JP2010052369A - Ink-jet recording medium and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet recording medium which suppresses generation of curling accompanying image recording, maintains high image density, superior ozone resistance, and which is recyclable, and to provide a method for manufacturing the same. <P>SOLUTION: The ink-jet recording medium comprises: base paper; a first layer containing a hydrophilic binder and a second layer which contains inorganic fine particles; a nitrogen-containing organic cation polymer; and a water-soluble aluminum compound on the first layer, wherein Cobb water absorbency at the surface of the first layer is 2.0 g/m<SP>2</SP>or below, when measured under a contact time of 120 seconds by a water absorbency test which is in compliance with JIS P8140, the nitrogen-containing organic cationic polymer is contained more, in a half side near the base paper than in a half side which is far from the base paper, when the second layer is divided into two equal parts by a plane parallel to the base paper; and the water-soluble aluminum compound is contained more in the half side far from the base paper than in the half side near the base paper. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inkjet recording medium and a method for manufacturing an inkjet recording medium.

  The ink jet apparatus has a simple structure, and high-quality image recording is possible by ink jet recording performed using the ink jet apparatus. Ink used for inkjet recording is designed to have a surface tension of 20 mN / m to 40 mN / m, adjusted to a viscosity of several mPa · s to 30 mPa · s so that it can be ejected from an inkjet head. .

  In general, the ink contains 50% to 90% of an ink solvent so that the viscosity of the ink falls within the above range. As the ink solvent, water, an organic solvent, oil, a photopolymerizable monomer, and the like are used, and water is often used particularly from the viewpoint of environmental suitability. Further, a high boiling point solvent such as glycerin is generally used as the ink solvent so that the discharge nozzle of the ink jet head does not cause clogging due to drying of the ink solvent.

  On the other hand, when a large amount of ink solvent is present in the ink-drawn recording medium, image bleeding and color mixing between colors are likely to occur due to the large amount of ink solvent. For this reason, a special inkjet paper having a solvent absorbing layer (ink receiving layer) of about 20 to 30 μm on the surface for absorbing the ink solvent is used as a recording medium, and the occurrence of image bleeding and color mixing between colors is suppressed. .

  Also, in the case of water-based ink using water as an ink solvent, paper penetration such as curling occurs when water penetrates into the base paper during recording, but when the ink-jet dedicated paper has a solvent absorption layer on the base paper, Infiltration of water into the base paper is suppressed, and paper deformation can be suppressed.

  In particular, when a graphical image with a high image density or image area ratio is to be formed, the amount of ink per unit area on the recording medium increases, and the solvent absorption layer cannot suppress the penetration of the ink solvent into the base paper. Therefore, water-resistant paper (for example, laminated paper) covered with a resin layer using polyolefin or the like is generally used (for example, see Patent Documents 1 and 2).

  However, the ink jet technology is not only applied in the fields of office printers, home printers, etc., but has recently been applied in the field of commercial printing. This commercial printing field does not have a photo-like surface that completely shuts out the penetration of the ink solvent into the base paper, but requires a printing texture like general-purpose printing paper. However, if the solvent absorption layer constituting the recording medium is as thick as 20 to 30 μm, the surface gloss, texture, stiffness, etc. of the recording medium are limited. However, it is limited to posters, form printing, and the like that are allowed to be limited in terms of surface gloss, texture, stiffness, etc., on the recording medium.

Since the recording medium has a solvent absorption layer and a water resistant layer, the cost is high. Further, since the recording medium is covered with the resin layer, the used paper cannot be recovered, which also contributes to the above limitation.
JP 2005-238829 A JP 2005-96285 A

However, the recording medium described in the above-mentioned patent document is actually not sufficient in terms of density and ozone resistance because it suppresses paper deformation such as curling, and the recording medium having a resin layer is not recyclable.
The present invention has been made in view of the above, and suppresses the occurrence of curling associated with image recording, can maintain a high image density, has excellent ozone resistance, and can be recycled. It is an object to provide a medium and a manufacturing method thereof.

<1>
A first layer containing a base paper, a hydrophilic binder, and a second layer containing inorganic fine particles, a nitrogen-containing organic cationic polymer, and a water-soluble aluminum compound on the first layer; Cobb water absorption degree during a contact time of 120 seconds by water absorption test conforming to JIS P8140 at a surface of the layer is not more 2.0 g / m ² or less, the nitrogen-containing organic cation polymer, said second layer to the base paper The water-soluble aluminum compound is contained more in the side half far from the base paper than in the side half near the base paper than in the side half near the base paper than in the side half far from the base paper when divided in half by a parallel plane. An ink jet recording medium characterized by comprising:
<2>
The inkjet recording medium according to <1>, wherein the nitrogen-containing organic cationic polymer is at least one selected from a cationic polyurethane and a cationic polymer having a quaternary ammonium base.
<3>
The ink jet recording medium according to <1> or <2>, wherein the hydrophilic binder in the first layer contains a thermoplastic resin.
<4>
The inkjet recording medium according to <3>, wherein the thermoplastic resin is at least one selected from urethane latex and acrylic silicone latex.
<5>
The ink jet recording medium according to any one of <1> to <4>, wherein the first layer further contains a white pigment.
<6>
The inkjet recording medium according to <5>, wherein the white pigment is kaolin.

<7>
The ink jet recording medium according to <5>, wherein the second layer further contains a sulfur compound.
<8>
The ink jet recording medium according to <7>, wherein the sulfur compound is a sulfoxide compound or a thioether compound.
<9>
A first layer forming step in which a first film-forming liquid containing a hydrophilic binder is applied to both sides of a base paper and dried to form a first layer; and on the first layer, inorganic fine particles and nitrogen-containing organic The second coating liquid containing the cationic polymer and the third coating liquid containing the inorganic fine particles and the water-soluble aluminum compound are coated with a coating liquid temperature of 35 so that the third coating liquid overlaps the second coating liquid. The nitrogen-containing organic cationic polymer is more contained in the side half closer to the base paper than the side half far from the base paper when the multilayer coating is performed in a plane parallel to the base paper and bisected in a plane parallel to the base paper, and is close to the base paper A second layer forming step of forming an ink-receiving layer containing a large amount of the water-soluble aluminum compound in the side half farther from the base paper than in the side half, and the method described in any one of the above items <1> to <8> Inkjet for producing inkjet recording media Manufacturing method of the recording medium.

  According to the present invention, it is possible to suppress the occurrence of curling accompanying image recording, to maintain a high image density, to have excellent ozone resistance, and to provide a recyclable inkjet recording medium and a method for manufacturing the same. be able to.

  Hereinafter, the ink jet recording medium of the present invention, a method for producing the same, and an ink jet recording method using the recording medium will be described in detail.

<Inkjet recording medium>
The ink jet recording medium of the present invention includes a base paper, a first layer containing a hydrophilic binder, and a second layer containing inorganic fine particles, a nitrogen-containing organic cationic polymer, and a water-soluble aluminum compound on the first layer ( And the nitrogen-containing organic cationic polymer has a side half closer to the base paper than a side half far from the base paper when the second layer is divided into two equal parts by a plane parallel to the base paper. The water-soluble aluminum compound is contained in a large amount on the side half far from the base paper, and if necessary, another layer appropriately selected can be provided.
The ink jet recording medium of the present invention can suppress curling due to image recording, maintain a high image density, have excellent ozone resistance, and be recyclable.

(Base paper)
There is no restriction | limiting in particular as a base paper, According to the objective, it can select suitably from well-known things.

  The pulp that can be used as the raw material of the base paper is preferably hardwood bleached kraft pulp (LBKP) from the viewpoint of improving the surface smoothness, rigidity, and dimensional stability (curlability) of the base paper to a high level at the same time. In addition, softwood bleached kraft pulp (NBKP), hardwood sulfite pulp (LBSP), and the like can be used.

  A beater or refiner can be used for beating the pulp. In the pulp slurry obtained after beating the pulp (hereinafter sometimes referred to as “pulp paper material”), various additives such as a filler, a dry paper strength enhancer, a sizing agent, and wet paper strength are used as necessary. An enhancer, a fixing agent, a pH adjuster, other chemicals, and the like are added.

Examples of the filler include calcium carbonate, clay, kaolin, white clay, talc, titanium oxide, diatomaceous earth, barium sulfate, aluminum hydroxide, magnesium hydroxide and the like.
Examples of the dry paper strength enhancer include cationized starch, cationized polyacrylamide, anionized polyacrylamide, amphoteric polyacrylamide, and carboxy-modified polyvinyl alcohol.
Examples of the sizing agent include rosin derivatives such as fatty acid salts, rosin and maleated rosin, paraffin wax, alkyl ketene dimer, alkenyl succinic anhydride (ASA), and epoxidized fatty acid amide.
Examples of the wet paper strength enhancer include polyamine polyamide epichlorohydrin, melamine resin, urea resin, and epoxidized polyamide resin.
Examples of the fixing agent include polyvalent metal salts such as aluminum sulfate and aluminum chloride, and cationic polymers such as cationized starch.
Examples of the pH adjuster include caustic soda and sodium carbonate.
Examples of other chemicals include antifoaming agents, dyes, slime control agents, fluorescent whitening agents, and the like.

  Moreover, a softening agent etc. can also be added to a pulp paper stock as needed. The softening agent is described in, for example, New Paper Processing Handbook (edited by Paper Medicine Time), pages 554 to 555 (issued in 1980).

The treatment liquid used for the surface sizing treatment may contain, for example, a water-soluble polymer, a sizing agent, a water-resistant substance, a pigment, a pH adjusting agent, a dye, and a fluorescent brightening agent.
Examples of the water-soluble polymer include cationized starch, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, cellulose sulfate, gelatin, casein, sodium polyacrylate, styrene-maleic anhydride copolymer sodium salt, Examples thereof include sodium polystyrene sulfonate.
Examples of the sizing agent include petroleum resin emulsion, ammonium salt of styrene-maleic anhydride copolymer alkyl ester, rosin, higher fatty acid salt, alkyl ketene dimer (AKD), epoxidized fatty acid amide and the like.
Examples of the water-resistant substance include latex / emulsions such as styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, polyethylene, vinylidene chloride copolymer, polyamide polyamine epichlorohydrin, and the like.
Examples of the pigment include calcium carbonate, clay, kaolin, talc, barium sulfate, and titanium oxide.
Examples of the pH adjuster include hydrochloric acid, caustic soda, sodium carbonate, and the like.

  Examples of the material of the base paper include synthetic pulp paper, mixed paper of natural pulp and synthetic pulp, and various types of combined paper, in addition to the above-described natural pulp paper.

As thickness of a base paper, 30-500 micrometers is preferable, More preferably, it is 50-300 micrometers, More preferably, it is 70-200 micrometers.
As the base paper, for example, general printing paper such as high-quality paper or coated paper can be used. Among them, a permeable paper material that is not covered with a thermoplastic resin or the like is preferable. Specifically, high quality paper such as “Shiraoi” made by Nippon Paper Industries, coated paper (A2, B2) such as “Aurora Coat” and “Ulite”, “OK Top Coat +” made by Oji Paper, and Mitsubishi Art paper (A1) such as “Tokuhishi Art” manufactured by Paper Industries Co., Ltd. can be used.

(First layer)
The recording medium of the present invention has a first layer on the base paper. Hereinafter, the base paper on which the first layer is formed is also referred to as a support.
By providing the first layer, the penetration of the ink solvent into the base paper is suppressed. For example, as a paper provided with a solvent blocking layer, a paper having a coating layer mainly composed of polyethylene resin on the surface of the base paper is known. However, with the paper provided with the above-described solvent blocking layer to give water resistance, the water penetration preventing effect can be obtained almost completely, but the paper texture is not always satisfactory.
The first layer contains at least a hydrophilic binder, and has a Cobb water absorbency of 2 seconds for a contact time of 120 seconds according to a water absorbency test according to JIS P8140 on the surface of the first layer of the base paper provided with the first layer. 0.0 g / m ² or less.
In the present invention, the first layer is not particularly limited as long as it is within this range, and the first layer can be appropriately selected from known additives depending on the purpose.
The first layer can be constituted by using other components as required in addition to the hydrophilic binder, for example.

  The first layer in the present invention is, for example, a thermoplastic resin (preferably latex, more preferably polyester-based urethane latex, acrylic silicone-based) as a hydrophilic binder in terms of suppressing penetration of the ink solvent and obtaining good surface properties. Latex) is a layer in which kaolin is used as a white pigment, and the mass ratio x / y of the mass (solid content) x of the thermoplastic resin to the mass y of kaolin is 1 or more and 30 or less. A layer using a crosslinking agent selected from a compound having a methylene group, cyanuric chloride, formaldehyde, and carbodiimide is preferred.

-Hydrophilic binder-
The first layer contains at least one hydrophilic binder (hereinafter also simply referred to as “binder”). The binder is used for the purpose of improving not only the dispersion but also the coating film strength. In the present invention, the “hydrophilic binder” includes an aqueous dispersion of binder particles such as latex.
Examples of the binder include polyvinyl alcohol (including modified polyvinyl alcohols such as acetoacetyl modification, carboxy modification, itaconic acid modification, maleic acid modification, silica modification and amino group modification), methylcellulose, carboxymethylcellulose, starches (modified starch). And water-soluble resins such as gelatin; arabic gum, casein, styrene-maleic anhydride copolymer hydrolyzate, polyacrylamide, saponified vinyl acetate-polyacrylic acid copolymer, and the like. Examples thereof also include latex binders of synthetic polymers such as styrene / butadiene copolymer, vinyl acetate copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, and polyvinylidene chloride.
In the present invention, it is preferable that at least one water-soluble resin is included as a binder from the viewpoint of production suitability.

  The polyvinyl alcohol includes polyvinyl alcohol obtained by saponifying a lower alcohol solution of polyvinyl acetate and derivatives thereof, and a saponified product of a copolymer of a monomer and vinyl acetate that can be copolymerized with vinyl acetate. It is. Here, as monomers that can be copolymerized with vinyl acetate, (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid and other unsaturated carboxylic acids and esters thereof, ethylene, propylene, etc. Α-olefin, olefin sulfonic acid such as (meth) allyl sulfonic acid, ethylene sulfonic acid, sulfonic acid malate, (meth) allyl sulfonic acid soda, ethylene sulfonic acid soda, sulfonic acid soda (meth) acrylate, sulfonic acid soda ( Monoalkylmalates), olefinic sulfonic acid alkali salts such as sodium disulfonic acid alkylmalate, amide group-containing monomers such as N-methylolacrylamide, alkali acrylamide alkylsulfonic acid salts, and N-vinylpyrrolidone derivatives Can be mentioned.

  Of the polyvinyl alcohols, acetoacetyl-modified polyvinyl alcohol can be generally produced by adding and reacting a liquid or gaseous diketene to the solution, dispersion or powder of the polyvinyl alcohol resin. The acetylation degree of acetoacetyl-modified polyvinyl alcohol can be appropriately selected according to the intended quality, but is preferably 0.1 mol% to 20 mol%, more preferably 0.5 mol% to 10 mol%. It is.

The binder further includes general-purpose thermoplastic polymers such as polyamide and polyimides; polyesters such as polyethylene terephthalate; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, ( Α-methylene aliphatic monocarboxylic acid esters such as dodecyl (meth) acrylate, octyl (meth) acrylate and phenyl (meth) acrylate; styrenes such as styrene, chlorostyrene and vinylstyrene; vinyl acetate and vinyl propionate , Vinyl esters such as vinyl benzoate and vinyl butyrate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone; , Or such as any of the copolymer containing these structural units can be appropriately selected from known thermoplastic resins and latexes thereof.
In the present invention, polyolefins such as homopolymers of α-olefins such as polyethylene, polypropylene, polyvinyl chloride and the like, or mixtures thereof, which are generally used as binders, are not included in the binder.

Among these, thermoplastic resin particles are preferable from the viewpoint of water blocking properties. Thermoplastic resins include acrylic, acrylic silicone, acrylic epoxy, acrylic styrene, urethane (acryl urethane, polyester urethane), styrene-butadiene latex, acrylonitrile-butadiene, and vinyl acetate. preferable.
From the viewpoint of recyclability, the hydrophilic binder is preferably contained using an aqueous dispersion such as latex.
The water-dispersible latex is obtained by dispersing a hydrophobic polymer insoluble or hardly soluble in water as fine particles in a water-phase dispersion medium. This dispersion state may be a polymer that is emulsified in a dispersion medium, an emulsion polymerized, a micelle-dispersed, or a polymer molecule that has a partially hydrophilic structure and the molecular chain itself is molecular. Any of those dispersed may be used. For such water-dispersible latexes, edited by Taira Okuda and Hiroshi Inagaki “Synthetic Resin Emulsion” (published by Kobunshi Publishing Co., Ltd., 1978), Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki and Keiji Kasahara Published by Kobunshi Shuppankai, 1993) and Soichi Muroi, “Chemistry of Synthetic Latex” (published by Kobunshi Shuppankai, 1970).
Latex includes acrylic latex, acrylic silicone latex, acrylic epoxy latex, acrylic styrene latex, acrylic urethane latex, styrene-butadiene latex, acrylonitrile-butadiene latex, polyester urethane latex, and vinyl acetate latex. And the like.
In particular, from the viewpoint of coating film strength, urethane latex (acrylic urethane latex, polyester urethane latex) and acrylic silicone latex are preferable, and urethane latex is more preferable.

