JP2007210315A - Ink jet recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording paper which has successful ink absorption, is feathering-free and can develop a high-density image. <P>SOLUTION: This inkjet recording paper has at least three ink absorptive layers such as a layer A, a layer B and a layer C laminated in that order, as viewed from the face side of the side where ink is printed, on a non-water absorbent support. In addition, each ink absorptive layer contains an inorganic fine particle and a binder. The recording paper is obtained by adding to the layer A an inorganic fine particle dispersion scattered in the presence of a water-soluble polyvalent metallic compound and drying the dispersion. Further, the recording paper is characterized in that the liquid transition level in 0.04" contact time measured by the Bristow process using a liquid mixed of diethylene glycol/triethylene glycol monobutyl ether/water in the mass ratio of 15/15/70, in compliance with J. TAPPI paper pulp test method No.51-87, is in the order of (the layer B)<(the layer C)<(the layer A). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording paper (hereinafter, also referred to as a recording paper) that is less likely to bleed, has a high image density, and has good ink absorbability.

  In recent years, recording paper has been improved in order to achieve photographic image quality equivalent with ink jet recording, and recently, with the improvement in image quality, characteristics required for recording paper such as high ink absorption and high drying properties have further increased. Is coming.

  In ink jet recording that achieves the same level of photographic image quality, a water-soluble dye is preferably used as a coloring material because of its beautiful image quality. However, because this water-soluble dye is highly hydrophilic, water droplets usually adhere to the recording surface. Alternatively, there is a problem that the dye tends to bleed when stored for a long time under high humidity after recording. That is, there is a problem with water resistance.

  In addition, an inkjet recording paper having a porous ink absorbing layer can obtain a uniform image with high ink absorbability and non-uniformity during inkjet recording, but fine particles forming a porous coating scatter light on the surface. There is a problem that the image density tends to decrease.

  As a means for solving the water resistance, a method is generally employed in which a dye fixing substance such as a cationic substance is added to a porous layer and bonded to an anionic dye to be firmly immobilized. Examples of the cationic substance include a cationic polymer such as a quaternary ammonium salt polymer, a method using a cationic surfactant, and a metal ion. For example, a method in which a cationic polymer and a water-soluble polyvalent metal salt are used in combination is described (for example, see Patent Document 1).

  However, these methods have insufficient water resistance, and the bleeding over time cannot be completely improved, and there has been no disclosure regarding the improvement of the color developability of the porous ink jet recording paper.

  Although silica particles whose surface is treated with aluminum are used for the outermost layer (see, for example, Patent Document 2), the effect is limited to the pigment ink, and the image density of the dye ink is still insufficient. Furthermore, although a dispersion containing inorganic fine particles having a high zeta potential and a water-soluble polyvalent metal compound is used (see, for example, Patent Document 3), there is no disclosure regarding color development improvement.

Moreover, although it is described that a zirconium compound or an aluminum compound is distributed more in a part away from the support (see, for example, Patent Document 4), this alone is insufficient in terms of bleeding and color developability.
JP 60-67190 A JP 2000-351267 A JP 2004-285308 A JP 2002-160442 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording paper that is less likely to bleed and has a high image density and good ink absorbability.

The above object of the present invention can be achieved by the following configuration.
1. An ink jet recording sheet provided with at least three ink absorbing layers laminated in the order of A layer, B layer, and C layer, as viewed from the surface side on which ink is printed, on a non-water absorbent support, Each ink absorbing layer contains inorganic fine particles and a binder, and the A layer is a recording paper formed by containing an inorganic fine particle dispersion dispersed in the presence of a water-soluble polyvalent metal compound and drying it. J. et al. TAPPI paper pulp test method no. In accordance with 51-87, the liquid transition amount at a contact time of 0.04 seconds measured by the Bristow method with a liquid mixed at a mass ratio of diethylene glycol / triethylene glycol monobutyl ether / water = 15/15/70 is B layer < An ink jet recording paper, wherein C layer is less than A layer.
2. 2. The ink jet recording paper according to 1, wherein the A layer is the outermost layer, and the dry film thickness thereof is 5% or more and 20% or less of the total dry film thickness.
3. 3. The ink jet recording paper according to 1 or 2, wherein the dry film thickness of the B layer is 10% or more and 20% or less of the total dry film thickness.
4). 3. The ink jet recording paper according to 1 or 2, wherein the water-soluble polyvalent metal compound is 10% by mass or more and 50% by mass or less with respect to the oxide equivalent value of the inorganic fine particles as an oxide equivalent value.
5). The inkjet recording paper according to any one of claims 1 to 4, wherein the turbidity of the coating liquid for the A layer is 50 ppm or less.
6). The inkjet recording paper according to 4, wherein the polyvalent metal of the water-soluble polyvalent metal compound is aluminum or zirconium.
7). The inkjet recording paper according to any one of 1 to 6, wherein the inorganic fine particles are vapor-phase method silica fine particles.

  According to the present invention, it is possible to provide an ink jet recording paper that is less likely to bleed and has a high image density and good ink absorbability.

  The present invention will be described in more detail. As a result of investigation by the present inventors, when the amount of liquid transition at a contact time of 0.04 seconds in the Bristow method is increased in the order of B layer (middle layer) <C layer <A layer (outermost surface layer), the ink is printed when printed. It was found that the ink stays on the outermost layer and the dye is adsorbed on the cationized inorganic fine particles on the outermost layer to improve the image density. In addition, since the A layer absorbs a large amount of ink at first, it is better that the liquid transfer amount is larger, and further, the C layer is less absorbed than the B layer by using a layer having a larger liquid transfer amount. It was found that the dye could be adsorbed and the ink solvent could be absorbed. On the other hand, the dye is adsorbed on the outermost layer, and the ink solvent can be separated from the C layer, the dye and the solvent.

