinyl acetate, polyvinyl acetal, polyethylene oxide, polyalkylene oxide, polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, hydroxyethyl cellulose, methyl cellulose, hydroxy And propyl cellulose.

  Among these, when the hydrophilic main chain is a saponified product of polyvinyl acetate, the introduction of the side chain is simplified and the handleability is improved. The degree of polymerization of the main chain is in the range of 200 to 2000, but the degree of polymerization is particularly preferably 200 to 500 from the viewpoint of sufficiently achieving the object effects of the present invention. If the degree of polymerization is 200 or more, a moderate increase in viscosity during the crosslinking reaction can be imparted, and color bleed and beading described later can be sufficiently prevented. If the degree of polymerization is 2000 or less, an increase in viscosity when added to the ink can be suppressed, and good emission stability can be obtained.

  For the side chain, a modifying group such as a photodimerization type, a photodecomposition type, a photopolymerization type, a photomodification type, and a photodepolymerization type can be introduced. From the viewpoint of reactivity with the color material to be combined, the side chain is preferably nonionic, anionic, or amphoteric (betaine compound). Particularly, when the color material is combined with an anionic dye or an anionic pigment, the side chain is It is preferably nonionic or anionic, and particularly preferably nonionic.

  The modification rate of the side chain with respect to the hydrophilic main chain is preferably 0.8 to 4.0 mol%, and more preferably 1.5 to 3.0 mol% 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 object effect of the present invention can be 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 ink-jet ink of the present invention, when a polymer compound having a photopolymerizable modifying group is used, it is preferable to use a known photopolymerization initiator, and it is particularly preferable to use a water-soluble photopolymerization initiator.

  As the water-soluble photopolymerization initiator applicable in the inkjet 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-crosslinked polymer compound, the main chain originally having a certain molecular weight is cross-linked between the side chains through a cross-linking bond. The effect of increasing the molecular weight per photon is remarkably large compared to a conventionally known active energy ray-curable resin produced by polymerization. Therefore, the crosslinkable groups of the polymer compound or the crosslinkable groups of the polymer compound and the reactive groups of the active energy ray resin fine particles repeat the reaction, thereby dramatically increasing the molecular weight and increasing the viscosity of the ink. It is considered that color bleeding and beading can be effectively prevented.

  Furthermore, since many inks using a conventionally known active energy ray-curable resin are components that are involved in curing, except for the color material, the dots after curing rise and the image quality represented by gloss is significantly deteriorated. On the other hand, in the ink of the present invention, a small amount of the active energy ray-crosslinking type polymer compound is used, and since there are many dry components, the image quality after drying is improved and the fixing property is good.

  The amount of the polymer compound added to the ink that has a plurality of side chains in the hydrophilic main chain according to the present invention and can be cross-linked between the side chains by irradiation with active energy rays is 0.8-5. It is preferably 0%.

  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 0.8% or more, sufficient crosslinkability to obtain the object effect of the present invention is obtained, and if it is 5.0% or less, there is little increase in viscosity due to ink drying, This is preferable because the intermittent emission stability is good.

  Next, the active energy ray reactive resin fine particles according to the present invention will be described.

<Active energy ray reactive resin fine particles>
The active energy ray-reactive resin fine particles according to the present invention have a group that reacts upon irradiation of active energy rays on the particle surface. Examples of the active energy ray reactive group include photopolymerizable groups such as acryloyl group, methacryloyl group, vinyl group, allyl group, and acryl group.

  The resin fine particles may be dispersed using an emulsifier, or may be dispersed without using an emulsifier. A surfactant is often used as an emulsifier, but a polymer having a water-soluble group such as a sulfonic acid group or a carboxylic acid group (for example, a polymer in which a solubilizing group is graft-bonded, a single group having a solubilizing group). It is also preferable to use a polymer obtained from a monomer and a monomer having an insoluble part.

  The resin fine particles dispersed without using an emulsifier are generally called soap-free latex. Many soap-free latexes have a hydrophilic group on the particle surface and can maintain dispersion stability in the ink for a long period of time. Examples of the hydrophilic group include a carboxyl group, a sulfonic acid group, an amide group, an amino group, and a hydroxyl group. Furthermore, a group obtained by neutralizing a carboxyl group or a sulfonic acid group with a basic compound and a group obtained by neutralizing an amino group with an acidic compound can also be used as preferred hydrophilic groups.