  The molecular weight of the latex is preferably 3,000 to 1,000,000 in terms of number average molecular weight, and more preferably about 5,000 to 100,000. When the molecular weight is 3,000 or more, the adhesion between the base paper and the second layer and the mechanical strength of the first layer can be secured, and when it is 1,000,000 or less, the dispersion stability, viscosity, etc. This is advantageous in terms of manufacturing aptitude.

Specifically, as the acrylic latex, a commercially available product can be used. For example, the following water-dispersible latex can be used. That is, examples of acrylic resins include “Cebian A4635, 46583, 4601” manufactured by Daicel Chemical Industries, Ltd., “Nipol Lx811, 814, 821, 820, 857” manufactured by Nippon Zeon Co., Ltd. . In particular, acrylic emulsions of acrylic silicon latex described in JP-A-10-264511, JP-A-2000-43409, JP-A-2000-343811, and JP-A-2002-120452 (commercially available products include, for example, Daicel Aquabrid series UM7760, UM7611, UM4901, Aquabrid 903, Asi-86, ASi-89, Asi-91, ASi-753, 4635, 4901, MSi-04S, Chemical Industries, Ltd. AU-124, AU-131, AEA-61, AEC-69, AEC-162, etc.) can also be suitably used.
In addition, as a polyester-based urethane latex, for example, as a commercial product, HYDRAN AP series (for example, HYDRAN AP-20, AP-30, AP-30F, AP-40 (F), manufactured by DIC Corporation, The same AP-50LM, the same APX-101H, the same APX-110, the same APX-501, etc.).
In addition, it is preferable to select and use at least one of the above thermoplastic resins from the above, and it may be used alone or in combination of two or more.

  The glass transition temperature (Tg) of the thermoplastic resin is preferably 5 to 70 ° C, and particularly preferably 15 to 50 ° C. When the Tg is particularly within the above range, problems such as burrs of the film forming liquid for forming the first layer (for example, coating liquid) are prevented, and handling in manufacturing is easy, and Tg is high. If the calendar temperature is not set too high, the desired gloss cannot be obtained, and adhesion to the metal roll surface is likely to occur. High planarity can be obtained.

  The minimum film-forming temperature of the thermoplastic resin (preferably latex resin fine particles) is preferably 20 to 60 ° C, and more preferably 25 to 50 ° C. When the minimum film forming temperature range where film formation is possible when trying to form a film is particularly within the above range, problems such as burrs of the film forming liquid for forming the first layer (for example, coating liquid) can be prevented. It is easy to handle in production, and the penetration when the second layer is formed is suppressed, the coated surface of the second layer to be formed is good, and the ink solvent can be quickly transmitted. A layer having sufficient microporosity can be formed. Although a layer only provided with a liquid (for example, a coating solution) does not necessarily have good glossiness, a high glossiness layer having microporosity can be obtained by performing a soft calender treatment later.

  As content in the 1st layer of a binder (preferably thermoplastic resin), 15-95 mass% is preferable with respect to the total solid of this 1st layer, and 30-90 mass% is more preferable. When the content is particularly within the above range, gloss and flatness are good when calendar treatment is performed, ink solvent permeability is obtained, and the occurrence of bleeding with time is more effectively prevented. Can do.

  Moreover, you may add the hardening agent of a suitable binder to a 1st layer according to the kind of these binder as needed.

~ Cobb water absorption ~
In the present invention, the Cobb water absorption for a contact time of 120 seconds measured by a water absorption test in accordance with JIS P8140 from the first layer side of the base paper provided with the first layer is 2.0 g / m ² or less. To do. When the Cobb water absorption is 2.0 g / m ² or less, the base paper provided with the first layer has a slow permeability and delays the absorption when a liquid such as ink is applied, thereby generating curls. Can be reduced.
Furthermore, the Cobb water absorption is more preferably 1.0 g / m ² or less. Further, the lower limit value of the Cobb water absorption is preferably 0.2 g / m ² .

  The Cobb water absorption is measured by a water absorption test according to JIS P8140, and water is supplied for a certain period of time from one surface of the base paper, specifically, the surface of the first layer of the base paper provided with the first layer. This is a measure of the amount of water that is absorbed when the water contacts. In the present invention, the contact time is 120 seconds (2 minutes).

<Example of First Layer Cobb Water Absorption Prediction Method for Second Layer Coated Product>
When the Cobb water absorption of the first layer is low, the second layer-forming coating solution at the time of coating the second layer (absorbing layer) is difficult to soak into the first layer. Therefore, the interface between the first layer and the second layer is relatively easy to understand.
The second layer is generally easily dyed by Magic Ink (registered trademark, sold by Teranishi Chemical Industry Co., Ltd.) and is easily dyed, but the first layer is made of, for example, styrene-butadiene or acrylic-urethane. When the latex is the main component or when the Cobb water absorption is 2 g / m ² or less, the magic ink (registered trademark) is difficult to permeate and is difficult to be dyed. Using such a phenomenon, after dyeing the second layer with magic ink (registered trademark, very thick), it is possible to scrape only the second layer with a razor blade or the like.
It is possible to predict the Cobb water absorption of the first layer after scraping the second layer by this method. However, because the sample cannot be cut uniformly due to the surface properties of the sample, the Cobb water absorption may increase due to the destruction of the first layer due to overcutting, or the Cobb water absorption measurement because the second layer remains. Since the value may be high, the sample is measured at least 5 times per sample, and the average value of 3 times excluding the maximum and minimum values is used for the Cobb water absorption on the surface of the first layer after cutting the second layer. Degree.

The Cobb water absorption on the surface of the first layer after cutting the second layer is about 0.5 to 3 g / m ² higher than the Cobb water absorption on the surface of the first layer before providing the second layer. There is a case. Therefore, if the Cobb water absorption on the surface of the first layer after cutting the second layer is 5 g / m ² or less, the Cobb water absorption on the surface of the first layer before providing the second layer is ² g / m ^2. m ² or less.

Furthermore, from the dyeing behavior of the magic ink (registered trademark), if the water absorption on the surface of the first layer is 2 g / m ² or less, the magic ink (registered trademark) does not show off on the back surface. Or it becomes a grade where the spot which turns over in the shape of a spot is recognized. Therefore, if such behavior appears, it is estimated that the Cobb water absorption on the surface of the first layer is 2 g / m ² or less.

In addition to the above components, other components such as a white pigment, a hardener, and a layered inorganic compound can be used for the first layer.
-White pigment-
The first layer preferably contains at least one kind of white pigment. When the first layer contains a white pigment, it is preferable from the viewpoint of easy application of the second layer applied on the first layer.
Examples of white pigments include titanium oxide, barium sulfate, barium carbonate, calcium carbonate, lithopone, alumina white, zinc oxide, silica antimony trioxide, titanium phosphate, aluminum hydroxide, kaolin, clay, talc, magnesium oxide, and hydroxide. And magnesium.

  Further, kaolin other than calcined kaolin is particularly preferred from the viewpoint of water blocking. Such kaolins include Astra Plus, Contour 1500, Contour Extreme, Capim DG, Capim NP, Capim CC, Astra Scene, Astra Gross, Astra Coat, Beta Bright, Astra Glaze from Imeris Minerals Japan Co., Ltd. , Premier LX, Premier, Casey S, Astra Plate, XP03-8390, etc. Union clay RC-1, NN kaolin clay, SPMA clay, kaolin clay 5M, hard sill, ST kaolin clay, catalpo, No. 5 clay, etc. M.M. Huber's Huber35, Huber35B, Huber80, Huber80B, Huber90, Huber90B, HuberHG90, Huber TEK2001, Polygloss90, PolyplateP, Polyplate P01, Polythpe 94

  Further, when the first layer contains a white pigment, sticking to the calendar can be prevented when the calendar process is performed after the first layer is formed.

  The particle size of the white pigment is preferably 75% or more (volume basis) of particles having a size of 2.0 μm or less. When the particle size is within the above range, the whiteness and glossiness become good.

The specific surface area of the white pigment by the BET method is preferably less than 100 m ² / g. When a white pigment having a specific surface area in this range is included, the penetration of the coating liquid when the second layer is applied and formed can be suppressed, and the ink absorbability of the second layer can be increased.

  The BET method is one of powder surface area measurement methods by a gas phase adsorption method, and is a method for obtaining a total surface area, that is, a specific surface area of a 1 g sample from an adsorption isotherm. Usually, nitrogen gas is used as the adsorbed gas, and a method of measuring the amount of adsorption from the change in pressure or volume of the gas to be adsorbed is common. A prominent expression of the isotherm of multimolecular adsorption is the Brunauer Emmett, Teller equation (BET equation). Based on this, the amount of adsorption is obtained, and the surface area is obtained by multiplying the area occupied by one adsorbed molecule on the surface. .

A white pigment can be used alone or in combination of two or more.
The content of the white pigment in the first layer varies depending on the type of white pigment, the type of thermoplastic resin, the layer thickness, etc., but is usually 5 to 200 mass with respect to the mass (solid content) of the binder. % Is desirable.

-Hardener-
The first layer may include a hardening agent that hardens the binder. As a hardener, an aldehyde compound, 2,3-dihydroxy-1,4-dioxane and its derivatives, and a vinyl group adjacent to a substituent whose Hammett's substituent constant σ _p is positive are contained in a single molecule. It can be selected from compounds having two or more.
By containing a hardener in the first layer, the water resistance of the recording medium can be improved without increasing the viscosity of the film-forming liquid for forming the first layer. As a result, the coating stability of the film-forming liquid for forming the first layer is improved, and the water resistance of the produced recording medium is also improved.

The substituents having a positive Hammett's substituent constant σ _p include CF ₃ group (σ _p value: 0.54), CN group (σ _p value: 0.66), COCH ₃ group (σ _p value: 0). .50), COOH group (σ _p value: 0.45), COOR (R represents an alkyl group) group (σ _p value: 0.45), NO ₂
Group (σ _p value: 0.78), OCOCH ₃ group (σ _p value: 0.31), SH group (σ _p value: 0.
15), SOCH ₃ group (σ _p value: 0.49), SO ₂ CH ₃ group (σ _p value: 0.72), SO ₂ NH ₂ group (σ _p value: 0.57), SCOCH ₃ group ( σ _p value: 0.44), F group (σ _p value: 0.06), Cl group (σ _p value: 0.23), Br group (σ _p value: 0.23), I group (σ _p Value: 0.18), IO ₂ group (σ _p value: 0.76), N ⁺ (CH ₃ ) ₂ group (σ _p value: 0.82), S ⁺ (CH ₃ ) ₂ group (σ _p value) : 0.90) and the like.

The compound having two or more vinyl groups adjacent to a substituent having a positive Hammett's substituent constant σ _p in a single molecule is 2-ethylenesulfonyl-N- [2- (2-ethylenesulfonyl-acetylamino). ) -Ethyl] acetamide, bis-2-vinylsulfonylethyl ether, bisacryloylimide, NN′-diaacryloylurea, 1,1-bisvinylsulfoneethane, ethylene-bis-acrylamide, and the following structural formula And 2-ethylenesulfonyl-N- [2- (2-ethylenesulfonyl-acetylamino) -ethyl] acetamide is particularly preferable among them.

  The content of the hardener in the first layer is preferably 0.1% by mass to 30% by mass, and more preferably 0.5% by mass to 10% by mass with respect to the solid content of the binder. When the content of the hardener is within the above range, the film-forming liquid for forming the first layer does not thicken, and the water resistance of the recording material can be improved.

-Layered inorganic compound-
The first layer may further contain a layered inorganic compound. As the layered inorganic compound, a swellable inorganic layered compound is preferable, for example, swelling viscosity minerals such as bentonite, hectorite, saponite, beiderite, nontronite, stevensite, beidellite, montmorite, swellable synthetic mica, swellable synthesis Examples include smectite. The swellable inorganic layered compound has a laminated structure consisting of unit crystal lattice layers with a thickness of 1 to 1.5 nm, and the lattice layer is insufficiently positively charged because the substitution of metal atoms in the lattice is significantly larger than other clay minerals. In order to compensate for this, cations such as Na ⁺ , Ca ²⁺ and Mg ²⁺ are adsorbed between the layers. The cations present between these layers are called exchangeable cations and exchange with various cations. In particular, when the cation between layers is Li ⁺ , Na ⁺ or the like, since the ionic radius is small, the bonds between the layered crystal lattices are weak, and the layers swell greatly with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swellable synthetic mica are preferred in that this tendency is strong. In particular, water-swellable synthetic mica is preferable.

Examples of water-swellable synthetic mica include Na tetrathic mica NaMg _2.5 (Si ₄ O ₁₀ ) F ₂ Na, Li teniolite (NaLi) Mg ₂ (Si ₄ O ₁₀ ) F ₂ Na, or Li hectorite (NaLi). / 3Mg ₂ / 3Li _1/3 Si ₄ O ₁₀ ) F _{2 and the} like.
The water-swellable synthetic mica preferably has a thickness of 1 to 50 nm and a surface size of 1 to 20 μm. For diffusion control, the thinner the better, the better the plane size, as long as the smoothness and transparency of the coated surface are not deteriorated. Therefore, the aspect ratio is preferably 100 or more, more preferably 200 or more, and particularly preferably 500 or more.

When the water-swellable synthetic mica is used, the mass ratio x / y between the mass (solid content) x of the binder in the first layer and the mass y of the water-swellable synthetic mica is preferably in the range of 1 to 30. The range of 5 or more and 15 or less is more preferable. When the mass ratio is within the above range, the effect is great in suppressing oxygen permeation and blistering.
In addition, well-known additives, such as antioxidant, can also be added to a 1st layer.

  The thickness of the first layer is preferably in the range of 1 to 30 μm, and more preferably in the range of 5 to 20 μm. When the thickness of the first layer is within the above range, the glossiness of the surface when calendering is performed later is improved, whiteness can be obtained with a small amount of white pigment, and handleability such as bendability. Can be equivalent to coated paper or art paper.

In the present invention, the first layer can be formed by applying the film forming liquid for forming the first layer.
Application of the film-forming agent is not particularly limited as long as it is a film-forming method. For example, the film-forming agent can be applied by any known method such as a coating method, an ink-jet method, or an immersion method. Therefore, it is preferable to use a coating method using the first layer-forming film forming solution as a coating solution.
As the coating method, a known coating method can be applied. Examples of the known coating method include a blade coating method, a slide bead method, a curtain method, an extrusion method, an air knife method, a roll coating method, and a Ked bar coating method. Is mentioned.

  In the present invention, it is preferable to heat-treat the coating film formed by coating in a temperature range equal to or higher than the minimum film-forming temperature of the thermoplastic resin after coating. The heat treatment may be performed in combination with the drying treatment after coating, or may be performed separately. The heat treatment can be performed, for example, by a method such as placing in an oven having a temperature equal to or higher than the minimum film-forming temperature or applying a drying air having a temperature equal to or higher than the minimum film-forming temperature.

(Second layer: ink receiving layer)
The second layer (hereinafter also referred to as “ink-receiving layer”) contains inorganic fine particles, a nitrogen-containing organic cationic polymer, and a water-soluble aluminum compound on the first layer, and the nitrogen-containing organic cationic polymer comprises: A side half closer to the base paper (hereinafter also referred to as “lower layer”) than a side half far from the base paper (hereinafter also referred to as “upper layer”) when the ink receiving layer is divided into two equal parts by a plane parallel to the base paper. The water-soluble aluminum compound is contained in a large amount in the side half far from the base paper.
By adopting the above-described configuration, the second layer can maintain high image density and improve ozone resistance while suppressing bleeding of the recorded image.

In the present invention, the ink receiving layer is formed by laminating two or more layers, the nitrogen-containing organic cationic polymer is contained in the lower layer more than the upper layer, and the water-soluble aluminum compound is contained more in the upper layer than the lower layer. Are stacked.
When the layers are stacked so that the nitrogen-containing organic cationic polymer is contained more in the upper layer than in the lower layer, or when they are stacked so that the contents of the lower layer and the upper layer are the same, the density of the recorded image decreases. , Ozone resistance deteriorates.
In addition, when laminated so that the water-soluble aluminum compound is contained more in the lower layer than in the upper layer, or when laminated so that the contents of the upper layer and the lower layer are the same, the surface may be cracked. The state deteriorates and ozone resistance is further reduced.

In the present invention, the distribution of the nitrogen-containing organic cationic polymer in the ink receiving layer can be confirmed by elemental analysis. Specifically, mapping analysis by the SEM-EDX method may be performed and the obtained image may be observed. In this case, the position of the entire ink receiving layer is confirmed by mapping analysis of the main component (for example, Si element) of the ink receiving layer, and then the mapping analysis of N element is performed, and the layer far from the base paper of the ink receiving layer and the base paper Which of the N element amounts in the near layer is larger is determined from the mapping image.
The presence distribution of the water-soluble aluminum compound in the ink receiving layer can be confirmed in the same manner.