  For example, if the amount of liquid transfer in the B layer (middle layer) is large, the dye is absorbed by the B layer and C layer before the dye is adsorbed to the A layer (outermost layer), resulting in poor color development. If the amount is small, overflow may occur, and if the amount of liquid transfer in the C layer is small, the dye and the ink solvent cannot be separated, and bleeding may be deteriorated.

(Layer structure)
In the ink jet recording paper according to the present invention, it is preferable that the coating liquid is applied and laminated on the support in the order of at least the A layer, the B layer, and the C layer from the outermost surface as the ink absorbing layer. . If four or more layers are provided, it is possible to provide one or more layers under the C layer.

  Each ink absorbing layer contains inorganic fine particles and a binder. In particular, the layer A contains an inorganic fine particle dispersion dispersed in the presence of a water-soluble polyvalent metal compound, which is then dried to form a layer. Thus, an ink jet recording sheet is obtained.

(Bristow method)
The Bristow method referred to in the present invention is a method for measuring the liquid absorption behavior of paper and paperboard in a short time. TAPPI paper pulp test method no. It is measured according to the liquid absorptivity test method (Bristow method) of 51-87 paper or paperboard, and is expressed as an ink transfer amount (ml / m ² ) at a contact time of 0.04 seconds. In the above measurement method, pure water (ion-exchanged water) is used for measurement. In the present invention, diethylene glycol / triethylene glycol monobutyl ether / water is mixed at a mass ratio of 15/15/70. Measure using solution.

An example of a specific measurement method will be described below. As a method for measuring the amount of ink transfer, the recording paper is allowed to stand for 12 hours or more in an atmosphere of 25 ° C. and 50% RH, and then, for example, the Bristow test, which is a liquid dynamic absorbency tester manufactured by Kumagai Riki Industry Co. Measure using machine II (pressurization type). The liquid used for the measurement is a solution mixed at a mass ratio of diethylene glycol / triethylene glycol monobutyl ether / water = 15/15/70, and a commercially available dye is added to improve the determination accuracy. By measuring the area of the above dyed portion, the amount of ink transfer can be determined. In addition, as a method for measuring the liquid transfer amount of each layer, each layer is coated on a support so that the solid content is 15 g / m ² and dried to form a recording paper. By using the coated recording paper, the liquid transfer amount by the Bristow method can be measured.

  The method for adjusting the liquid transfer amount at a contact time of 0.04 seconds as defined in the present invention is not particularly limited, but by increasing the ratio (F / B) of the inorganic fine particles to the binder, or the particles of the inorganic fine particles The amount of transfer can be increased by increasing the diameter, but when dispersing inorganic fine particles, a cationic polymer resin (also called a cationic polymer) can be used in the dispersion solution to adjust the amount. . That is, the smaller the amount of the cationic polymer used, the more the liquid transfer amount increases. For example, in the present invention, a cationic polymer having a molecular weight of 5000 or less is used for the layer where the liquid transfer amount is to be increased. It can be adjusted by adjusting the amount. Further, it is more preferable to use an inorganic mordant such as a water-soluble polyvalent metal compound instead of the cationic polymer from the viewpoint of water absorption.

(Water-soluble polyvalent metal compound)
The water-soluble polyvalent metal compound generally tends to agglomerate when it is present in a coating solution containing inorganic fine particles, and this tends to cause a slight coating failure and a decrease in glossiness. In order to contain a water-soluble polyvalent metal compound, in particular, the inorganic fine particles are dispersed in the presence of the water-soluble polyvalent metal compound and this is contained in the A layer, so that the water-soluble polyvalent metal compound is contained in the layer. It is necessary to make it.

Examples of the water-soluble polyvalent metal compound according to the present invention include sulfates such as Mg ₂ ⁺ , Ca ₂ ⁺ , Zn ₂ ⁺ , Zr ₂ ⁺ , Ni ₂ ⁺ and Al ₃ ⁺ , chlorides, nitrates and acetates. In particular, those containing Zr ₂ ⁺ and Al ₃ ⁺ are preferable.

  In addition, inorganic polymer compounds such as basic polyaluminum hydroxide and zirconyl acetate are also included as examples of preferable water-soluble polyvalent metal compounds.

  The compound containing a zirconium atom used in the present invention excludes zirconium oxide, and specific examples thereof include zirconium difluoride, zirconium trifluoride, zirconium tetrafluoride, hexafluorozirconium salt (for example, Potassium salt), heptafluorozirconate (eg, sodium salt, potassium salt or ammonium salt), octafluorozirconate (eg, lithium salt), fluorinated zirconium oxide, zirconium dichloride, zirconium trichloride, zirconium tetrachloride , Hexachlorozirconate (for example, sodium salt and potassium salt), zirconium oxychloride (zirconyl chloride), zirconium dibromide, zirconium tribromide, zirconium tetrabromide, zirconium bromide oxide, zirconium triiodide, tetraiodine Zirconide Zirconium, zirconium peroxide, zirconium hydroxide, zirconium sulfide, zirconium sulfate, zirconium p-toluenesulfonate, zirconyl sulfate, sodium zirconyl sulfate, acidic zirconyl sulfate trihydrate, potassium zirconium sulfate, zirconium selenate, zirconium nitrate, nitric acid Zirconyl, zirconium phosphate, zirconyl carbonate, zirconyl ammonium carbonate, zirconium acetate, zirconyl acetate, zirconyl ammonium acetate, zirconyl lactate, zirconyl citrate, zirconyl stearate, zirconyl phosphate, zirconium oxalate, zirconium isopropylate, zirconium butyrate, Zirconium acetylacetonate, acetylacetone zirconium butyrate, zirconium stearate butyrate, di Benzalkonium acetate, bis (acetylacetonato) dichloro zirconium and tris (acetylacetonato) chloro zirconium, and the like.

