JP2007076033A - Ink jet image recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet image recording method, by which a layer having stability with time and being excellent in scratch resistance is formed on the surface of ink jet media and, in addition, excellent ozone gas resistance, ink absorbency and lustrous properties are obtained. <P>SOLUTION: In the ink jet image recording method, in which image data are printed by injecting ink from an ink jet head against the ink jet media, the ink jet media are void type ink jet media having a top layer with pores having the diameter of 6-50 nm, and the ink jet head can inject at least two kinds of ink and further one between the ink jet heads has a structure, by which an ink, which includes no coloring agent and is substantially colorless, (a colorless ink) can be injected, and furthermore, the colorless ink is one including at least two kinds of water dispersible resin particles, the characteristics and glass transition temperature of each of which are set to be different from each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming method in which latex-containing ink is ejected by ink jet onto void-type ink jet media (hereinafter also referred to as ink jet media or media), and more specifically, a high image print having high weather resistance and scratch resistance is formed. The present invention relates to an image forming method.

  Inkjet printing systems are still inferior to silver halide photography, especially in terms of image storage and gloss. Particularly problematic is fading due to atmospheric ozone or NOx.

  As means for solving ozone fading, a technique for forming a gas barrier layer on a medium after printing by incorporating resin fine particles or latex fine particles in ink has been introduced (for example, see Patent Documents 1 to 4).

  Furthermore, not only by incorporating latex fine particles in the color ink, but also by newly providing a substantially “colorless ink” composition that does not contain a colorant, and in particular injecting it in a form that compensates for the low density portion ( For example, refer to Patent Document 4.) A uniform gas barrier layer is formed to significantly improve ozone resistance.

  As other effects required for this gas barrier layer, improvement of glossiness (for example, see Patent Documents 4 to 6), water resistance, light resistance, scratch resistance, etc. have been proposed (for example, patents). Reference 7).

  Introducing ink jet media that achieves both ink absorbency and high scratch resistance by allowing two types of latex fine particles with different MFTs to be present on the surface of the media in the manufacturing process and then partially fusing them (for example, patent documents) 8). However, in this configuration, there is a problem that the recording medium is limited, and the MFT of the latex fine particles is too high to form a natural fusion film completely, so that effects such as ozone barrier performance and gloss performance cannot be obtained.

By including two types of polymer fine particles with different particle sizes in the ink, high gloss is achieved without losing the ink absorbability, but total ozone resistance, heat storage stability, scratch resistance, etc. The configuration was insufficient to satisfy the performance.
JP 2004-50545 A (paragraph number 0010) JP 2005-125585 A JP 2004-50545 A JP 2005-88411 A (paragraph number 0007) Japanese Patent Laid-Open No. 2005-22281 JP 2003-286428 A Japanese Patent Laid-Open No. 2002-201428 JP 2002-254805 A

  An object of the present invention is to provide an ink jet image recording method in which a layer having high aging stability and excellent scratch resistance is formed on the surface of an ink jet media, and further, ozone gas resistance, ink absorbability, and glossiness are excellent. It is in.

  The above object of the present invention can be achieved by the following configuration.

  1. In an inkjet image forming method of ejecting ink from an inkjet head onto an inkjet media and printing image data, the inkjet media is a void-type inkjet media having a pore diameter of the outermost layer of 6 to 50 nm. At least two or more types of ink can be ejected, and one of the inkjet heads is configured to eject a substantially colorless ink (colorless ink) that does not contain a colorant. The ink-jet image recording method according to claim 1, wherein the colorless ink is an ink containing at least two kinds of water-dispersible resin particles having different glass transition temperatures.

  2. 2. The inkjet image recording method according to 1 above, wherein the colorless ink is an ink containing two types of water-dispersible resin particles having glass transition temperatures of 15 to 80 ° C.

  3. The two kinds of water-dispersible resin fine particles are at least latex A having a glass transition temperature of −50 ° C. or more and less than −10 ° C. and latex B having a glass transition temperature of −10 ° C. or more and less than 30 ° C. 3. The inkjet image recording method as described in 1 or 2 above.

  4). 4. The inkjet image recording method according to 3 above, wherein the latexes A and B have different tensile elongation at break.

  5. 5. The inkjet image recording method according to 4 above, wherein the latexes A and B are a latex having a tensile elongation at break of 500% or more and a latex having a tensile elongation at break of less than 500%.

  According to the present invention, it is possible to form an ink-jet image recording method that forms a layer with high aging stability and excellent scratch resistance on the ink-jet media surface, and further has excellent ozone gas resistance, ink absorbability, and glossiness. It was.

  The present invention will be described in more detail. The ink according to the present invention comprises a resin, a liquid medium, and a colorant, and preferably comprises a resin, a water-soluble solvent, a water-soluble dye colorant (or a water-dispersible pigment colorant), and water as main components. The resin is not particularly limited as long as it exhibits the effects of the present invention, and may be, for example, a water-soluble resin or a water-insoluble resin. Resin fine particles dispersed in water are preferred. Specific examples of the resin include acrylonitrile, styrene, acrylates (acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, methacrylic acid, methyl methacrylate, butyl methacrylate), Vinyl acetate, butadiene, vinyl chloride, polyvinylidene chloride, silicone, urethane, olefin (ethylene, propylene), or a copolymer obtained by combining two or more of these monomers is preferable. Further, the resin used preferably has less residual monomer components from the viewpoint of odor and safety, preferably 3% or less, more preferably 1% or less, particularly 0.1% or less, based on the solid content mass of the polymer. Is preferred.

  The resin fine particles according to the present invention are preferably latex, and the average particle diameter is preferably 10 to 200 nm, more preferably 30 to 150 nm, still more preferably 30 to 100 nm. If the average particle size of the latex is 10 nm or more, the latex does not penetrate into the void layer and exists on the surface of the void layer, which is preferable in terms of gloss performance. Further, if the average particle diameter is 30 nm or more, it does not enter the pores of the void media, which is preferable in terms of ink absorbency in high-speed printing. If the average particle size of the latex is 200 nm or less, the latex is somewhat small, which is advantageous in terms of leveling properties on the surface of the void layer and is preferable in terms of gloss performance.

  The average particle size of the latex can be easily measured using a commercially available particle size measuring device using a light scattering method or a laser Doppler method, such as Zetasizer 1000 (manufactured by Malvern).

  In the latex according to the present invention, a glass transition temperature (Tg) of −60 to 60 ° C. can be used, but it is about −40 to 20 ° C. from the viewpoint of achieving both initial film formability and storage stability over time. Preferably, -30-10 degreeC is preferable in order to achieve the effect of this invention.

  In particular, the colorless ink of the present invention preferably contains at least a latex having a glass transition temperature of −50 ° C. or more and less than −10 ° C. and a latex having a glass transition temperature of −10 ° C. or more and less than 30 ° C.

  In the process of concentrated film formation of latex after ink landing, it is generally preferable that the minimum film forming temperature (hereinafter sometimes referred to as MFT) is lower as a property contributing to film strength after film formation. The larger the difference between the drying temperature and the minimum film-forming temperature, the higher the film performance, which is preferable. In the latex according to the present invention, it is used if the minimum film-forming temperature (MFT) is −60 to 30 ° C., but −40 to 10 ° C. is preferable, and −30 to 0 ° C. is film formability and film storage stability. From the viewpoint of, it is more preferable.

  MFT is a parameter that depends on Tg. Generally, the lower the Tg, the lower the MFT. However, it can be adjusted to some extent by controlling the latex dispersion layer. In the present invention, a film-forming aid may be added to control the MFT of latex fine particles. The film-forming aid is an organic compound that is also called a plasticizer and lowers the MFT of latex.

  Similarly, as a method for controlling MFT, latex fine particles modified with an anionic group such as a carboxyl group have an effect that the dispersion ability of latex fine particles is improved and the apparent MFT is lowered due to pH increase.

  As a method for controlling the pH of the ink according to the present invention, it is preferable to add a pH adjusting agent to the ink. In the ink of the present invention, alkylamines and alkanolamines can be used as pH adjusters. The pH adjusting agent has an effect of suppressing an abrupt change in ink pH when the ink lands on the inkjet medium. Regardless of the presence or absence of a colorant, the inclusion of the amines in the ink suppresses precipitation due to the interaction of fine particles upon landing with the material contained in the inkjet media and poor aggregation. This is preferable. Specific examples of the alkylamines that can be applied include triethylamine, diethylamine, monoethylamine, and dimethylethylamine. Examples of the alkanolamines include triethanolamine, diethanolamine, monoethanolamine, dimethylethanolamine and the like.

