JP2010046946A - Recording medium and method of ink-jet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording medium in which the generation of curling upon recording images, the bleeding of the images and intercolor color mixing are prevented from being developed, the chipping of ink is hardly developed and high quality images can be formed. <P>SOLUTION: The recording medium is constituted in such a manner that: original paper, a first layer containing a hydrophilic binder, and a second layer containing silica and polyvinyl alcohol are sequentially laminated; a Cobb water absorption degree in a contact time of 120 seconds by a water absorption degree test according to JIS P8140 at the surface of the first layer is ≤2.0 g/m<SP>2</SP>; and a diethylene glycol absorbing capacity in a contact time of 30 seconds at the surface of the second layer is ≥2 mL/m<SP>2</SP>and ≤8 mL/m<SP>2</SP>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a recording medium and an ink jet recording method using the same.

  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, an ink jet dedicated paper (see FIG. 4) having a solvent absorbing layer (ink receiving layer) of about 20 to 30 μm that absorbs the ink solvent on the surface is used as a recording medium, and image bleeding and color mixing between colors occur. Is suppressed.

  Further, in the case of water-based ink using water as the ink solvent, paper permeation such as curling occurs when water penetrates into the base paper during recording. However, as shown in FIG. When the solvent absorption layer 22 is provided on the top, water can be prevented from penetrating into the base paper, 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.

Further, the recording medium has a high cost due to the solvent absorption layer and the water resistant layer, 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 cannot sufficiently suppress paper deformation such as curling, coating unevenness (coating property, coating surface shape), and the like. Further, in the printing method described in the above-mentioned patent document, the actual situation is that image bleeding, color mixing between colors, ink peeling and the like cannot be sufficiently suppressed.

  The present invention has been made in view of the above, and prevents the occurrence of curling, image bleeding and color mixing between images, and prevents the ink from peeling off and forms a high-quality image. It is an object of the present invention to provide an ink jet recording method capable of forming a high quality image at a low cost and at a high speed by suppressing image bleeding and color mixing between colors on the recording medium.

<1>
A base paper, a first layer containing a hydrophilic binder, and a second layer containing silica and polyvinyl alcohol are sequentially laminated, and a water absorption test based on JIS P8140 on the surface of the first layer. The Cobb water absorption for a contact time of 120 seconds is 2.0 g / m ² or less, and the absorption capacity of diethylene glycol for a contact time of 30 seconds on the surface of the second layer is 2 mL / m ² or more and 8 mL / m ² or less. A recording medium.
<2>
The recording medium according to <1>, wherein the silica of the second layer is vapor phase silica having an average primary particle diameter of 30 nm or less.
<3>
The recording medium according to <1> or <2>, wherein the second layer further contains a hardener.

<4>
The recording medium according to any one of <1> to <3>, wherein the hydrophilic binder of the first layer is thermoplastic resin particles.
<5>
The recording medium according to any one of <1> to <4>, wherein the first layer further contains a white pigment.

<6>
An ink drawing process in which ink is applied to the recording medium according to any one of <1> to <5> by an ink jet method and ink is drawn according to predetermined image data; and the ink drawn recording And a drying and removing step of drying and removing the ink solvent in the medium.
<7>
A treatment liquid supply step of supplying a treatment liquid containing an acidic compound to the recording medium described in any one of <1> to <5> above, and any one of <1> to <5> above. <6, further comprising: an ink drawing step of applying ink to the recording medium and drawing ink according to predetermined image data; and a drying removal step of drying and removing the ink solvent in the recording medium drawn with ink. > The ink jet recording method described in the above.
<8>
The inkjet recording method according to <6> or <7>, wherein the acidic compound is a divalent or higher acid.

  According to the present invention, it is possible to provide a recording medium that can prevent the occurrence of curling accompanying image recording, image bleeding, and color mixing between colors, hardly cause ink peeling, and can form a high-quality image. be able to. Further, it is possible to provide an ink jet recording method in which image bleeding and color mixing between colors are suppressed, and a high-quality image can be formed at low cost and at high speed.

(recoding media)
The recording medium of the present invention comprises a base paper and a first layer and a second layer provided in that order from the base paper side, and further comprises other layers appropriately selected as necessary. be able to.
The recording medium of the present invention includes, for example, a high-quality paper 11 as a base paper, a solvent blocking layer 12 as a first layer formed on the high-quality paper 11, like a recording medium 100 shown in FIG. It has a coat layer (ink receiving layer) 13 as a second layer formed on the solvent blocking layer 12.
The above example is an embodiment having an ink receiving layer on one side of the fine paper, but may be an embodiment in which two ink receiving layers are provided on both sides on which a solvent blocking layer is formed. Of these, the former is preferred.
The recording medium may be either sheet paper or roll paper.

<Base paper>
There is no restriction | limiting in particular as said 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 balanced and sufficient level. However, softwood bleached kraft pulp (NBKP), hardwood sulfite pulp (LBSP) and the like can also 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 filler, dry paper strength enhancer, sizing agent, wet paper strength enhancement may be used as necessary. An agent, a fixing agent, a pH adjuster, other agents, 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 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, and polyamide polyamine epichlorohydrin.

  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. The thickness of the base paper is 30 to 500 μm, preferably 50 to 300 μm, and more preferably 70 to 200 μm.
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.
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 absorption of 2.0 g / m ² or less at a contact time of 120 seconds according to a water absorption test according to JIS P8140 on the surface of the first layer of the base paper.
In the present invention, when the first layer has the above characteristics, good adhesion to the substrate is obtained, and further, the first layer and the second layer are good when the second layer described later is applied. Adhesiveness can be obtained.
Although there will be no restriction | limiting in particular if the 1st layer is the said range, It is preferable to add a white pigment other than the said hydrophilic binder, Furthermore, it can comprise using a well-known component as needed.

  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 preferably 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.

-Hydrophilic binder-
The first layer contains at least one hydrophilic binder. A hydrophilic binder (hereinafter also simply referred to as a binder) is used for the purpose of improving not only the dispersion but also the adhesion between the base paper and the second layer and the coating strength.
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 viewpoints of adhesion between the base paper and the second layer and 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.

  There is no restriction | limiting in particular as the polymerization degree of the said polyvinyl alcohol, For example, the thing of the polymerization degree of 300-5000 can be used. Especially, it is preferable that it is 1500-5000 from a viewpoint of adhesiveness with a base paper and a 2nd layer, and coating-film intensity | strength.

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 hydrophilic binder in the present invention.

Among these, from the viewpoint of coating film strength, a thermoplastic resin is preferable, and latex is more preferable. 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, polyester urethane latex and acrylic silicone latex are preferable from the viewpoints of adhesion to the base paper and the second layer, and coating strength.

  The molecular weight of the latex is preferably 3,000 to 100,000 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 the molecular weight is 100,000 or less, production of dispersion stability, viscosity, etc. It is advantageous in terms of 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, 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 absorbability 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, it is necessary that the Cobb water absorption at a contact time of 120 seconds measured by a water absorption test in accordance with JIS P8140 on the surface of the first layer be 2.0 g / m ² or less. More preferably, it is 0 g / m ² or less. .
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. Further, the lower limit value of the Cobb water absorption is preferably 0.2 g / m ² .

  The Cobb water absorbency is measured by a water absorbency test in accordance with JIS P8140, and the first surface on the base paper provided with one side of the support, specifically, the first layer (binder-containing layer). This is a measure of the amount of water that is absorbed when water contacts the surface of the layer for a certain period of time. In the present invention, the contact time is 120 seconds.

<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.

-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.

  The white pigment is not particularly limited. For example, calcium carbonate, kaolin, calcined kaolin, amorphous silica, titanium dioxide, aluminum trihydroxide, zinc oxide, barium sulfate, satin white, talc, etc. are generally coated paper for printing. Can be selected from those used as white pigments.