  Among these compounds, zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate, zirconyl oxychloride, zirconyl lactate, zirconyl citrate in terms of further prominently preventing bleeding after printing, which is the object of the present invention. In particular, zirconyl ammonium carbonate, zirconyl acid chloride, and zirconyl acetate are preferable. Specific trade names of the above compounds include zirconyl acetate ZA (trade name) manufactured by Daiichi Rare Earth Chemical Co., Ltd., zirconyl oxychloride (trade name) manufactured by Daiichi Rare Earth Chemical Co., Ltd., and the like.

  A compound containing a zirconium atom may be used alone, or two or more different compounds may be used in combination. When two or more types are used, there is an advantage that bronzing (a phenomenon that promotes crystallization of a dye in the ink and exhibits a metallic luster) that easily occurs when a compound containing a zirconium atom is used can be considered. .

  Specific examples of the compound having an aluminum atom that can be used in the present invention include aluminum fluoride, hexafluoroaluminic acid (for example, potassium salt), aluminum chloride, basic aluminum chloride (for example, polyaluminum chloride), tetra Chloroaluminate (eg, sodium salt), aluminum bromide, tetrabromoaluminate (eg, potassium salt), aluminum iodide, aluminate (eg, sodium salt, potassium salt, calcium salt), Aluminum chlorate, aluminum perchlorate, aluminum thiocyanate, aluminum sulfate, basic aluminum sulfate, potassium aluminum sulfate (alum), ammonium aluminum sulfate (ammonium alum), sodium aluminum sulfate, phosphoric acid Aluminum, Aluminum nitrate, Hydrogen phosphate, Aluminum carbonate, Aluminum polysulfate, Aluminum formate, Aluminum acetate, Aluminum lactate, Aluminum oxalate, Aluminum isopropylate, Aluminum butyrate, Ethyl acetate Aluminum diisopropylate, Aluminum tris (acetylacetonate) ), Aluminum tris (ethyl acetoacetate), aluminum monoacetylacetonate bis (ethyl acetoacetonate), and the like.

  In the present invention, among the compounds having an aluminum atom in the molecule, a polyaluminum chloride compound, a polyaluminum sulfate compound or a polysulfuric acid aluminum silicate compound is preferable.

The polyaluminum chloride compound is represented by the general formula [Al ₂ (OH) _n Cl _6-n ] _m , [Al (OH) ₃ ] _n · AlCl ₃ , for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ and other basic and polynuclear condensed ions (polymeric) with high positrons as active ingredients Polyaluminum chloride, containing stably.

  Examples of commercially available polyaluminum chloride compounds include polyaluminum hydroxide (Paho) manufactured by Asada Chemical Co., Ltd., polyaluminum chloride (PAC) manufactured by Taki Chemical Co., Ltd., and Purakem manufactured by Riken Green Co., Ltd. WT.

The polyaluminum sulfate compound is represented by the general formula [Al ₂ (OH) _n (SO ₄ ) _{6-n / 2} ] _m (where 0 <n <6). As a commercial product, Asada Examples include basic aluminum sulfate (AHS) manufactured by Chemical Co., Ltd.

  As a commercial item of a polysulfuric acid aluminum silicate compound, PASS made from Nippon Light Metal Co., Ltd. is mentioned.

  The water-soluble polyvalent metal compound is preferably added in an oxide equivalent value of 10% by mass or more and 50% by mass or less with respect to the oxide equivalent value of the inorganic fine particles from the viewpoint of increasing the image density, and 15% by mass or more and 30% by mass. % Or less is more preferable. If the water-soluble polyvalent metal compound is less than 10% by mass, the image density may be lowered due to weak cationicity, and if it exceeds 50% by mass, the dispersion stability and coating solution stability are deteriorated. Further, from the viewpoint of the stability of the coating solution, the water-soluble polyvalent metal compound is preferably put in the dispersion.

(Dispersion of inorganic fine particles dispersed in the presence of a water-soluble polyvalent metal compound)
Next, the inorganic fine particle dispersion dispersed in the presence of the water-soluble polyvalent metal compound according to the present invention will be described.

  Specifically, the inorganic fine particle dispersion liquid dispersed in the presence of the water-soluble polyvalent metal compound according to the present invention is dispersed by adding gas phase method silica fine particles having anionic surface to water (primary dispersion). The resulting primary dispersion is added to an aqueous solution containing a water-soluble polyvalent metal compound, then a pH adjuster is added, and the mixture is dispersed (secondary dispersion). The aqueous solution containing the polyvalent metal compound is preferably added by the time of secondary dispersion.

  As the primary dispersion method, known methods can be used. For example, by using a jet stream inductor mixer manufactured by Mitamura Riken Kogyo Co., Ltd., vapor phase silica fine particles are dispersed in a dispersion medium mainly composed of water. A primary dispersion can be obtained by suction dispersion. Subsequently, an inorganic fine particle dispersion can be prepared by adding a water-soluble polyvalent metal compound and a pH adjuster to the primary dispersion and dispersing and finely pulverizing the mixture.