In the present invention, the content ratio of the nitrogen-containing organic cationic polymer in the ink receiving layer (content in the layer far from the base paper of the ink receiving layer / content in the layer near the base paper of the ink receiving layer), Content / content of the lower layer] is preferably less than 1.0.
From the viewpoint of obtaining the effects of the present invention more effectively, the content ratio is preferably 0 to 0.8, and more preferably 0 to 0.4.
The ink receiving layer containing the nitrogen-containing organic cationic polymer in the above-described content ratio is, for example, the content ratio of the nitrogen-containing organic cationic polymer [third coating liquid (upper layer) in the method for producing an inkjet recording medium of the present invention described later. The content in the coating liquid for coating / the content in the second coating liquid (the coating liquid for the lower layer)] can be formed as described below.

Further, from the viewpoint of obtaining the effect of the present invention more effectively, the content of the nitrogen-containing organic cationic polymer in the lower layer in the ink receiving layer is preferably 2 to 25% by mass with respect to the total solid content of the lower layer. 4-20 mass% is more preferable, and 6-18 mass% is especially preferable.
On the other hand, from the viewpoint of obtaining the effect of the present invention more effectively, the content of the nitrogen-containing organic cationic polymer in the upper layer of the ink receiving layer is preferably 1 to 20% by mass with respect to the total solid content of the upper layer. 2-15 mass% is more preferable, and 4-12 mass% is especially preferable.
Furthermore, from the viewpoint of obtaining the effect of the present invention more effectively, the content of the nitrogen-containing organic cationic polymer in the entire ink receiving layer including the lower layer and the upper layer is the total solid content of the entire ink receiving layer. On the other hand, 1-15 mass% is preferable, 1.5-12 mass% is more preferable, and 2-10 mass% is especially preferable.
In the present invention, the total solid content of the ink receiving layer refers to all components excluding water from the composition constituting the ink receiving layer.
Further, from the viewpoint of obtaining the effect of the present invention more effectively, the ratio of nitrogen-containing organic cation polymer / inorganic fine particles in the lower layer is preferably larger than the ratio of nitrogen-containing organic cation polymer / inorganic fine particles in the upper layer.

In the present invention, the content ratio of the water-soluble aluminum compound in the ink receiving layer [content in the layer near the base paper of the ink receiving layer / content in the layer far from the base paper of the ink receiving layer], that is, [content in the lower layer] Amount / content in upper layer] needs to be less than 1.0.
From the viewpoint of obtaining the effects of the present invention more effectively, the content ratio is preferably 0 to 0.8, and more preferably 0 to 0.4.
The ink-receiving layer containing the water-soluble aluminum compound in the above content ratio is, for example, a water-soluble aluminum compound content ratio [second coating liquid (for lower layer)] in the method for producing an inkjet recording medium of the present invention described later. The content in the content / the content in the third coating liquid (for the upper layer)] can be formed as described below.

Moreover, from the viewpoint of obtaining the effect of the present invention more effectively, the content of the water-soluble aluminum compound in the upper layer in the ink receiving layer is preferably 2 to 25% by mass with respect to the total solid content of the upper layer. 4-20 mass% is more preferable, and 6-18 mass% is especially preferable.
On the other hand, from the viewpoint of obtaining the effect of the present invention more effectively, the content of the water-soluble aluminum compound in the upper layer of the ink receiving layer is preferably 1 to 20% by mass with respect to the total solid content of the upper layer. -15 mass% is more preferable, and 4-12 mass% is especially preferable.
Furthermore, from the viewpoint of obtaining the effect of the present invention more effectively, the content of the water-soluble aluminum compound in the entire ink receiving layer including the lower layer and the upper layer is based on the total solid content of the entire ink receiving layer. 1-15 mass% is preferable, 1.5-12 mass% is more preferable, and 2-10 mass% is especially preferable.

  Further, from the viewpoint of improving the glossiness of the ink receiving layer, the ink receiving layer in the present invention is preferably composed of two or more layers, and the uppermost layer farthest from the base paper contains colloidal silica. Hereinafter, the uppermost layer containing colloidal silica is also referred to as “colloidal silica layer”.

The thickness of the ink receiving layer is preferably determined in relation to the void ratio in the layer from the viewpoint of obtaining an absorption capacity sufficient to absorb all droplets. For example, if the ink amount is 8 nL / mm ² and the porosity is 60%, a film having a layer thickness of about 15 μm or more is required. Considering this point, the thickness of the ink receiving layer is preferably 10 to 50 μm, and more preferably 20 to 40 μm.
Moreover, 5-25 micrometers is preferable respectively and the layer thickness of the lower layer and upper layer in this invention has more preferable 10-20 micrometers.
On the other hand, the thickness of the colloidal silica layer that may be contained in the ink receiving layer is preferably 0.05 to 5 μm, more preferably 0.1 to 3 μm, from the viewpoint of ink absorbability and gloss.

The pore diameter of the ink receiving layer is preferably 0.005 to 0.030 μm, more preferably 0.01 to 0.025 μm in terms of median diameter.
The porosity and pore median diameter can be measured using a mercury porosimeter (trade name “Pore Sizer 9320-PC2” manufactured by Shimadzu Corporation).

Further, the ink receiving layer is preferably excellent in transparency, but as a guide, the haze value when the ink receiving layer is formed on a transparent film support is preferably 30% or less, More preferably, it is 20% or less.
The haze value can be measured using a haze meter (HGM-2DP: Suga Test Instruments Co., Ltd.).

  Hereinafter, the nitrogen-containing organic cationic polymer, the inorganic fine particles, and the water-soluble aluminum compound, which are essential components in the second coating liquid and the third coating liquid constituting the ink receiving layer in the present invention, will be described, and subsequently, they are optional components. The water-soluble resin, sulfur compound, magnesium salt, colloidal silica, crosslinking agent, water-soluble polyvalent metal salt, and other components will be described.

(Nitrogen-containing organic cationic polymer)
The ink receiving layer in the invention contains at least one nitrogen-containing organic cationic polymer as an essential component from the viewpoint of suppressing bleeding of the recorded image and from the viewpoint of dispersing silica.
The nitrogen-containing organic cationic polymer in the present invention is not particularly limited, but a polymer having a primary to tertiary amino group or a quaternary ammonium base is preferable.
The nitrogen-containing organic cation polymer is a nitrogen-containing organic cation which is a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof or a quaternary ammonium base (nitrogen-containing organic cation monomer). Conjugated dienes such as polymers, nitrogen-containing organic cationic polymers obtained as copolymers or condensation polymers of the nitrogen-containing organic cationic monomers and other monomers, styrene-butadiene copolymers, methyl methacrylate-butadiene copolymers, etc. Acrylic polymers such as acrylic acid and methacrylic acid ester polymers or copolymers, acrylic acid and methacrylic acid polymers or copolymers; styrene-acrylic acid ester copolymers, styrene Styrene-acrylic polymers such as methacrylate copolymers; ethylene vinyl acetate copolymer Vinyl polymer and the like; the urethane polymer or the like having a urethane bond include a nitrogen-containing organic cation polymers obtained by cationizing modified with a compound containing a cationic group.

  Examples of the nitrogen-containing organic cation monomer include trimethyl-p-vinylbenzylammonium chloride, trimethyl-m-vinylbenzylammonium chloride, triethyl-p-vinylbenzylammonium chloride, triethyl-m-vinylbenzylammonium chloride, N, N -Dimethyl-N-ethyl-Np-vinylbenzylammonium chloride, N, N-diethyl-N-methyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-Nn-propyl-Np -Vinylbenzylammonium chloride, N, N-dimethyl-Nn-octyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-benzyl-Np-vinylbenzylammonium chloride, N, N- Ethyl-N-benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N- (4-methyl) benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-phenyl-N -P-vinylbenzylammonium chloride;

Trimethyl-p-vinylbenzylammonium bromide, trimethyl-m-vinylbenzylammonium bromide, trimethyl-p-vinylbenzylammonium sulfonate, trimethyl-m-vinylbenzylammonium sulfonate, trimethyl-p-vinylbenzylammonium acetate, trimethyl-m-vinyl Benzylammonium acetate, N, N, N-triethyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N, N-triethyl-N-2- (3-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride Tate;

N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N- Methyl chloride, ethyl chloride, methyl bromide of dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide , Quaternized products of ethyl bromide, methyl iodide or ethyl iodide, or sulfonates, alkyl sulfonates, acetates or alkyl carboxylates substituted with their anions.

  Specific examples of the compound include monomethyl diallylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium chloride, triethyl-2- (methacryloyloxy) ethylammonium chloride, trimethyl-2- (acryloyloxy) ethylammonium chloride, Triethyl-2- (acryloyloxy) ethylammonium chloride, trimethyl-3- (methacryloyloxy) propylammonium chloride, triethyl-3- (methacryloyloxy) propylammonium chloride, trimethyl-2- (methacryloylamino) ethylammonium chloride, triethyl- 2- (methacryloylamino) ethylammonium chloride, trimethyl-2- (acryloylua) C) ethylammonium chloride, triethyl-2- (acryloylamino) ethylammonium chloride, trimethyl-3- (methacryloylamino) propylammonium chloride, triethyl-3- (methacryloylamino) propylammonium chloride, trimethyl-3- (acryloylamino) Propylammonium chloride, triethyl-3- (acryloylamino) propylammonium chloride;

N, N-dimethyl-N-ethyl-2- (methacryloyloxy) ethylammonium chloride, N, N-diethyl-N-methyl-2- (methacryloyloxy) ethylammonium chloride, N, N-dimethyl-N-ethyl- 3- (acryloylamino) propylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium bromide, trimethyl-3- (acryloylamino) propylammonium bromide, trimethyl-2- (methacryloyloxy) ethylammonium sulfonate, trimethyl-3- And (acryloylamino) propylammonium acetate. In addition, examples of copolymerizable monomers include N-vinylimidazole and N-vinyl-2-methylimidazole. In addition, a polymerization unit such as N-vinylacetamide, N-vinylformamide or the like, which is converted into a vinylamine unit by hydrolysis after polymerization, and a salt thereof can be used.

  Examples of the other monomer that can be copolymerized (or polycondensed) with the nitrogen-containing organic cation monomer include basic groups such as primary to tertiary amino groups and salts thereof, or quaternary ammonium bases. Or the monomer which does not contain a cationic part, does not show interaction with the dye in an inkjet ink, or interaction is substantially small is mentioned. For example, (meth) acrylic acid alkyl ester; (meth) acrylic acid cycloalkyl ester such as cyclohexyl (meth) acrylic acid; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate; benzyl (meth) acrylic acid Aralkyl esters of styrene; vinyl aromatics such as styrene, vinyl toluene and α-methyl styrene; vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatate; allyl esters such as allyl acetate; vinylidene chloride, vinyl chloride, etc. Halogen-containing monomers, vinyl cyanides such as (meth) acrylonitrile, olefins such as ethylene and propylene, and the like.

  The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl moiety, specifically, for example, methyl (meth) acrylate or ethyl (meth) acrylate. Propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, (meth) Examples include octyl acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and hydroxyethyl methacrylate are preferable. The other monomers can also be used alone or in combination of two or more.

  Moreover, as a monomer which comprises a urethane type polymer, the polyvalent isocyanate compound (For example, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, m-phenylene diisocyanate, 4,4 which has two or more isocyanate groups). '-Diphenylmethane diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanatemethyl) -cyclohexane, 1,5-diisocyanate-2-methylpentane, hydrogenated Xylylene diisocyanate, hydrogenated 4,4′-diphenylmethane diisocyanate, etc.) and a compound that can react with an isocyanate group to form a urethane bond (eg, glycerin) Polyol compounds such as 1,6-hexanediol, triethanolamine, polypropylene glycol, polyethylene glycol, bisphenol A, hydroquinone; succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1 , 3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalene Acid, biphenylcarboxylic acid, sorbitol, sucrose, aconitic acid, trimellitic acid, hemimellitic acid, phosphoric acid, ethylenediamine, propylenediamine, diethylenetriamine, triisopropanolamine, pyrogallol, Such as hydroxybenzoic acid, hydroxyphthalic acid, 1,2,3-propanetrithiol, ethylenediamine, propylenediamine, hexamethylenediamine, phenylenediamine, tolylenediamine, diphenyldiamine, diaminodiphenylmethane, diaminocyclohexylmethane, piperazine, isophoronediamine Such diamines; and hydrazine).

  Furthermore, examples of the compound that introduces a cationic group into a copolymer or condensate having no cationic group include alkyl halides and methylsulfuric acid.

Among the nitrogen-containing organic cationic polymers described above, from the viewpoint of suppressing bleeding, cationic polyurethanes and cationic polyacrylates described in JP-A No. 2004-167784 are preferable, and cationic polyurethanes are more preferable.
Examples of commercial products of cationic polyurethane include “Superflex 650”, “F-8564D”, “F-8570D” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., “Neofix IJ-150” manufactured by Nikka Chemical Co., Ltd. Or the like.

Further, from the viewpoint of dispersion of inorganic fine particles, polydiallyldimethylammonium chloride and polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride derivatives are preferable, and polydiallyldimethylammonium chloride is more preferable.
Examples of commercially available products include “Charol DC902P” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

Further, these nitrogen-containing organic cationic polymers can be used in any form of a water-soluble polymer, water-dispersible latex particles, and an aqueous emulsion.
Examples of the aqueous emulsion include a conjugated diene copolymer emulsion; an acrylic polymer emulsion; a styrene-acrylic polymer emulsion; a vinyl polymer emulsion; And those obtained by cationizing the emulsion surface with a cationic surfactant, polymerized under cationic polyvinyl alcohol, and distributing the polyvinyl alcohol on the emulsion surface. Among these cationic emulsions, a cationic polyurethane emulsion whose main component is a urethane emulsion is preferable.

  In the present invention, the nitrogen-containing organic cationic polymer contained in the ink receiving layer forming coating solution is preferably a cationic polyurethane, more preferably a cationic polyurethane emulsion, from the viewpoint of suppressing bleeding.

(Inorganic fine particles)
The ink receiving layer in the invention contains at least one inorganic fine particle as an essential component.
The inorganic fine particles form a porous structure when the ink receiving layer is formed, and have a role of improving the ink absorption performance.
In particular, if the solid content of the inorganic fine particles in the ink receiving layer is 50% by mass or more, more preferably more than 60% by mass, it is possible to form a more favorable porous structure, and sufficient ink absorption. This is preferable because an ink jet recording medium having the properties can be obtained. Here, the solid content in the ink receiving layer of fine particles is a content calculated based on components other than water in the composition constituting the ink receiving layer.

Examples of the inorganic fine particles in the present invention include silica fine particles, colloidal silica, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, pseudoboehmite, zinc oxide. Zinc hydroxide, alumina, aluminum silicate, calcium silicate, magnesium silicate, zirconium oxide, zirconium hydroxide, cerium oxide, lanthanum oxide, yttrium oxide and the like. Among these, silica fine particles, colloidal silica, alumina fine particles, or pseudoboehmite are preferable from the viewpoint of forming a good porous structure. The fine particles may be used as primary particles or in a state where secondary particles are formed. The average primary particle size of these fine particles is preferably 2 μm or less, and more preferably 200 nm or less.
Further, silica fine particles having an average primary particle size of 30 nm or less, colloidal silica having an average primary particle size of 30 nm or less, alumina fine particles having an average primary particle size of 20 nm or less, or pseudoboehmite having an average pore radius of 2 to 15 nm is more preferable. In particular, silica fine particles, alumina fine particles, and pseudoboehmite are preferable.

  Silica fine particles are generally roughly classified into wet method particles and dry method (gas phase method) particles according to the production method. In the above wet method, a method is mainly used in which activated silica is produced by acid decomposition of a silicate, and this is appropriately polymerized and agglomerated and precipitated to obtain hydrous silica. On the other hand, the gas phase method is a method by high-temperature gas phase hydrolysis of silicon halide (flame hydrolysis method), a method in which silica sand and coke are heated and reduced by an arc in an electric furnace and oxidized with air. A method of obtaining anhydrous silica by the (arc method) is the mainstream, and “gas phase method silica” means silica (anhydrous silica fine particles) synthesized by the gas phase method. As the silica fine particles used in the present invention, gas phase method silica fine particles are particularly preferable.

The gas phase method silica is different from hydrous silica in terms of the density of silanol groups on the surface, the presence or absence of vacancies, etc., and exhibits different properties, but is suitable for forming a three-dimensional structure with a high porosity. The reason is not clear, in the case of hydrated silica, many density of silanol groups at 5 to 8 / nm ² in the fine particle surface, liable silica fine particles are densely aggregated (aggregation), while the gas phase In the case of the method silica, the density of silanol groups on the surface of the fine particles is 2 to 3 / nm ² , so that it is sparse soft agglomeration (flocculate), resulting in a structure with a high porosity. Is done.

  The above-mentioned vapor phase silica has a particularly large specific surface area, so the ink absorption and retention efficiency is high, and the refractive index is low. Therefore, if the dispersion is made to an appropriate particle size, transparency can be imparted to the receiving layer. It is characterized by high color density and good color development. The transparency of the receiving layer is not only for applications that require transparency, such as OHP, but also in terms of obtaining high color density and good color development gloss even when applied to recording media such as photo glossy paper. is important.