Among these, kaolin is particularly preferable in terms of gloss. As kaolin, for example, Kaoblite 90 manufactured by Shiraishi Calcium Co., Ltd., Kao Gloss, Kao White, etc., Contour 1500 manufactured by Imeris Minerals Japan Co., Ltd., Astra Plate, XP03-8390, Milagros manufactured by Engelhard Inc. Etc.
Among kaolins, kaolin having an aspect ratio of 30 or more is more preferable. When the aspect ratio is 30 or more, the ink (particularly the pigment in the ink) can be easily retained in the absorption layer, and the ink fixing property can be further improved.

The particle size of the white pigment is preferably 0.1 to 5 μm. When the particle size is within the above range, the whiteness and gloss become better.
In the present invention, white pigments can be used alone or in combination of two or more.

-Hardener-
Hardeners that can be added to the first layer include aldehyde compounds, 2,3-dihydroxy-1,4-dioxane and derivatives thereof, and substituents with Hammett's substituent constant σ _p being positive. It can be selected from compounds having two or more adjacent vinyl groups in a single molecule.
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 groups (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>
The second layer (ink receiving layer) is provided on the first layer, and includes silica and a polyvinyl alcohol-based resin. The second layer (diethylene glycol (DEG)) has a contact time of 30 seconds on the surface of the second layer. The absorption capacity is 2 mL / m ² or more and 8 mL / m ² or less.
The second layer comprises silica and polyvinyl alcohol resin, as long as the absorption capacity of DEG is ^{2mL / m 2 ~8mL / m 2} , not particularly limited and may be appropriately selected depending on the intended purpose. For example, a porosity of 50% or more is preferable from the viewpoint of ink absorbability, and other components can be further contained as necessary.

-Silica-
The recording medium of the present invention is characterized in that the second layer contains silica as inorganic fine particles.
The recording medium of the present invention can form a layer with a good porous structure by containing silica in the second layer.
Examples of the silica include silica fine particles and colloidal silica.
As other inorganic fine particles, for example, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, pseudoboehmite as long as the effects of the present invention are not impaired. Zinc oxide, zinc hydroxide, alumina, aluminum silicate, calcium silicate, magnesium silicate, zirconium oxide, zirconium hydroxide, cerium oxide, lanthanum oxide, yttrium oxide, and the like can be used. Among these, alumina fine particles or pseudoboehmite is preferable from the viewpoint of forming a good porous structure.
The inorganic fine particles containing the silica 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, more preferably 200 nm or less. Further, silica fine particles having an average primary particle size of 20 nm or less and colloidal silica having an average primary particle size of 30 nm or less are preferred, and silica fine particles are particularly preferred.
Other inorganic fine particles are more preferably 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, and alumina fine particles and pseudoboehmite are particularly 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 wet method, a method is mainly used in which active silica is produced by acid decomposition of 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. The method of obtaining anhydrous silica by the (arc method) is the mainstream, and “gas phase method silica” means anhydrous silica fine particles obtained 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 for this is not clear, but in the case of hydrous silica, the density of silanol groups on the fine particle surface is high at 5 to 8 / nm ² , and the silica fine particles tend to aggregate (aggregate) easily. 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.

  Since the vapor phase silica has a particularly large specific surface area, the ink absorption and retention efficiency is high, and since the refractive index is low, if the dispersion is performed to an appropriate particle size, transparency is imparted to the ink receiving layer. And high color density and good color developability can be obtained. The transparency of the ink-receiving layer is not only for applications that require transparency, such as OHP, but also for high color density and good color development gloss even when applied to recording sheets such as photo glossy paper. Is important.

  The average primary particle size of the gas phase method silica and the other inorganic fine particles is preferably 30 nm or less, more preferably 3 to 30 nm, and more preferably 3 to 30 nm, from the viewpoint of the quick drying property (ink absorption rate). 20 nm is particularly preferable, and 3 to 10 nm is most preferable. Since the vapor phase silica is easily adhered to each other by hydrogen bonding with a silanol group, when the average primary particle diameter is 50 nm or less, a structure having a large porosity can be formed, and ink absorption characteristics can be effectively obtained. It is preferable because it can be improved.

  Gas phase method silica may be used in combination with the other inorganic 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 that can be used 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 cc / g, more preferably 0.5 to 1.5 cc / 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 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.

-Polyvinyl alcohol resin-
The second layer contains a polyvinyl alcohol resin. By containing a polyvinyl alcohol-based resin, ink absorbability can be improved and ink bleeding can be highly prevented.
.
Examples of the polyvinyl alcohol resin used for the second layer (ink receiving layer) include, for example, a polyvinyl alcohol resin (polyvinyl alcohol (PVA), an acetoacetyl-modified polyvinyl alcohol, a cation, which is a resin having a hydroxy group as a hydrophilic structural unit). Modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, polyvinyl acetal, etc.].

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 2000-18801, JP 2001-213045, JP 2001-328345, JP 8 -324105, JP-A-11-348417, etc. It is below.
In addition, hydrophilic binders other than polyvinyl alcohol resins can be used as long as the effects of the present invention are not impaired. Examples thereof include cellulose resins [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose ( HEC), carboxymethylcellulose (CMC), hydroxypropylcellulose (HPC), hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, etc.], chitins, chitosans, starch, resins having an ether bond [polyethylene oxide (PEO), polypropylene oxide (PPO) ), Polyethylene glycol (PEG), polyvinyl ether (PVE), etc.], resins having a carbamoyl group [polyacrylamide (PAAM), polyvinylpyrrolidone (P P), 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.
Further, compounds described in “0011” to “0014” of JP-A No. 11-165461 are also included.
The polyvinyl alcohol resin and these hydrophilic binders may be used alone or in combination of two or more.

  As content of the polyvinyl alcohol-type resin in this invention, 9-40 mass% is preferable with respect to the total solid content mass of a 2nd layer (ink receiving layer), and 12-33 mass% is more preferable.

The silica and the polyvinyl alcohol-based resin constituting the second layer in the present invention may be a single material or a mixed system of a plurality of materials.
From the viewpoint of maintaining transparency, the type of polyvinyl alcohol resin combined with the silica fine particles is important. When the vapor phase silica is used, the polyvinyl alcohol resin is preferably a polyvinyl alcohol resin having a saponification degree of 70 to 100%, and particularly preferably a polyvinyl alcohol resin having a saponification degree of 80 to 99.5%.

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.

  Moreover, although polyvinyl alcohol-type resin and the said other hydrophilic binder may be used together, when using this other hydrophilic binder and the said polyvinyl alcohol-type resin together, polyvinyl alcohol-type resin in all the hydrophilic binders The content of is preferably 50% by mass or more, and more preferably 70% by mass or more.

<< Content Ratio of Silica (Inorganic Fine Particles) and Polyvinyl Alcohol Resin (Hydrophilic Binder) >>
The mass content ratio [PB ratio (x / y)] between the inorganic fine particles (x) and the hydrophilic binder (y) greatly affects the film structure and film strength of the ink receiving layer. That is, as the mass content ratio [PB ratio] increases, the porosity, pore volume, and surface area (per unit mass) increase, but the density and strength tend to decrease.

  The ink receiving layer of the present invention prevents the decrease in film strength and cracking during drying caused by the PB ratio being too large as the mass content ratio [PB ratio (x / y)], and When the PB ratio is too small, the gap is easily blocked by the resin, and from the viewpoint of preventing the ink absorbency from being lowered due to the decrease in the porosity, 1.5 to 10 is preferable.

  Since stress may be applied to the recording sheet when passing through the conveyance system of the inkjet printer, the ink receiving layer needs to have sufficient film strength. Also, when cutting into a sheet, the second layer (ink receiving layer) has sufficient film strength to prevent cracking or peeling of the second layer (ink receiving layer). is required. Considering these cases, the mass ratio (x / y) is more preferably 5 or less, while it is more preferably 2 or more from the viewpoint of ensuring high-speed ink absorbency in an inkjet printer.