  Examples of the secondary dispersion method include conventionally known high-speed rotary dispersers, medium stirring dispersers (ball mill, sand mill, etc.), ultrasonic dispersers, colloid mill dispersers, roll mill dispersers, high pressure dispersers, and the like. Various dispersers can be used. In the present invention, an ultrasonic disperser or a high-pressure disperser is preferably used from the viewpoint of efficiently dispersing the formed inorganic fine particles.

  Ultrasonic dispersers are usually dispersed by concentrating energy at the solid-liquid interface by irradiating ultrasonic waves of 20 kHz to 25 kHz, and are very efficiently dispersed to prepare a small amount of dispersion liquid. It is especially suitable for On the other hand, the high-pressure disperser is provided with one or two homogeneous valves at the outlet of a high-pressure pump having three or five pistons, the gap of which can be adjusted by screws or hydraulic pressure. In addition, the liquid medium fed by the high-pressure pump is squeezed by the homogeneous valve and pressure is applied, and minute dust material is pulverized at the moment of passing through the homogeneous valve. Since this method can disperse a large amount of liquid continuously, it is a particularly preferable method when preparing a large amount of dispersion. The pressure applied to the homogeneous valve is usually 5 MPa or more and 100 MPa or less, and the dispersion can be performed in one pass or repeated many times.

  The inorganic fine particle dispersion liquid dispersed in the presence of the water-soluble polyvalent metal compound according to the present invention is preferably one in which the surface of the inorganic fine particles is completely replaced with cationic and stabilized. The above range is preferable as the mass ratio (the oxide mass of the water-soluble polyvalent metal compound / the oxide mass of the inorganic fine particles) when the mixing ratio of the water-soluble polyvalent metal compound to the inorganic fine particles is converted into an oxide. As described above, gas phase method silica fine particles are preferable as the inorganic fine particles. When the mixing ratio of the water-soluble polyvalent metal compound to the vapor phase silica fine particles is within the above range, the anion component of the vapor phase silica fine particles is almost completely covered with the cation component. This is preferable because it does not cause the formation of coarse particles by ionic bonding with the functional polyvalent metal compound. In addition, when preparing a coating solution when the ratio of the water-soluble polyvalent metal compound is small, it becomes easy to gel when mixed with a hydrophilic binder. Conversely, when the ratio of the water-soluble polyvalent metal compound is large, the stagnation of the coating solution is stabilized May cause gender problems.

  The inorganic fine particle dispersion liquid dispersed in the presence of the water-soluble polyvalent metal compound according to the present invention is preferably obtained by changing the pH from the primary dispersion state with a pH adjuster. As a result, a uniform dispersion of cation-converted silica fine particles can be obtained, and a stable coating liquid free from turbidity change and viscosity change can be obtained in the subsequent process of preparing the ink absorbing layer coating liquid. As a result, it is possible to obtain a highly glossy recording material having a coating film quality free from coating failure defects such as cracks during production, which is the object of the present invention. More preferably, the pH is raised during dispersion to obtain a cationic fine particle dispersion, and as a result, ink absorbability and ink fixability can be improved. The pH change range is preferably 0.20 or more and 1.0 or less. If the change width is 0.20 or less, it is difficult to obtain the effect of the present invention. If the change width is 1.0 or more, gelation and aggregation of the dispersion may occur. Here, the time of dispersion means a period from the end of primary dispersion to the end of secondary dispersion.

  Examples of the pH adjusting acid include formic acid, acetic acid, glycolic acid, oxalic acid, propionic acid, malonic acid, succinic acid, adipic acid, maleic acid, malic acid, tartaric acid, citric acid, benzoic acid, phthalic acid, and isophthalic acid. Examples thereof include organic acids such as acid, terephthalic acid, glutaric acid, gluconic acid, lactic acid, aspartic acid, glutamic acid, pimelic acid, and suberic acid, and inorganic acids such as hydrochloric acid, nitric acid, boric acid, and phosphoric acid. Examples of the alkali include sodium hydroxide, potassium hydroxide, calcium hydroxide, aqueous ammonia, potassium carbonate, sodium carbonate, trisodium phosphate, and triethanolamine, but the present invention is not limited thereto. . Further, the amount of these various acids or alkalis to be added needs to be determined in consideration of the acidity or alkalinity of the various acids depending on the progress of dispersion and the stability of the dispersion.

Among the pH adjusting agents, boron compounds are preferable. A boron compound means boric acid and its salt, for example, borax, boric acid, borate (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ ( BO ₃ ) ₂ , diborate (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 ), four Borate (for example, Na ₂ B ₄ O ₇ · 10H ₂ O), pentaborate (for example, KB ₅ O ₈ · 4H ₂ O, Ca ₂ B ₆ O ₁₁ · 7H ₂ O, CsB ₅ O ₅ )) Can be mentioned. As the boron compound aqueous solution, a single aqueous solution or a mixture of two or more may be used. Particularly preferred is a mixture of borax and boric acid. Each of the aqueous solutions of boric acid and borax can be added only in a relatively dilute aqueous solution, but by mixing the two, a concentrated aqueous solution can be obtained and the dispersion can be concentrated. Further, there is an advantage that the pH can be controlled relatively freely by the mixing ratio of borax and boric acid.