  The active energy ray-reactive resin fine particles according to the present invention are preferably composed mainly of a thermoplastic polymer. Examples of the thermoplastic polymer include acrylic, acrylate copolymer, polyester, vinyl acetate, vinyl chloride, styrene-butadiene copolymer, polyurethane, polystyrene, vinyl acetate-acrylic copolymer, vinyl acetate-acrylamide copolymer. Examples thereof include polymers such as a polymer, an ethylene-vinyl acetate copolymer, an epoxy resin, a polyamide resin, a silicone resin, an acrylonitrile-butadiene copolymer polyurethane, a silicone-acrylic copolymer, a fluororesin, and an acrylic-modified fluororesin.

  The average particle diameter of the active energy ray reactive fine particles according to the present invention is preferably 400 nm or less, more preferably 10 to 300 nm. An average particle diameter of 400 nm or less is preferable in terms of ejection stability and image gloss. The average particle size can be determined by a commercially available particle size measuring instrument using a light scattering method, an electrophoresis method, or a laser Doppler method.

  The active energy ray-reactive resin fine particles according to the present invention can be prepared by a known method. For example, it can be produced by first preparing resin fine particles by a method such as emulsion polymerization or soap-free polymerization, and then introducing an active energy ray-reactive group on the surface of the resin fine particles. A method for producing active energy ray-reactive resin fine particles is described in, for example, JP-A Nos. 62-177007, 64-80942 and 2003-40923.

  In the ink-jet ink of the present invention, the content of the active energy ray-reactive resin fine particles is preferably added so as to be less than 0.1 to 10% by mass relative to the total mass of the ink, and 0.5 to 5 mass % Is particularly preferable. When the amount of the solid content of the latex is 0.1% by mass or more, it is easy to obtain a sufficient effect with respect to weather resistance, and when it is less than 10% by mass, the ink storage stability such as thickening of the ink with time is increased. Problems are less likely to occur.

  Specific examples of the active energy ray-reactive resin fine particles include NK polymers RP-116ES, RP-116E, and RP-116EH manufactured by Shin-Nakamura Chemical Co., Ltd.

  Next, other components of the inkjet ink of the present invention will be described.

《Coloring material》
As the coloring material used in the inkjet ink of the present invention, a dye or a pigment can be used.

  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 inkjet ink of the present invention are listed below, but the present invention is not limited to these exemplified dyes.

  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.

  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.

  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 .

  Specific examples of pigments applicable to the ink-jet ink of the present invention are listed below, but the present invention is not limited 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, C.I. I. Pigment yellow 150, 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 ink-jet ink of the present invention, a self-dispersing pigment can also be used as a 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.

  As a method for obtaining pigment particles having a polar group on the surface, for example, WO 97/48769 pamphlet, JP-A Nos. 10-110129, 11-246807, 11-57458, 11- No. 189739, 11-323232, JP-A-2000-265094, etc., the surface of the pigment particles is treated with an appropriate oxidizing agent, so that at least a part of the pigment surface has a sulfonic acid group or a salt thereof. The method of introduce | transducing a polar group is mentioned. Specifically, it is prepared by oxidizing carbon black with concentrated nitric acid, or in the case of color pigments by oxidizing with sulfamic acid, sulfonated pyridine salt, amide sulfuric acid, etc. in sulfolane or N-methyl-2-pyrrolidone. can do. 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 derivatives described in JP-A-11-49974, JP-A-2000-273383, JP-A-2000-303014, etc. on the surface of pigment particles 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.

(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 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 size of the pigment in the ink of the present invention is preferably 10 to 1000 nm, more preferably 10 to 70 nm, from the viewpoint of light resistance and dispersion stability. If it is 10 nm or more, the light resistance of the image is hardly deteriorated, and if it is 100 nm or less, the problem that the head is clogged due to aggregation of the pigment is less likely to occur. Here, in order to obtain the 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.

"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.

  One or more water-soluble organic solvents may be used 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.

<Inkjet ink set>
The inkjet ink set of the present invention is composed of two or more types of inkjet inks, and at least one of the inkjet inks is the inkjet ink of the present invention.

  The ink-jet ink set of the present invention comprises the ink-jet ink described in claims 1 to 5, preferably two or more inks are the ink-jet ink of the present invention, and particularly preferably all the inks of the present invention. By being an inkjet ink, the effect of the present invention is remarkably exhibited.