  The pH can be adjusted by appropriately combining various acids or alkalis. Examples of the acid include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid, and organic acids such as acetic acid, citric acid, and succinic acid. Examples of the alkali include sodium hydroxide, potassium hydroxide, and calcium hydroxide. Aqueous ammonia, potassium carbonate, sodium carbonate, trisodium phosphate and the like can be used.

  The pH of the ink can be arbitrarily adjusted, but is preferably pH 6.5 to 12.0, more preferably pH 7.0 to pH 11.0 from the viewpoint of the stability of the colorant and the dispersion stability of the latex fine particles. PH 8.0 to pH 11.0 is more preferable for expressing the effects of the present invention. However, it is not necessary to similarly adjust the pH depending on the presence or absence of the colorant and the color.

  The ink of the present invention contains 0.1 to 50.0% by mass of resin, more preferably 1 to 20% by mass, and most preferably about 1 to 10% by mass from the viewpoint of dispersibility and performance after film formation. . Moreover, 1-50 mass% of water-soluble media are contained, and each functional compound such as a surfactant, an ultraviolet absorber, an antioxidant, and an antifungal agent may be included as necessary. Furthermore, the “colorless ink” according to the present invention does not substantially contain a colorant, which means that it has substantially no function as a recording liquid. Slight coloring may be applied to check the amount, to adjust the color tone of the white background when printing on a white background, to check the ejection property, and to improve the weather resistance.

  In order to exhibit the effects of the present invention, it is necessary to use ink sets having different colorant concentrations or colorant types of two or more kinds of light and shade for the purpose of improving not only the ink absorbability but also the gradation required for photographic image quality. Common and important in the industry. In order to expand color reproducibility and color gamut, it is widely used to achieve high-level photographic image quality using special color inks. It is preferable to apply the configuration of the present invention to these dark and light inks and spot color inks because the same effect can be obtained. Furthermore, the present invention can be similarly applied when using an ink set for forming an overcoat layer or the like not intended for coloring.

  As the organic solvent, surfactant, and other additives that can be added to the colorless ink according to the present invention, those that can be added to a recording liquid containing a coloring material can be used.

  For the ink and colorless ink according to the present invention, the surface tension of the ink is preferably 40 mN / m or less, and preferably 20 to 40 mN / m, in order to stably discharge and to increase the expression of high gloss and the resistance to ozone. Is more preferable. For the same reason, the ink viscosity is preferably 1.5 to 10 mPa · s, more preferably 3.0 to 8.0 mPa · s.

  In the image recording method of the present invention, water-based pigment ink and dye ink are preferably used. The water-based dye ink is an ink using a water-soluble dye as a coloring material, and is an ink obtained by mixing water or an organic solvent having high miscibility with water as an ink solvent. Examples of the dye include conventionally known azo dyes, xanthene dyes, phthalocyanine dyes, quinone dyes, anthraquinone dyes, etc., which are improved in water solubility by introducing a sulfo group or a carboxy group. Basic dyes are typically used.

  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, diphenylmethane dyes, and the like. The compounds are shown below. However, it is not limited to these exemplified compounds.

[C. I. Acid Yellow)
1, 3, 11, 17, 18, 19, 23, 25, 36, 38, 40, 42, 44, 49, 59, 61, 65, 67, 72, 73, 79, 99, 104, 110, 114, 116, 118, 121, 127, 129, 135, 137, 141, 143, 151, 155, 158, 159, 169, 176, 184, 193, 200, 204, 207, 215, 219, 220, 230, 232, 235, 241, 242, 246
[C. I. Acid Orange)
3, 7, 8, 10, 19, 24, 51, 56, 67, 74, 80, 86, 87, 88, 89, 94, 95, 107, 108, 116, 122, 127, 140, 142, 144, 149, 152, 156, 162, 166, 168
[C. I. Acid Red)
1, 6, 8, 9, 13, 18, 27, 35, 37, 52, 54, 57, 73, 82, 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, 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
These dyes listed above are described in “Dyeing Note 21st Edition” (publishing; Color Dyeing Co., Ltd.) and the like, but are not limited to these exemplified compounds.

  On the other hand, as the pigment used in the pigment ink, various conventionally known inorganic or organic pigment inks can be used by inkjet. Examples of inorganic pigment inks include carbon black, titanium oxide, and iron oxide. Examples of organic pigments include various azo pigments, phthalocyanine pigments, anthraquinone pigments, quinacridone pigments, indigo pigments, or lake pigments obtained by reacting water-soluble dyes with polyvalent metal ions. I can do it.

  These pigment particles are preferably used together with various dispersants and dispersion stabilizers such as hydrophilic polymers and surfactants. It is preferable to use the pigment particles dispersed to an average particle size of about 70 to 150 [mu] m with these components and dispersion stabilizers.

  The concentration of the dye and the pigment in the ink depends on the type of the dye or pigment, the form in which the ink is used (whether or not the light and dark ink is used), and also the type of the ink jet media, but is generally 0.2 to 10 % By mass.

  Various solvents are used in the ink, and as such an ink solvent, water or an organic solvent having high miscibility with water can be used alone or mixed with water. Specifically, alcohol solvents such as ethanol, 2-propanol, ethylene glycol, propylene glycol, glycerin, 1,2-hexanediol, 1,6-hexanediol, diethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, 2- Amides such as pyrrolidinone, N-methylpyrrolidone, N, N-dimethylacetamide, amines such as triethanolamine, N-ethylmorpholine, triethylenetetramine, sulfolane, dimethyl sulfoxide, urea, acetonitrile, acetone, etc. These solvents may be used alone or in combination.

  In addition, various surfactants can be used in the ink for the purpose of increasing the permeability of the ink solvent and other purposes. As such a surfactant, an anionic or nonionic surfactant is preferably used. Of these, acetylene glycol surfactants are particularly preferred.

  The ink jet medium used in the present invention is an ink jet medium suitable for the ink jet image recording method, and has a porous ink absorbing layer on at least one surface on a non-water-absorbing support.

  Non-water-absorbing supports that can be preferably used in the present invention include transparent supports and opaque supports. Examples of the transparent support include polyester resins, diacetate resins, triatesate resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, polyimide resins, cellophane, celluloid, and other films. Among them, those having the property of resisting radiant heat when used as OHP are preferable, and polyethylene terephthalate is particularly preferable. The thickness of such a transparent support is preferably 50 μm to 200 μm.

  As the opaque support, for example, resin-coated paper (so-called RC paper) having a polyolefin resin coating layer in which a white pigment or the like is added to at least one of the base paper, polyolefin (polyethylene, polypropylene, etc.), polyethylene terephthalate, barium sulfate An opaque resin film to which a white pigment such as titanium oxide is added, or a film support in which two or more of them are bonded together can be used.

  The thickness of these opaque various supports can vary widely depending on the application, but is generally in the range of 60 to 300 μm.

  Prior to application of the ink absorbing layer, the support is subjected to corona discharge treatment or subbing treatment with gelatin, other hydrophilic polymer or hydrophobic polymer for the purpose of increasing the adhesive strength between the various supports and the ink absorbing layer. Etc. are preferably performed. Furthermore, the inkjet media according to the present invention need not necessarily be transparent or white, and may be a colored recording sheet.

  In the inkjet media according to the present invention, it is particularly preferable to use a paper support obtained by laminating both sides of a base paper support with polyethylene because the recorded image is close to photographic image quality and a high-quality image can be obtained at a relatively low cost. . Such a paper support laminated with polyethylene will be described below.

  The base paper used for the paper support is made from wood pulp as a main raw material, and if necessary, paper is made using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp. As the wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, and NUKP can be used, but it is preferable to use more LBKP, NBSP, LBSP, NDP, and LDP with a short fiber content. However, the ratio of LBSP and / or LDP is preferably 10% by mass to 70% by mass.

  The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities, and a pulp having a whiteness improved by bleaching is also useful.

  In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength enhancing agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, polyethylene glycols A water retaining agent such as a dispersant, a softening agent such as a quaternary ammonium, and the like can be appropriately added.