(Inorganic fine particles in each ink absorption layer)
In addition, in the ink absorbing layer other than the A layer, it is preferable to disperse the inorganic fine particles using a cationic polymer having a quaternary ammonium base from the viewpoint of ink absorbability, film strength, and the like. Particularly preferred is a homopolymer of a monomer having a quaternary ammonium base or a copolymer with one or more other copolymerizable monomers. When used, it is preferably added at the time of secondary dispersion. . In addition, from the viewpoint of ink absorbability, the B layer is preferably an inorganic fine particle dispersion using a cationic polymer and a water-soluble polyvalent metal compound in combination.

  Examples of the monomer having a quaternary ammonium base include the compound examples described in paragraphs [0028] and [0029] of JP-A No. 11-301096. The monomer that can be copolymerized with the quaternary ammonium base is a compound having an ethylenically unsaturated group, and examples thereof include compound examples described in paragraph [0031] of JP-A No. 11-301096.

  In particular, when the cationic polymer having a quaternary ammonium base is a copolymer, the proportion of the cationic monomer is preferably 10 mol% or more, more preferably 20 mol% or more, and particularly preferably 30 mol% or more. .

  The monomer having a quaternary ammonium base may be a single monomer or two or more types.

  Specific examples of the cationic polymer having a quaternary ammonium base preferably used in the present invention include the compounds described in paragraphs [0035] to [0038] of JP-A No. 11-301096.

  In preparing the inorganic fine particle dispersion, various additives can be added. For example, various nonionic or cationic surfactants, antifoaming agents, nonionic hydrophilic polymers (polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, polyacrylamide, various sugars, gelatin, pullulan, etc.), nonionic or A cationic latex dispersion, a water-miscible organic solvent (such as ethyl acetate, methanol, ethanol, isopropanol, n-propanol, and acetone), inorganic salts, and the like can be used as necessary.

  In particular, a water-miscible organic solvent suppresses the formation of fine lumps when mixed with an aqueous solution containing vapor-phase silica particles having an anionic surface and a water-soluble polyvalent metal compound and / or a cationic polymer. To be preferred. Such a water-miscible organic solvent is used in the dispersion in the range of 0.1% by mass to 20% by mass, particularly preferably 0.5% by mass to 10% by mass.

(Dry film thickness of layer A)
The dry film thickness of the A layer is preferably 5% or more and 20% or less of the total dry film thickness, and 5% or more and 15% or less is preferable from the viewpoint that both high image density and ink absorbency can be achieved. If it exceeds 20%, the image density may be lowered, and if it is less than 5%, a high image density cannot be obtained.

  Here, the total dry film thickness refers to the dry film thickness of all the layers coated on the support of the inkjet recording paper.

(Dry film thickness of layer B)
The dry film thickness of layer B is preferably 10% or more and 20% or less of the total dry film thickness, and preferably 10% or more and 15% or less from the viewpoint of ink absorbability. If it is less than 10%, it cannot function as a barrier layer, and the dye cannot be adsorbed to the A layer. If it exceeds 20%, the ink absorbability is lowered and overflow may occur.

(4 layers or more)
When four or more layers are provided from the viewpoint of the amount of absorption, etc., a layer can be provided further below the C layer. In that case, it is preferable that it is 75% or more and 85% or less of the total dry film thickness in A, B, and C layers. If it is less than 75%, the effect of the present invention cannot be obtained. Further, when a layer having almost the same liquid transition amount as the C layer is provided below the C layer, the layer can be regarded as the C layer together.

  The total dry film thickness of each ink layer of the present invention is preferably 30 μm or more and 60 μm or less. If it is less than 30 μm, ink absorbability is insufficient, and if it exceeds 60 μm, problems such as cracking may occur during production.

(Turbidity)
When an inorganic fine particle dispersion is used for inkjet recording paper, the final dispersion degree of the dispersion greatly affects the color developability and the like, and only the number average particle diameter obtained with an electron microscope or a particle size measuring instrument as in the past is used. In the current situation, the quality cannot be guaranteed, and it is important to grasp the coarse particles in the dispersion to improve the color developability. It was found that this can be solved by using turbidity evaluation. Of course, it is preferable to use the number average particle diameter and turbidity in combination for evaluation of dispersity. The number average particle diameter is generally preferably 300 nm or less and 3 nm or more in order to obtain gloss.

  In the case of the inorganic fine particle dispersion used for the ink jet recording paper, the turbidity value is preferably 50 ppm or less, and in this layer configuration, the turbidity of the A layer is more preferably 50 ppm or less from the viewpoint of color development. Although a lower limit is not specifically limited, it is so preferable that it is small, and it can be said that it is practically preferable to be 5 ppm. As a method for reducing turbidity, a method such as changing a dispersing agent such as a cationic polymer, changing a dispersion method, increasing a dispersion concentration, extending a dispersion time, or lowering a pH at the time of dispersion is employed. be able to.

  The turbidity of the present invention is a value measured by putting the dispersion in a quartz cell having a width of 5 mm using an integrating sphere turbidimeter. As a measuring device, turbidimeter SEP-PT-706D (made by Mitsubishi Chemical Corporation) etc. are mentioned.

  In general, the inorganic fine particles used to form the ink absorbing layer of inkjet recording paper include, for example, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, Titanium, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, hydroxylation White inorganic pigments such as aluminum, lithopone, zeolite, and magnesium hydroxide can be mentioned. In the ink jet recording paper of the present invention, it is preferable to use gas phase method silica fine particles synthesized by a gas phase method.