  The average primary particle diameter of the vapor phase silica is preferably 30 nm or less, more preferably 20 nm or less, particularly preferably 10 nm or less, and most preferably 3 to 10 nm. Since the vapor phase silica is easily adhered to each other by hydrogen bonding with a silanol group, a structure having a large porosity can be formed when the average primary particle diameter is 30 nm or less, and ink absorption characteristics are effectively improved. Can be improved.

  Silica fine particles may be used in combination with the other fine particles described above. When the other fine particles and the vapor phase silica are used in combination, the content of the vapor phase silica in all the fine particles is preferably 30% by mass or more, and more preferably 50% by mass or more.

As the inorganic fine particles in the present invention, alumina fine particles, alumina hydrate, a mixture or a composite thereof are also preferable. Of these, alumina hydrate is preferable because it absorbs and fixes ink well, and pseudoboehmite (Al ₂ O ₃ .nH ₂ O) is particularly preferable. Alumina hydrates can be used in various forms, but it is preferable to use sol boehmite as a raw material because a smooth layer can be easily obtained.

About the pore structure of pseudo boehmite, the average pore radius is preferably 1 to 30 nm, and more preferably 2 to 15 nm. The pore volume is preferably 0.3 to 2.0 ml / g, more preferably 0.5 to 1.5 ml / g. Here, the pore radius and pore volume are measured by a nitrogen adsorption / desorption method, and can be measured by, for example, a gas adsorption / desorption analyzer (for example, trade name “Omni Soap 369” manufactured by Coulter). .
Among the alumina fine particles, vapor-phase method alumina fine particles are preferable because of their large specific surface area. The average primary particle size of the vapor phase alumina is preferably 30 nm or less, and more preferably 20 nm or less.

  When the above-mentioned fine particles are used in an ink jet recording medium, for example, JP-A-10-81064, JP-A-10-119423, JP-A-10-157277, JP-A-10-217601, JP-A-11-348409, JP-A-2001-138621. No. 2000-43401 No. 2000-2111235 No. 2000-309157 No. 2001-96897 No. 2001-138627 No. 11-91242 No. 8-2087 No. 8-2090 No. 8-2091, 8-2093, 8-174992, 11-192777, JP-A-2001-301314, and the like can also be preferably used.

(Water-soluble aluminum compound)
The ink receiving layer in the present invention contains at least one water-soluble aluminum compound as an essential component.
Examples of water-soluble aluminum compounds include inorganic salts such as aluminum chloride or hydrates thereof, aluminum sulfate or hydrates thereof, ammonium alum, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, acetic acid. Aluminum, aluminum lactate, basic aluminum thioglycolate and the like are known.
Furthermore, basic polyaluminum hydroxide compounds (hereinafter also referred to as “basic polyaluminum chloride” and “polyaluminum chloride”), which are inorganic aluminum-containing cationic polymers, are known and preferably used.

The basic polyaluminum hydroxide compound has a main component represented by the following general formula 1, 2 or 3, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ , [Al ₂₁ (OH) ₆₀ ] ³⁺ , and the like, which are water-soluble polyaluminum hydroxides that stably contain basic and high-molecular polynuclear condensed ions.

[Al ₂ (OH) _n Cl _6-n ] _m ·· Formula 1
[Al (OH) ₃ ] _n AlCl ₃ .. Formula 2
Al _n (OH) _m Cl _(3n-m) 0 <m <3n Formula 3

  These are water treatment agents from Taki Chemical Co., Ltd. under the name of polyaluminum chloride (PAC), from Asada Chemical Co., Ltd. under the name of polyaluminum hydroxide (Paho), and from Riken Green Co., Ltd. In the name of HAP-25, it is marketed by Daimei Chemical Co., Ltd. under the name of Alpha-In 83 and from other manufacturers for the same purpose, and various grades can be easily obtained.

  The above-mentioned water-soluble aluminum compound is preferably added at a ratio of 0.1 to 10% by mass, more preferably 0.5 to 8% by mass with respect to the inorganic fine particles.

(Water-soluble resin)
The ink receiving layer in the present invention preferably contains at least one water-soluble resin from the viewpoint of improving ink absorbability.
Examples of the water-soluble resin include polyvinyl alcohol resins that are resins having a hydroxy group as a hydrophilic structural unit [polyvinyl alcohol (PVA), acetoacetyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified. Polyvinyl alcohol, polyvinyl acetal, etc.], cellulose resins [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.] , Chitins, chitosans, starch, resins with ether linkages [polyethylene oxide (PEO), Propylene oxide (PPO), polyethylene glycol (PEG), poly ether (PVE)], and resins having carbamoyl groups [polyacrylamide (PAAM), polyvinyl pyrrolidone (PVP), polyacrylic acid hydrazide, etc.] and the like.
Moreover, the polyacrylic acid salt which has a carboxyl group as a dissociable group, maleic acid resin, alginate, gelatins, etc. can be mentioned.

Among these, the water-soluble resin used in the present invention is at least one selected from polyvinyl alcohol resins, cellulose resins, resins having an ether bond, resins having a carbamoyl group, resins having a carboxyl group, and gelatins. In particular, polyvinyl alcohol (PVA) resin is preferable.
Examples of the polyvinyl alcohol include Japanese Patent Publication No. 4-52786, Japanese Patent Publication No. 5-67432, Japanese Patent Publication No. 7-29479, Japanese Patent No. 2537827, Japanese Patent Publication No. 7-57553, Japanese Patent No. 2502998, and Japanese Patent No. 3053231. JP-A-63-176173, JP-A-2604367, JP-A-7-276787, JP-A-9-207425, JP-A-11-58941, JP-A-2000-135858, JP-A-2001-205924, JP 2001-287444, JP 62-278080, JP 9-39373, JP 2750433, JP 2000-158801, JP 2001-213045, JP 2001-328345, JP 8 -324105, JP-A-11-348417, JP-A58-18168 JP, 10-259213, JP 2001-72711, JP 2002-103805, JP 2000-63427, JP 2002-308928, JP 2001-205919, JP 2002-264489. Etc. are mentioned.
Examples of water-soluble resins other than polyvinyl alcohol resins include compounds described in JP-A-11-165461, [0011] to [0012], JP-A-2001-205919, and JP-A-2002-264489. The described compounds are also included.

  These water-soluble resins may be used alone or in combination of two or more. In the present invention, the content of the water-soluble resin is preferably 9 to 40% by mass, and more preferably 12 to 33% by mass with respect to the total solid content of the ink receiving layer.

The water-soluble resin and the inorganic fine particles that mainly constitute the ink receiving layer in the invention may be a single material or a mixed system of a plurality of materials.
From the viewpoint of maintaining transparency, the type of water-soluble resin combined with inorganic fine particles, particularly silica fine particles, is important. When the gas phase method silica is used, the water-soluble resin is preferably a polyvinyl alcohol resin, more preferably a polyvinyl alcohol resin having a saponification degree of 70 to 100%, and a saponification degree of 80 to 99.5. % Of polyvinyl alcohol resin is particularly preferable.

The polyvinyl alcohol-based resin has a hydroxyl group in its structural unit. Since this hydroxyl group and the surface silanol group of the silica fine particle form a hydrogen bond, a three-dimensional network having a secondary particle of the silica fine particle as a network chain unit. It becomes easy to form a structure. By forming this three-dimensional network structure, it is considered that a porous ink receiving layer having a high porosity and sufficient strength is formed.
In ink-jet recording, the porous ink-receiving layer obtained as described above can absorb ink rapidly by capillary action, and can form dots with good roundness without ink bleeding.

  In addition, the polyvinyl alcohol resin may be used in combination with the other water-soluble resin. When the other water-soluble resin and the polyvinyl alcohol resin are used in combination, the content of the polyvinyl alcohol resin in the total water-soluble resin is preferably 50% by mass or more, and more preferably 70% by mass or more.

-Content ratio of inorganic fine particles and water-soluble resin-
By optimizing the mass content ratio [PB ratio (x: y)] of the inorganic fine particles (x) and the water-soluble resin (y), the film structure and film strength of the ink receiving layer can be further improved. It is.

As the mass content ratio [PB ratio (x: y)] in the ink receiving layer, it is possible to prevent a decrease in film strength and cracking during drying caused by the PB ratio being too large, and the PB ratio is When it is too small, the gap is easily blocked by the resin, and the ratio of 1.5: 1 to 10: 1 is preferable from the viewpoint of preventing the ink absorbency from being lowered due to the decrease in the void ratio.
In particular, the x / y ratio of the upper layer of the ink receiving layer is preferably equal to or higher than the x / y ratio of the lower layer (the upper layer and the lower layer have the same PB ratio, or the lower layer is binder-rich). It is particularly preferable that the PB ratio is equal.

  Since stress may be applied to the recording medium when passing through the transport system of the ink jet printer, the ink receiving layer needs to have sufficient film strength. Further, when cutting into a sheet shape, the ink receiving layer needs to have sufficient film strength in order to prevent cracking or peeling of the ink receiving layer. In consideration of these cases, the mass ratio (x: y) is more preferably 5: 1 or less, while it is more preferably 2: 1 or more from the viewpoint of ensuring high-speed ink absorbency in an inkjet printer. preferable.

For example, a coating solution in which vapor-phase method silica fine particles having an average primary particle diameter of 20 nm or less and a water-soluble resin are completely dispersed in an aqueous solution at a mass ratio (x: y) of 2: 1 to 5: 1 is provided on the support. When the coating layer is dried, a three-dimensional network structure in which the secondary particles of silica fine particles are network chains is formed, the average pore diameter is 30 nm or less, the porosity is 50 to 80%, the pore ratio A translucent porous film having a volume of 0.5 ml / g or more and a specific surface area of 100 m ² / g or more can be easily formed.

~ Diethylene glycol (DEG) absorption capacity ~
The diethylene glycol absorption capacity is a value obtained by the following measurement method.
That is, 1 mL of diethylene glycol was dropped on the ink receiving layer of a test piece obtained by cutting the recording medium so as to be 10 cm square, and after 30 seconds, the excess was wiped off, and the diethylene glycol absorption capacity (mL) was determined from the mass difference before and after the dropping. / M ² ).
In the present invention, it is preferable to 5 mL / ^{m 2} or more ~35mL / ^{m 2} or less in the measurement conditions the absorption capacity of diethylene glycol (DEG) in the surface of the second layer, 10 mL / ^{m 2} or more -30 mL / m more preferably ² or less, 15 mL / ^{m 2} or more ~25mL / ^{m 2} or less is more preferable.
By this absorption capacity and 5 mL / m ² or more ~35mL / m ² or less, to suppress the malabsorption of ink, cracking during manufacture, it tends to be possible to curl suppressing when high humidity.

(Sulfur compounds)
The ink receiving layer in the invention preferably contains at least one sulfur compound from the viewpoint of further improving the ozone resistance.
The sulfur compound is at least one selected from thioether compounds, thiourea compounds, disulfide compounds, sulfinic acid compounds, thiocyanic acid compounds, sulfur-containing heterocyclic compounds, and sulfoxide compounds. More preferred are thioether compounds and sulfoxide compounds.

~ Thioether compounds ~
The thioether compound may be a water-soluble compound or an oil-soluble compound. Further, it may be a low molecule or a polymer, and any molecule that contains one or more thioether groups in the molecule may be used.
The thioether compound preferably has 2 or more carbon atoms, more preferably 4 or more.
The thioether-based compound preferably contains an atom (for example, an oxygen atom, a sulfur atom, a nitrogen atom, or a phosphorus atom) containing a lone pair in addition to a sulfur atom, a carbon atom, and a hydrogen atom.
Examples of the thioether-based compound include those represented by the following general formula (1).

R < ₁ >-(S-R < ₃ >) _m- S-R < ₂ > General formula (1)

In the general formula (1), R ₁ and R ₂ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a group containing them, and R ₁ and R ₂ are the same However, they may be different and may be combined to form a ring. However, at least one of R ₁ and R ₂ is a hydroxyl group, a sulfo group, a carboxy group, a hydrophilic group such as a (poly) ethyleneoxy group, or an amino group, an amide group, an ammonium group, a nitrogen-containing heterocyclic group, or an aminocarbonyl group. , An alkyl group substituted with a group having a basic nitrogen atom such as an aminosulfonyl group or a group containing the same (for example, the substituted alkyl group is further bonded via a divalent linking group such as a carbamoyl group, a carbonyl group, or a carbonyloxy group). And may be bonded to the sulfur atom of the thioether). R ₃ represents an optionally substituted alkylene group, and optionally represents an alkylene group having an oxygen atom. m represents an integer of 0 to 10, and when m is 1 or more, at least one sulfur atom bonded to R ₃ may be a sulfoxide group or a sulfonyl group. R ₁ and R ₂ may each be a polymer residue.

Particularly preferred compounds of the general formula (1) are compounds having an alkyl group in which at least one of R ₁ and R ₂ is substituted with a hydroxy group, a carboxy group, an amino group, or an ammonium group. The amino group of the amino group-substituted alkyl group includes an amino group, a monoalkyl (preferably an alkyl group having 1 to 5 carbon atoms) substituted amino group, and a dialkyl (preferably an alkyl group having 1 to 5 carbon atoms) substituted amino group. And a nitrogen-containing heterocyclic group. Specific examples of the compound of the general formula (1) are shown below, but the present invention is not limited to these.

~ Sulphoxide compounds ~
The sulfoxide compound may be a water-soluble compound or an oil-soluble compound. Further, it may be a low molecule or a polymer, and any molecule that contains one or more sulfoxide groups in the molecule may be used.
The sulfoxide compound preferably has 2 or more carbon atoms, more preferably 4 or more.
In addition to the sulfoxide group, carbon atom, and hydrogen atom, the sulfoxide-based compound preferably further contains an atom containing a lone pair (for example, an oxygen atom, a sulfur atom, a nitrogen atom, or a phosphorus atom).
Specific compounds are shown below.

  Furthermore, as the sulfur-containing compound used in the present invention, the compounds described in Japanese Patent Application No. 2008-144103, sulfone compounds, sulfonamide compounds, thioester compounds, thioamide compounds, sulfonic acid compounds, thiosulfonic acid compounds Thiosulfinic acid compounds, sulfamine compounds, thiocarbamic acid compounds, sulfite compounds and the like.

At this time, the form in which the ink receiving layer contains the sulfur compound is not particularly limited, but from the viewpoint of keeping the density of the recorded image higher, the sulfur compound is more than the upper layer in the ink receiving layer. A form that is contained so as to be contained in a large amount in the lower layer is preferable.
That is, the content ratio of the sulfur compound in the ink receiving layer [content in the upper layer / content in the lower layer] is preferably less than 1.0, more preferably 0 to 0.6, and 0 (that is, The form in which the sulfur-based compound is not contained in the layer far from the base paper is particularly preferable.
More preferably, the content ratio of the sulfur compound [content in the upper layer / content in the lower layer] is 0 to 0.6, and the content ratio of the nitrogen-containing organic cation polymer [content in the upper layer / content in the lower layer] Amount] is 0 to 0.8.

Furthermore, in the present invention, the sulfur compound in the ink receiving layer is a thioether compound or a sulfoxide compound, and the nitrogen-containing organic cationic polymer is at least one selected from cationic polymers having a cationic urethane and a quaternary ammonium base. It is preferable that
More preferably, the sulfur compound in the ink receiving layer is a thioether compound or a sulfoxide compound, and the content ratio of sulfur compound (content in the upper layer / content in the lower layer) is 0 to 0.6. The nitrogen-containing organic cationic polymer is at least one selected from a cationic polymer having a cationic urethane and a quaternary ammonium base, and the content ratio of the nitrogen-containing organic cationic polymer [content in the upper layer / content in the lower layer] Is 0 to 0.8.

  In the present invention, the presence distribution of the sulfur compound in the ink receiving layer can be confirmed by elemental analysis. Specifically, mapping analysis by the SEM-EDX method may be performed and the obtained image may be observed. In this case, the presence position of the entire ink receiving layer is confirmed by mapping analysis of the main component (for example, Si element) of the ink receiving layer, and then S element mapping analysis is performed, and the S element in the lower layer and the upper layer in the ink receiving layer. It is determined from the mapping image which one is larger.

Further, from the viewpoint of further improving the ozone resistance and maintaining the image density higher, the content of the sulfur-based compound in the lower layer in the ink receiving layer is 1 to 20 relative to the total solid content of the lower layer. % By mass is preferable, 3 to 15% by mass is more preferable, and 4 to 10% by mass is particularly preferable.
On the other hand, from the viewpoint of keeping the density of the recorded image higher, the content of the sulfur compound in the upper layer in the ink receiving layer is preferably 0 to 5% by mass with respect to the total solid content of the upper layer. -3 mass% is more preferable, and 0 mass% (that is, a form in which the upper layer does not contain a sulfur compound) is particularly preferable.
Further, from the viewpoint of further improving the ozone resistance and maintaining the image density higher, the content of the sulfur-based compound in the entire ink receiving layer including the upper layer and the lower layer is as follows. The total solid content is preferably 0.5 to 5% by mass, more preferably 1 to 4% by mass, and particularly preferably 1.5 to 3% by mass.

(Magnesium salt)
The ink receiving layer in the invention preferably contains at least one magnesium salt from the viewpoint of further improving the ozone resistance.
Examples of the magnesium salt include magnesium acetate, magnesium oxalate, magnesium sulfate, magnesium chloride hexahydrate, and magnesium citrate nonahydrate.
Of these, magnesium chloride hexahydrate is preferred.