For example, a coating solution in which vapor-phase method silica fine particles having an average primary particle size of 20 nm or less and a polyvinyl alcohol-based resin are completely dispersed in an aqueous solution at a mass ratio (x / y) of 2 to 5 is applied to a non-water-absorbing support. When the coating layer is dried, a three-dimensional network structure in which 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.
Moreover, when the vapor phase method silica whose average particle diameter of a primary particle is 30 nm or less is used as an inorganic fine particle, it is preferable that the said polyvinyl alcohol-type resin is 50 mass% or less with respect to the said vapor phase method silica.

~ 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, the absorption capacity of diethylene glycol (DEG) on the surface of the second layer is 2 mL / m ² or more and 8 mL / m ² or less under the above measurement conditions.
When the absorption capacity is ² to 8 mL / m ² , image bleeding and color mixing between colors are prevented. To prevent image bleeding and color mixing between colors, as described later, the pH of the surface of the second layer is adjusted to acidic (particularly pH 4 or lower), or a treatment liquid containing an acidic compound described later is used together with ink. Is particularly effective.
Absorption capacity of the diethylene glycol (DEG), the curl prevention, more preferably 3 mL / ^{m 2} or more ~7mL / ^{m 2} or less in terms of those quality high quality is obtained by the image blurring and color mixing prevention, 4 mL / M ² or more and 7 mL / m ² or less is more preferable.

~ Porosity ~
The porosity is a value obtained by the following measurement method.
The thickness of the ink receiving layer is measured by observing a cross section of the second layer (ink receiving layer) with an electron microscope, and the porosity is calculated from the measured thickness of the ink receiving layer and the DEG absorption capacity. .

-Hardener-
It is also a preferable aspect that the second layer contains a hardener.
By containing the hardener, the polyvinyl alcohol resin can be hardened.
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 the hardening agent in the second layer, the water resistance of the recording medium can be improved without increasing the viscosity of the film-forming liquid for forming the second layer. Thereby, the coating stability of the film forming liquid for forming the second 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.

For the hardener according to the present invention, a boron compound may be mentioned as one suitable. Examples of boron compounds include borax, boric acid, borates (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , diboric acid. Salt (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 O8 · 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.

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

-Other ingredients-
There is no particular limitation and can be appropriately selected according to the purpose. For example, a crosslinking agent capable of crosslinking the hydrophilic binder other than the hardener, a cationic polymer, a water-soluble polyvalent metal compound (water-soluble polyvalent metal) Salt), mordant, surfactant and the like.

<Other layers>
There is no restriction | limiting in particular as another layer, According to the objective, it can select suitably.

(Recording medium manufacturing method)
The method for producing the recording medium of the present invention described above is not particularly limited, but includes a first layer forming step of forming a first layer by applying a film-forming solution containing a binder on a base paper, On the layer, it can manufacture by the method which has the 2nd layer formation process of providing the film forming liquid containing a silica and polyvinyl alcohol-type resin, and forming a 2nd layer. The recording medium of the present invention can have the second layer on one side or both sides.
The recording medium manufacturing method of the present invention may further include other processes appropriately selected as necessary.

  The coating amount (solid content) of the film-forming solution for forming the first layer and the film-forming solution for forming the second layer in the present invention can be appropriately selected according to the purpose.

-First layer forming step-
In the first layer forming step, a first layer can be formed by applying a film-forming liquid containing a hydrophilic binder (first film-forming liquid for forming a layer) on the base paper. Preferably, the heat treatment is performed in a temperature range equal to or higher than the minimum film forming temperature of the hydrophilic binder. In the heat treatment, pressure may be applied.

  The details of the components such as the hydrophilic binder contained in the base paper and the first layer are as described in the first layer, and the preferred embodiments are also the same.

  As latex particles as the hydrophilic binder, those having an average particle diameter of 10 to 200 nm are preferable. Here, the average particle diameter of the latex particles is a value measured by a dynamic light scattering method (device name: ELS-800, manufactured by Otsuka Electronics Co., Ltd.).

As the coating amount of the hydrophilic binder is preferably 1 to 30 g / m ^2.

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 coating, the coating film formed by coating is subjected to heat treatment in a temperature range equal to or higher than the minimum film forming temperature of the binder. 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 forming step-
In the second layer forming step, a film-forming liquid (second layer forming step) containing silica and polyvinyl alcohol-based resin forming the second layer on the first layer formed in the first layer forming step. Film-forming solution) can be applied to form the second layer.
The second layer forming film-forming solution can be prepared by a known method.
The components contained in the second layer-forming film forming liquid are as described in the second layer of the recording medium, and the preferred embodiments are also the same.
For example, water, silica, and polyvinyl alcohol resin are mixed and dispersed in water to prepare a pigment dispersion. Under the present circumstances, the additive (surfactant, ammonium carbonate, etc.) which can be contained in the said 2nd layer as needed can be added in the range which does not impair the effect of this invention.
In addition, the preparation of the film-forming solution may include other steps such as filter filtration as necessary, and can be appropriately selected depending on the purpose.

The application of the second 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. It is preferable to use a coating method using the second layer-forming film forming solution as a coating solution in that the film surface is smooth and high gloss is obtained.
As a coating method, a known coating method can be applied. Examples of the known coating method include a blade coating method (vent method, bevel method), a slide bead method, a curtain method, an extrusion method, an air knife method, and roll coating. Examples thereof include a method and a Ked bar coating method.

  In addition to the above steps, other steps may be provided without particular limitation. Other steps can be appropriately selected according to the purpose.

(Inkjet recording method)
The ink jet recording method of the present invention includes an ink drawing process in which ink is applied to the recording medium of the present invention described above and ink is drawn according to predetermined image data, and an ink solvent in the ink drawn ink is recorded on the recording medium. A drying removal step for drying and removing can be provided.
Among the ink jet recording methods described above, among the recording media of the present invention described above, the second layer (coating layer on the first layer) is preliminarily incorporated with an aggregating agent (treatment liquid) to lower the pH of the layer surface. It is preferable that the ink jet recording method (see FIG. 2; hereinafter referred to as “the ink jet recording method according to the first aspect”) in which ink is drawn on the recording medium.
In addition, an ink jet recording system for drawing ink after supplying a treatment liquid containing an acidic compound (pre-coating) to the recording medium of the present invention described above (see FIG. 3; hereinafter, “ink jet according to second embodiment” It is preferably referred to as a “recording method”.

In the ink jet recording method according to the first aspect of the present invention, ink is applied to the recording medium of the present invention in which the surface of the second layer is adjusted to pH 4 or less, and ink drawing is performed according to predetermined image data. What comprises the ink drawing process and the drying removal process of drying and removing the ink solvent in the ink-drawn recording medium is preferable.
Further, the ink jet recording method according to the second aspect of the present invention includes a treatment liquid supply step of supplying a treatment liquid containing an acidic compound to the recording medium of the present invention described above, and a recording medium of the present invention described above. It is preferable to provide an ink drawing process for applying ink and drawing ink according to predetermined image data, and a drying removal process for drying and removing the ink solvent in the ink-drawn recording medium. The treatment liquid supply step may be a step after the ink drawing step, but is preferably a step before the ink drawing step.
The ink jet recording method of the present invention including the ink jet recording method according to the first and second aspects may further include other steps selected as appropriate.

-Ink drawing process-
The ink drawing process of the first aspect uses the recording medium of the present invention in which the surface of the second layer is preferably adjusted to pH 4 or less, among the recording media of the present invention described above. By applying ink to the second layer, ink drawing is performed according to predetermined image data. When ink (for example, pigment ink) is applied to the second layer, the ink (for example, pigment in the ink) aggregates due to pH change at the time of landing, thereby preventing ink bleeding and color mixing between colors. The

  In the ink drawing step of the second aspect, the processing liquid is supplied in the following processing liquid supply step without adjusting or adjusting the layer surface pH of the second layer to 4 or less as in the first aspect. By applying ink to the recording medium, ink drawing is performed according to predetermined image data. In the second aspect, at least a part of the second layer is in an acidic state (preferably pH 4 or less) by the treatment liquid supplied to the second layer before applying the ink or simultaneously with applying the ink. The ink (for example, pigment ink) applied here undergoes a pH change at the time of landing, and the ink (for example, pigment in the ink) aggregates, thereby preventing ink bleeding and color mixing between colors.