  The freeness of pulp used for papermaking is preferably 200 to 500 ml as defined by CSF, and the fiber length after beating is 24% by weight as defined in JIS-P-8207, and 42 mesh residue. The sum of 30% and 70% by mass is preferable. In addition, it is preferable that the mass% of 4 mesh remainder is 20 mass% or less.

  The basis weight of the base paper is preferably 40 to 250 g, particularly preferably 60 to 220 g. The thickness of the base paper is preferably 40 to 250 μm.

The base paper can be given high smoothness by calendering at the paper making stage or after paper making. The density of the base paper is generally 0.7 to 1.2 g / m ³ (JIS-P-8118). Furthermore, the base paper stiffness is preferably 20 to 200 g under the conditions specified in JIS-P-8143.

  A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, a sizing agent similar to the size that can be added to the base paper can be used.

  The pH of the base paper is preferably 5 to 9 when measured by the hot water extraction method defined in JIS-P-8113.

  The polyethylene that covers the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene, and the like can also be partially used.

  In particular, the polyethylene layer on the ink absorbing layer side is preferably one in which rutile or anatase type titanium oxide is added to polyethylene to improve opacity and whiteness, as is widely done in photographic paper. The content of titanium oxide is usually 3% by mass to 20% by mass, preferably 4% by mass to 13% by mass with respect to polyethylene.

  The surface of the polyethylene-coated paper may be finely roughened to improve the adhesion to the ink absorbing layer and the coating property. In this case, it is preferable that the fine rough surface is formed in a range of Ra = 0.10 to 0.25 μm. In the polyethylene-coated paper, the moisture content in the paper is particularly preferably maintained at 3% by mass to 10% by mass.

  The stiffness of these supports mainly depends mainly on the thickness of the base paper, and the desired stiffness can be obtained by appropriately selecting the thickness of the base paper. The curling of the support is an important characteristic that determines the curling characteristics provided with the ink absorbing layer, and an optimal curl balance is achieved in combination with the ink absorbing layer, but the ink absorbing layer is a porous ink absorbing layer ( In the inkjet media according to the present invention, which is a porous absorbent layer, also referred to as a porous layer, generally, a negative curl (when left on a horizontal board with the ink-absorbing layer-coated side on the bottom surface) It is preferable to design the curl so that it is lifted. Although the curl design of the base paper is determined by the relationship with the ink absorbing layer, it is roughly -5 to -50 mm (the A4 size base paper is lifted at the four corners when left at a temperature of 23 ° C and a relative humidity of 20 to 80% for 1 hour. (Average height) is preferable.

  Next, the porous ink absorbing layer provided on the support will be described.

  The ink absorbing layer may be on only one side of the support or on both sides. When providing on both surfaces, each may have the same structure and thickness, or may differ. The ink absorption layer may be a single layer or may be composed of a plurality of layers.

The porous ink absorbing layer of the inkjet media according to the present invention is preferably composed of a hydrophilic binder and an inorganic pigment.
Examples of inorganic pigments include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite, Examples include white inorganic pigments such as aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, and magnesium hydroxide. . The inorganic pigment can be used as primary particles or in a state where secondary aggregated particles are formed.

  In the present invention, from the viewpoint of obtaining high-quality prints with inkjet media, silica-based particles or alumina are used from the viewpoint that inorganic pigments having a low refractive index and an average particle size of about 0.1 μm or less can be obtained relatively inexpensively. Diameter particles are preferable, and alumina, pseudoboehmite, colloidal silica, fine particle silica synthesized by a gas phase method, and the like are preferable, and fine particle silica synthesized by a gas phase method is particularly preferable. The silica synthesized by this vapor phase method may have a surface modified with aluminum. The aluminum content of vapor-phase process silica whose surface is modified with aluminum is preferably 0.05 to 5% by mass with respect to silica.

  The particle size of the inorganic pigment is preferably 200 nm or less, and particularly preferably 100 nm or less from the viewpoint of glossiness and color density. Although the minimum of a particle size is not specifically limited, From a viewpoint on manufacture of an inorganic pigment, about 10 nm or more is preferable.

  The average particle diameter of the inorganic pigment is obtained as a simple average value (number average) by observing the cross section or surface of the porous layer with an electron microscope and determining the particle diameter of 100 arbitrary particles. Here, each particle size is expressed by a diameter assuming a circle equal to the projected area.

  The pigment may be present in the porous coating as primary particles or as secondary particles or higher-order aggregated particles, but the average particle diameter is determined by observation with an electron microscope. Among them, the particle size of the particles forming independent particles.

  When the pigment is a secondary or higher aggregated particle, the average primary particle size is not more than the average particle size observed in the porous layer, and the primary particle size of the pigment is not more than 50 nm. Are preferable, more preferably 30 nm or less, and most preferably 4 to 20 nm.

The content of the pigment in the water-soluble coating solution is 5 to 40% by mass, and particularly preferably 7 to 30% by mass. The pigment needs to form an ink-absorbing layer having sufficient ink absorptivity and less cracking of the film, and the amount of the pigment is preferably 5 to 50 g / m ^{2 in} the ink-absorbing layer. Furthermore, it is especially preferable that it is 10-30 g / m < ² >.

  The hydrophilic binder contained in the porous layer is not particularly limited, and conventionally known hydrophilic binders can be used. For example, gelatin, polyvinyl pyrrolidone, polyethylene oxide, polyacrylamide, polyvinyl alcohol, and the like can be used. Polyvinyl alcohol is particularly preferable from the viewpoint of relatively low moisture absorption characteristics of the binder and less curling of the ink-jet media, and from the viewpoint of high binder ability of inorganic fine particles and excellent cracking and film-forming properties when used in a small amount.

  As polyvinyl alcohol preferably used in the present invention, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, modified polyvinyl alcohol such as polyvinyl alcohol having a cation-modified terminal or anion-modified polyvinyl alcohol having an anionic group. Alcohol is also included.

  The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 300 or more, particularly preferably an average degree of polymerization of 1,000 to 5,000, and a saponification degree of 70. -100% is preferable, and 80-99.8% is particularly preferable.

  Examples of the cation-modified polyvinyl alcohol include polyvinyl having a primary to tertiary amino group or a quaternary amino group in the main chain or side chain of the polyvinyl alcohol as described in JP-A No. 61-10383. These are alcohols, which are obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

  Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamide-2,2-dimethylethyl) ammonium chloride, trimethyl- (3-acrylamide-3,3-dimethylpropyl) ammonium chloride, Examples thereof include N-vinylimidazole, N-methylvinylimidazole, N- (3-dimethylaminopropyl) methacrylamide, hydroxyethyltrimethylammonium chloride, trimethyl- (3-methacrylamideamidopropyl) ammonium chloride and the like.

  The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, relative to vinyl acetate.

  Examples of the anion-modified polyvinyl alcohol include polyvinyl alcohols having an anionic group described in JP-A-1-206088, vinyl alcohols described in JP-A-61-237681 and JP-A-63-330779, and water-soluble. Examples thereof include a copolymer with a vinyl compound having a group, and a modified polyvinyl alcohol having a water-soluble group described in JP-A-7-285265.

  Nonionic modified polyvinyl alcohols include, for example, polyvinyl alcohol derivatives obtained by adding a polyalkylene oxide group described in JP-A-7-9758 to a part of vinyl alcohol, and hydrophobic resins described in JP-A-8-25955. And a block copolymer of a vinyl compound having a functional group and vinyl alcohol.

  Polyvinyl alcohol can be used in combination of two or more, such as the degree of polymerization and the type of modification. In particular, when polyvinyl alcohol having a degree of polymerization of 2,000 or more is used, 0.05 to 10% by mass, preferably 0.1 to 5% by mass is added to the inorganic pigment in advance, and then the degree of polymerization is increased. Addition of 2,000 or more polyvinyl alcohol is preferred because there is no significant thickening.

  The ratio of the inorganic pigment to the hydrophilic binder of the porous layer is preferably 2 to 20 by mass ratio. If the mass ratio is twice or more, a porous layer having a sufficient porosity can be obtained, and a sufficient void volume can be easily obtained without causing a situation in which the voids are blocked by swelling during ink jet recording with a hydrophilic binder that can be maintained. As a result, a high ink absorption speed can be maintained. On the other hand, if this ratio is 20 times or less, cracks are less likely to occur when the porous layer is applied as a thick film. The ratio of the inorganic pigment to the particularly preferred hydrophilic binder is 2.5 to 12 times, most preferably 3 to 10 times.