  Examples of commercially available magnesium salts include “White Nigari NS” and “Mag Chloride (Special Name) NS” manufactured by Naikai Shigyo Co., Ltd.

  Further, from the viewpoint of obtaining the effect of the present invention more effectively, the content of the magnesium salt in the ink receiving layer is preferably 0.05 to 5% by mass, more preferably 0.1 to 3% by mass. Preferably, 0.2-2 mass% is especially preferable.

(Colloidal silica)
When the ink receiving layer in the present invention has a colloidal silica layer as the uppermost layer, the average primary particle size of the colloidal silica used is preferably 10 nm to 200 nm, more preferably 50 nm to 150 nm.
In addition, the colloidal silica in the present invention is preferably anionic and nonionic. An anionic property is particularly preferable. The ^{content, 0.01g / m 2 ~5g / m} 2 is preferred. 0.05 g / m ² to ² g / m ² is particularly preferable.

(Crosslinking agent)
The ink receiving layer in the invention preferably contains at least one crosslinking agent from the viewpoint of crosslinking the water-soluble resin.
In particular, the ink receiving layer in the invention is preferably a porous layer in which the inorganic fine particles and the water-soluble resin are used in combination, and further cured by a cross-linking reaction between the cross-linking agent and the water-soluble resin.

Boron compounds are preferred for the crosslinking of the water-soluble resin, particularly polyvinyl alcohol. Examples of the boron compound include borax, boric acid, borate (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , two Borate (eg, Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ ), metaborate (eg, LiBO ₂ , Ca (BO ₂ ) ₂ , NaBO ₂ , KBO ₂ ), tetraborate (eg, Na ₂ B ₄ O ₇ · 10H ₂ O), pentaborate (for example, KB ₅ O ₈ · 4H ₂ O, Ca ₂ B ₆ O ₁₁ · 7H ₂ O, CsB ₅ O ₅ ), etc. Of these, borax, boric acid, and borate are preferable, and boric acid is particularly preferable in that a crosslinking reaction can be promptly caused.

The following compounds other than the boron compound can also be used as a crosslinking agent for the water-soluble resin.
For example, aldehyde compounds such as formaldehyde, glyoxal, and glutaraldehyde; ketone compounds such as diacetyl and cyclopentanedione; bis (2-chloroethylurea) -2-hydroxy-4,6-dichloro-1,3,5- Active halogen compounds such as triazine and 2,4-dichloro-6-S-triazine sodium salt; divinylsulfonic acid, 1,3-vinylsulfonyl-2-propanol, N, N′-ethylenebis (vinylsulfonylacetamide) ), Active vinyl compounds such as 1,3,5-triacryloyl-hexahydro-S-triazine; N-methylol compounds such as dimethylolurea and methyloldimethylhydantoin; melamine resins (for example, methylolmelamine, alkylated methylolmelamine) ;Epoxy resin;

Isocyanate compounds such as 1,6-hexamethylene diisocyanate; aziridine compounds described in US Pat. Nos. 3,017,280 and 2,983611; carboximide compounds described in US Pat. No. 3,100,704; glycerol triglycidyl Epoxy compounds such as ether; Ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; Halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; 2,3-dihydroxy Dioxane-based compounds such as dioxane; titanium-containing aluminum sulfate, chromium alum, potassium alum, metal-containing compounds such as zirconyl acetate, chromium acetate, polyamine compounds such as tetraethylenepentamine, hydrazide compounds such as adipic acid dihydrazide, A low molecule or polymer containing two or more oxazoline groups can be used.
Said crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type.
1-50 mass% is preferable with respect to water-soluble resin, and, as for the usage-amount of a crosslinking agent, 5-40 mass% is more preferable.

(Water-soluble polyvalent metal salt)
The ink receiving layer in the invention may further contain a water-soluble polyvalent metal salt other than those described above. For example, the water-soluble polyvalent metal salt functions as a mordant to further improve the ozone property.

The water-soluble polyvalent metal salt used in the present invention is preferably a trivalent or higher metal compound. For example, further, a water-soluble salt of a metal selected from calcium, barium, manganese, copper, cobalt, nickel, iron, zinc, zirconium, chromium, tungsten, and molybdenum can be given.
Specifically, for example, calcium acetate, calcium chloride, calcium formate, calcium sulfate, calcium butyrate, barium acetate, barium sulfate, barium phosphate, barium oxalate, barium naphthoresorcin carboxylate, barium butyrate, manganese chloride, manganese acetate, Manganese formate dihydrate, manganese ammonium sulfate hexahydrate, cupric chloride, ammonium copper (II) chloride dihydrate, copper sulfate, copper (II) butyrate, copper oxalate, copper phthalate, copper citrate , Copper gluconate, copper naphthenate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, cobalt acetate (II), cobalt naphthenate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, sulfuric acid Nickel ammonium hexahydrate, nickel amidosulfate tetrahydrate, nitric acid sulfamate , Nickel 2-ethylhexanoate, ferrous bromide, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, iron (III) citrate, iron (III) lactate trihydrate , Triammonium iron (III) trioxalate trihydrate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, zinc acetate, zinc lactate, zirconium acetate, zirconyl acetate, zirconium tetrachloride, chloride Zirconium, zirconium oxychloride octahydrate, hydroxy zirconium chloride, chromium acetate, chromium sulfate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride , 12 molybdophosphoric acid n hydrate, etc., zinc phenol sulfonate, zinc ammonium acetate, zinc ammonium carbonate, etc. It is. Two or more of these water-soluble polyvalent metal salts may be used in combination. In the present invention, the water-soluble in the water-soluble polyvalent metal salt means that 1% by weight or more dissolves in 20 ° C. water.

  Among the water-soluble polyvalent metal salts, compounds composed of Group 4A metals (for example, zirconium and titanium) of the periodic table are preferable.

  As the water-soluble compound containing the Group 4A element of the periodic table, a water-soluble compound containing titanium or zirconium is more preferable. Examples of the water-soluble compound containing titanium include titanium chloride, titanium sulfate, titanium tetrachloride, tetraisopropyl titanate, titanium acetylacetonate, and titanium lactate. Water-soluble compounds containing zirconium include zirconium acetate, zirconyl acetate, zirconium chloride, hydroxy zirconium chloride, zirconium nitrate, zirconyl nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium lactate, zirconyl lactate, zirconium / ammonium carbonate, zirconium carbonate -Potassium, zirconyl carbonate / ammonium carbonate, zirconyl carbonate / potassium carbonate, zirconium sulfate, zirconium fluoride, zirconyl sulfate, zirconyl fluoride and the like.

  The water-soluble polyvalent metal salt described above is preferably used within the range of the amount of the water-soluble aluminum compound added.

(Other ingredients)
The ink receiving layer in the invention may contain other components such as a mordant other than the nitrogen-containing organic cationic polymer, magnesium salt, and water-soluble polyvalent metal salt, and various surfactants.
As other components, the components described in paragraph numbers 0088 to 0117 in JP-A-2005-14593, the components described in paragraph numbers 0138 to 0155 in JP-A-2006-321176, and the like are included. Can be appropriately selected and used.

(Other layers)
In addition to the ink receiving layer, the ink jet recording medium of the present invention can further be provided with an intermediate layer, a protective layer and the like as appropriate.

  A polymer fine particle dispersion may be added to a constituent layer (for example, an ink receiving layer or a back coat layer) of the ink jet recording medium of the present invention. This polymer fine particle dispersion is used for the purpose of improving film properties such as dimensional stabilization, curling prevention, adhesion prevention, and film cracking prevention. The polymer fine particle dispersion is described in JP-A-62-245258 and JP-A-10-228076. If a polymer fine particle dispersion having a low glass transition temperature (40 ° C. or lower) is added to the layer containing the mordant, cracking and curling of the layer can be prevented. Further, even when a polymer fine particle dispersion having a high glass transition temperature is added to the back layer, curling can be prevented.

  The ink receiving layer may be provided only on one side of the support, or may be provided on both sides of the support for the purpose of preventing deformation such as curling. When the ink receiving layer is provided only on one side of the support, the anti-reflection film may be provided on the opposite side surface or both sides for the purpose of increasing light transmission. .

  In addition, by applying boric acid or a boron compound to the surface of the support on the side where the ink receiving layer is provided, and forming an ink receiving layer thereon, the glossiness and surface smoothness of the ink receiving layer can be improved. In addition, it is possible to suppress aging blurring of an image after printing in a high temperature and high humidity environment.

<Inkjet recording medium manufacturing method>
In the method for producing an ink jet recording medium of the present invention (first aspect), a first layer formation is performed in which a first film-forming liquid containing a hydrophilic binder is applied to both sides of a base paper and dried to form a first layer. Process,
In order from the first layer side on the first layer,
A second coating liquid (for lower layer) containing inorganic fine particles and a nitrogen-containing organic cationic polymer, and a third coating liquid (for upper layer) containing inorganic fine particles and a water-soluble aluminum compound are applied at a coating liquid temperature of 35 ° C. or higher. The side half closer to the base paper than the side half far from the base paper (upper layer) when the nitrogen-containing organic cationic polymer is applied in multiple layers at 45 ° C. or lower and the ink receiving layer is divided into two equal parts in a plane parallel to the base paper A second layer forming step of forming a second layer (ink-receiving layer) so that the water-soluble aluminum compound is contained in a large amount in the (lower layer) and contained in the side half (upper layer) far from the base paper; It is characterized by including.

The inkjet recording medium manufacturing method (second aspect) of the present invention includes a first layer forming step of forming a coating layer by applying a first coating liquid containing a hydrophilic binder on both sides of a base paper,
In order from the first layer side on the first layer,
A second coating liquid containing inorganic fine particles and a nitrogen-containing organic cationic polymer and a third coating liquid containing inorganic fine particles and a water-soluble aluminum compound are applied in a multilayer manner at a coating liquid temperature of 35 ° C. or higher and 45 ° C. or lower. A step of forming a coating layer;
(1) At least the second coating solution and the third coating solution are applied to the coating layer, and (2) at least the second coating solution and the third coating solution are applied. At any time during the drying of the formed coating layer and before the coating layer exhibits reduced-rate drying, a step of applying a liquid containing a basic compound and crosslinking and curing the coating layer; The coating layer is cross-linked, and the nitrogen-containing organic cationic polymer has a base paper that is farther from the side half (upper layer) farther from the base paper when the ink receiving layer is divided into two equal parts in a plane parallel to the base paper. The second layer forming the second layer (ink-receiving layer) is contained in a large amount in the side half (lower layer) close to the substrate and the water-soluble aluminum compound is contained in a large amount in the side half (upper layer) far from the base paper. An embodiment having a forming step is preferred.

In addition, in the method for producing an inkjet recording medium of the present invention (third aspect), the first layer formation in which a first film-forming liquid containing a hydrophilic binder is applied to both sides of a base paper and dried to form a coating layer. Process,
A second coating solution containing inorganic fine particles and a nitrogen-containing organic cationic polymer in order from the first layer side on the first layer, and a third coating solution containing inorganic fine particles and a water-soluble aluminum compound, Coating the coating solution at a coating liquid temperature of 35 ° C. or higher and 45 ° C. or lower to form a coating layer;
Cooling the formed coating layer so as to decrease by 5 ° C. or more with respect to the lower one of the temperature of the second coating solution at the time of coating and the temperature of the third coating solution at the time of coating; Drying the cooled coating layer to form a second layer,
The nitrogen-containing organic cationic polymer is contained in the side half (lower layer) closer to the base paper more than the side half (upper layer) far from the base paper when the ink receiving layer is divided into two equal parts in a plane parallel to the base paper, So that a lot of water-soluble aluminum compound is contained in the side half (upper layer) far from the base paper,
An embodiment having a second layer forming step of forming a second layer (ink receiving layer) is also preferable.

By configuring the method for producing an ink jet recording medium of the present invention as described above,
The nitrogen-containing organic cationic polymer is contained in the side half (lower layer) closer to the base paper more than the side half (upper layer) far from the base paper when the ink receiving layer is divided into two equal parts in a plane parallel to the base paper, The ink receiving layer can be formed so that a large amount of the water-soluble aluminum compound is contained in the side half (upper layer) far from the base paper. As a result, while suppressing bleeding (bleeding over time) of the recorded image, it is possible to maintain a high image density without yellowing, excellent ozone resistance, good surface condition, and recyclable. An ink jet recording medium can be manufactured.

<First layer (binder layer) formation step>
-First forming step-
In the first forming step, a first layer is formed by applying and drying a film-forming solution containing a hydrophilic binder (first film-forming solution for forming a layer) on both surfaces of the base paper.

The details of the base paper are as described in the first layer described above, and the preferred embodiments are also the same.
Moreover, about a thermoplastic resin and its particle | grains, the thing similar to the thermoplastic resin and its latex which can be used by the above-mentioned 1st layer can be mentioned, There is no restriction | limiting in particular. The thermoplastic resin particles may be used alone or in combination of two or more.

  The thermoplastic resin particles preferably have an average particle size of 10 to 200 nm. Here, the average particle diameter of the thermoplastic resin particles is a value measured by a dynamic light scattering method (device name: ELS-800, manufactured by Otsuka Electronics Co., Ltd.).

Further, the thermoplastic resin constituting the thermoplastic resin particles preferably has a minimum film-forming temperature (MFT) of 5 ° C to 60 ° C.
The coating amount of the thermoplastic resin is preferably ¹ to 30 g / m2.

  As the thermoplastic resin particles, those containing water-dispersible latex-dispersed particles are preferable from the viewpoints of suppression of cockling, improvement of bleeding over time, production suitability, and the like.

  Specific examples of the water-dispersible latex include polyester urethane latex, acrylic latex, acrylic silicone latex, acrylic epoxy latex, acrylic styrene latex, acrylic urethane latex, styrene-butadiene latex, and acrylonitrile. Preferable examples include at least one selected from butadiene latex and vinyl acetate latex.

The molecular weight of the water-dispersible latex is preferably 3,000 to 1,000,000 in terms of number average molecular weight, and more preferably about 5,000 to 100,000. When the molecular weight is 3,000 or more, the mechanical strength of the first layer can be secured, and when it is 1,000,000 or less, it is advantageous in terms of production suitability such as dispersion stability and viscosity.
Among the water-dispersible latexes, the first layer is selected from polyester-based urethane latex and acrylic silicone-based latex from the viewpoint that the ink solvent permeability and the effect of suppressing cockling are high and the economy and manufacturing suitability can be combined. 1 type or 2 types or more are most preferable.

The application of the first layer-forming film-forming liquid is not particularly limited as long as it is a film-forming method, and can be performed by any known method such as a coating method, an ink-jet method, or an immersion method. In view of the smoothness of the film surface, it is preferable to use a coating method using the first layer-forming film forming solution as a coating solution.
As the coating method, a known coating method can be applied. Examples of the known coating method include a blade coating method, a slide bead method, a curtain method, an extrusion method, an air knife method, a roll coating method, and a Ked bar coating method. Is mentioned.

After the application, the application layer formed and applied is dried. For drying, a generally used method can be adopted. In particular, the imparting layer is preferably formed by using thermoplastic resin particles (more preferably latex) as the hydrophilic binder and heat-treating in a temperature range equal to or higher than the minimum film-forming temperature of the thermoplastic resin particles. .
The heat treatment may be performed in combination with the drying treatment after application, or may be performed separately. The heat treatment can be performed, for example, by a method such as placing in an oven having a temperature equal to or higher than the minimum film-forming temperature, or applying drying air having a temperature equal to or higher than the minimum film-forming temperature. Note that pressure may be applied in the heat treatment.

<Second layer forming step>
The step of forming the second layer includes a second coating liquid (for lower layer) containing at least inorganic fine particles and a nitrogen-containing organic cationic polymer on both sides of the base paper on which the first layer is formed, inorganic fine particles, A third coating liquid (for upper layer) containing at least a water-soluble aluminum compound;
In order from the first layer side, a coating layer is formed by coating multiple layers at a coating solution temperature of 35 ° C. or higher and 45 ° C. or lower (hereinafter, this step may be referred to as “coating layer forming step”).
In the coating layer forming step, it is necessary to apply at least a plurality of coating solutions of the second coating solution and the third coating solution in this order on the support, but if necessary, Other coating liquids may be applied on the second coating liquid. A barrier layer coating solution (intermediate layer coating solution) may be interposed between the coating solutions.

The form of applying the second coating liquid and the third coating liquid (and other coating liquids if necessary) is not particularly limited, and each liquid is simultaneously applied in a known manner to form a coating layer. Alternatively, the coating layers may be formed by coating each solution one by one (sequential coating) by a known method. In the present invention, these are all referred to as simultaneous or sequential multilayer coating.
The simultaneous multilayer coating can be performed using a known coating apparatus such as an extrusion die coater or a curtain flow coater.
The sequential coating can be performed using a known coating apparatus such as an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, or a bar coater.