  In the present invention, the vapor phase silica fine particles are hydrolyzed silicon tetrachloride in a hydrogen and oxygen burner at a high temperature of 1000 ° C. or higher in synthetic silica which is a synthetic silicon compound mainly composed of silicon dioxide. It refers to ultrafine silica synthesized by a so-called dry method or gas phase method typified by a production method. Examples of such vapor-phase method silica fine particles include AEROSIL series manufactured by Nippon Aerosil Co., Ltd. and Leorosil series manufactured by Tokuyama Corporation. The silica fine particles synthesized by the vapor phase method may be those whose surfaces are modified with aluminum. In this case, the aluminum content of the vapor phase silica fine particles is 0.05 by mass with respect to silica. % To 5% is preferable.

  The vapor phase silica fine particles may have any particle size, but the average particle size (primary average particle size) is preferably 1 μm or less. When it exceeds 1 μm, glossiness or color developability tends to be lowered, and therefore, 200 nm or less is preferable. Further, silica of 100 nm or less is most preferable. The lower limit of the particle size is not particularly limited, but is preferably about 3 nm or more, particularly preferably 5 nm or more from the viewpoint of production of inorganic fine particles.

  The average particle diameter of the vapor phase silica fine particles is obtained as a simple average value (number average) by observing the cross section and surface of the ink absorption layer with an electron microscope, and determining the particle diameter of 100 arbitrary particles. Here, each particle size is represented by a diameter assuming a circle equal to the projected area.

  Further, in the present invention, from the viewpoint of obtaining a high-quality print on an inkjet recording paper, vapor phase method silica fine particles having an average particle diameter of 60 nm or less and an isolated silanol group ratio of 5.0 or more and 7.0 or less are used. preferable.

  In the recording paper of the present invention, by using vapor phase method silica fine particles having an average particle diameter of 60 nm or less and an isolated silanol group ratio of 5.0 or more and 7.0 or less in the ink absorption layer, a high temperature of 40 ° C. or more is used. A void volume ratio of 60% or more can be achieved even under drying conditions. A more preferable range of the isolated silanol group ratio is 5.5 or more and 7.0 or less. The higher the isolated silanol group ratio, the higher the interparticle interaction and the easier to obtain high voids. However, when the isolated silanol group ratio exceeds 7.0, the viscosity at the time of preparing the coating solution becomes too high, which is not preferable for handling. The isolated silanol group ratio can be adjusted by changing the water content of the vapor phase silica fine particles described below.

  As a method for controlling the isolated silanol group ratio of the gas phase method silica fine particles, it is preferable to adjust by spraying water vapor on the gas phase method silica fine particles.

  Examples of the method of spraying water vapor include a method of spraying water vapor continuously while transporting vapor-phase method silica fine particles, a method of spraying water vapor while introducing gas-phase method silica fine particles into a closed batch and aeration. Further, a method of adjusting the water content of the vapor phase silica fine particles by storing the vapor phase silica fine particles in an environment having a humidity of 20% to 60% for 3 days or more is also preferable.

  In addition, the isolated silanol group ratio as used in the field of this invention can be calculated | required according to the following method using FT-IR.

The vapor phase silica fine particles are dried at 120 ° C. for 24 hours, and the dried vapor phase silica fine particles are subjected to FT-IR measurement. Absorbance 3750Cm ^-1 attributable to Si-OH, determine the absorbance of 1870cm ^-1 attributable to Si-O-Si, a value obtained by the following formula was isolated silanol group ratio.

Isolated silanol group ratio (hereinafter, also referred to as IR ratio) = (Absorbance / 1870Cm absorbance ^-1 3750Cm ^-1)
(binder)
As the binder for the ink absorbing layer of the ink jet recording paper of the present invention, those commonly used can be applied, but hydrophilic binders, particularly polyvinyl alcohol and derivatives thereof are preferred. Polyvinyl alcohol preferably used includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, modified polyvinyl alcohol such as cation-modified polyvinyl alcohol and anion-modified polyvinyl alcohol having an anionic group. It is.

  The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 300 or more, particularly preferably an average degree of polymerization of 1,000 or more and 5,000 or less. 70% or more and 100% or less are preferable, and 80% or more and 99.8% or less are especially preferable.

  Examples of the cation-modified polyvinyl alcohol include primary to tertiary amino groups and quaternary amino groups in the main chain or side chain of the polyvinyl alcohol as described in JP-A-61-10383. Polyvinyl alcohol, which is obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

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

  The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1% or more and 10 mol% or less, preferably 0.2% or more and 5 mol% or less with respect to vinyl acetate.

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

  Nonionic modified polyvinyl alcohol includes, for example, a polyvinyl alcohol derivative obtained by adding a polyalkylene oxide group described in JP-A-7-9758 to a part of vinyl alcohol, and described in JP-A-8-25795. And a block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol.

  Polyvinyl alcohol can be used in combination of two or more, such as the degree of polymerization and the type of modification. In particular, when polyvinyl alcohol having a degree of polymerization of 2,000 or more is used, it is previously 0.05% by mass or more and 10% by mass or less, preferably 0.1% by mass or more and 5% by mass or less with respect to the vapor phase method silica fine particles. It is preferable to add polyvinyl alcohol having a polymerization degree of 2,000 or more after the addition, since there is no significant thickening.