The ink drawing process is not particularly limited except that ink is drawn according to predetermined image data, and can be appropriately selected according to the purpose. For example, ink can be drawn by ejecting ink by an inkjet method. There are no particular restrictions on the ink jet recording system, for example, a charge control system that ejects ink using electrostatic attraction, a drop-on-demand system (pressure pulse system) that uses the vibration pressure of a piezo element, and an electrical signal. Either an acoustic ink jet method that irradiates ink using an acoustic beam instead of an acoustic beam and ejects ink using radiation pressure, or a thermal ink jet method that uses ink to form bubbles by heating ink and generate pressure. May be. The inkjet 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.
Among these, the drop-on-demand method (pressure pulse method) using a piezoelectric element is suitable.

-Processing liquid supply process-
In the ink jet recording method according to the second aspect, the treatment liquid supply step is provided before the ink drawing step or as a step simultaneously with the ink drawing, and the treatment liquid containing an acidic compound in the second layer of the recording medium in advance. Supply. The treatment liquid supply step is not particularly limited except that a treatment liquid containing the following acidic compound is supplied, and can be appropriately selected according to the purpose. Further, this treatment liquid supply step may be provided in the ink jet recording method according to the first aspect, if necessary.

(Processing liquid)
The treatment liquid containing an acidic compound may be a liquid that contains an acidic compound and is adjusted to have an acidic liquid property, and is preferably an aqueous treatment liquid obtained by mixing an acidic compound with an aqueous medium. The pH of the treatment liquid in the present invention is preferably 4 or less from the viewpoint of preventing ink bleeding and color mixing between colors.

As the acidic compound, known acidic compounds can be used. For example, in addition to hydrochloric acid and nitric acid, a phosphoric acid group, a phosphonic group, a phosphine group, a sulfuric acid group, a sulfonic acid group, a sulfinic acid group, a carboxylic acid group, or these A compound having a group derived from the above salt can be used. Moreover, an acid polymer can also be used suitably.
For example, examples of the compound having a phosphate group include phosphoric acid, polyphosphoric acid, derivatives of these compounds, and salts thereof. Examples of the compound having a carboxylic acid group include furan, pyrrole, pyrroline, pyrrolidone, pyrone, pyrrole, thiophene, indole, pyridine, a compound having a quinoline structure and a carboxyl group as a functional group, such as pyrrolidone carboxylic acid, Examples include pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, or salts thereof.

Among the above acidic compounds, hydrochloric acid, sulfuric acid, nitric acid, methanesulfonic acid, phosphonic acid, phosphoric acid, polyphosphoric acid, metaphosphoric acid, oxalic acid, tartaric acid, malic acid, malonic acid, citric acid, fumaric acid, maleic acid, succinic acid, Salicylic acid, phthalic acid, lactic acid, acetic acid, trichloroacetic acid, chloroacetic acid, 2-pyrrolidone-5-carboxylic acid, picolinic acid, quinolinic acid, polyacrylic acid, polysulfonic acid, and polyphosphonic acid are preferred. Long-term storage and long-term stability of paper Oxalic acid, tartaric acid, malonic acid, and citric acid are more preferable from the standpoint of the characteristics, methanesulfonic acid and phosphoric acid are more preferable from the viewpoint of the aggregation speed of the pigment ink, and succinic acid and phthalic acid from the viewpoint of image fixability. Acid is more preferred.
In addition, an acidic compound may be used by 1 type and may be used together 2 or more types.

The treatment liquid may contain other additives as long as the effects of the present invention are not impaired.
Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, Well-known additives, such as a foaming agent, a viscosity modifier, a dispersing agent, a dispersion stabilizer, a rust preventive agent, a chelating agent, are mentioned.

  The treatment liquid may be supplied to the entire recording surface of the recording medium, or may be supplied according to at least a part of the recording surface, for example, predetermined image data. Moreover, there is no restriction | limiting in particular in the supply method of a process liquid, A coating method, an inkjet method, a dipping method etc. are mentioned, For example, you may discharge and supply a process liquid by the inkjet method.

  In the ink jet recording method according to the second aspect, drawing may be performed using an aqueous two-liquid aggregation ink described later.

-Dry removal process-
In the drying and removing step, the ink solvent in the recording medium on which ink has been drawn is removed by drying. There is no particular limitation other than drying and removing the ink solvent of the ink applied to the recording medium, and it can be appropriately selected according to the purpose.
In the recording medium of the present invention, the drying removal step is performed in a state where the ink solvent (particularly water) is present near the surface of the recording medium because the coat layer as the second layer is slowly permeable. The drying and removal can be performed by, for example, a method of applying a drying air at a predetermined temperature, a method of passing a heated and / or pressurized roll pair, or the like.

-Other processes-
The inkjet recording method of the present invention may be provided with other steps in addition to the above steps. There is no restriction | limiting in particular as another process, According to the objective, it can select suitably. For example, a heat fixing step may be mentioned.

  The ink jet recording method of the present invention may be provided with a heat fixing step of melting and fixing latex particles contained in, for example, ink used in the ink jet recording method after the drying and removing step. By this heat fixing step, the fixing property of the ink to the recording medium can be improved. The heat fixing step is not particularly limited except for the above-described melt fixing, and can be appropriately selected according to the purpose.

-Aspect example of first ink jet recording method-
In the first ink jet recording method, for example, ink drawing, drying (water drying, blow drying), and heat fixing can be performed under the following conditions.
<Ink drawing>
Head: 1,200 dpi / 20 inch width full line head Discharge droplet volume: 4-value recording of 0, 2.0, 3.5, 4.0 pL Driving frequency: 30 kHz (recording medium conveyance speed 635 mm / sec)
<Drying (water drying, blow drying)>
Wind speed: 8-15m / s
Temperature: 40-80 ° C
Air blowing area: 640 mm (drying time 1 second)
<Heat fixing>
Silicone rubber roller (hardness 50 °, nip width 5mm)
Roller temperature: 70-90 ° C
Pressure: 0.5-2.0 MPa

-Aspect example of second ink jet recording method-
In the second ink jet recording method, for example, pre-coating, ink drawing, drying (water drying, blow drying), and heat fixing can be performed under the following conditions.
<Processing liquid head for precoat module>
Head: 600 dpi / 20ichi width full line head Discharge droplet volume: 0, 4.0 pL binary recording Drive frequency: 15 kHz (recording medium conveyance speed 635 mm / sec)
Drawing pattern: In the ink drawing process, a pattern in which a treatment liquid is applied in advance to a position where at least one color ink is drawn is applied.
<Water drying for precoat module (air drying)>
Wind speed: 8-15m / s
Temperature: 40-80 ° C
Air blowing area: 450 mm (drying time 0.7 seconds)
<Ink drawing>
Head: 1200 dpi / 20 inch width full line head Discharged droplet amount: 4-value recording of 0, 2.0, 3.5, 4.0 pL Driving frequency: 30 kHz (recording medium conveyance speed 635 mm / sec)
<Drying (water drying, blow drying)>
Wind speed: 8-15m / s
Temperature: 40-80 ° C
Air blowing area: 640 mm (drying time 1 second)
<Heat fixing>
Silicone rubber roller (hardness 50 °, nip width 5mm)
Roller temperature: 70-90 ° C
Pressure: 0.5-2.0 MPa

-Ink-
The ink constituting the aqueous two-liquid aggregation ink can be used not only for forming a single color image but also for forming a full color image. In order to form a full color image, a magenta color ink, a cyan color ink, and a yellow color ink can be used, and a black color ink may be further used to adjust the color tone. Further, red, green, blue, and white inks other than yellow, magenta, and cyan color inks, and so-called special color inks (for example, colorless) in the printing field can be used. Examples of the ink include those containing latex particles, an organic pigment, a dispersant, and a water-soluble organic solvent, and further containing other additives as necessary.

<Latex particles>
Examples of the latex particles include particles such as a polymer of a compound composed of a nonionic monomer, an anionic monomer, and a cationic monomer dispersed in an aqueous medium.