  In addition to inorganic fine particles and binders, various additives can be used for the porous ink absorption layer. Among them, cationic polymers, crosslinking agents, and polyvalent metal compounds are used for improving ink absorption and bleeding with respect to dye ink. Play an important role.

  A cationic polymer is preferably used for the purpose of preventing bleeding of the image due to storage after recording with a dye ink.

Examples of cationic polymers include polyethyleneimine, polyallylamine, polyvinylamine, dicyandiamide polyalkylene polyamine condensate, polyalkylene polyamine dicyandiamide ammonium salt condensate, dicyandiamide formalin condensate, epichlorohydrin-dialkylamine addition polymer, diallyldimethylammonium chloride Polymer, diallyldimethylammonium chloride / SO ₂ copolymer, polyvinyl imidazole, vinyl pyrrolidone / vinyl imidazole copolymer, polyvinyl pyridine, polyamidine, chitosan, cationized starch, vinyl benzyl trimethyl ammonium chloride polymer, (2-methacryloyl) Oxyethyl) trimethylammonium chloride polymer, dimethylaminoethyl methacrylate Over preparative polymer, and the like.

  Examples include the cationic polymers described in Chemical Industry Times, August 15 and 25, 1998, and polymer dye fixing agents described in “Introduction to Polymer Drugs” issued by Sanyo Chemical Industries, Ltd.

  The porous ink absorbing layer of the inkjet media according to the present invention preferably contains a compound represented by the following general formula (1) and having a molecular weight of 200 or less.

In the formula, R ₁ represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, an acyl group, a heteroaryl group, a heterocyclic group, an NR ₄ R ₅ or OR _6,. R _{2 to} R ₆ each have the same meaning as R ₁ . R ₁ and R ₂ , R ₁ and R ₃ may be bonded to each other to form a ring. X represents an oxygen atom or NH.

In the general formula (1), R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group (for example, methyl group, ethyl group, isopropyl group, t-butyl group, hexyl group, dodecyl group, cycloalkyl group, etc.), substituted Or an unsubstituted alkenyl group (eg, propenyl group, butenyl group, nonenyl group), a substituted or unsubstituted aryl group (eg, phenyl group), a substituted or unsubstituted acyl group (eg, acetyl group, propionyl group) , Butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), substituted or unsubstituted heteroaryl group (eg, triazole group, imidazole group, pyridine group, furan group, thiophene group, etc.), substituted or Unsubstituted heterocyclic groups (eg, pyridyl, thiazolyl, oxazolyl, Dazoriru group, a furyl group, a pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, Surihoraniru group, a piperidinyl group, a pyrazolyl group, etc. tetrazolyl group), represents a NR ₄ R ₅ or OR _6,. R ₁ and R ₂ , R ₁ and R ₃ may be bonded to each other to form a ring. X represents an oxygen atom or NH.

  In the present invention, the compound represented by the general formula (1) preferably has no alcoholic hydroxyl group from the viewpoint of exhibiting the object effect of the present invention.

  In the general formula (1), the molecular weight is characterized by 200 or less, the number of atoms excluding hydrogen atoms is preferably 15 or less, and water-soluble is preferable from the viewpoint of easy addition. .

  Although the example of a compound represented by General formula (1) based on this invention is enumerated below, this invention is not limited only to these.

  The compound represented by the general formula (1) according to the present invention can be easily synthesized by a person skilled in the art according to a known method, or can be obtained as a commercial product.

  In the inkjet media according to the present invention, it is preferable to use urea or a urea derivative among the compounds represented by the general formula (1), and urea is particularly preferable.

  In order to improve the water resistance and moisture resistance of the image, it is preferable to contain a polyvalent metal ion. The polyvalent metal ion is not particularly limited as long as it is a divalent or higher-valent metal ion, but preferable polyvalent metal ions include aluminum ions, zirconium ions, titanium ions, and the like.

  These polyvalent metal ions can be contained in the ink absorbing layer in the form of a water-soluble or water-insoluble salt. Specific examples of the salt containing aluminum ions include aluminum fluoride, hexafluoroaluminic acid (for example, potassium salt), aluminum chloride, basic aluminum chloride (for example, polyaluminum chloride), and tetrachloroaluminate (for example, sodium). Salt), aluminum bromide, tetrabromoaluminate (eg potassium salt), aluminum iodide, aluminate (eg sodium salt, potassium salt, calcium salt), aluminum chlorate, aluminum perchlorate, thiocyanic acid Aluminum, aluminum sulfate, basic aluminum sulfate, potassium aluminum sulfate (alum), ammonium aluminum sulfate (ammonium alum), sodium aluminum sulfate, aluminum phosphate, aluminum nitrate, hydrogen phosphate Aluminum, Aluminum carbonate, Aluminum polysulfate silicate, Aluminum formate, Aluminum acetate, Aluminum lactate, Aluminum oxalate, Aluminum isopropylate, Aluminum butyrate, Ethyl acetate Aluminum diisopropylate, Aluminum tris (acetylacetonate), Aluminum tris (ethylacetate) Acetate), aluminum monoacetylacetonate bis (ethylacetoacetonate) and the like.

  Among these, aluminum chloride, basic aluminum chloride, aluminum sulfate, basic aluminum sulfate, and basic aluminum sulfate silicate are preferable, and basic aluminum chloride and basic aluminum sulfate are most preferable.

  Specific examples of the salt containing zirconium ions include zirconium difluoride, zirconium trifluoride, zirconium tetrafluoride, hexafluorozirconium salt (for example, potassium salt), heptafluorozirconium salt (for example, sodium salt). Potassium salts and ammonium salts), octafluorozirconium salts (for example, lithium salts), zirconium fluoride oxide, zirconium dichloride, zirconium trichloride, zirconium tetrachloride, hexachlorozirconium salts (for example, sodium salts and potassium salts) , Zirconium oxychloride (zirconyl chloride), zirconium dibromide, zirconium tribromide, zirconium tetrabromide, zirconium bromide oxide, zirconium triiodide, zirconium tetraiodide, zirconium peroxide, zirconium hydroxide, sulfide Luconium, zirconium sulfate, zirconium p-toluenesulfonate, zirconyl sulfate, sodium zirconyl sulfate, acidic zirconyl sulfate trihydrate, zirconium potassium sulfate, zirconium selenate, zirconium nitrate, zirconyl nitrate, zirconium phosphate, zirconyl carbonate, zirconyl carbonate Ammonium, zirconium acetate, zirconyl acetate, zirconyl ammonium acetate, zirconyl lactate, zirconyl citrate, zirconyl stearate, zirconyl phosphate, zirconium oxalate, zirconium isopropylate, zirconium butyrate, zirconium acetylacetonate, acetylacetone zirconium butyrate, stearin Zirconate butyrate, zirconium acetate, bis (acetylacetonato) dichroic acid Zirconium tris (acetylacetonato) chloro zirconium, and the like.

  Among these compounds, zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate, zirconyl chloride, zirconyl lactate, zirconyl citrate are used in the viewpoint of further prominently preventing bleeding after printing, which is the object of the present invention. Particularly preferred are zirconyl ammonium carbonate, zirconyl chloride and zirconyl acetate.

  These polyvalent metal ions may be used alone or in combination of two or more different kinds. The compound containing a polyvalent metal ion may be added to the coating solution for forming the ink absorption layer, or after the porous layer is applied once, in particular, after the porous layer is once applied and dried, the compound is added to the ink absorption layer. You may supply by an overcoat method. When adding a compound containing polyvalent metal ions to the coating solution for forming the ink absorbing layer as in the former, a method of uniformly dissolving in water, an organic solvent or a mixed solvent thereof, or wet grinding such as a sand mill A method of dispersing and adding to fine particles by a method such as a method or emulsification dispersion can be used. When the ink absorbing layer is composed of a plurality of layers, only one layer may be added, or it may be added to the coating liquid of two or more layers or all the constituent layers. In addition, when the porous ink absorbing layer is once formed as in the latter and then added by the overcoat method, the compound containing polyvalent metal ions is uniformly dissolved in a solvent and then supplied to the ink absorbing layer. Is preferred.

These polyvalent metal ions are generally used in an amount of 0.05 to 20 mmol, preferably 0.1 to 10 mmol, per 1 m ² of the ink jet media.