  The ratio of the vapor phase method silica fine particles to the hydrophilic binder of the ink absorbing layer is preferably 2 or more and 20 or less in terms of mass ratio. If the mass ratio is 2 or more, a porous film having a sufficient porosity can be obtained, it is easy to obtain a sufficient void volume, and does not cause a situation where the voids are blocked by swelling during inkjet recording with a hydrophilic binder that can be maintained, This is a factor that can maintain a high ink absorption speed. On the other hand, if this ratio is 20 or less, cracks are less likely to occur when the gap layer is applied as a thick film. The ratio of the vapor phase method silica fine particles to the particularly preferred hydrophilic binder is 2.5 or more and 12 or less, and most preferably 3 or more and 10 or less.

In the ink absorbing layer, the total amount of voids (void volume) is preferably 20 ml or more per 1 m ^{2 of} inkjet recording paper. By setting the void volume to 20 ml / m ² or more, the ink absorbability can be improved even when the amount of ink increases, so that the image quality can be improved and the decrease in the drying property can be suppressed.

  In the inkjet recording paper of the present invention, it is preferable that polyvinyl alcohol or a derivative thereof is polymerized by ionizing radiation.

(Support)
As the support that can be used in the present invention, those conventionally known for inkjet recording paper can be used as appropriate, and may be a water-absorbing support, but is preferably a non-water-absorbing support. When an absorbent support is used, cockling may occur due to the support absorbing water in the ink, and the quality after printing is impaired.

  Examples of the water-absorbing support herein include sheets and plates having general paper, cloth, wood and the like. Examples of paper supports include chemical pulps such as LBKP and NBKP, mechanical pulps such as GP, CGP, RMP, TMP, CTMP, CMP, and PGW, and wood pulp such as waste paper pulp such as DIP. Can do. In addition, various fibrous materials such as synthetic pulp, synthetic fiber, and inorganic fiber can be appropriately used as a raw material as necessary. If necessary, various conventionally known additives such as sizing agents, pigments, paper strength enhancers, fixing agents, fluorescent whitening agents, wet paper strength agents, cationizing agents and the like are added to the paper support. be able to. The paper support can be produced with various paper machines such as a long net paper machine, a circular net paper machine, and a twin wire paper machine by mixing the above-mentioned fibrous material such as wood pulp and various additives. Further, if necessary, the paper can be subjected to size press treatment with starch, polyvinyl alcohol or the like, various coating treatments, or calendar treatment on a paper making stage or a paper machine.

  The non-water-absorbing support according to the present invention includes a transparent support and an opaque support. Examples of the transparent support include films having materials such as polyester resins, diacetate resins, triatesate resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, polyimide resins, cellophane, and celluloid. Among them, those having a property of resisting radiant heat when used for overhead projectors (OHP) are preferable, and polyethylene terephthalate is particularly preferable. The thickness of such a transparent support is preferably 50 μm or more and 200 μm or less. Further, as the opaque support, for example, resin-coated paper (so-called RC paper) having a polyolefin resin coating layer in which white pigment or the like is added to at least one of the base paper, white pigment such as barium sulfate is added to polyethylene terephthalate. A so-called white pet is preferable. For the purpose of increasing the adhesive strength between the various supports and the ink absorbing layer, the support is preferably subjected to corona discharge treatment, subbing treatment or the like prior to application of the ink absorbing layer. Furthermore, the inkjet recording paper of the present invention is not necessarily colorless, and may be a colored recording sheet.

  In the ink jet recording paper of the present invention, it is particularly preferable to use a paper support obtained by laminating both sides of a base paper support with polyethylene because the recorded image is close to photographic image quality and a high-quality image can be obtained at low cost.

  Such a paper support laminated with polyethylene will be described below.

The base paper used for the paper support is made from wood pulp as a main raw material and, if necessary, paper making using synthetic pulp such as polypropylene or synthetic fibers such as nylon or polyester in addition to wood pulp. As wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, and NUKP can be used, but it is preferable to use more LBKP, NBSP, LBSP, NDP, and LDP with a large amount of short fibers. . However, the ratio of LBSP or LDP is preferably 10% by mass or more and 70% by mass or less. The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities, and a pulp having a whiteness improved by bleaching is also useful. In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength enhancing agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, polyethylene glycols A water retaining agent such as a dispersant, a softening agent such as a quaternary ammonium, and the like can be appropriately added. The freeness of pulp used for papermaking is preferably 200 ml or more and 500 ml or less as defined by CSF, and the fiber length after beating is the mass% of the remaining 24 mesh defined by JIS-P-8207 and 42 mesh. The sum of the remaining mass% is preferably 30% or more and 70% or less. In addition, it is preferable that the mass% of 4 mesh remainder is 20 mass% or less. The basis weight of the base paper is preferably from 30 g to 250 g, particularly preferably from 50 g to 200 g. The thickness of the base paper is preferably 40 μm or more and 250 μm or less. The base paper can be given a high smoothness by calendering at the paper making stage or after paper making. The density of the base paper is generally 0.7 g / cm ³ or more and 1.2 g / cm ³ or less (JIS-P-8118). Furthermore, the base paper stiffness is preferably 20 g or more and 200 g or less under the conditions specified in JIS-P-8143. A surface sizing agent may be applied to the surface of the base paper. The pH of the base paper is preferably 5 or more and 9 or less when measured by a hot water extraction method defined in JIS-P-8113. The polyethylene that covers the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but some other LLDPE, polypropylene, and the like can also be used. In particular, the polyethylene layer on the ink absorbing layer side is preferably one in which rutile or anatase type titanium oxide is added to polyethylene to improve opacity and whiteness, as is widely done in photographic paper. The titanium oxide content is usually 3% by mass or more and 20% by mass or less, and preferably 4% by mass or more and 13% by mass or less with respect to polyethylene. Polyethylene-coated paper can be used as glossy paper, or when the polyethylene is melt-extruded onto the surface of the base paper and coated, a so-called molding process is performed to form a matte or silky surface that can be obtained with ordinary photographic printing paper. These can also be used in the present invention. In the polyethylene-coated paper, the moisture content in the paper is particularly preferably maintained at 3% by mass or more and 10% by mass or less.