Here, a preferable coating amount of each coating solution will be described.
The wet coating amount of the second coating solution is preferably ^{50~200ml / m 2, 75~150ml / m} 2 is more preferable. Moreover, as a solid content application quantity of a 2nd coating liquid, 5-25 g / m < ² > is preferable and 10-18 g / m < ² > is more preferable.
The wet coating amount of the third coating solution is preferably ^{50~200ml / m 2, 75~150ml / m} 2 is more preferable. Moreover, as a solid content application quantity of a 3rd coating liquid, 5-25 g / m < ² > is preferable and 10-18 g / m < ² > is more preferable.
Other coating liquid, for example, when using a coating solution containing colloidal silica, the wet coating amount of the coating, preferably ^{10~150ml / m 2, 20~100ml / m} 2 is more preferable. Moreover, as solid content coating amount of this coating liquid, 0.01-10 g / m < ² > is preferable and 0.05-5 g / m < ² > is more preferable.
Hereinafter, the second coating solution, the third coating solution, and other coating solutions used as necessary will be described.

(Second coating liquid)
The second coating liquid contains at least one inorganic fine particle and at least one nitrogen-containing organic cationic polymer.
The details of the inorganic fine particles in the second coating liquid are as described for the inorganic fine particles in the ink receiving layer. Moreover, there is no restriction | limiting in particular as content rate of the inorganic fine particle in a 2nd coating liquid, However, It is preferable that it is 50-90 mass% with respect to the total solid of a 2nd coating liquid, and 60-80 mass%. It is more preferable that
In the present invention, the total solid content in the second coating liquid refers to all components excluding water from the second coating liquid. The same applies to other liquids.

The nitrogen-containing organic cationic polymer contained in the second coating liquid in the present invention is preferably at least one selected from cationic polyurethanes and cationic polymers having a quaternary ammonium base from the viewpoint of suppressing bleeding. A cationic polyurethane is more preferable.
The nitrogen-containing organic cationic polymer is preferably contained in the second coating liquid in the form of an aqueous emulsion, and more preferably contained in the first coating liquid in the form of an aqueous emulsion of cationic polyurethane.

  The second coating liquid in the present invention preferably further contains a nitrogen-containing organic cationic polymer other than cationic polyurethane from the viewpoint of dispersibility of the inorganic fine particles, and polydiallyldimethylammonium chloride, polymethacryloyloxyethyl-β. It is more preferable to further contain at least one selected from hydroxyethyldimethylammonium chloride derivatives, and it is more preferable to further contain polydiallyldimethylammonium chloride.

  In addition, from the viewpoint of more effectively obtaining the effects of the present invention, the content of the nitrogen-containing organic cationic polymer in the second coating liquid is 1 to 20 mass relative to the total solid content of the second coating liquid. % Is preferable, 2 to 15% by mass is more preferable, and 4 to 12% by mass is particularly preferable.

The second coating liquid preferably further contains a sulfur compound from the viewpoint of further improving the ozone resistance.
In this case, from the viewpoint of obtaining the effect of the present invention more effectively, the content of the sulfur-based compound in the second coating solution is 1 to 20 masses based on the total solid content of the second coating solution. % Is preferable, 3 to 15% by mass is more preferable, and 4 to 10% by mass is particularly preferable.

In addition to the above essential components, the second coating liquid further contains other components such as other water-soluble resins, crosslinking agents, water-soluble polyvalent metal salts, mordants, dispersants, surfactants, and the like. Also good.
Moreover, in application | coating of a 2nd coating liquid, it is also preferable to apply, after carrying out in-line mixing of the liquid containing the above-mentioned water-soluble polyvalent metal salt (preferably basic polyaluminum chloride).
Details of each component such as a sulfur-based compound, a water-soluble resin, a cross-linking agent, a mordant, and a water-soluble polyvalent metal salt are the same as described in the section of <Second Layer: Ink Receiving Layer>, which is preferable. The form is also the same. The dispersant will be described later.

  The second coating solution is preferably acidic, and the pH is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less. The pH of the second coating solution can be adjusted by appropriately selecting the type and amount of the nitrogen-containing organic cationic polymer. Moreover, you may adjust by adding an organic or inorganic acid. When the pH of the second coating solution is 5.0 or less, for example, the crosslinking reaction of the water-soluble resin by the crosslinking agent (particularly boron compound) in the second coating solution can be more sufficiently suppressed.

-Preparation method of second coating liquid-
In the present invention, the second coating liquid containing at least inorganic fine particles and a nitrogen-containing organic cationic polymer can be prepared, for example, as follows.
That is, inorganic fine particles (preferably gas phase method silica fine particles) and a dispersant are added to water (for example, 10 to 20% by mass of inorganic fine particles in water), and a high-speed rotating wet colloid mill (for example, M Technique). (Cleamix) manufactured by Co., Ltd.), for example, under high speed rotation conditions of 10,000 rpm (preferably 5000 to 20000 rpm), for example, for 20 minutes (preferably 10 to 30 minutes). For example, boric acid), a polyvinyl alcohol (PVA) aqueous solution (for example, PVA having a mass of about 1/3 of the inorganic fine particles) and a nitrogen-containing organic cationic polymer are added, and the water-soluble polyvalent metal is further added. It can be prepared by adding a salt (for example, basic polyaluminum hydroxide) and dispersing under the same rotational conditions as described above.
The water-soluble polyvalent metal salt may be added by in-line mixing immediately before application.
Moreover, a liquid-liquid collision type disperser (for example, an optimizer manufactured by Sugino Machine Co., Ltd.) can also be used for the dispersion.
The obtained coating liquid is in a uniform sol state, and a porous ink-receiving layer having a three-dimensional network structure can be formed by applying the coating liquid onto a support by the following coating method and drying it.

In addition, the preparation of an aqueous dispersion composed of the inorganic fine particles (preferably gas phase method silica) and a dispersant may be performed by preparing an inorganic fine particle aqueous dispersion in advance and adding the aqueous dispersion to the aqueous dispersant solution. Alternatively, the dispersant aqueous solution may be added to the inorganic fine particle aqueous dispersion, or may be mixed at the same time. Further, instead of the inorganic fine particle aqueous dispersion, powdery inorganic fine particles may be added to the aqueous dispersant solution as described above.
After mixing the inorganic fine particles and the dispersant, the mixture is finely divided using a disperser, whereby an aqueous dispersion having an average particle size of 50 to 300 nm can be obtained. Dispersers used for obtaining the aqueous dispersion include various types of conventionally known high-speed rotating dispersers, medium stirring dispersers (ball mill, sand mill, etc.), ultrasonic dispersers, colloid mill dispersers, high pressure dispersers and the like. Although a disperser can be used, a stirrer-type disperser, a colloid mill disperser, or a high-pressure disperser is preferable from the viewpoint that the formed fine particles are efficiently dispersed.

  Moreover, water, an organic solvent, or these mixed solvents can be used as a solvent in each process. Examples of the organic solvent that can be used for this coating include alcohols such as methanol, ethanol, n-propanol, i-propanol, and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate, and toluene. It is done.

In addition, a chaotic polymer can be used as the dispersant. Examples of the chaotic polymer include mordant examples described in paragraphs [0138] to [0148] of JP-A-2006-321176. It is also preferable to use a silane coupling agent as the dispersant.
The amount of the dispersant added to the fine particles is preferably 0.1% to 30%, more preferably 1% to 10%.

(Third coating solution)
The third coating liquid in the present invention contains at least one inorganic fine particle and at least one water-soluble aluminum compound.
The details of the inorganic fine particles in the third coating liquid are as described for the inorganic fine particles in the ink receiving layer. Moreover, there is no restriction | limiting in particular as content rate of the inorganic fine particle in a 3rd coating liquid, However, It is preferable that it is 50-85 mass% with respect to the total solid of a 3rd coating liquid, and 55-70 mass%. It is more preferable that

  The water-soluble aluminum compound contained in the third coating liquid in the present invention is as described for the water-soluble aluminum compound in the ink receiving layer. Further, the content of the water-soluble aluminum compound in the third coating solution is not particularly limited, but from the viewpoint of ozone resistance, it is preferably 0.1 to 10% by mass with respect to the inorganic fine particles, More preferably, it is 0.5-8 mass%.

The 3rd coating liquid in this invention can contain a nitrogen-containing organic cationic polymer in the range which does not impair the effect of this invention.
For example, from the viewpoint of forming the nitrogen-containing organic cationic polymer in the formed ink receiving layer so as to be contained in a layer closer to the base paper than to a layer far from the base paper in the ink receiving layer, the third coating liquid It is preferable that the content of the nitrogen-containing organic cationic polymer in the inside is less than the content of the nitrogen-containing organic cationic polymer in the second coating solution.
That is, the content ratio of the nitrogen-containing organic cationic polymer [the content in the third coating solution / the content in the second coating solution] needs to be less than 1.0.
Further, the third coating liquid in the present invention may be at least one selected from cationic polyurethanes and cationic polymers having a quaternary ammonium base (hereinafter referred to as “specific nitrogen-containing organic cationic polymer”) as the nitrogen-containing organic cationic polymer. ), The content ratio is preferably 0 to 0.7, more preferably 0 to 0.4, and 0 (that is, the third coating solution) from the viewpoint of obtaining the effect of the present invention more effectively. Is a form in which the specific nitrogen-containing organic cationic polymer is not included.

  Moreover, from the viewpoint of obtaining the effect of the present invention more effectively, the content of the specific nitrogen-containing organic cationic polymer in the third coating solution is 0 to 8 with respect to the total solid content of the third coating solution. % By mass is preferable, 0% by mass to 4% by mass is more preferable, and 0% by mass (that is, the form in which the third coating liquid does not include the specific nitrogen-containing organic cationic polymer) is particularly preferable.

Further, the third coating solution may contain a sulfur compound, but from the viewpoint of keeping the density of the recorded image higher, the content of the sulfur compound in the third coating solution is set to the second coating solution. It is preferable to make it less than content of the sulfur type compound in a liquid.
That is, the sulfur compound content ratio [content in the third coating solution / content in the second coating solution] needs to be less than 1.0.
In this case, the content ratio of sulfur-based compound [content in the third coating solution / content in the second coating solution] is preferably 0 to 0.6, more preferably 0 to 0.3, 0 (that is, a form in which the third coating solution does not contain a sulfur compound) is particularly preferable.

  Moreover, from the viewpoint of obtaining the effect of the present invention more effectively, the content of the sulfur compound in the third coating solution is 0 to 5% by mass with respect to the total solid content of the third coating solution. 0 to 3% by mass is more preferable, and 0% by mass (that is, the form in which the third coating solution does not contain a sulfur compound) is particularly preferable.

Further, the third coating liquid may contain other components such as a water-soluble resin, a dispersant, a crosslinking agent, a water-soluble polyvalent metal salt, a mordant, and a surfactant other than the above components.
In the application of the third coating solution, it is also preferable to apply the solution after in-line mixing a solution containing the water-soluble polyvalent metal salt (preferably basic polyaluminum chloride).
Details of each component such as a sulfur-based compound, a water-soluble resin, a mordant, a surfactant, and a water-soluble polyvalent metal salt are as described in the section of <Second Layer: Ink Receiving Layer> above. The preferable form is also the same. The dispersant is as described in the description of the first coating liquid, and the preferable range is also the same.
Furthermore, the third coating solution can be prepared by the same method as the second coating solution described above.

  As with the second coating solution, the third coating solution is preferably acidic, and the pH is preferably 5.0 or less, more preferably 4.5 or less. More preferably, it is 0 or less. This pH can be adjusted by appropriately selecting the type and addition amount of the cationic resin. Moreover, you may adjust by adding an organic or inorganic acid. When the pH of the third coating solution is 5.0 or less, for example, the crosslinking reaction of the water-soluble resin by the crosslinking agent (particularly boron compound) in the third coating solution can be more sufficiently suppressed.

(Other coating solutions)
Hereinafter, other coating solutions that may be used as necessary will be described.
The other coating liquid preferably contains colloidal silica. By further applying another coating solution containing colloidal silica onto the third coating solution, a colloidal silica layer can be formed as the uppermost layer in the ink receiving layer. Thereby, the glossiness of the formed ink receiving layer can be further improved.
The colloidal silica is as described above in the section <Second layer: ink receiving layer>, and the preferred range is also the same.
Other coating liquids can be prepared, for example, by adding colloidal silica to ion-exchanged water, and mixing and stirring.

<Curing process>
In the second embodiment, the coating layer formed in the coating layer forming step is
(1) At the same time as applying at least the second coating liquid and the third coating liquid,
(2) At least during the drying of the coating layer formed by applying the second coating solution and the third coating solution, and before the coating layer exhibits reduced-rate drying,
In any of the cases, it is preferable to have a step of applying a liquid containing a basic compound and crosslinking and curing the coating layer (hereinafter, this step may be referred to as a “curing step”).

Examples of the method of applying the “(1) at least the second coating liquid and the third coating liquid simultaneously with the application of the“ liquid containing a basic compound ”” include the second coating liquid and the third coating liquid. It is preferable that the coating solution (the other coating solution if necessary) and the “liquid containing a basic compound” are simultaneously applied (multilayer coating) in this order from the support side.
Alternatively, after the second coating solution is applied, the third coating solution and the “liquid containing a basic compound” are simultaneously applied onto the applied second coating solution (hereinafter referred to as “simultaneous multilayer coating”). You may say).
The simultaneous coating (simultaneous multilayer coating) can be performed using a known coating device such as an extrusion die coater or a curtain flow coater.

“(2) Basic compound in the middle of drying of the coating layer formed by coating at least the second coating solution and the third coating solution and before the coating layer exhibits reduced-rate drying” The method of applying the “liquid containing” is a method called “Wet-On-Wet method” or “WOW method”. Details of the “Wet-On-Wet method” are described, for example, in paragraph numbers [0016] to [0037] of JP-A-2005-14593.
In the present invention, the second coating liquid and the third coating liquid (and other coating liquids as required) are simultaneously applied (simultaneous multi-layer coating) from the support side in this order. Alternatively, after forming the coating layer by coating one layer at a time, before the coating layer is in the course of drying, and before the coating layer exhibits reduced-rate drying, (i) further “basic compound” (Ii) a method of spraying the “liquid containing a basic compound” by spraying or the like, (iii) the support on which the coating layer is formed in the “liquid containing a basic compound” And a method of immersing in water.

  In the above (i), as a coating method for applying the “liquid containing a basic compound”, for example, curtain flow coater, extrusion die coater, air doctor coater, bread coater, rod coater, knife coater, squeeze coater, reverse A known coating method such as a roll coater or a bar coater can be used. However, it is preferable to use a method in which the coater does not directly contact an already formed coating layer, such as an extrusion die coater, a curtain flow coater, a bar coater or the like.

  In the cross-linking curing step, “before the coating layer comes to show reduced-rate drying” usually means a coating solution for an ink receiving layer (in the present invention, the second coating solution and the third coating solution ( Furthermore, it refers to a process for several minutes immediately after the application of other coating liquids)) as necessary, during which the content of the solvent (dispersion medium) in the coated coating layer decreases in proportion to time. The phenomenon of “constant rate drying” is shown. About the time which shows this "constant rate drying", it describes in chemical engineering handbook (pages 707-712, Maruzen Co., Ltd. issue, October 25, 1980), for example.

  As a condition for the above-mentioned “drying until the coating layer exhibits reduced rate drying”, it is generally carried out at 40 to 180 ° C. for 0.5 to 10 minutes (preferably 0.5 to 5 minutes). The drying time naturally varies depending on the coating amount, but usually the above range is appropriate.

(Liquid containing basic compound)
Here, the “liquid containing a basic compound” in the crosslinking curing step will be described.
~ Basic compounds ~
The “liquid containing a basic compound” in the present invention contains at least one basic compound.
Basic compounds include ammonium salts of weak acids, alkali metal salts of weak acids (eg, lithium carbonate, sodium carbonate, potassium carbonate, lithium acetate, sodium acetate, potassium acetate, etc.), alkaline earth metal salts of weak acids (eg, carbonate Magnesium, barium carbonate, magnesium acetate, barium acetate, etc.), hydroxyammonium, primary to tertiary amines (eg, triethylamine, tripropylamine, tributylamine, trihexylamine, dibutylamine, butylamine, etc.), primary to tertiary anilines ( For example, diethylaniline, dibutylaniline, ethylaniline, aniline, etc.), pyridine which may have a substituent (for example, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 4- (2-hydroxyethyl) -Aminopyrid Etc.), and the like.

  In addition to the basic compound, other basic substances and / or salts thereof may be used in combination with the basic compound. Examples of other basic substances include ammonia, primary amines such as ethylamine and polyallylamine, secondary amines such as dimethylamine, tertiary amines such as N-ethyl-N-methylbutylamine, and alkali metals. And alkaline earth metal hydroxides.

Among the above, ammonium salts of weak acids are particularly preferable. The weak acid is an inorganic acid or an organic acid described in Chemical Handbook Fundamentals II (Maruzen Co., Ltd.) or the like and having an pKa of 2 or more. Examples of the weak acid ammonium salt include ammonium carbonate, ammonium hydrogen carbonate, ammonium borate, ammonium acetate, and ammonium carbamate. However, it is not limited to these. Among these, ammonium carbonate, ammonium hydrogen carbonate, and ammonium carbamate are preferable, and are effective in that ink bleeding can be reduced without remaining in the layer after drying.
Two or more basic compounds can be used in combination.