  In the ink jet media according to the present invention, it is preferable to add a hardener of a water-soluble binder that forms a porous ink absorbing layer.

  The curing agent that can be used in the present invention is not particularly limited as long as it causes a curing reaction with a water-soluble binder, but boric acid and its salts are preferable, but other known ones can be used. Specifically, it is a compound having a group capable of reacting with a water-soluble binder or a compound that promotes the reaction between different groups of the water-soluble binder, and is appropriately selected depending on the type of the water-soluble binder. Specific examples of the curing 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 and the like.

  Boric acid or a salt thereof refers to an oxygen acid having a boron atom as a central atom and a salt thereof, specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, and octaboron. Examples include acids and their salts.

  Boric acid having a boron atom and a salt thereof as a curing agent may be used alone or in combination of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax.

  The aqueous solutions of boric acid and borax can be added only in relatively dilute aqueous solutions, respectively, but by mixing them both can be made into a concentrated aqueous solution and the coating solution can be concentrated. Further, there is an advantage that the pH of the aqueous solution to be added can be controlled relatively freely.

  The total amount of the curing agent used is preferably 1 to 600 mg per 1 g of the water-soluble binder.

  Various additives other than those described above can be added to the porous ink absorbing layer of the present invention. For example, organic latex fine particles such as polystyrene, polyacrylic acid esters, polymethacrylic acid esters, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or a copolymer thereof, urea resin, or melamine resin , Various cationic 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, JP-A-60-27285, JP-A-61-146591, JP-A-1-95091 and JP-A-3-13376, etc., and JP-A-59-42993, JP-A-59-52689, JP-A-62. -280069, 61-242871 and JP-A-4-219266. Brighteners, sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and other pH adjusters, antifoaming agents, preservatives, thickeners, antistatic agents, mats Various known additives such as an agent can also be contained.

  Next, the manufacturing method of the inkjet media according to the present invention will be described.

  As a method for producing the inkjet media according to the present invention, each constituent layer including the ink absorbing layer is selected from a known coating method, either individually or simultaneously, and coated and dried on a support. Can do. Examples of the coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or US Pat. Nos. 2,761,419 and 2,761,791. A slide bead coating method using an hopper, an extrusion coating method, or the like is preferably used.

  When the slide bead coating method is used, the viscosity of each coating solution at the time of simultaneous multilayer coating is preferably in the range of 5 to 100 mPa · s, more preferably in the range of 10 to 70 mPa · s. Moreover, when using a curtain application | coating system, the range of 5-1200 mPa * s is preferable, More preferably, it is the range of 25-500 mPa * s.

  Further, the viscosity at 15 ° C. of the coating solution is preferably 100 mPa · s or more, more preferably 100 to 30,000 mPa · s, further preferably 3,000 to 30,000 mPa · s, and most preferably 10 , 30,000 to 30,000 mPa · s.

  As a coating and drying method, the coating liquid is heated to 30 ° C. or more, and after simultaneous multi-layer coating, the temperature of the formed coating film is once cooled to 1 to 15 ° C. and dried at 10 ° C. or more. Is preferred. More preferably, the drying conditions are a wet bulb temperature of 5 to 50 ° C. and a film surface temperature of 10 to 50 ° C. Moreover, as a cooling method immediately after application | coating, it is preferable to carry out by a horizontal set system from a viewpoint of the formed coating-film uniformity.

  Also, after applying an ink absorbing layer as patented by the present applicant in Japanese Patent Application Laid-Open No. 2004-90588 and drying it, it is overcoated with another water-soluble additive online before being wound up in a roll. A method of producing by drying can also be applied to the present invention.

  Moreover, it is preferable to have the process preserve | saved 24 hours or more and 60 days or less on the conditions of 35 degreeC or more and 70 degrees C or less in the manufacture process of an inkjet media.

The heating condition is not particularly limited as long as it is stored at a temperature of 35 ° C. or more and 70 ° C. or less for 24 hours or more and 60 days or less, but preferable examples include, for example, 36 ° C. for 3 days to 4 weeks, 2 days to 2 weeks at 40 ° C. or 1 to 7 days at 55 ° C. By performing this heat treatment, the curing reaction of the water-soluble binder can be promoted, or the crystallization of the water-soluble binder can be promoted, and as a result, preferable ink absorbability can be achieved.
In the inkjet media according to the present invention, since a non-water-absorbing support is used as the support, it retains an ink absorption capacity that can absorb almost all of the ink forming the image and the ink forming the protective film almost simultaneously. It is necessary. If there is not a sufficient amount of ink absorption, ink overflows when colorless ink forming a protective film is ejected, causing glare due to point-like thickness changes.

The absorption capacity of the ink absorption layer is preferably about 20 ml / m ² or more. The upper limit is not particularly limited. Increasing the ink absorption amount not only increases the thickness of the layer, but also greatly increases the curling problem. It becomes a big cause. The upper limit of the preferred ink absorption is approximately 30 ml / m ² .

When recording an image, it is necessary to design so that the sum of the ink for forming the image and the colorless ink for forming the protective film is equal to or less than the ink absorption amount of the inkjet media. The sum total of the image forming ink is approximately 15 to 25 ml / m ² , and the sum total of the colorless ink is 3 to 10 ml / m ² .

  Next, the surface characteristics of the inkjet media according to the present invention will be described.

  The center line average roughness (Ra) when measured with a reference length of 2.5 mm as defined in JISB-0601 and a cutoff value of 0.8 mm on the surface of the porous ink absorbing layer of the inkjet media according to the present invention is 0.08. It is preferable that it is -0.20 micrometer.

When Ra on the surface of the porous ink absorbing layer is less than 0.08 μm, when a protective film having a dry solid content of 0.05 to 0.3 g / m ² is formed on a white background portion, the viewing angle caused by interference fringes It is easy to change the color of the white background due to the difference. This is because the smoothness of the surface of the ink absorbing layer is too high, and the smoothness of the interface between the protective coating layer and the surface of the ink absorbing layer is too high. It is conceivable that the point-like glare derived from the interference fringes can be suppressed by suppressing regular reflection of light by slightly roughening the surface.

  On the other hand, when Ra exceeds 0.20 μm, the spot-like glare is particularly noticeable in a high density portion, particularly in a black solid portion. Originally, if the surface quality is typed, this point is not so much of a concern, but the white background and low density areas are more glossy and have a uniform recording surface. The glare has a great influence on print quality and is not preferable.

  A preferable Ra is 0.10 to 0.18 μm.

As a method for adjusting the Ra of the ink absorbing layer surface within the above range, various methods can be appropriately selected and used. In particular,
1. Adjust the smoothness of the surface of the support medium (adjust the fiber length of the pulp, adjust the pressure when calendering, adjust the amount of surface sizing agent, etc.)
2. Adjust the thickness of the polyolefin resin that covers the inner paper,
3. Adjustment of the surface shape of the cooling roll for melting and extruding onto a polyolefin resin paper support (use of mirror roller, fine rough surface roller, mat surface roller, etc.)
4). Adjusting the composition and thickness of the undercoat layer,
5. Adjusting the particle size of the inorganic fine particles contained in the surface layer of the porous ink absorbing layer,
6). Addition of various surface additives to the surface layer,
7). Adjustment of drying conditions after application of the porous ink absorbing layer,
8). After applying and drying the porous ink absorbing layer, applying water and other solvents again and drying,
Etc. can be performed.

  The Ra of the white background portion after providing the protective coating layer depends on the discharge conditions of the colorless ink, but is generally lower than before the protective coating layer is provided, and is generally 0.05 to 0.15 μm.

  Further, the 60-degree specular gloss by S-Z8741 on the surface of the porous ink absorbing layer is generally 30 to 70%. The gloss level itself does not necessarily correspond completely to Ra, but generally the higher the Ra, the lower the gloss level.

  The glossiness of the white background portion after the coating layer is provided is changed by providing the protective layer in the same manner as Ra, and is usually 5 to 40% higher than that before the protective layer is provided.

  Further, the 10-point average roughness (Rz) when measured at a reference length of 2.5 mm and a cut-off value of 0.8 mm defined in JIS-B-0601 on the surface of the porous ink absorbing layer is 0.5 to 5. A filtered waviness curve derived from a cross-sectional curve measured in accordance with JIS-B-0610 at 0 μm and a cut-off value of 0.8 mm, with a reference length of 2.5 mm, a maximum waviness of filtration of 0.5 to 5 μm, and JIS K7105 The 60 degree C value specified is in the range of 30-90%.