  The said nonionic monomer means the monomer compound which does not have a dissociative functional group. In the broad sense, the monomer compound means a compound that is polymerized alone or with another compound. The monomer compound is preferably a monomer compound having an unsaturated double bond.

  The anionic monomer means a monomer compound containing an anionic group that can have a negative charge. The anionic group may be any as long as it has a negative charge, but is preferably a phosphate group, phosphonic acid group, phosphinic acid group, sulfuric acid group, sulfonic acid group, sulfinic acid group or carboxylic acid group. More preferably a phosphoric acid group or a carboxylic acid group, and even more preferably a carboxylic acid group.

  The cationic monomer means a monomer containing a cationic group that can have a positive charge. The cationic group may be any as long as it has a positive charge, but is preferably an organic cationic substituent, and more preferably a nitrogen or phosphorus cationic group. Further, it is more preferably a pyridinium cation or an ammonium cation.

<Organic pigment>
Examples of organic pigments for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185.

  Examples of organic pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 222, C.I. I. Pigment violet 19 and the like.

  Examples of organic pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment Green 7 and siloxane-crosslinked aluminum phthalocyanine described in U.S. Pat. No. 4,311,775.

  Examples of organic pigments for black include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

  Further, the average particle diameter of the organic pigment is preferably as small as possible from the viewpoint of transparency and color reproducibility, but is preferably large from the viewpoint of light resistance. As an average particle diameter which balances these, 10-200 nm is preferable, 10-150 nm is more preferable, 10-100 nm is further more preferable. In addition, the particle size distribution of the organic pigment is not particularly limited, and may be either a wide particle size distribution or a monodispersed particle size distribution. Two or more kinds of organic pigments having a monodispersed particle size distribution may be mixed and used.

  The addition amount of the organic pigment is preferably 1 to 25% by mass, more preferably 2 to 20% by mass, further preferably 5 to 20% by mass, and particularly 5 to 15% by mass with respect to the ink. preferable.

<Dispersant>
The organic pigment dispersant may be a polymer dispersant or a low molecular surfactant type dispersant. The polymer dispersant may be either a water-soluble dispersant or a water-insoluble dispersant.

  The low molecular surfactant type dispersant is added for the purpose of stably dispersing the organic pigment in an aqueous solvent while keeping the ink at a low viscosity. The low molecular dispersant is a low molecular dispersant having a molecular weight of 2,000 or less. The molecular weight of the low molecular dispersant is preferably 100 to 2,000, more preferably 200 to 2,000.

  The low molecular weight dispersant has a structure including a hydrophilic group and a hydrophobic group. In addition, the hydrophilic group and the hydrophobic group may be independently contained in one molecule or more, and may have a plurality of types of hydrophilic groups and hydrophobic groups. In addition, a linking group for linking a hydrophilic group and a hydrophobic group can be appropriately included.

The hydrophilic group is anionic, cationic, nonionic, or a betaine type that combines these.
The anionic group may be any as long as it has a negative charge, and is preferably a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfonic acid group, a sulfinic acid group, or a carboxylic acid group, A phosphoric acid group and a carboxylic acid group are more preferable, and a carboxylic acid group is further preferable.
The cationic group may be any as long as it has a positive charge, and is preferably an organic cationic substituent, more preferably a nitrogen or phosphorus cationic group. Further, it is more preferably a pyridinium cation or an ammonium cation.
Examples of the nonionic group include polyethylene oxide, polyglycerin, a part of sugar unit, and the like.

  The hydrophilic group is preferably an anionic group. The anionic group is preferably a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfonic acid group, a sulfinic acid group or a carboxylic acid group, more preferably a phosphoric acid group or a carboxylic acid group. More preferably, it is a carboxylic acid group.

  Moreover, when a low molecular dispersing agent has an anionic hydrophilic group, it is preferable that pKa is 3 or more from a viewpoint of making it contact with an acidic process liquid and promoting an aggregation reaction. The pKa of the low molecular dispersant in the present invention is determined experimentally from a titration curve by titrating a solution obtained by dissolving 1 mmol / L of the low molecular dispersant in a tetrahydrofuran-water (3: 2 = V / V) solution with an acid or alkaline aqueous solution. It is the value. If the pKa of the low molecular dispersant is 3 or more, theoretically, 50% or more of the anionic groups are in a non-dissociated state when in contact with a treatment solution having a pH of about 3. Accordingly, the water solubility of the low molecular weight dispersant is remarkably lowered, and an agglutination reaction occurs. That is, the aggregation reactivity is improved. Also from this viewpoint, the low molecular dispersant preferably has a carboxylic acid group as an anionic group.

The hydrophobic group has a hydrocarbon-based, fluorocarbon-based, or silicone-based structure, and is particularly preferably a hydrocarbon-based structure. Further, these hydrophobic groups may have a linear structure or a branched structure. Further, the hydrophobic group may have a single chain structure or a chain structure of more than this, and in the case of a structure of two or more chains, it may have a plurality of types of hydrophobic groups.
The hydrophobic group is preferably a hydrocarbon group having 2 to 24 carbon atoms, more preferably a hydrocarbon group having 4 to 24 carbon atoms, and further preferably a hydrocarbon group having 6 to 20 carbon atoms.

  Of the polymer dispersants, hydrophilic polymer compounds can be used as the water-soluble dispersant. For example, natural hydrophilic polymer compounds include plant polymers such as gum arabic, tragan gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin, quince seed starch, seaweeds such as alginic acid, carrageenan and agar. Examples include molecules, animal polymers such as gelatin, casein, albumin and collagen, and microorganism polymers such as xanthene gum and dextran.

  For hydrophilic polymer compounds modified from natural products, fiber polymers such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and carboxymethylcellulose, starch starches such as sodium starch glycolate and sodium phosphate phosphate Examples include molecules, seaweed polymers such as sodium alginate and propylene glycol alginate.

  Examples of the synthetic water-soluble polymer compound include vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl methyl ether, non-crosslinked polyacrylamide, polyacrylic acid or alkali metal salts thereof, water-soluble styrene acrylic resins, and the like. Acrylic resin, water-soluble styrene maleic acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic resin, polyvinyl pyrrolidone, polyvinyl alcohol, alkali metal salts of β-naphthalene sulfonic acid formalin condensate, quaternary ammonium and amino And a polymer compound having a salt of a cationic functional group such as a group in the side chain, a natural polymer compound such as shellac, and the like.

  Among these, those having a carboxyl group introduced from a homopolymer of acrylic acid, methacrylic acid or styrene acrylic acid or a copolymer of a monomer having another hydrophilic group are particularly preferred as the polymer dispersant.

  As the water-insoluble dispersant among the polymer dispersants, a polymer having both a hydrophobic part and a hydrophilic part can be used. For example, styrene- (meth) acrylic acid copolymer, styrene- (meth) acrylic Acid- (meth) acrylic acid ester copolymer, (meth) acrylic acid ester- (meth) acrylic acid copolymer, polyethylene glycol (meth) acrylate- (meth) acrylic acid copolymer, vinyl acetate-maleic acid copolymer Examples thereof include a polymer and a styrene-maleic acid copolymer.

  The weight average molecular weight of the dispersant is preferably 3,000 to 100,000, more preferably 5,000 to 50,000, still more preferably 5,000 to 40,000, and particularly preferably 10,000 to 40,000. It is.

  The mixing mass ratio of the organic pigment and the dispersant is preferably in the range of 1: 0.06 to 1: 3, more preferably in the range of 1: 0.125 to 1: 2, and still more preferably 1: 0.125. ~ 1: 1.5.

<Water-soluble organic solvent>
The water-soluble organic solvent is used for the purpose of preventing drying and promoting wetting.
A water-soluble organic solvent as a drying inhibitor is suitably used at an ink jet port of a nozzle in an ink jet recording system, and prevents clogging due to drying of the ink for ink jet.