  The content of the basic compound (particularly the ammonium salt of a weak acid) in the “liquid containing the basic compound” is 0.5 to 0.5% relative to the total mass (including the solvent) of the “liquid containing the basic compound”. 10 mass% is preferable, More preferably, it is 1-5 mass%. When the content of the basic compound (particularly the ammonium salt of the weak acid) is particularly in the above range, a sufficient degree of curing can be obtained, and the ammonia concentration becomes too high without impairing the working environment.

~ Metal compound ~
The “liquid containing a basic compound” in the present invention preferably contains at least one metal compound.

  As the metal compound contained in the “liquid containing a basic compound”, those that are stable under basicity can be used without limitation, and the above-mentioned water-soluble polyvalent metal salts, metal complex compounds, inorganic oligomers, or inorganic polymers can be used. Any of these may be used. For example, zirconium compounds and compounds listed as inorganic mordants in paragraphs [0100] to [0101] of JP-A-2005-14593 are suitable. Examples of the metal complex compound include metal complexes described in “Chemistry Review No. 32 (1981)” edited by the Chemical Society of Japan, “Coordination Chemistry Review”, Vol. 84, pages 85-277. (1988) and JP-A-2-182701, transition metal complexes containing a transition metal such as ruthenium can be used.

  Among the above, zirconium compounds and zinc compounds are preferable, and zirconium compounds are particularly preferable. Examples of the zirconium compound include zirconium carbonate / ammonium, zirconium nitrate / ammonium, zirconium carbonate / potassium, zirconium citrate / ammonium citrate, zirconyl stearate, zirconyl octylate, zirconyl nitrate, zirconium oxychloride, and zirconium zirconium hydroxychloride. Particularly preferred is zirconium ammonium carbonate. Moreover, two or more metal compounds (preferably containing a zirconium compound) may be used in combination in the “liquid containing a basic compound”.

  As content in the "liquid containing a basic compound" of the said metal compound (especially zirconium compound), it is 0.05-5 mass% with respect to the total mass (a solvent is included) of "the liquid containing a basic compound". Is more preferable, and 0.1 to 2% by mass is more preferable. By setting the content of the metal compound (especially zirconium compound) in the above range, the coating layer can be sufficiently hardened, and the mordant ability is lowered, so that a sufficient printing density cannot be obtained, or beading is not achieved. It does not occur, and the working environment is not deteriorated due to the concentration of a basic compound such as ammonia becoming too high. Two or more metal compounds can be used in combination, and when other mordant components to be described later are used in combination with a metal compound other than the metal compound, the total amount is within the above range and does not impair the effects of the present invention. It can be contained in a range.

From the viewpoint of image density and ozone resistance, the “liquid containing a basic compound” preferably contains the aforementioned magnesium salt as a metal compound. As the magnesium salt, magnesium chloride is particularly preferable.
In this case, the addition amount of the magnesium salt is preferably 0.1 to 1% by mass and more preferably 0.15 to 0.5% by mass with respect to the total mass of the “liquid containing a basic compound”.

The “liquid containing a basic compound” can contain a crosslinking agent and other mordant components as necessary.
The “liquid containing a basic compound” can promote dura mater when used as an alkaline solution, and is preferably adjusted to pH 7.1 or higher, more preferably pH 8.0 or higher, and particularly preferably pH 9.0. That's it. When the pH is 7.1 or more, the crosslinking reaction of the water-soluble resin that may be contained in the second coating solution and / or the third coating solution can be further promoted, and bronzing and cracking of the ink receiving layer can be performed. Can be suppressed more effectively.

  The “liquid containing a basic compound” includes, for example, ion-exchanged water, a metal compound (eg, zirconia compound; eg, 1 to 5%) and a basic compound (eg, ammonium carbonate; eg, 1 to 5%), It can be prepared by adding para-toluenesulfonic acid (for example, 0.5 to 3%) as necessary and stirring sufficiently. In addition, all "%" of each composition means solid content mass%.

  In addition, water, an organic solvent, or a mixed solvent thereof can be used as a solvent used for preparing the “liquid containing a basic compound”. Examples of the organic solvent that can be used for coating include alcohols such as methanol, ethanol, n-propanol, i-propanol, and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate, and toluene. .

<Cooling process and drying process>
In the third aspect, the coating layer formed in the coating layer forming step is applied to the lower one of the temperature of the second coating solution at the time of coating and the temperature of the third coating solution at the time of coating. A step of cooling to lower by 5 ° C. or more (hereinafter also referred to as “cooling step”), a step of drying the cooled coating layer to form an ink receiving layer (hereinafter also referred to as “drying step”), It is preferable to have.

As a method of cooling the coating layer in the cooling step, a method of cooling the support on which the coating layer is formed in a cooling zone maintained at 0 to 10 ° C. for 5 to 30 seconds is preferable.
In a cooling process, it is preferable to cool so that it may fall 0-10 degreeC, and it is more preferable to cool so that it may fall 0-5 degreeC or more.
Here, the temperature of the coating layer is measured by measuring the temperature of the film surface.

<Other processes>
In the second embodiment and the third embodiment, after the ink receiving layer is formed on the base paper on which the first layer is formed, the ink receiving layer is heated using, for example, a super calender, a gloss calendar, or the like. By applying a calender treatment through the roll nip under pressure, it is possible to improve surface smoothness, glossiness, transparency and coating strength. However, the calendar process may cause a decrease in the porosity (that is, the ink absorptivity may be decreased), so it is necessary to set conditions under which the decrease in the porosity is small.

As roll temperature in the case of performing a calendar process, 30-150 degreeC is preferable and 40-100 degreeC is more preferable.
Moreover, as a linear pressure between rolls at the time of a calendar process, 50-400 kg / cm is preferable and 100-200 kg / cm is more preferable.

≪Inkjet recording method≫
An ink jet recording medium manufactured by the method for manufacturing an ink jet recording medium of the present invention is an ink jet method in which at least one ink containing a water-soluble dye represented by the following general formula (M) or general formula (Bk) is used. It is preferable to use the ink jet recording method including the applying step because the effect such as ozone resistance becomes remarkable.
By combining the ink jet recording medium produced by the method for producing an ink jet recording medium of the present invention and an ink containing a water-based dye having a specific structure, the effect of suppressing blur (bleeding over time) of the recorded image, high image density, The ozone resistance effect can be realized at a better level. The ink receiving layer of the ink jet recording medium in the present invention contains a large amount of a nitrogen-containing organic cationic polymer in a layer close to the support. Therefore, for example, when the water-soluble dye represented by the general formula (M) or the general formula (Bk) penetrates to the layer close to the support of the ink receiving layer, the effect of suppressing the occurrence of bleeding is more effectively achieved. It is considered a thing.
In the present invention, the water-soluble dye means a dye that dissolves 1% by mass or more in water at 20 ° C.

In the general formula (M), A ₃₁ represents a 5-membered heterocyclic group.
B ₃₁ and _{B 32} are each ₌ CR 31 -, - or represents _{CR 32} =, or either one nitrogen atom and the other = _{CR 31} - represents a or _{-CR 32} =. R ₃₅ and R ₃₆ are each independently a hydrogen atom, aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group, alkyl or arylsulfonyl group Represents a heterocyclic sulfonyl group or a sulfamoyl group, and each group may further have a substituent.
G ₃ , R ₃₁ and R ₃₂ are each independently a hydrogen atom, a halogen atom, an aliphatic group, an aromatic group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, Heterocyclic oxycarbonyl group, acyl group, hydroxy group, alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (arylamino) Group, including heterocyclic amino group), acylamino group, ureido group, sulfamoylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkyl or arylsulfonylamino group, heterocyclic sulfonylamino group, nitro group, alkyl And Represents an alkylthio group, an alkyl and arylsulfonyl group, a heterocyclic sulfonyl group, an alkyl and arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group, a sulfonic acid group, or a heterocyclic thio group, and each group may be further substituted. .
R ₃₁ and R ₃₅ , or R ₃₅ and R ₃₆ may combine to form a 5- to 6-membered ring.
Note that at least one of A ₃₁ , R ₃₁ , R ₃₂ , R ₃₅ , R ₃₆ and G ₃ has a sulfonic acid group, and has Li ⁺ or a quaternary ammonium ion as a counter ion.

Specific examples of the water-soluble dye represented by the general formula (M) include International Patent Publication No. 2002/83795 (pages 35-55), 2002-83661 (pages 27-42), and JP-A No. 2004-149560. (Paragraph numbers [0046] to [0059]) and 2004-149561 (paragraph numbers [0047] to [0060]), the water-soluble group is only a sulfonic acid group, and the counter ion is Examples include Li ⁺ ions or quaternary ammonium ions. Specific examples of particularly preferred water-soluble dyes represented by the general formula (M) are shown below in terms of the structure of a free acid, but they are preferably used as salts.

  In the present invention, the content of the water-soluble dye (heterocyclic azo dye) represented by formula (M) in the magenta ink is preferably 0.2 to 20% by mass, more preferably 0.5 to 15% by mass. preferable.

In general formula (Bk), A ₁ , A ₂ and A ₃ each independently represents an optionally substituted aromatic group or an optionally substituted heterocyclic group. A ₁ and A ₃ are monovalent groups, and A ₂ is a divalent group. At least one of A ₁ , A ₂ and A ₃ is preferably a heterocyclic group.

  Examples of the water-soluble dye represented by the general formula (Bk) in the present invention include water-soluble dyes described in paragraph numbers [0041] to [0059] of JP-A-2007-70573. The range is the same.

  In the present invention, the content of the compound represented by the general formula (Bk) in the ink is preferably 0.2 to 20% by mass, and more preferably 0.5 to 15% by mass.

In addition, it is preferable that the ink containing the water-soluble dye represented by the general formula (Bk) in the present invention further contains a water-soluble short wave dye.
Specific examples of the water-soluble short wave dye include water-based dyes described in paragraph numbers [0061] to [0072] of JP-A-2007-70573, and the same applies to preferred embodiments.

  The ink in the present invention contains at least one water-soluble dye represented by the general formula (M) and the general formula (Bk) and an aqueous medium, and other additives may be added as necessary. Other additives include, for example, boron compounds, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, antiseptics, anti-fungal agents, pH adjusters, and surface tension adjusters. Known additives such as an agent, an antifoaming agent, a viscosity modifier, a dispersant, a dispersion stabilizer, a rust inhibitor, and a chelating agent can be used.

  As the aqueous medium, a mixture containing water as a main component and optionally adding a water-miscible organic solvent can be used. Examples of the water-miscible organic solvent include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol), polyvalent Alcohols (eg, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), glycol derivatives (eg , Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl Ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether , Triethylene glycol monoethyl ether, ethylene glycol monophenyl ether), amine (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine) , Triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine) and other polar solvents (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 2-pyrrolidone, N-methyl- 2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone). In addition, the said water miscible organic solvent may use 2 or more types together.

  The anti-drying agent is preferably used for the purpose of preventing clogging due to drying of ink at an ink ejection port of a nozzle used in an ink jet recording system.

  The anti-drying agent is preferably a water-soluble organic solvent having a vapor pressure lower than that of water. Specific examples include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, acetylene glycol derivatives, glycerin. Polyhydric alcohols typified by trimethylolpropane, etc., lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether , Heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethylmorpholine, sulfolane, dimethyl sulfoxide, 3 Sulfur-containing compounds such as sulfolane, diacetone alcohol, polyfunctional compounds such as diethanolamine, and urea derivatives. Of these, polyhydric alcohols such as glycerin and diethylene glycol are more preferred. Moreover, said anti-drying agent may be used independently and may be used together 2 or more types. These drying inhibitors are preferably contained in the ink in an amount of 10 to 50% by mass.

  The penetration accelerator is preferably used for the purpose of allowing the ink to penetrate better into paper. Examples of the penetration enhancer include alcohols such as ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether, 1,2-hexanediol, sodium lauryl sulfate, sodium oleate, and nonionic surfactants. it can. If these are contained in the ink in an amount of 5 to 30% by mass, they usually have a sufficient effect, and it is preferable to use them in a range of addition amounts that do not cause printing bleeding and paper loss (print through).

  The ultraviolet absorber is used for the purpose of improving image storage stability. Examples of the ultraviolet absorber include benzotriazoles described in JP-A Nos. 58-185677, 61-190537, JP-A-2-782, JP-A-5-97075, JP-A-9-34057, and the like. Compounds, benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194433, US Pat. No. 3,214,463, etc., JP-B Nos. 48-30492, 56-211141, Cinnamic acid compounds described in, for example, Kaihei 10-88106, JP-A-4-298503, 8-53427, 8-239368, 10-182621, JP-A-8- No. 501291, etc., triazine compounds, Research Disclosure No. The compounds described in No. 24239, compounds that emit fluorescence by absorbing ultraviolet rays typified by stilbene-based compounds and benzoxazole-based compounds, so-called fluorescent brighteners, can also be used.

  The anti-fading agent is used for the purpose of improving image storage stability. As the anti-fading agent, various organic and metal complex anti-fading agents can be used. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, thioethers, thioureas (thioethers and thioureas) Examples include JP-A-2002-36717, and examples of thioethers are described in JP-A-2002-86904), heterocycles, etc., and metal complexes include nickel complexes and zinc complexes. More specifically, Research Disclosure No. No. 17643, Nos. VII to I, J; 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of the representative compounds described in pages 127 to 137 of JP-A-62-215272 can be used.

  Examples of the antifungal agent include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one and salts thereof. These are preferably used in the ink in an amount of 0.02 to 1.00% by mass.

  The neutralizer (organic base, inorganic alkali) can be used as the pH adjuster. For the purpose of improving the storage stability of the ink, the pH adjuster is preferably added so that the ink has a pH of 6 to 10, and more preferably added to have a pH of 7 to 10.

  Examples of the surface tension adjusting agent include nonionic, cationic and anionic surfactants. The surface tension of the ink according to the present invention is preferably 25 to 70 mN / m. Furthermore, 25-60 mN / m is preferable. The viscosity of the ink according to the present invention is preferably 30 mPa · s or less. Furthermore, it is more preferable to adjust to 20 mPa · s or less.

  Examples of surfactants include fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonate formalin condensates, polyoxyethylene alkyl sulfates. Anionic surfactants such as ester salts, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester Nonionic surfactants such as oxyethyleneoxypropylene block copolymers are preferred. Further, SURFYNOLS (Air Products & Chemicals), which is an acetylene-based polyoxyethylene oxide surfactant, is also preferably used. Also preferred are amine oxide types such as N, N-dimethyl-N-alkylamine oxide and betaine type amphoteric surfactants containing quaternary ammonium salts such as N, N-dimethyl-N-lauryl-carbomethylammonium. . Further, JP-A-59-157,636, pages (37) to (38), Research Disclosure No. The surfactants described in 308119 (1989) can also be used.

  As the antifoaming agent, fluorine-based, silicone-based compounds, chelating agents represented by EDTA, and the like can be used as necessary.

  The method for preparing the ink in the present invention is not particularly limited. For example, JP-A Nos. 5-148436, 5-295212, 7-97541, 7-82515, 7-118584, and JP-A-2004. Details are described in each method of No. 331871 and can also be applied to the preparation of ink in the present invention.

The ink in the present invention can be used as an ink set including at least a yellow ink containing a yellow dye and a cyan ink containing a cyan dye.
Although there is no restriction | limiting in particular as said yellow dye, For example, the yellow dye as described in Paragraph [0025]-[0040] etc. of Unexamined-Japanese-Patent No. 2007-70573 can be used.
The cyan dye is not particularly limited. For example, cyan dyes described in paragraphs [0083] to [0090] of JP-A-2007-70753 can be used.

  There is no particular limitation on the ink jet system for recording an image on the ink jet recording medium of the present invention, and a known system, for example, a charge control system for ejecting ink using electrostatic attraction, and the vibration pressure of the piezo element are controlled. Drop-on-demand method (pressure pulse method) to be used, an acoustic signal is converted into an acoustic beam, the ink is irradiated, an acoustic ink jet method that ejects ink using radiation pressure, and ink is heated to form bubbles, A thermal ink jet method using the generated pressure can be used. The ink jet recording method includes a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent. A method using ink is included.

  The present invention will be described more specifically with reference to the following examples. The scope of the present invention is not limited to the specific examples shown below. Unless otherwise specified, “part” and “%” are based on mass.

Example 1
<Preparation of inkjet recording medium>
(Preparation of first layer forming coating solution (first coating solution))
Kaolin (trade name: Kaoblite 90, manufactured by Shiraishi Calcium Co., Ltd.) 100 parts, 0.1N sodium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) 3.8 parts, 40% sodium polyacrylate (trade name: Aron T-50, manufactured by Toagosei Co., Ltd. (1.2 parts) and water (48.8 parts) were mixed and dispersed using a non-bubbling kneader (trade name: NBK-2, manufactured by Nippon Seiki Seisakusho Co., Ltd.). To obtain a 65% kaolin dispersion. Next, 22.5% polyester-based urethane latex aqueous dispersion (glass transition temperature 49 ° C., minimum film-forming temperature 29 ° C .; trade name: Hydran AP-40F, manufactured by Dainippon Ink & Chemicals, Inc.) 100 parts of water 5 parts, 6.9 parts of the obtained 65% kaolin dispersion liquid and 0.8 part of 10% Emulgen 109P (manufactured by Kao Corporation) were added and thoroughly stirred and mixed. The temperature was maintained at 15 to 25 ° C. to obtain a first layer coating solution having a solid content concentration of 24.0%.