  As inks 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 light yellow 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 preferable 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 same color inks having different densities in two or more inks, and in particular, at least two inks having the same color having different densities in three or more inks. It is preferable to use an inkjet ink set composed of

  This is because by using a low-density inkjet ink, the graininess can be reduced, and a high-quality image free from so-called “roughness” can be formed. 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 an arbitrary value. However, in order to perform 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 colorant density of the 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.

(White ink)
In the inkjet ink set of the present invention, a white ink containing a white pigment may be used in addition to the colored pigment. The white pigment used is not particularly limited as long as it makes the inkjet ink white, and examples thereof include inorganic white pigments, organic white pigments, and white hollow polymer fine particles.

  Examples of inorganic white pigments include sulfates of alkaline earth metals such as barium sulfate, carbonates of alkaline earth metals such as calcium carbonate, silicas such as fine silicate, synthetic silicate, calcium silicate, alumina , Alumina hydrate, titanium oxide, zinc oxide, talc, clay and the like. In particular, since titanium oxide has a high refractive index, it is fine and has high concealability and colorability, and can be preferably used.

  Examples of the organic white pigment include organic compound salts disclosed in JP-A No. 11-129613 and alkylene bismelamine derivatives disclosed in JP-A Nos. 11-14365 and 2001-234093. Specific examples of the white pigment include Shigenox OWP, Shigenox OWPL, Shigenox FWP, Shigenox FWG, Shigenox UL, and Shigenox U (all trade names manufactured by Hackol Chemical Co.).

  Examples of the white hollow polymer fine particles include thermoplastic fine particles made of a substantially organic polymer disclosed in US Pat. No. 4,089,800.

  In the present invention, the white pigment may be used alone or in combination. For the dispersion of the pigment, 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, a paint shaker, or the like can be used. Further, it is possible to add a dispersant when dispersing the pigment.

  A normal dispersant can be used as the dispersant, but a polymer dispersant is preferably used.

  The pigment is preferably dispersed with an average particle diameter of 0.05 to 1.0 μm, more preferably 0.08 to 0.3 μm.

(Colorless ink)
In the inkjet ink set of the present invention, a colorless ink (also referred to as a transparent ink) that does not substantially contain a color material can be used in combination.

  In the present invention, the colorless ink containing substantially no color material means a state in which the content of the color material is 0.1% or less with respect to the total ink mass, and preferably contains no color material. is there.

  The component contained in the colorless ink according to the present invention may be either uniformly dissolved or present in a non-uniform dispersion system. Examples of the resin that can be added include an aqueous resin in a dissolved state, an aqueous resin in a dispersed state, an organic solvent based resin in a dissolved state, an organic solvent based resin in a dispersed state, and the like. A resin dispersed in an aqueous system is preferred. Although colorless inks obtained by removing only the color material from the ink-jet ink used can be used, it is preferable to add the following additives in order to add various functions.

  Examples of resins that are dissolved in water include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, color ginnan (κ, ι, λ, etc.), agar, pullulan, water-soluble Polyvinyl butyral, hydroxyethyl cellulose, carboxymethyl cellulose and the like can be added.

  As the resin dispersed in an aqueous system, it is particularly preferable to add fine particles of a thermoplastic resin because the glossiness of the image is improved. As the thermoplastic resin fine particles, the thermoplastic resin that can be added to the surface layer of the recording medium or the kind described in the description of the fine particles can be used. In particular, it is preferable to apply those which do not cause thickening or precipitation even when added to the ink. The average particle size of the thermoplastic resin particles is preferably 0.5 μm or less. The fine particles of the thermoplastic resin to be added are preferably those that melt and soften in the range of 0 to 150 ° C.

《Other additives》
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, ultraviolet 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, JP-A-1-95091 and JP-A-3-13376, etc., and 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.