  The membrane surface pH of the porous ink absorbing layer is preferably 2.5 to 7.0, and particularly preferably 4.0 to 6.5. In order to achieve the effects of the present invention, it is important that the difference from the pH of the ink composition is 4.0 or less. By minimizing the pH fluctuation at the time of ink landing, latex in the inks In addition, it is possible to suppress the generation of poor aggregates with the colorant and to form an image excellent in glossiness and color developability.

In the present invention, the film surface pH is a value measured using a commercially available surface pH electrode at room temperature by dropping 20 to 50 μL of pure water onto the surface of the ink-absorbing layer side of the inkjet media with a microsyringe or the like. .
As a method of adjusting the film surface pH within the scope of the present invention,
1. A method in which the pH of the coating liquid for forming the ink absorbing layer is set to a predetermined value, and a desired pH is obtained after coating and drying;
2. A method of overcoating a liquid having an appropriate pH after applying and drying the ink absorbing layer and drying to obtain a desired pH;
3. A method of immersing and drying in an aqueous solution having an appropriate pH after coating and drying the ink absorbing layer. Etc.

  Among the above methods 1 to 3, 1 is not preferable for achieving the object of the present invention because the cationic polymer may be deactivated due to the stagnation of the coating solution. Preferably, 2 or 3 can be selected, but 2 is suitable as an easy manufacturing method.

  Adjustment of the film surface pH by overcoating with an appropriate pH solution is performed by appropriately combining various acids or alkalis. Examples of the acid include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid, and organic acids such as acetic acid, citric acid, and succinic acid. Examples of the alkali include sodium hydroxide, potassium hydroxide, and calcium hydroxide. Ammonia water, potassium carbonate, sodium carbonate, trisodium phosphate, triethanolamine, and the like are used.

  In order to express the effect of the present invention, pH adjustment is required. Particularly when an anionic dye is used as a colorant, the mordant used for mordanting this dye causes a decrease in mordant power due to an increase in pH. There is a problem that not only the color developability deteriorates but also the ozone gas resistance and image storability such as ink bleeding under high humidity deteriorate. Therefore, in the present invention, by providing a layer having a film thickness of 10.0 μm or less that does not contain a mordant on the outermost layer of the porous media, both high pH and suppression of mordant power reduction can be achieved. The thinner the film thickness, the better. However, considering the stability in production and the possibility of coating failure when it is too thin, about 1.0 to 5.0 μm is preferable. 0-3.0 micrometers is more preferable.

  Further, the layer not containing the mordant may be composed of colloidal silica having an average particle diameter of 10 nm to 100 nm. The average particle size of the colloidal silica is more preferably 10 to 50 nm for ink absorption and high gloss expression.

  When providing the outermost layer which does not contain a mordant, 1 to 3 can be preferably selected from the above pH adjustment methods, and 1 is most preferable in terms of production suitability.

  Next, a method for applying colorless ink will be described.

  As a method for applying the colorless ink, any method can be used as long as it can be selected and applied to at least a part of the image, but a method of applying using an ink jet head as in the recording ink is preferable. At this time, one or more heads for colorless ink may be prepared and colorless inks having different compositions may be applied. The colorless ink head may be fixed to the same carriage as the recording ink or may be separate. The colorless ink may be applied before, at the same time as, or after the recording ink is recorded, but it is preferably fixed to the same carriage and applied at the same time or after the recording ink is recorded. It is preferable for further manifesting the effects of the invention.

  The colorless ink application region can be applied to at least a part of the inkjet media. In order to achieve the effect of the present invention, it is preferable to apply the colorless ink together to the area where the recording ink is not applied and the area where the recording ink is applied.

Application amount of clear ink, recording ink, clear ink, the characteristics of the ink jet media, but an appropriate amount of the most effective is obtained different, they are preferably applied at least 2 ml / m ² or more. However, if more colorless ink than 20 ml / m ² is applied, image quality degradation and gloss reduction are undesirable. The amount of colorless ink applied is preferably adjusted so that the recording ink amount and the total amount of colorless ink are within a certain range for each pixel. In this case, the minimum total amount is preferably ² ml / m ² or more, more preferably 8 ml / m ² or more.

It is also preferable to control the total amount of resin applied by both inks for each pixel in consideration of the resin fine particles contained in the recording ink and the amount of resin contained colorless. At this time, the total resin amount of each pixel is preferably 0.5 g / m ² or more, more preferably 1 g / m ² .

  Next, a method for recording an image using the colorant-containing ink and the colorless ink on the inkjet media according to the present invention will be described.

  In the ink jet media according to the present invention, after an image is recorded with a colorant-containing ink, a colorless ink is preferably ejected onto substantially the entire area of the ink jet medium to form a protective film on the substantially entire area of the ink jet media. Is.

  Here, “formation of a protective film on substantially the entire area of the inkjet medium” refers to a state in which it can be recognized that the protective film is formed on the entire area of the inkjet medium in normal observation. For example, even if the protective film is not formed in the minute range of the edge part of the inkjet media, the influence on the print quality is small, and the observer recognizes that the protective film is present in the entire region. Usually, a protective film may be formed in the remaining area except for an area of about 1 mm, preferably about 0.5 mm or less from the edge of the ink jet media. As another example, an area that is not recorded with colorless ink may be cut off or covered with a frame after printing. It is not necessary to discharge colorless ink in an area that is not valuable as an image. In short, in a normal image print, the recording method to which the inkjet medium according to the present invention is applied is to cover all areas of the white background area as an image and the area where the colored ink is discharged. .

  According to the study by the present inventors, in order to form a thin and uniform protective film, the composition and application method of the colorless ink to be applied are important, but since the amount of the colorless ink applied is small, the colorless ink is used. It was found that the uniformity of the surface of the applied inkjet media is extremely important. In other words, if there are fine dot defects or cracks on the surface of the inkjet media, non-uniformity occurs in the protective film formed on that part (thickening, thinning, not forming, etc.), appearing as point defects, Incurs a decline.

  The ink jet media according to the present invention preferably contains the compound of the general formula (1), and it is considered that the surface defects and cracks of the ink jet media are reduced as an effect thereof. In addition, it is known that the ink absorbency is improved as an effect of adding the compound of the general formula (1), and the amount of ink solvent remaining on the surface of the ink jet medium is rapidly reduced, so that a colorless ink is applied following the colored ink. It is considered that a uniform protective film can be obtained without causing repelling or unevenness. These are beyond the scope of speculation, and future research must be awaited for the mechanism of action that provides the effects of the present invention.

  When the inkjet media according to the present invention is used, glossiness (glossiness, image clarity) after applying a colorless ink to form a protective film is brought about. In particular, the image clarity is improved in a high density portion when an image is formed with pigment ink. This is considered to be an effect brought about by obtaining a uniform protective film, but the mechanism of action is not clear.

  The time when the colorless ink is ejected is preferably immediately after the image is formed from the viewpoint of obtaining the effect of improving the image clarity. This is because when the ink solvent used for the ink is dried after the image is formed, a clear interface is formed between the surface of the ink-forming film driven by the color ink and the colorless ink-forming film. Conceivable. It is preferable to perform both ejections by shifting the timing in the same printer, and it is preferable that the clear ink is applied before the latex fine particles contained in the ink composition are fused and formed. It is important from a viewpoint.

The protective film is formed with colorless ink so as to have a dry solid content of 0.1 to 1.0 g per 1 m ² of the ink-jet media. It tends to occur. As a result, the effect of improving the color fading prevention with respect to the dye ink is rapidly reduced, or the effect of improving the glossiness change and the image clarity change of the image portion is reduced in the pigment ink. The dry solid content of the film formed with the preferred colorless ink is 0.1 to 1.0 g, and it is preferable that the film thickness is 350 nm or more in combination with the color ink.