<Preparation of third coating liquid (for upper layer of second layer)>
(1) Gas phase method silica fine particles, (2) ion-exchanged water, (3) “Charol DC-902P”, and (4) “ZA-30” shown in the following composition are mixed, After dispersion using a collision type disperser (Ultimizer, manufactured by Sugino Machine Co.), the obtained dispersion was heated to 45 ° C. and held for 20 hours. Thereafter, (5) boric acid and (6) polyvinyl alcohol solution were added to the dispersion at 30 ° C. to prepare a second coating solution (for the upper layer).
The mass ratio between the silica fine particles and the water-soluble resin (PB ratio = (1) :( 5)) is 4.0: 1, and the pH of the second coating liquid (for the upper layer) is 3.4 and acidic. showed that.

-Composition of third coating solution-
(1) Gas phase method silica fine particles (inorganic fine particles) 8.9 parts (AEROSIL300SF75, manufactured by Nippon Aerosil Co., Ltd.)
(2) Ion-exchanged water ... 58.1 parts (3) "Charol DC-902P" (51.5% aqueous solution) ... 0.78 parts (dispersant, nitrogen-containing organic cationic polymer, Daiichi Kogyo Seiyaku) (Made by Co., Ltd.)
(4) “ZA-30”: 0.48 part (Daiichi Rare Element Chemical Co., Ltd., zirconyl acetate)
(5) Boric acid (crosslinking agent) ... 0.3 part (6) Polyvinyl alcohol (water-soluble resin) solution ... 31.2 parts-Composition of solution-
・ PVA235 (saponification degree 88%, polymerization degree 3500, manufactured by Kuraray Co., Ltd.)
・ ・ ・ 2.2 parts ・ Ion-exchanged water ・ ・ ・ 28.2 parts ・ Diethylene glycol monobutyl ether (Buticenol 20P) ・ ・ ・ 0.7 parts (Kyowa Hakko Chemical Co., Ltd.)
・ Emulgen 109P (surfactant, manufactured by Kao Corporation) ・ ・ ・ 0.1 part (7) Synthetic alcohol AP-7 (Japanese alcohol) ・ ・ ・ 1.58 parts

<Preparation of second coating liquid (for lower layer of second layer)>
(1) Gas phase method silica fine particles, (2) ion-exchanged water, (3) “Charol DC-902P”, (4) “ZA-30”, (5) “30” shown in the following composition % Methionine sulfoxide ”was mixed and dispersed using a liquid-liquid collision type disperser (Ultimizer, manufactured by Sugino Machine Co., Ltd.), and then the dispersion was heated to 45 ° C. and held for 20 hours. Thereafter, (6) boric acid, (7) polyvinyl alcohol solution, and (8) “Superflex 650” were added to the dispersion at 30 ° C. to prepare a second coating liquid (for the lower layer).
The mass ratio between the silica fine particles and the water-soluble resin (PB ratio = (1) :( 7)) is 4.0: 1, and the pH of the second coating liquid (for the lower layer) is 3.8 and acidic. showed that.

-Composition of the second coating solution-
(1) Gas phase method silica fine particles (inorganic fine particles) 8.9 parts (AEROSIL300SF75, manufactured by Nippon Aerosil Co., Ltd.)
(2) Ion-exchanged water ... 53.3 parts (3) "Charol DC-902P" (51.5% aqueous solution) ... 0.78 parts (dispersant, nitrogen-containing organic cationic polymer, Daiichi Kogyo Seiyaku) (Made by Co., Ltd.)
(4) “ZA-30”: 0.48 part (Daiichi Rare Element Chemical Co., Ltd., zirconyl acetate)
(5) 30% methionine sulfoxide (sulfur compound) aqueous solution ... 1.76 parts (6) boric acid (crosslinking agent) 0.4 parts (7) Polyvinyl alcohol (water-soluble resin) solution -31.7 parts-Composition of the solution-
・ PVA235 (saponification degree 88%, polymerization degree 3500, manufactured by Kuraray Co., Ltd.)
・ ・ ・ 2.2 parts ・ Ion-exchanged water ・ ・ ・ 28.2 parts ・ Diethylene glycol monobutyl ether (Buticenol 20P) ・ ・ ・ 0.7 parts (Kyowa Hakko Chemical Co., Ltd.)
Emulgen 109P (surfactant, manufactured by Kao Corporation) 0.7 part (8) "Superflex 650" 3.1 parts (nitrogen-containing organic cationic polymer emulsion, 25% aqueous dispersion, Daiichi Kogyo Seiyaku Co., Ltd.)

(Formation of first layer <binder layer>)
The obtained coating liquid for the first layer is applied to both sides of a high-quality paper (trade name: Shiraoi, manufactured by Nippon Paper Industries Co., Ltd.) having a basis weight of 81.4 g / m ² using an extrusion die coater. The first layer was formed by coating one side at a time while adjusting the coating amount to 8.0 g / m ² and drying at a temperature of 85 ° C. and a wind speed of 15 m / sec for 1 minute. Furthermore, the soft calendar process shown below was performed with respect to the formed 1st layer, and the support body was obtained. The thickness of the formed first layer was 8.1 μm.

~ Soft calendar processing ~
Using a soft calender having a roll pair in which a metal roll and a resin roll are paired with respect to the fine paper having the first layer formed on the surface, the surface temperature of the metal roll is 50 ° C., and the nip pressure is 50 kg / cm. Soft calendar processing was performed under conditions.

(Second layer <ink receiving layer> formation)
To the support obtained above,
The prepared second coating solution (for the lower layer) and the third coating solution (for the upper layer) are applied simultaneously at an application temperature of 38 ° C. with an extrusion die coater to form a coating layer. did.
Specifically, in the above simultaneous multilayer coating,
The second coating solution (for lower layer) at 105.1 g / ^{m 2,} coated with the following line liquid in the lower layer after line mixing at a rate of 3.3 g / ^{m 2,}
The third coating solution (for upper layer) at 106 g / m ^2, the following line liquid was coated on the upper layer after line mixing at a rate of 13.2 g / m ² (coating solution for the layer structure, the third coating Liquid (for upper layer) / second coating liquid (for lower layer) / support (first coating liquid / base paper / first coating liquid).

~ Composition of inline liquid ~
(1) Alphain 83 (Daimei Chemical Co., Ltd., 23% solid content) 2.0 parts (2) 7.8 parts of ion-exchanged water (3) Himax SC-507 (dimethylamine / epichlorohydrin heavy) Condensate, 70% aqueous solution, made by Hymo Co., Ltd.) 0.2 parts

The coating layer formed by the simultaneous multilayer coating was dried with a hot air drier at 80 ° C. (wind speed 3 to 8 m / sec) until the solid content concentration of the coating layer became 24%. This coating layer exhibited a constant rate of drying during this period. Immediately after that, it was immersed in a solution containing a basic compound having the following composition for 3 seconds to deposit 13 g / m ² on the coating layer, and further dried at 72 ° C. for 10 minutes (drying step). An ink receiving layer was formed on the base paper (support) on which was formed.

~ Composition of liquid containing basic compound ~
(1) Boric acid ... 0.8 part (2) Ammonium carbonate (1st grade: manufactured by Kanto Chemical Co., Ltd.) ... 5.0 parts (3) Magnesium chloride ... 0.3 parts (white bittern) NS, manufactured by Naikai Shigyo Co., Ltd.)
(4) Ion-exchanged water ... 85.2 parts (5) Polyoxyethylene lauryl ether (surfactant) ... 6.0 parts ("Emulgen 109P" (10% aqueous solution) manufactured by Kao Corporation, HLB Value 13.6)

  As described above, an ink jet recording medium of the present invention in which an ink receiving layer having a dry film thickness of 35 μm was provided on the support was obtained.

≪Preparation of ink≫
After adding deionized water to the following components to make 1 liter, the mixture was stirred for 1 hour while being heated at 30 to 40 ° C. Thereafter, the pH was adjusted to 9 with KOH 10 mol / L, and filtration under reduced pressure was performed using a microfilter having an average pore size of 0.25 μm to prepare an ink liquid for light magenta.

-Magenta dye (compound M-1) represented by the following structural formula 7.5 g / L
・ Diethylene glycol 50g / L
・ Urea 10g / L
・ Glycerin 200g / L
・ Triethylene glycol monobutyl ether 120g / L
・ Triethanolamine 6.9g / L
・ Benzotriazole 0.08g / L
・ 2-Pyrrolidone 20g / L
・ Surfinol 465
(Surfactant manufactured by Air Products Japan) 10.5g / L
・ PROXEL XL-2 (bactericidal agent: manufactured by ICI Japan) 3.5g / L

  Further, magenta ink, light cyan ink, cyan ink, yellow ink, and black ink were prepared by changing the dye species and additives, and ink set 101 having the concentrations shown in Table 1 was prepared.

≪Evaluation≫
The following evaluation was performed about the ink jet recording medium obtained above. The evaluation results are shown in Table 2.

1. Cobb water absorbency According to the water absorbency test according to JIS P8140, the Cobb water absorbency (water when contacted with water at 20 ° C. for 2 minutes on the surface of the first layer of the fine paper on which the first layer is formed) Penetration amount g /

2. Curl test Cut the inkjet recording medium to make a test piece of 50mm x 5mm size, and apply it to this test piece so that the water is 10g / m ^{2 in} each direction of MD and CD, JAPAN TAPPI paper pulp test Method No. 15-2: 2000 (Paper-Curl Test Method-Part 2) In accordance with the curl curvature measurement method defined in 15-2: 2000, the curl degree after standing for 8 hours at 23 ° C. and 50% RH is as follows. Evaluation was made according to criteria.
<Evaluation criteria>
A: The curl degree was less than 10.
B: The curl degree was 10 or more and less than 20.
C: Curling degree was 20 or more and less than 30.
D: Curling degree was 30 or more.

3. Measurement of Black Density Using the inkjet printer PM-A820 loaded with the ink set 101, solid black was printed, and the resulting black portion density was measured with a reflection densitometer (Xrite 938, manufactured by Xrite).
m ² ) was measured.

4). Ozone resistance Instead of the genuine ink set, using an ink jet printer ("PM-A820" manufactured by Epson Corporation) loaded with the ink set 101, solid images of yellow, cyan and magenta were printed on each recording medium. Each sample was printed, and the sample was stored for 80 hours in an atmosphere of 23 ° C., 60% RH, and ozone concentration of 10 ppm. The residual ratios of yellow density, cyan density and magenta density before and after storage were calculated, and the ozone resistance was evaluated according to the following criteria for the residual ratio of the color having the smallest residual ratio.
~Judgment criteria~
◎: 75% or more ○: 70% or more and less than 75% △: 60% or more and less than 70% ×: less than 60%

5). Confirmation of the presence distribution of nitrogen-containing organic cationic polymer A cross-section of the obtained recording medium was cut out by a microtome, and mapping of Si element and N element using SEM-EDX (Hitachi S-2150 combined with EDX apparatus) Analysis was carried out. The presence position of the ink receiving layer was confirmed from the mapping image of the Si element, and confirmed by observing it side by side with the N element mapping image. It was confirmed that the ink jet recording media of Examples and Comparative Examples were contained in the upper and lower layers of the ink receiving layer as set.

6). Confirmation of presence distribution of water-soluble aluminum compound A cross section of the obtained recording medium is cut out by a microtome, and mapping analysis of Si element and Al element is performed using SEM-EDX (Hitachi S-2150 combined with EDX apparatus). Went. The location of the ink receiving layer was confirmed from the mapping image of the Si element, and confirmed by observing it side by side with the Al element mapping image. It was confirmed that the ink jet recording media of Examples and Comparative Examples were contained in the upper and lower layers of the ink receiving layer as set.

[Example 2]
Ink-jet printing was carried out in the same manner as in Example 1 except that the in-line liquid mixed in-line with the third coating liquid (for upper layer) was changed to a speed of 6.6 g / m ² in the formation of the ink receiving layer in Example 1. A recording medium was obtained.

Example 3
In the formation of the support in Example 1, the polyester-based urethane latex aqueous dispersion of the first coating solution was replaced with a 35% acrylic silicone-based latex dispersion (glass transition temperature 25 ° C., minimum film-forming temperature 20 ° C .; trade name: An ink jet recording medium was obtained in the same manner as in Example 1 except that it was changed to Aquabrid ASi-91 (manufactured by Daicel Chemical Industries).

[Comparative Example 1]
An ink jet recording medium was obtained in the same manner as in Example 1 except that the support was changed to base paper in Example 1.

[Comparative Example 2]
In Example 1, the inkjet recording medium was obtained like Example 1 except having changed the application quantity at the time of forming a 1st layer into 4 g / m < ² >.

[Comparative Example 3]
In Example 1, 3.1 parts of “Superflex 650” was further added to the third coating solution, and “Superflex 650” was not added to the second coating solution. Thus, an ink jet recording medium was obtained.

[Comparative Example 4]
In Example 1, the in-line liquid mixed in-line with the third coating liquid was changed to a speed of 3.3 g / m ² , and the in-line liquid mixed in-line with the second coating liquid was changed to a speed of 13.2 g / m ² . An ink jet recording medium was obtained in the same manner as in Example 1 except for the change.

[Comparative Example 5]
In the formation of the ink receiving layer in Example 1, instead of the second coating liquid and the third coating liquid, the coating liquid was changed to a coating liquid having the following composition, the coating liquid was 209 g / m ² , and the in-line liquid was 16 An ink jet recording medium was obtained in the same manner as in Example 1 except that coating was performed after in-line mixing at a speed of ³ g / m ² .
~ Composition of coating liquid ~
(1) Gas phase method silica fine particles (inorganic fine particles) 8.9 parts (AEROSIL300SF75, manufactured by Nippon Aerosil Co., Ltd.)
(2) Ion-exchanged water ... 58.1 parts (3) "Charol DC-902P" (51.5% aqueous solution) ... 0.78 parts (dispersant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
(4) “ZA-30”: 0.48 part (made by Daiichi Rare Element Chemical Industries, Ltd., zirconium acetate)
(5) Boric acid (crosslinking agent) ... 0.35 part (6) Polyvinyl alcohol (water-soluble resin) solution ... 31.2 parts-Composition of solution-
・ PVA235 (saponification degree 88%, polymerization degree 3500, manufactured by Kuraray Co., Ltd.)
・ ・ ・ 2.2 parts ・ Ion-exchanged water ・ ・ ・ 28.2 parts ・ Diethylene glycol monobutyl ether (Buticenol 20P) ・ ・ ・ 0.7 parts (Kyowa Hakko Chemical Co., Ltd.)
Emulgen 109P (surfactant, manufactured by Kao Corporation) 0.4 part (7) "Superflex 650" 1.6 parts (nitrogen-containing organic cationic polymer emulsion, 25% aqueous dispersion, Manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

  As is apparent from Tables 1 and 2, one or more of the curl, black density, and ozone properties are inferior, while the examples having the configuration of the present invention are good in curl, black density, and ozone properties. It turned out that.

Claims (9)

A first layer containing a base paper, a hydrophilic binder, and a second layer containing inorganic fine particles, a nitrogen-containing organic cationic polymer, and a water-soluble aluminum compound on the first layer; Cobb water absorption degree during a contact time of 120 seconds by water absorption test conforming to JIS P8140 at a surface of the layer is not more 2.0 g / m ² or less, the nitrogen-containing organic cation polymer, said second layer to the base paper The water-soluble aluminum compound is contained more in the side half far from the base paper than in the side half near the base paper than in the side half near the base paper than in the side half far from the base paper when divided in half by a parallel plane. An ink jet recording medium characterized by comprising: 2. The ink jet recording medium according to claim 1, wherein the nitrogen-containing organic cationic polymer is at least one selected from a cationic polyurethane and a cationic polymer having a quaternary ammonium base. The inkjet recording medium according to claim 1, wherein the hydrophilic binder in the first layer contains a thermoplastic resin. 4. The ink jet recording medium according to claim 3, wherein the thermoplastic resin is at least one selected from urethane latex and acrylic silicone latex. The inkjet recording medium according to claim 1, wherein the first layer further contains a white pigment. 6. The ink jet recording medium according to claim 5, wherein the white pigment is kaolin. The ink jet recording medium according to claim 5, wherein the second layer further contains a sulfur-based compound. 8. The ink jet recording medium according to claim 7, wherein the sulfur compound is a sulfoxide compound or a thioether compound. A first layer forming step in which a first film-forming liquid containing a hydrophilic binder is applied to both sides of a base paper and dried to form a first layer; and on the first layer, inorganic fine particles and nitrogen-containing organic The second coating liquid containing the cationic polymer and the third coating liquid containing the inorganic fine particles and the water-soluble aluminum compound are coated with a coating liquid temperature of 35 so that the third coating liquid overlaps the second coating liquid. The nitrogen-containing organic cationic polymer is more contained in the side half closer to the base paper than the side half far from the base paper when the multilayer coating is performed in a plane parallel to the base paper and bisected in a plane parallel to the base paper, and is close to the base paper And a second layer forming step of forming an ink receiving layer containing a large amount of the water-soluble aluminum compound in a side half farther from the base paper than in the side half. Inkjet for manufacturing recording media Manufacturing method of the recording medium.