(Outgoing stabilizer for thermal)
The inkjet ink of the present invention may be used in a thermal inkjet printer. At this time, in order to solve the clogging of the head called kogation, (M ₁ ) ₂ SO ₄ , CH ₃ COO (M ₁ ), Ph-COO (M ₁ ) disclosed in Japanese Patent Laid-Open No. 2001-81379 ), (M ₁ ) NO ₃ , (M ₁ ) Cl, (M ₁ ) Br, (M ₁ ) I, (M ₁ ) ₂ SO ₃ and (M ₁ ) ₂ CO ₃ Good. Here, M ₁ represents an alkali metal, ammonium, or organic ammonium, and Ph represents a phenyl group. Examples of the alkali metal include Li, Na, K, Rb, and Cs. Examples of organic ammonium include methylammonium, dimethylammonium, trimethylammonium, ethylammonium, diethylammonium, triethylammonium, trihydroxymethylamine, dihydroxymethylamine, monohydroxymethylamine, monoethanolammonium, diethanolammonium, triethanol. Ammonium, N-methylmonoethanolammonium, N-methyldiethanolammonium, monopropanolammonium, dipropanolammonium, tripropanolammonium, etc. are mentioned.

(Crosslinking agent)
The inkjet ink of the present invention may contain a crosslinking agent. Specific examples of the crosslinking agent include, for example, epoxy curing agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl- 4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde curing agents (formaldehyde, glioxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy-1,3,5) , -S-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum, boric acid or a salt thereof.

(Anti-fading agent)
In the ink-jet ink of the present invention, a known anti-fading agent can be used in conventional ink-jet inks. This anti-fading agent suppresses fading caused by light irradiation and fading caused by various oxidizing gases such as ozone, active oxygen, NOx, and SOx. Examples of such anti-fading agents include antioxidants described in JP-A-57-74192, JP-A-57-87989, and JP-A-60-72785, and ultraviolet absorbers described in JP-A-57-74193. Hydrazides described in JP-A-61-154989, hindered amine antioxidants described in JP-A-61-146591, nitrogen-containing heterocyclic mercapto compounds described in JP-A-61-177279, The thioether antioxidants described in 1-111577 and 1-36479, the hindered phenol antioxidants having a specific structure described in JP-A-1-36480, JP-A-7-195824 and 8-150773. Ascorbic acids described in No. 7, zinc sulfate described in JP-A-7-149037, thiocyanic acid described in JP-A-7-314882 Thiourea derivatives described in JP-A-7-314883, saccharides described in JP-A-7-276790 and 8-108617, and phosphate-based antioxidants described in JP-A-8-118791. Examples thereof include nitrites, sulfites and thiosulfates described in JP-A-8-300807, and hydroxylamine derivatives described in JP-A-9-267544 as anti-fading agents. Furthermore, polycondensates of dicyandiamide and polyalkylene polyamines described in JP-A No. 2000-266928 and the like are also effective anti-fading agents in inkjet.

(PH buffer)
In the inkjet ink of the present invention, a pH buffer agent may be added to the ink. For example, organic acids and inorganic acids. Examples of the organic acid include nonvolatile phthalic acid, terephthalic acid, salicylic acid, benzoic acid, sebacic acid, lauric acid, palmitic acid, ascorbic acid, citric acid, malic acid, lactic acid, succinic acid, succinic acid, and polyacrylic acid. And various organic acids such as benzylic acid.

(Defoamer)
In the inkjet ink of the present invention, an antifoaming agent can be added, and a commercially available product can be used without any 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. When the compounding amount is 0.001% by mass or more, it is easy to generate bubbles during ink preparation and to remove small bubbles in the ink. When the compounding amount is 2% by mass or less, the print quality is deteriorated. Hateful.

(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, 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.

<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, an inorganic fine particle, or a resin fine particle is prepared, aggregation or sedimentation does not occur in the preparation process. It is preferable to prepare an 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 dispersion and redispersing the agglomeration generated during the blending of the ink during or after blending, a dispersion process using a bead mill or ultrasonic waves, a heat treatment, or the like may be performed.

《Ink physical properties》
(viscosity)
Although there is no restriction | limiting in particular in the viscosity of the inkjet ink of this invention, It is preferable that the viscosity in 25 degreeC is 2-10 mPa * s. Moreover, it is preferable that the viscosity of the inkjet ink of the present invention has no shear rate dependency.

  The ink viscosity (mPa · s) in the present invention is not particularly limited as long as it is tested with a standard solution for calibration of a viscometer specified in JIS Z 8809, and is measured at 25 ° C. according to a known method. As the viscosity measuring device, a rotary, vibration or capillary type viscometer can be used, for example, a Saybolt viscometer, a Redwood viscometer, etc., for example, a cone plate type manufactured by Tokimec E type viscometer, Toki Sangyo E Type Viscometer (rotary viscometer), Tokyo Keiki B type viscometer BL, Yamaichi Denki FVM-80A, Nametor Kogyo Viscoliner VISCO MATE MODEL VM-1A, DD-1 manufactured by Denki Co., Ltd. can be exemplified.