  The image clarity referred to in the present invention is a method defined by JIS-K-7105, which is a method for obtaining image clarity as image clarity from a light intensity waveform obtained through an optical comb using an optical device. It represents the performance of the image surface that reflects an image of an object facing the image surface formed on the medium, and is a value that indicates how accurately the incident image is reflected or projected on the image surface. The more accurately the reflected image is given to the incident image, the higher the image clarity and, as a result, the C value increases. The C value shows the effect of combining the specular gloss and the smoothness of the surface. The higher the reflectivity and the higher the smoothness, the larger the C value. For example, the image clarity (gloss value C value%) can be measured using a image clarity measuring instrument ICM-1DP (manufactured by Suga Test Machine Co., Ltd.) under the conditions of 60 degrees reflection and 2 mm optical comb. In the present invention, it is preferable that the image clarity C value is 70 or more in an image area of any density.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the examples, “%” represents mass% unless otherwise specified.

Preparation of ink composition [Preparation of ink set 1]
Ink set 1 includes seven types of yellow ink (Y), light magenta ink (LM), dark magenta ink (DM), light cyan (LC), dark cyan (DC), black (BK), and clear ink (CL). Each of the ink compositions was mixed as follows, and triethanolamine was added dropwise to adjust the pH to a range of 9.0 ± 0.3. After filtration through a 3 μm membrane filter, the ink set 1 was packed in an empty ink cartridge.

[Preparation of dark dark ink]
Diethylene glycol 13% by mass
Glycerin 10% by mass
Triethylene glycol monobutyl ether 5% by mass
Dye (* 1) 3% by mass
SBR latex SX1105A
(Resin Tg = 0 ° C. Average particle diameter = 109 nm Nippon Zeon)
1.5% by mass (solid content conversion)
Surfinol 465 (Air Products) 1% by mass
The total amount was finished to 100% by mass with water to prepare dark ink of each color.

[Preparation of light color ink]
Diethylene glycol 10% by mass
Glycerin 10% by mass
10% by mass of triethylene glycol monobutyl ether
Dye (* 1) 0.8% by mass
SBR latex SX1105A
(Resin Tg = 0 ° C. Average particle diameter = 109 nm Nippon Zeon)
1.0% by mass (solid content conversion)
Surfynol 465 0.8% by mass
* 1: As dyes,
Yellow ink is direct yellow 86,
Dark magenta / light magenta ink is direct red 227,
Dark cyan / light cyan ink is direct blue 199,
Food black 2 was used as the black ink.

[Preparation of colorless ink]
Diethylene glycol 10% by mass
Glycerin 10% by mass
10% by mass of triethylene glycol monobutyl ether
SBR latex SX1105A
(Resin Tg = 0 ° C. Average particle diameter = 109 nm Nippon Zeon)
2.0% by mass (solid content conversion)
Surfynol 465 0.5 mass%
[Preparation of ink sets 2 to 10]
According to the production method of ink set 1, SBR latex SX1105A was replaced with latex 1 and latex 2 according to the following “latex combination table”. Here, the ink set in which the latex 2 is “none” was prepared so that the entire amount of the latex 1 was replaced with the SX1105A, and ink sets 2 to 10 were produced.

[Latex combination table]
Ink set Latex 1 Latex 2 Tg (concept) Remarks 1 SX1105A None High-Comparison 2 P6030 None High-Comparison 3 SR110 None Low-Comparison 4 SR111 None Low-Comparison 5 P6030 SX1105A High-high Comparison 6 SR110 SR111 Low Low Comparison 7 P6030 SR110 High and Low Present Invention 8 P6030 SR111 High and Low Present Invention 9 SX1105A SR110 High and Low Present Invention 10 SX1105A SR111 High and Low Present Invention (Dark Color Ink)
Latex 1 1.12% by mass
Latex 2 0.38% by mass
(Light color ink)
Latex 1 0.75% by mass
Latex 2 0.25% by mass
(Colorless ink)
Latex 1 1.5% by mass
Latex 2 0.5% by mass
[Latex properties]
P6030 10 ° C 300% 137nm Asahi Kasei SX1105A 0 ° C 450% 109nm Nippon Zeon SR110 -27 ° C 800% 116nm Nippon A & L SR111 -34 ° C 850% 120nm Nippon A & L (Method of measuring elongation at break)
Polyethylene glycol (1.0% by mass) was added to the latex as a thickener and laminated on a polytetrafluoroethylene plate by cast coating to form a film having a thickness of 500 μm. After heat treatment at 120 ° C. for 15 minutes, a test film was obtained by peeling from the polytetrafluoroethylene plate. The test film was cut into a 1.0 cm wide test piece, and the elongation at break was measured with a tensile break tester.

[Production of inkjet media]
100 parts of wood pulp (LBKP / NBSP = 50/50), 1 part of polyacrylamide, 4 parts of ash (talc), 2 parts of cationized starch, 0.5 part of polyamide epichlorohydrin resin, and various A slurry liquid containing an added amount of an alkyl ketene dimer (sizing agent) was prepared, and a base paper was made using a long paper machine so that the basis weight was 170 g / m ² . After calendering this, a low-density polyethylene resin having a density of 0.92 containing 7% by mass of anatase-type titanium oxide and a small amount of a color tone adjusting agent was melt extruded at a temperature of 320 ° C. to a thickness of 28 μm. One side of the paper was covered and cooled immediately with a mirror cooling roller. Next, the opposite surface was coated with a mixed melt of high density polyethylene of density 0.96 / low density polyethylene of density 0.92 = 70/30 to a thickness of 32 μm by the melt extrusion method.

  The surface on the side where the ink absorbing layer is provided had a 60 ° glossiness of 56% and a centerline average roughness Ra of 0.12 μm.

After corona discharge on the titanium oxide-containing layer side of the support, 0.05 g / m ² of gelatin was applied as an undercoat layer.

  On the other side, a styrene / acrylic emulsion containing silica fine particles (matting agent) with an average particle diameter of about 1 μm and a small amount of cationic polymer (conducting agent) is applied to a dry film thickness of about 0.5 μm. To prepare a support for applying the ink absorbing layer.

  On the back surface side, the glossiness was about 18%, SRa≈4.5 μm, and the Beck smoothness was 160 to 200 seconds.

  The moisture content of the base paper of the support thus obtained was 7.0 to 7.2%.

The support had an opacity of 96.5% and whiteness of L ^* = 95.2, a ^* = 0.56, and b ^* = − 4.35.
Next, a coating solution having the following composition for the front side was prepared.

<Preparation of titanium oxide dispersion>
20 kg of titanium oxide having an average particle size of about 0.25 μm (Ishihara Sangyo: W-10), 150 g of sodium tripolyphosphate having pH = 7.5, 500 g of polyvinyl alcohol (Kuraray Co., Ltd .: PVA235), cationic polymer (P- 1) After adding 150 g and 90 g of an aqueous solution containing 10 g of Sanbuco Co., Ltd. defoaming agent SN381 and dispersing with a high-pressure homogenizer (manufactured by Sanwa Kogyo Co., Ltd.), the total amount is finished to 100 L to obtain a uniform titanium oxide dispersion 1 Obtained.

<Preparation of silica dispersion 1>
A solution having the following composition was prepared.

Water 71L
Boric acid 0.27kg
Borax 0.24kg
Ethanol 2.2L
Cationic polymer (P-1) 25% aqueous solution 17L
Anti-fading agent (AF1) 10% aqueous solution 0.5L
Optical brightener aqueous solution (W1 *) 0.1L
The whole volume is finished to 100 L with pure water.

(W1 *) Ciba Specialty Chemicals, UVITEX NFW LIQUID
As inorganic fine particles, 50 kg of vapor phase method silica (average primary particle diameter of about 7 nm) was prepared. The above liquid was supplied to a spiral pin mixer SPM25W (manufactured by Taiyo Koki Co., Ltd., hereinafter referred to as SPM) as a disperser 1 at a rate of 1.56 kg / min and gas phase method silica at a rate of 0.44 kg / min. Thereafter, the dispersion machine 2 was supplied to a fine flow mill FM-25 (continuous high-speed stirring dispersion machine, manufactured by Taiyo Kiko Co., Ltd., hereinafter referred to as FM). Thereafter, LMK-4 (continuous wet media type pulverizer, manufactured by Ashizawa, hereinafter referred to as LMK) is used as the disperser 3, and the dispersion liquid from the disperser 2 is added to the LMK at 2.0 kg / min using a mono pump. Supplied with. The SPM conditions are a peripheral speed of 36 m / sec, a residence time of 30 seconds, and the LMK conditions are a bead diameter of 0.5 mm zirconia, a residence time of 2 minutes, a rotor rotational peripheral speed of 8 m / sec, a material urethane, and a vessel material urethane. Dispersing in this way gave silica dispersion 1.