  As the drying inhibitor, a water-soluble organic solvent having a vapor pressure lower than that of water is preferable. Specific examples of such an anti-drying agent include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6- Hexanetriol, acetylene glycol derivatives, polyhydric alcohols such as glycerin and trimethylolpropane, ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether, etc. Lower alkyl ethers of polyhydric alcohols, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, heterocyclic rings such as N-ethylmorpholine, sulfolane, Methyl sulfoxide, sulfur-containing compounds such as 3-sulfolene, diacetone alcohol, polyfunctional compounds such as diethanolamine, and urea derivatives. Of these, the drying inhibitor is preferably a polyhydric alcohol such as glycerin or diethylene glycol. Moreover, said drying inhibitor may be used independently or 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.

  In addition, a water-soluble organic solvent as a penetration accelerator is preferably used for the purpose of allowing the ink to penetrate better into the recording medium (printing paper). Specific examples of such penetration enhancers include alcohols such as ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether, 1,2-hexanediol, sodium lauryl sulfate, sodium oleate, and nonionic properties. A surfactant or the like can be suitably used. These penetration enhancers exhibit a sufficient effect when contained in the ink composition in an amount of 5 to 30% by mass. Further, it is preferable that the penetration enhancer is used within a range of an addition amount that does not cause printing bleeding and paper loss (print through).

  In addition to the above, the water-soluble organic solvent is also used for adjusting the viscosity. Specific examples of water-soluble organic solvents that can be used to adjust the viscosity include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, Cyclohexanol, benzyl alcohol), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, Thiodiglycol), glycol derivatives (eg, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether) Ter, 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 (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, Tylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine) and other polar solvents (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone). In addition, a water-soluble organic solvent may be used independently and may use 2 or more types together.

<Other additives>
Examples of the other additives include a drying inhibitor (wetting agent), an antifading agent, an emulsion stabilizer, a penetration accelerator, an ultraviolet absorber, an antiseptic, an antifungal agent, a pH adjuster, a surface tension adjuster, Well-known additives, such as an antifoamer, a viscosity modifier, a dispersing agent, a dispersion stabilizer, an antirust agent, a chelating agent, are mentioned. In the case of water-soluble ink, these various additives are added directly to the ink. When an oil-soluble dye is used in the form of a dispersion, it is generally added to the dispersion after the preparation of the dye dispersion, but it may be added to the oil phase or the aqueous phase at the time of preparation.

  The ultraviolet absorber is used for the purpose of improving image storability. Examples of ultraviolet absorbers 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 antifading agent, various organic and metal complex antifading agents can be used. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc. Complex, zinc complex and the like. 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 Japanese Patent No. 15162 and the compounds included in the general formulas and compound examples of typical compounds described on 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 an amount of 0.02 to 1.00% by weight in the ink.

  As the pH adjuster, a neutralizer (organic base, inorganic alkali) can be used. For the purpose of improving the storage stability of the inkjet ink, the pH adjuster is preferably added so that the inkjet 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 surfactants, cationic surfactants, anionic surfactants, betaine surfactants, and the like.

  In addition, the addition amount of the surface tension adjusting agent is preferably an addition amount that adjusts the surface tension of the ink to 20 to 60 mN / m, and preferably an addition amount that is adjusted to 20 to 45 mN / m, in order to eject droplets well by inkjet. More preferable is an addition amount adjusted to 25 to 40 mN / m.

  Specific examples of surfactants include fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate esters, naphthalene sulfonate formalin condensation in hydrocarbons Products, anionic surfactants such as polyoxyethylene alkyl sulfates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxy Nonionic surfactants such as ethylene alkylamine, glycerin fatty acid ester and oxyethyleneoxypropylene block copolymer are preferred. Further, SURFYNOLS (Air Products & Chemicals), which is an acetylene-based polyoxyethylene oxide surfactant, is also preferably used. An amine oxide type amphoteric surfactant such as N, N-dimethyl-N-alkylamine oxide is also preferred.

  Further, pages (37) to (38) of JP-A-59-157636, Research Disclosure No. The surfactants described in 308119 (1989) can also be used.

  Also, fluorine (fluorinated alkyl) surfactants, silicone surfactants, and the like described in JP-A Nos. 2003-322926, 2004-325707, and 2004-309806 are disclosed. By using, the abrasion resistance can be improved.

  These surface tension modifiers can also be used as antifoaming agents, and fluorine compounds, silicone compounds, chelating agents represented by EDTA, and the like can also be used.

-Aqueous two-liquid aggregation ink-
In the ink jet recording method according to the second aspect, an aqueous two-liquid aggregation ink comprising a treatment liquid and an ink that reacts and aggregates with the treatment liquid may be used.
As the treatment liquid for the aqueous two-liquid aggregation ink, the same treatment liquid as described above can be used. Details of the treatment liquid are as described above.

  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 coating liquid for first layer (undercoat layer)>
50 parts of water, 100 parts of kaolin (trade name: Kaoblite 90, manufactured by Shiraishi Calcium Co., Ltd.) and 1.3 parts of 40% sodium polyacrylate (trade name: Aron T-50, manufactured by Toagosei Co., Ltd.) And 22.5% polyester urethane latex aqueous dispersion (glass transition temperature 49 ° C., minimum film forming temperature 29 ° C .; trade name: Hydran AP-40F, Dainippon Ink & Chemicals, Inc.) 2200 parts of 10% Aerosol MA80 (American Cyanamid Co., Ltd.) aqueous solution and 100 parts of 2% Lapisol A-90 (Nissho Co., Ltd.) aqueous solution were added, and 1 After adding 800 parts of a 1% serogen EP aqueous solution (Daiichi Kogyo Seiyaku Co., Ltd.) and thoroughly stirring and mixing, the liquid temperature of the obtained mixed liquid is kept at 15 to 25 ° C., and 18% undercoat layer coating liquid Got.

<Formation of undercoat layer>
Using a curtain coater, apply the resulting coating solution for the undercoat layer on both sides of high-quality paper (trade name: Shiraoi, made by Nippon Paper Industries) with a basis weight of 81.4 g / m ^2. The resultant was applied at 8.0 g / m ² and dried at a drying air temperature of 120 ° C. for 20 seconds to form an undercoat layer.

<Preparation of second layer forming coating solution a, second layer formation>
While preparing the coating liquid (first liquid) by in-line mixing the following mordant mixed solution with the ink receiving layer forming liquid A (coating liquid preparing step), applying a slide bead coater on one side of the fine paper on which the undercoat layer is formed It apply | coated using the apparatus (application | coating process).
Here, the coating was performed so that the coating amount of the ink receiving layer forming liquid A was 35 mL / m ² and the coating amount of the mordant mixed solution was 2.2 mL / m ² . The coating layer was dried at 80 ° C. (wind speed 3 to 8 m / sec) with a hot air dryer 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, 13 g / m ² was immersed in a second liquid having the following composition for 3 seconds (step of applying the second liquid), and further dried at 72 ° C. for 10 minutes to form an ink jet recording medium. Obtained (drying step).