(surface tension)
Moreover, in the inkjet ink of this invention, it is preferable that surface tension is 40 mN / m or less, More preferably, it is 25-35 mN / m.

  The surface tension (mN / m) of the ink referred to in the present invention is a value obtained by measuring the surface tension measured at 25 ° C., and the measurement method is described in general interface chemistry, colloid chemistry reference books, etc. For example, New Experimental Chemistry Course Volume 18 (Interface and Colloid), The Chemical Society of Japan, published by Maruzen Co., Ltd. 68-117 can be referred to. Specifically, it can be determined using a ring method (Dunoi method) or a platinum plate method (Wilhelmy method), but in the present invention, it is represented by a surface tension value (mN / m) measured by the platinum plate method. For example, it can be measured using a surface tension meter CBVP-Z manufactured by Kyowa Interface Science.

(Electrical conductivity)
In the inkjet ink of the present invention, from the viewpoint of ink storage stability, the electrical conductivity is preferably 1 to 500 mS / m, more preferably 1 to 200 mS / m, and still more preferably 10 to 100 mS / m. It is. If the electric conductivity of the ink is 1 mS / m or more, sufficient electrostatic repulsion can be obtained and the dispersion can be made to exist stably. If the ink conductivity is 500 mS / m or less, poor emission due to deposition of coloring material occurs. It becomes difficult.

  In the ink-jet ink of the present invention, there is no particular limitation as a means for achieving a desired electrical conductivity. In the present invention, a pigment is used as a colorant, and a polymer compound (polymer dispersant) is used as a pigment dispersant. The method used or a method using an electrical conductivity modifier, for example, an inorganic salt such as potassium chloride, ammonium chloride, sodium sulfate, sodium nitrate, or sodium chloride, or an aqueous amine such as triethanolamine is appropriately selected or combined. Can be achieved.

  The measurement of the electrical conductivity of the ink in the present invention should be easily performed according to the method described in JIS K 0400-13-10 (1999) or the method disclosed in JP-A-61-61164. Can do.

(Ion concentration adjustment)
In preparing the inkjet ink of the present invention, it is preferable to adjust the ion concentration as appropriate.

  An aqueous dye solution having a predetermined concentration is measured by ICP-AES, and the ion concentration of the ink state is calculated in terms of the dye concentration used in the ink. By using distilled water or ion-exchanged water, the ion concentration at the time of ink formation can be estimated.

  Next, an ink is prepared by adding other additives and the like, and the ion concentration in the ink is measured by ICPAES. When the target ion concentration is exceeded, the ion concentration can be lowered by passing the aqueous dye solution through an ion exchange resin. Ion exchange can be performed multiple times to further reduce the ion concentration. If the desired ion concentration is not reached, the additives other than the dye are also subjected to treatment such as ion exchange. Moreover, you may add processes, such as filtration by an activated carbon process or an ultrafiltration membrane, as needed.

(Deaeration treatment)
The dissolved oxygen concentration in the inkjet ink of the present invention is preferably 2 ppm or less, more preferably 1 ppm or less. When the dissolved oxygen concentration in the ink-jet ink is 2 ppm or less, cavitation at the time of ink ejection is suppressed, and emission defects are less likely to occur.

  The method for adjusting the dissolved oxygen concentration is not particularly limited. However, as described in JP-A-11-209670, a method for degassing an inkjet ink under reduced pressure, a method for degassing by irradiating ultrasonic waves, and a method for degassing. Examples include a degassing method using a hollow fiber membrane. In particular, degassing with a degassing hollow fiber membrane is preferred.

"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. The recording medium is preferably a recording medium.

[Coated paper for printing]
Coated paper for printing is coated paper often used in printing. Generally, high-quality paper or medium-quality paper is used as the base paper, and after applying a pigment such as clay on the surface of the paper, smoothness is improved. Therefore, it is produced by applying a calendar process. Such processing improves whiteness, smoothness, printing ink acceptability, halftone dot reproducibility, printing gloss, printing opacity, and the like. The paper is classified into art paper, coated paper, lightweight coated paper, etc., depending on the coating amount, and is classified into glossy, dull, matte, etc., depending on the gloss of the paper.