(Preparation of silica dispersion 2)
In the preparation of silica dispersion 1, silica dispersion 2 was prepared by dispersing in the same manner as silica dispersion 1 except that the cationic polymer was changed from P-1 to P-2.

<Preparation of coating solution>
Each coating solution for the first layer, the second layer, the third layer, and the fourth layer was prepared by the following procedure.

First layer coating solution The following additives were sequentially mixed in 610 ml of silica dispersion 1 while stirring at 40 ° C.

5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA235)
220ml
5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA245)
80ml
Titanium oxide dispersion 30ml
Polybutadiene dispersion (average particle size ≒ 0.5μm, solid content 40%) 15ml
Surfactant (SF1) 5% aqueous solution 1.5ml
10% urea 10% aqueous solution
Finish the whole volume to 1000ml with pure water.

Second layer coating solution The following additives were sequentially mixed in 630 ml of silica dispersion 1 while stirring at 40 ° C.

5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA235)
180ml
5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA245)
80ml
Polybutadiene dispersion (average particle size ≒ 0.5μm, solid content 40%) 15ml
10% urea 10% aqueous solution
Finish the whole volume to 1000ml with pure water.

The following additives were sequentially mixed in 650 ml of the third layer coating solution at 40 ° C. with stirring.

5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA235)
180ml
5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA245)
80ml
10% urea 10% aqueous solution
Finish the whole volume to 1000ml with pure water.

The following additives were sequentially mixed into 650 ml of the silica layer 2 coating solution at 40 ° C. with stirring.

5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA235)
180ml
5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA245)
80ml
Saponin 50% aqueous solution 4ml
Surfactant (SF1) 5% aqueous solution 6ml
10% urea 10% aqueous solution
Finish the whole volume to 1000ml with pure water.

  The coating solution obtained as described above was subjected to two-stage filtration with a 20 μm-capable filter. Each of the coating solutions showed viscosity characteristics of 30 to 80 mPa · s at 40 ° C. and 30 to 100 Pa · s at 15 ° C.

  In addition, the coating solution pH of the third layer and the fourth layer was obtained by changing the boric acid / borax mixing ratio of the silica dispersion so that the molar amounts of boric acid and borax were equal. , And adjusted to 4.6 at 25 ° C.

Each coating solution thus obtained was coated on the front side of the support coated on both sides with polyolefin on the first layer (35 μm), second layer (45 μm), third layer (45 μm), fourth layer ( Each layer was applied simultaneously so as to be in the order of 40 μm). The inside of parenthesis shows each wet film thickness. The coating was carried out at the same time using a four-layer curtain coater for each coating solution at 40 ° C. with a coating width of about 1.5 m and a coating speed of 100 m / min. Immediately after the coating, it is cooled for 20 seconds in a cooling zone maintained at 8 ° C., then 20 to 30 ° C., relative humidity 20% or less for 30 seconds, 60 ° C./relative humidity 20% or less for 120 seconds, 55 ° C./relative humidity 20% In the following, after drying for 60 seconds, each drying air was blown (the film temperature in the constant rate drying area was 8 to 30 ° C., and the film temperature gradually increased in the decreasing rate drying area), and then 23 ° C. and relative humidity 40 The ink was conditioned in a -60% humidity adjustment zone and wound up into a roll to obtain an inkjet media. The obtained inkjet media was then heated and stored at 40 ° C. for 5 days while being on a roll, and then cut into a predetermined size. The ink absorption capacity of the inkjet media was 25 ml / m ² from the Bristow measurement results. The pore diameter on the outermost surface measured with a mercury porosimeter was 27.2 nm.

Evaluation Each color of the ink set was sent to an inkjet head and controlled to print at 1440 × 1440 dpi (dpi represents 1 inch, that is, the number of dots per 2.54 cm). In addition, dark dark ink is ejected at a high density portion where the amount of light ink emitted becomes severe due to the ink absorption capacity of the medium, and colorless ink is in accordance with the amount of color ink as described in JP-A-2005-88411. And printed with an algorithm that emits light in reverse imagewise.

  For each of the ink sets 1 to 10, image data used for each evaluation was printed on an inkjet medium.

  The evaluation results are shown in Table 1.

(Ozone life evaluation method)
Seven types of inks of Y, LM, DM, LC, DC, BK, CL are ejected, and the optical density is 1. using an algorithm in which the total amount of ink applied is 17 ml / m ² with the YMCK composite. The gray patch was printed by adjusting to 0. After this print was dried at room temperature for one day, it was exposed at a concentration of 10 ppm / hour using an ozone tester (model name) manufactured by Suga Test Instruments Co., Ltd., and optical density (X-rite 938 manufactured by X-Rite Co., Ltd. was used). The amount of ozone exposure was determined when the color faded to 70%. Furthermore, the ozone exposure at the time of 70% fading obtained with the ink set 1 was set to 100 and compared with other samples. The higher the value, the greater the ozone exposure and the better the resistance.

(Image clarity C value evaluation method)
The image clarity referred to in the present invention is defined by JIS-K-7105, and is a method for obtaining image clarity as image clarity from a waveform of light quantity obtained through an optical comb using an optical device. The value represents the performance of the image surface that reflects the image of the object facing the image surface, and indicates how accurately the incident image is reflected or projected on the image surface. The more accurately the reflected image is given to the incident image, the higher the image clarity and, as a result, the C value increases. The C value shows the effect of combining the specular gloss and the smoothness of the surface. The higher the reflectivity and the higher the smoothness, the larger the C value. For example, the image clarity (gloss value C value%) can be measured using a image clarity measuring instrument ICM-1DP (manufactured by Suga Test Machine Co., Ltd.) under the conditions of 60 degrees reflection and 2 mm optical comb.

  In the present invention, Y, M, C, B, G, R, BK, and W of the measurement sample (Y, M, and C are single colors. B, G, R, and BK are printed by composite. W is CL ink only on one side. Printed.) For each patch, the image clarity (gloss value C value%) was measured at a 60 ° angle and an optical comb of 2 mm with the standard reflector as a reference, and the lowest C value in each patch was compared. did.

(Aging storage evaluation)
Samples printed with each ink set were dried at room temperature for 1 day, left in an air blowing environment of 40 ° C. and 80% RH for 4 days, and each of the above “ozone life evaluation method” and “imaging C value evaluation method” Samples were compared.

(Abrasion resistance evaluation method)
The scratch resistance was evaluated by quantitative measurement using a scratch meter. A solid solid image with an optical density of 1.0 was printed using the same algorithm as the ozone life evaluation, and the sample was allowed to dry for 1 day. A 0.2Φ sapphire needle (the tip is a curve) was used to change the load from 0 to 100 g. (25 ° C., 55% RH environment, 10 mm / sec), the sample was exposed with a 100 ppm ozone tester, and the scratch load values at which fading due to ozone gas began to become noticeable were compared.

  From the above results, by using the configuration of the present invention, it was possible to improve storage stability over time with respect to ozone resistance and image clarity C value, and to greatly improve scratch resistance.

Claims (5)

In an inkjet image forming method of ejecting ink from an inkjet head onto an inkjet media and printing image data, the inkjet media is a void-type inkjet media having a pore diameter of the outermost layer of 6 to 50 nm. At least two or more types of ink can be ejected, and one of the inkjet heads is configured to eject a substantially colorless ink (colorless ink) that does not contain a colorant. The ink-jet image recording method according to claim 1, wherein the colorless ink is an ink containing at least two kinds of water-dispersible resin particles having different glass transition temperatures. 2. The inkjet image recording method according to claim 1, wherein the colorless ink is an ink containing two kinds of water-dispersible resin fine particles having glass transition temperatures of 15 to 80 [deg.] C. different from each other. The two kinds of water-dispersible resin fine particles are at least latex A having a glass transition temperature of −50 ° C. or more and less than −10 ° C. and latex B having a glass transition temperature of −10 ° C. or more and less than 30 ° C. The inkjet image recording method according to claim 1 or 2, wherein: 4. The inkjet image recording method according to claim 3, wherein the latexes A and B have different tensile elongation at break. The inkjet image recording method according to claim 4, wherein the latexes A and B are a latex having a tensile elongation at break of 500% or more and a latex having a tensile elongation at break of less than 500%.