<Composition of ink receiving layer forming liquid A>
(1) Gas phase method silica fine particles (AEROSIL300SF75, manufactured by Nippon Aerosil Co., Ltd., average particle size of primary particles: 7 nm) (inorganic fine particles) 8.9 parts (2) ion-exchanged water 51.4 parts ( 3) “Charol DC-902P (Daiichi Kogyo Seiyaku Co., Ltd.)” (51.5% aqueous solution) (dispersant, cationic polymer) 0.78 parts (4) “ZA-30 (1st rare) Elemental Chemical Industry Co., Ltd.) ”(water-soluble polyvalent metal salt)
... 0.48 parts (5) Boric acid (crosslinking agent) ... 0.33 parts (6) Polyvinyl alcohol (water-soluble binder) solution ... 28.6 parts (7) "Superflex 600 ( Daiichi Kogyo Seiyaku Co., Ltd.) ”(cationic polyurethane) ・ ・ ・ 1.11 parts (8) Ethanol ・ ・ ・ 4.1 parts

-(6) Composition of polyvinyl alcohol solution-
The composition of the polyvinyl alcohol (water-soluble binder) solution (6) was as shown below.
(A) "PVA235 (manufactured by Kuraray Co., Ltd.)", saponification degree 88%, polymerization degree 3,500 ... 2.0 parts (b) ion-exchanged water ... 26.6 parts

<Composition of mordant mixed solution>
(1) Basic polyaluminum hydroxide compound (water-soluble polyvalent metal compound) (Alphain 83, manufactured by Daimei Chemical Industry Co., Ltd.) ... 4.0 parts (2) Ion-exchanged water ... 4.6 parts (3) Polyoxyethylene lauryl ether (“Emulgen 109P” (10% aqueous solution) manufactured by Kao Corporation, HLB value 13.6) (surfactant) 0.7 parts (4) Himax SC-505 (Himo Corporation) (cationic polymer)
... 0.7 parts

<Composition of the second liquid>
(1) Boric acid ... 0.65 part (2) Ammonium carbonate (1st grade: manufactured by Kanto Chemical Co., Ltd.) ... 4.0 parts (3) Ion-exchanged water ... 89.4 parts (4 ) Polyoxyethylene lauryl ether ("Emulgen 109P" manufactured by Kao Corporation (10% aqueous solution), HLB value 13.6) (surfactant) 6.0 parts

(Evaluation)
The following evaluation was performed about the inkjet recording medium obtained above. The evaluation results are shown in Table 1 below.

-1. Cobb water absorption test
According to the water absorption test in accordance with JIS P8140, the Cobb water absorption on the surface of the first layer of the fine paper on which the first layer was formed (the amount of water permeation when contacted with water at 20 ° C. for 2 minutes g / M ² ) was measured.

-2. Absorption capacity test of diethylene glycol (DEG) of the second layer
1 mL of diethylene glycol was dropped on the ink receiving layer of the test piece obtained by cutting each 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 / L) was determined from the weight difference before and after the dropping. m ² ) was determined.

-3. Curl test
A 50 mm × 5 mm size test piece is prepared by cutting the ink jet recording medium, and is applied to the test piece so that the water is 10 g / m ² in the MD and CD directions, and the 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.

<Preparation of ink>
(1) Preparation of Cyan Pigment Ink C-Preparation of Pigment Dispersion-
A dispersion was prepared by stirring and mixing 10 g of cyanine blue A-22 (PB15: 3) manufactured by Dainichi Seika Co., Ltd., 10.0 g of the following low molecular weight dispersant, 4.0 g of glycerin, and 26 g of ion-exchanged water. Next, using an ultrasonic irradiation device (Vibra-cell VC-750, manufactured by SONICS, tapered microchip: φ5 mm, Amplitude: 30%), the dispersion is intermittently irradiated with ultrasonic waves (irradiation 0.5 seconds, pause) (1.0 second) for 2 hours to further disperse the pigment to obtain a 20% by mass pigment dispersion.

Apart from the pigment dispersion, the following compounds were weighed, stirred and mixed to prepare a mixture I.
・ Glycerin ... 5.0g
・ Diethylene glycol: 10.0 g
・ Orphine E1010 (manufactured by Nissin Chemical Industry) ・ ・ ・ 1.0g
・ Ion-exchanged water ... 11.0 g

This mixed liquid I was slowly dropped into 23.0 g of a stirred 44% SBR dispersion (polymer fine particles: 3% acrylic acid, Tg (glass transition temperature) 30 ° C.) and stirred and mixed to prepare mixed liquid II. did.
Next, this mixed liquid II was stirred and mixed while slowly dropping into the above-mentioned 20% by mass pigment dispersion to prepare 100 g of cyan pigment ink C (cyan ink). When the pH of the pigment ink C prepared as described above was measured using a pH meter WM-50EG manufactured by Toa DKK, the pH value was 8.5.

(2) Preparation of Magenta Pigment Ink M In the preparation of Pigment Ink C, Chromatic Jet Magenta DMQ (PR-122) manufactured by Ciba Specialty Chemicals was used in place of the pigment used in the preparation of Pigment Ink C. Prepared a magenta pigment ink M (magenta ink) in the same manner as the pigment ink C. When the pH of the pigment ink M prepared as described above was measured with a pH meter WM-50EG manufactured by Toa DKK, the pH value was 8.5.

(3) Preparation of Yellow Pigment Ink Y In the preparation of Pigment Ink C, instead of using the pigment used for the preparation of Pigment Ink C, Ibarga Yellow GS (PY74) manufactured by Ciba Specialty Chemicals was used. Yellow pigment ink Y (yellow ink) was prepared in the same manner as the preparation of ink C. When the pH of the pigment ink Y prepared as described above was measured with a pH meter WM-50EG manufactured by Toa DKK, the pH value was 8.5.

(4) Preparation of black pigment ink K In the preparation of pigment ink C, a dispersion CAB-O-JETTM_200 (carbon black) manufactured by CABOT was used instead of the pigment dispersion used for the preparation of pigment ink C. Except for this, a black pigment ink K (black ink) was prepared in the same manner as in the preparation of pigment ink C. When the pH of the pigment ink K prepared as described above was measured with a pH meter WM-50EG manufactured by Toa DKK, the pH value was 8.5.

<Preparation of treatment liquid>
The treatment liquid was prepared by mixing the following components.
・ Phosphoric acid ... 10g
・ Glycerin 20g
・ Diethylene glycol ... 10g
・ Orphine E1010 (manufactured by Nissin Chemical Industry) ・ ・ ・ 1g
・ Ion-exchanged water ... 59g
When the pH of the treatment solution thus prepared was measured with a pH meter WM-50EG manufactured by Toa DKK Co., Ltd., the pH value was 1.0.

<Image formation and droplet ejection method and conditions>
Using the cyan pigment ink C, the magenta pigment ink M, the yellow pigment ink Y, the black pigment ink K, and the treatment liquid, a four-color single-pass image is formed using the apparatus shown in FIG. 3 under the following conditions. did. At this time, a gray scale and a character image were formed.

~ Head for treatment liquid for precoat module ~
Head: 600 dpi / 20 inch width piezo full line head Discharge droplet volume: binary recording of 0, 4.0 pL Drive frequency: 15 kHz (recording medium conveyance speed 635 mm / sec)
Drawing pattern: In the ink drawing process, a pattern that applies at least one color ink to the processing liquid in advance at the drawing position is applied.

~ Water drying for precoat module (blow drying) ~
Wind speed: 15m / s
Temperature: Heated from the back surface of the recording medium recording surface with a contact type flat heater so that the surface temperature of the recording medium becomes 60 ° C. Air blowing area: 450 mm (drying time 0.7 seconds)

~ Ink drawing ~
Head: 1,200 dpi / 20 inch width piezo full line head is arranged for 4 colors. Ejected droplet volume: 4-value recording of 0, 2.0, 3.5, 4.0 pL Drive frequency: 30 kHz (Recording medium transport speed 635 mm / sec)

~ Drying (water drying, blow drying) ~
Wind speed: 15m / s
Temperature: 60 ° C
Air blowing area: 640 mm (drying time 1 second)

-Heat fixing-
Silicone rubber roller (hardness 50 °, nip width 5mm)
Roller temperature: 90 ° C
Pressure: 0.8 MPa

Subsequently, the following droplet ejection test and tape peeling test were performed.
-4. Evaluation of droplet ejection
The gray scale and character image formed above were visually observed and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1 below.
<Evaluation criteria>
A: Image bleeding and color mixing were not observed, and “hawk” characters of 4 pt or less could be resolved.
B: No image blur or color mixing was observed, and resolution was possible up to 5 pt “hawk” characters.
C: Image blurring and color mixing were often observed, and the practicality was low.
D: Image bleeding, color mixing between colors was severe, and practicality was extremely low.

-5. Tape peeling test
After 3 hours of fixing and drying, a 12 mm wide mending tape (manufactured by 3M) was attached to the printed portion, and then the peeled state of the printed portion when the tape was peeled off was evaluated according to the following criteria. The evaluation results are shown in Table 1 below.
A: No peeling of the printed part was observed.
B: Although peeling of the printed part was observed, there was almost no influence on the image on the paper.
C: Peeling of the printed part was observed, and a part of the image on the paper remained.
D: The print part was severely peeled off, and almost no image on the paper remained.