Art paper is coated paper having a coating amount of about 20 g / m ^{2 on} one side, and is generally prepared by applying a pigment to the paper surface and then applying a calendar treatment. There are special art, medium art, matte (matte) art, single art (single side coating), double art (double side coating), and more specifically, OK Kanto N, Satin Kanto N, SA Kanou, Ultra Satin Kinto N, OK Ultra Aqua Satin, OK Kanto One Side, N Art Post, NK Special Sided Art, Thunderbird Super Art N, Thunderbird Super Art MN, Thunderbird Art N, Thunderbird Dull Art N, Hi McKinley Art, Hi McKinley Mat, High McKinley Pure Dull Art, Hi McKinley Super Dal, Hi McKinley Mat Elegance, Hi McKinley Deep Mat, etc.

The coated paper is a coated paper having a coating amount of about 10 g / m ^{2 on} one side, and is generally produced by processing with a coating apparatus provided in the middle of the paper machine. The coating amount is smaller than that of art paper, and the smoothness is slightly reduced, but the advantages are low cost and light weight. There is also a type of coated paper with a smaller coating amount, such as a light-weight coat and a finely coated paper. Specific examples of these coated papers include POD gloss coat, OK top coat +, OK top coat S, aurora coat, mu coat, mu white, thunderbird coat N, utrilo coat, pearl coat, white pearl coat, POD mat coat, New Age, New Age W, OK top coat mat N, OK royal coat, OK top coat dull, Z coat, Silver diamond, Ulite, Neptune, Mu mat, White mu mat, Thunderbird mat coat N, Utrilogros mat, New V mat, white new V mat, etc. are mentioned.

[Non-absorbent recording medium]
As the non-absorbent 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, YUPO paper that is synthetic paper, and the like can also be used.

<Inkjet recording method>
The ink jet recording method of the present invention is characterized in that the ink jet ink or ink jet ink set of the present invention is ejected onto a recording medium, and the ink is cured by irradiating active energy rays and then dried.

  Hereinafter, a method for irradiating the inkjet ink with active energy rays 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 0.1 Mrad or more, a sufficient irradiation effect is easily obtained, and if it is 30 Mrad or less, there is little possibility of deteriorating the support or the like, which is preferable.

  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 first, the active energy rays are 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. The irradiation of the active energy ray at the second stage may be performed before or after the drying process. 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.

(Drying after curing)
In the ink jet recording method of the present invention, the ink jet ink discharged onto the recording medium is irradiated with active energy rays and cured, and then dried for the purpose of removing unnecessary water-soluble organic solvents and the like.

  The ink drying means is not particularly limited. For example, a method of drying the recording medium by bringing the back surface of the recording medium into contact with a heating roller or a flat heater, a means of blowing hot air on the printing surface with a dryer, or a decompression process. A method for removing volatile components and the like can be appropriately selected or combined.

(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. .

  In addition, the irradiation unit is preferably equipped with a shutter. 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, and 100 or more. More preferred 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. Device configured by a linear encoder sensor that outputs a clock signal and the like.

(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 attraction method (for example, an electric field control type, a slit jet type, etc.), and a discharge method (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.

<< Preparation of crosslinkable polymer compound >>
[Preparation of Crosslinkable Polymer Compound 1]
After 100 g of polyacrylic acid (degree of polymerization 300) was heated and dissolved in 750 g of ethanol, 5.6 g of 4-hydroxybutyl acrylate glycidyl ether (corresponding to a modification rate of 2 mol% with respect to polyacrylic acid) and pyridine as a catalyst 11g was added and it stirred for 24 hours, keeping at 60 degreeC. Furthermore, after raising the temperature of this solution to 95 ° C. and distilling off ethanol while adding water dropwise, it was treated with an ion exchange resin (Mitsubishi Chemical: PK-216H) to remove pyridine, and the nonvolatile content concentration was reduced. A 15% aqueous solution was obtained. Then, it diluted with ion-exchange water and the 10 mass% aqueous solution of the crosslinkable polymer compound 1 was obtained. The crosslinkable polymer compound 1 has a plurality of side chains in polyacrylic acid, which is a hydrophilic main chain, and is a polymer compound that can be cross-linked between the side chains by irradiation with active energy rays.

[Preparation of crosslinkable polymer compound 2]
56 g of glycidyl methacrylate, 48 g of p-hydroxybenzaldehyde, 2 g of pyridine and 1 g of N-nitroso-phenylhydroxyamine ammonium salt were put in a reaction vessel, respectively, 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 250 and a saponification rate of 88% was dispersed in 225 g of ion-exchanged water, and then 4.5 g of phosphoric acid was added to this solution to obtain p- (3 -Methacryloxy-2-hydroxypropyloxy) benzaldehyde was added so that the modification rate was 0.7 mol% with respect to polyvinyl alcohol, and the mixture was stirred at 90 ° C. for 6 hours. After cooling the obtained solution to room temperature, 30 g of basic ion exchange resin was added and stirred for 1 hour. Thereafter, the ion exchange resin was filtered and diluted with pure water to obtain a 15% by mass aqueous solution of the crosslinkable polymer compound 2. The crosslinkable polymer compound 2 has a plurality of side chains in a saponified product of polyvinyl acetate, which is a hydrophilic main chain, and can be crosslinked between side chains by irradiating active energy rays. It is.

[Preparation of Crosslinkable Polymer Compound 3]
In the preparation of the crosslinkable polymer compound 2, the polymerization degree of the polyvinyl acetate saponified product was 300, the saponification rate was 98%, and the modification rate of p- (3-methacryloxy-2-hydroxypropyloxy) benzaldehyde with respect to polyvinyl alcohol was 3 A 15% by mass aqueous solution of the crosslinkable polymer compound 3 was obtained in the same manner except that the mol% was changed. The crosslinkable polymer compound 3 has a plurality of side chains in a saponified product of polyvinyl acetate, which is a hydrophilic main chain, and can be cross-linked between the side chains by irradiating active energy rays. It is.

<Preparation of ink set>
[Preparation of ink set 1]
Ink set 1 composed of yellow ink 1, magenta ink 1, cyan ink 1 and black ink 1 was prepared according to the following method.

(Preparation of yellow ink 1)
The following additives were sequentially mixed, dispersed using a bead mill, and then filtered through a # 3000 metal mesh filter to prepare yellow ink 1.

Active energy ray reactive compound: Crosslinkable polymer compound 1 2 parts as solid content Active energy ray reactive resin fine particle: NK polymer RP-116E
3 parts as solid content Ethylene glycol 10 parts Triethylene glycol monobutyl ether 5 parts Surfactant: Olphine E1010 (manufactured by Nissin Chemical Industry) 1 part Polymerization initiator: Irgacure 2959 (manufactured by Ciba Specialty Chemicals) 1 part Pigment: Cab -O-Jet270 (Yellow self-dispersing pigment manufactured by Cabot)
3 parts as a solid content Antifungal agent: Proxel GXL (manufactured by Avicia) 0.2 parts Ion exchange water was added to each of the above additives to finish 100 parts.

(Preparation of magenta ink 1, cyan ink 1, black ink 1)
In the preparation of the yellow ink 1, the pigment was replaced with Cab-O-Jet 270, Cab-O-Jet 260 (magenta self-dispersing pigment manufactured by Cabot), Cab-O-Jet 250 (cyan self-dispersing pigment manufactured by Cabot), respectively. Magenta ink 1, cyan ink 1, and black ink 1 were prepared in the same manner except that Cab-O-Jet 300 (black self-dispersing pigment manufactured by Cabot) was used.

[Preparation of ink sets 2 to 7]
In the preparation of the ink set 1, the type and amount of the active energy ray-reactive compound in each color ink, the amount of active energy ray-reactive resin fine particles added, the type and amount of organic solvent, the amount of pigment added, the surfactant Ink sets 2 to 7 were prepared in the same manner except that the types and amounts added were changed as shown in Table 1.

  The details of each solvent and surfactant described in abbreviations in Table 1 are as follows.