[Example 2]
In Example 1, the composition of the ink receiving layer forming liquid A was changed to the following composition B, and the coating amount of the ink receiving layer forming liquid B was changed to 50 mL / m ^2. 2 inkjet recording media were produced.

<Composition of ink receiving layer forming liquid B>
(1) Gas phase method silica fine particles (AEROSIL300SF75 manufactured by Nippon Aerosil Co., Ltd.,
Average particle size of primary particles 7 nm) (inorganic fine particles) 8.9 parts (2) ion-exchanged water 51.4 parts (3) “Sharol DC-902P (Daiichi Kogyo Seiyaku Co., Ltd.)” "(51.5% aqueous solution) (dispersant, cationic polymer) 0.78 part (4)" ZA-30 (Daiichi Rare Element Chemical Co., Ltd.) "(water-soluble polyvalent metal salt) ... 0.48 parts (5) Boric acid (crosslinking agent) ... 0.33 parts (6) Polyvinyl alcohol (water-soluble binder) solution ... 48 parts (7) "Superflex 600 (first 1.11 parts (8) Ethanol ... 20 parts

-Composition of polyvinyl alcohol solution-
The composition of the polyvinyl alcohol (water-soluble binder) solution (6) was as shown below.
(A) "PVA235" manufactured by Kuraray Co., Ltd., saponification degree 88%, polymerization degree 3500 ... 2.0 parts (b) ion-exchanged water ... 26.6 parts

[Comparative Example 1]
In Example 1, instead of the support provided with the first layer, an example for forming the second layer after corona treatment was performed on the front surface of the non-absorbent support prepared as follows. An ink jet recording medium was obtained in the same manner as in Example 1 except that the coating liquid described in 1 was applied, and evaluated in the same manner.

<Production of non-water-absorbing support>
50 parts of LBKP made of acacia and 50 parts of LBKP made of aspen were beaten to 300 mL of Canadian freeness with a disc refiner to prepare a pulp slurry.

  Next, to the pulp slurry obtained above, the cationic starch (CATO 304L manufactured by NSC Japan) 1.3%, the anionic polyacrylamide (DA4104 manufactured by Seiko PMC Co., Ltd.) 0.15%, alkyl per pulp. After adding 0.29% ketene dimer (size pine K, manufactured by Arakawa Chemical), 0.29% epoxidized behenamide, 0.32% polyamide polyamine epichlorohydrin (Arakawa Chemical Co., Ltd .: Arafix 100), 0.12% foam was added.

In the process of making the pulp slurry prepared as described above with a long paper machine and pressing the felt surface of the web against the drum dryer cylinder through the dryer canvas for drying, the tensile force of the dryer canvas is 1.6 kg / After drying at a setting of cm, 1 g / m ² of polyvinyl alcohol (manufactured by Kuraray Co., Ltd .: KL-118) was applied to both sides of the base paper with a size press and dried to perform calendar treatment. The base paper was made with a basis weight of 166 g / m ² to obtain a base paper (base paper) having a thickness of 160 μm.

After the corona discharge treatment was performed on the wire surface (back surface) side of the obtained base paper, high-density polyethylene was coated to a thickness of 30 μm using a melt extruder to form a thermoplastic resin layer (hereinafter referred to as “the thermoplastic resin layer”). The surface of the thermoplastic resin layer is referred to as “back surface”). The thermoplastic resin layer on the back side is further subjected to corona discharge treatment, and then, as an antistatic agent, aluminum oxide (“Alumina Sol 100” manufactured by Nissan Chemical Industries, Ltd.) and silicon dioxide (manufactured by Nissan Chemical Industries, Ltd.) Of “Snowtex O”) was dispersed in water at a mass ratio of 1: 2 so that the dry mass was 0.2 g / m ² .

Further, after the corona discharge treatment is performed on the felt surface (surface) side where the thermoplastic resin layer is not provided, 10% of anatase-type titanium dioxide and 0.3% of ultramarine manufactured by Tokyo Ink Co., Ltd. are contained. Low density of MFR (melt flow rate) 3.8, adjusted to a content of 0.08% with a whitening agent “Whitefloor PSN conc” manufactured by Nippon Chemical Industry Co., Ltd. Polyethylene is extruded using a melt extruder so as to have a thickness of 25 μm, and a high gloss thermoplastic resin layer is formed on the surface side of the base paper (hereinafter, this high gloss surface is referred to as “front side”). A non-water-absorbing support was produced. This non-water-absorbing support was aligned to a width of 1.5 m and a winding length of 3,000 m to form a long roll body.
The non-water-absorbent support had a Cobb water absorption of 0 g / m ² with a contact time of 120 seconds according to a water absorption test specified in JIS P8140. The Cobb water absorbency is obtained by a water absorbency test specified in JIS P8140, and measures the amount of water absorbed when water contacts from one side of a non-water-absorbent support for a certain time. . The contact time was 120 seconds.

[Comparative Example 2]
An ink jet recording medium was prepared in the same manner as in Comparative Example 1 except that the ink receiving layer forming liquid B was used in Comparative Example 1.

[Comparative Examples 3 to 4]
In Example 1, changing the coating amount 35 ml / m ² and 50 ml / m ² of the ink-receiving layer-forming solution A and B in the second layer forming coating liquid so that the corresponding coating amount shown in Table 1 An ink jet recording medium was produced in the same manner as in Example 1 except that.

[Comparative Example 5]
In Example 2, the coating amount of the coating liquid for the first layer (undercoat layer) 8.0 g / m ² was changed to the coating amount shown in Table 1 and was the same as in Example 2. Thus, an ink jet recording medium was produced.

  As is clear from Table 1, any of the evaluations in the comparative example not satisfying the configuration of the present invention was significantly inferior. On the other hand, in the Example of this invention, it became the result excellent in all of evaluation.

It is a schematic block diagram which shows the structural example of the recording medium of this invention. It is explanatory drawing for demonstrating an example of the inkjet recording method which concerns on the 1st aspect using the recording medium of this invention. It is explanatory drawing for demonstrating an example of the inkjet recording method which concerns on the 2nd aspect using the recording medium of this invention. It is a schematic block diagram which shows the structure of the conventional recording medium.

Explanation of symbols

11 ... fine paper 12 ... solvent blocking layer (first layer)
13 ... Coat layer (second layer)
21 ... Base paper 22 ... Solvent absorption layer 100 ... Recording medium

Claims (8)

A base paper, a first layer containing a hydrophilic binder, and a second layer containing silica and polyvinyl alcohol are sequentially laminated, and a water absorption test based on JIS P8140 on the surface of the first layer. The Cobb water absorption for a contact time of 120 seconds is 2.0 g / m ² or less, and the absorption capacity of diethylene glycol for a contact time of 30 seconds on the surface of the second layer is 2 mL / m ² or more and 8 mL / m ² or less. A recording medium. The recording medium according to claim 1, wherein the silica of the second layer is vapor phase silica having an average primary particle diameter of 30 nm or less. The recording medium according to claim 1, wherein the second layer further contains a hardener. The recording medium according to any one of claims 1 to 3, wherein the hydrophilic binder of the first layer is thermoplastic resin particles. The recording medium according to any one of claims 1 to 4, wherein the first layer further contains a white pigment.   An ink drawing step of applying ink to the recording medium according to any one of claims 1 to 5 by an ink jet method and drawing ink according to predetermined image data, and the recording medium on which ink has been drawn And a drying removal step of drying and removing the ink solvent.   The process liquid supply process which supplies the process liquid containing an acidic compound to the recording medium of any one of Claims 1-5, and the recording of any one of Claims 1-5. The ink drawing step of applying ink to a medium and drawing the ink according to predetermined image data, and the drying and removing step of drying and removing the ink solvent in the recording medium on which the ink has been drawn. Inkjet recording method. 8. The ink jet recording method according to claim 6, wherein the acidic compound is a divalent or higher acid.