<Active energy ray reactive compound>
Reactive compound A: A-TMPT-3EO (manufactured by Shin-Nakamura Chemical Co., Ltd.)
Reactive compound B: Polyethylene glycol diacrylate Reactive compound C: Glycerin triacrylate <Solvent>
EG: ethylene glycol DEG: diethylene glycol Gly: glycerol PDN: 2-pyrrolidinone HDO: 1,2-hexanediol TEGBE: triethylene glycol monobutyl ether IPA: isopropanol (boiling point 82 ° C.)
<Surfactant>
Orphine E1010: acetylenol surfactant, manufactured by Nissin Chemical Industry Co., Ltd. BYK347: polysiloxane surfactant, manufactured by Big Chemie

《Image formation》
A piezo head having a nozzle diameter of 25 μm, a driving frequency of 15 kHz, a nozzle number of 256, a minimum liquid amount of 4 pL, and a nozzle density of 180 dpi (where dpi represents the number of dots per 2.54 cm) is mounted on both ends of the piezo head. An on-demand inkjet printer having a maximum recording density of 1440 × 1440 dpi was prepared by arranging a 120 W / cm metal halide lamp (MAL 400NL, power supply power 3 kW · hr, manufactured by Nihon Batteries Co., Ltd.). While irradiating a metal halide lamp, each ink set of ink sets 1 to 7 was ejected, and a polyethylene terephthalate film with a solid image of 5 cm x 5 cm overlapped with a black thin line with a width of 0.5 mm and a landscape photograph Images were recorded. After image recording, it was dried with warm air for 1 minute with a dryer and then naturally dried for 24 hours.

《Image evaluation》
Each image obtained from the ink sets 1 to 7 formed by the above method was evaluated according to the following methods. In all cases, the performance of ◯ or higher was regarded as an acceptable level.

(Evaluation of color bleed resistance)
The solid image in which the produced thin wires overlapped was visually observed, and color bleed resistance was evaluated according to the following criteria.

A: No blur between colors is observed at all, and the boundary between the fine line and the solid image is very clear. B: Almost no blur between colors is observed, but there is a slight blur around the fine line. : Bleeding between colors occurs, thin lines ooze out to the surrounding solid image area, and thicker ×: Bleeding between colors is severe, and fine lines and solid image area are mixed (Evaluation of gloss of image area) )
The produced photographic image was visually observed, and the gloss of the image portion was evaluated according to the following criteria.

○: There is no difference in glossiness between the high density part and the low density part of the image, and the glossy feeling is uniform. ×: The glossiness is different between the high density part and the low density part of the image, and the gloss is uniform. -: Color bleeding and beading have occurred and evaluation is impossible. <Evaluation of weather resistance>
The landscape photograph image produced above was rubbed back and forth five times with a tissue paper moistened with water, and the weather resistance was evaluated according to the following criteria.

○: There was almost no change in the image before and after the test. Δ: The image density of the rubbed part was slightly lowered. X: The image of the rubbed part almost disappeared. The results obtained as described above are shown in Table 2. Show.

  As apparent from the results shown in Table 2, the ink set of the present invention comprising the ink containing the crosslinkable polymer compound according to the present invention and the active energy ray-reactive resin fine particles was formed with respect to the comparative example. The color bleed resistance, the image gloss, and the weather resistance are excellent.

Claims (10)

It has a plurality of side chains in water, active energy ray-reactive resin fine particles, and a hydrophilic main chain, and contains a polymer compound that can be cross-linked between side chains by irradiating active energy rays. Inkjet ink. The inkjet ink according to claim 1, wherein the hydrophilic main chain of the polymer compound that can be cross-linked between the side chains is a saponified product of polyvinyl acetate. The inkjet according to claim 1 or 2, wherein a modification rate of the side chain with respect to the hydrophilic main chain of the polymer compound capable of cross-linking between the side chains is 0.8 to 4.0 mol%. ink. The inkjet ink according to any one of claims 1 to 3, wherein a polymerization degree of the hydrophilic main chain of the polymer compound capable of crosslinking between the side chains is 200 to 500. The inkjet ink according to any one of claims 1 to 4, wherein the content of the polymer compound capable of crosslinking between the side chains is 0.8 to less than 5% by mass. 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 5. An inkjet recording method comprising: discharging the inkjet ink according to any one of claims 1 to 5 onto a recording medium; irradiating the inkjet ink with an active energy ray; and drying the inkjet ink. An inkjet recording method comprising: discharging an inkjet ink constituting the inkjet ink set according to claim 6 onto a recording medium; irradiating the inkjet ink with an active energy ray; and drying the inkjet ink. The ink jet recording method according to claim 7 or 8, wherein the recording medium is a coated paper for printing. The ink jet recording method according to claim 7 or 8, wherein the recording medium is a non-absorbable recording medium.