  In the ink jet recording paper of the present invention, the method for applying the constituent layers such as the ink absorbing layer according to the present invention on the support can be appropriately selected from known methods. A preferred method is obtained by coating a coating liquid constituting each layer on a support and drying. In this case, two or more layers can be applied simultaneously. As the coating method, for example, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferable. Used.

(Cationic silica dispersion A)
To 50 g of a 20% aqueous solution of the cationic polymer (1), 500 g of a 20% aqueous solution of vapor-phase silica particles (manufactured by Nippon Aerosil: Aerosil 200), 3 g of boric acid and 0.5 g of borax are added and dispersed with a high-pressure homogenizer. A cationic silica dispersion A was prepared.

(Cationic silica dispersion B)
Cationic silica dispersion was similarly performed except that 50 g of the cationic polymer (1) aqueous solution was changed to 90 g of polyaluminum chloride (Taki Chemical: Takibaine # 1500, 23% in terms of Al ₂ O ₃ ) from the cationic silica dispersion A. Liquid B was prepared.

(Cationic silica dispersion C)
The same except that 20 g of the cationic polymer (1) aqueous solution of the cationic silica dispersion A is changed to 25 g and 1.6 g of polyaluminum chloride (Taki Chemical: Takibaine # 1500, 23% in terms of Al ₂ O ₃ ) is added. Thus, a cationic silica dispersion C was prepared.

(Recording paper 1) Comparative example The following coating solutions were applied simultaneously in the order of the second layer and the first layer so that the respective dry film thicknesses were 20 μm, respectively, and dried with a wind of 20 to 40 ° C., Inkjet recording paper 1 was produced.

First layer (upper layer) (B layer)
Cationic silica dispersion A (17%) 500 g
270 ml of polyvinyl alcohol (6%) (Kuraray: PVA235)
Amphoteric surfactant (6%) (manufactured by Neos: Aftergent 400S) 2ml
Finally, pure water was added so that the total volume of the liquid was 1000 ml.

Second layer (lower layer) (C layer)
Cationic silica dispersion A (17%) 500 g
280 ml of polyvinyl alcohol (6%) (manufactured by Kuraray: PVA235)
Emulsion resin (55%) (Sumitomo Chemical: Sumikaflex 400HQ)
10ml
Finally, pure water was added so that the total deposition of the liquid was 1000 ml.

(Recording paper 2) Comparative example The following coating solutions were applied in the order of C layer, B layer, and A layer so that the respective dry film thicknesses would be 13 μm, respectively, and dried with a wind of 20 to 40 ° C. Inkjet recording paper 2 was prepared.

Layer A (outermost layer)
Cationic silica dispersion B (15%) 690 g
290 ml of polyvinyl alcohol (6%) (Kuraray: PVA235)
Cationic surfactant (6%) (Kao product: Coatamine 24P) 2ml
Amphoteric surfactant (6%) (manufactured by Neos: Aftergent 400S) 2ml
Finally, pure water was added so that the total volume of the liquid was 1000 ml.

B layer Common with the upper layer of recording paper 1.

C layer Common to the lower layer of the recording paper 1.

(Recording paper 3) Present invention Recording paper 3 was prepared in the same manner except that the cationic silica dispersion A in layer B of recording paper 2 was changed to cationic silica dispersion C.

(Recording paper 4) Comparative example A recording paper 4 was produced in the same manner as the recording paper 3 except that the A layer and the C layer were reversed.

(Recording paper 5) The present invention In the A layer of the recording paper 3, the polyaluminum chloride of the cationic silica dispersion B is changed to zircozole ZC-2 (manufactured by Daiichi Rare Chemicals Co., Ltd.), and the same as the amount of Al ₂ O _{3 applied} . Recording paper 5 was produced in the same manner except that the amount of ZrO _{2 was} added.

(Recording paper 6)
A recording paper 6 was produced in the same manner except that the dry film thickness of the A layer (outermost layer) in the recording paper 3 was 4 μm and the other layers were 18 μm each.

(Recording paper 7)
A recording paper 7 was prepared in the same manner except that the dry thickness of the B layer (adjacent layer of the A layer) was 6 μm and the C layer (adjacent layer of the B layer) was 20 μm.

(Recording paper 8)
Cationic silica dispersion A is used in place of cationic silica dispersion B as the coating liquid for layer A, and polyaluminum chloride (manufactured by Taki Chemical Co., Ltd .: TAKIBINE # 1500) is used so that the amount of Al ₂ O _{3 is} added to recording paper 3. The recording paper 8 was produced in the same manner as the recording paper 3 except that the solution added with the above was added to the coating solution and used.

(Recording paper 9)
Recording sheet 9 was prepared in the same manner except that the amount of polyaluminum chloride in cationic silica dispersion B was changed to 17 g in layer A of recording sheet 3.

(Recording paper 10)
A recording paper 10 was prepared in the same manner except that the layer A of the recording paper 3 was replaced with commercially available magnesium chloride so as to have the same amount of MgCl ₂ as polyaluminum chloride (amount of Al ₂ O ₃ ).

(Recording paper 11)
Recording paper 11 was prepared in the same manner except that the amount of polyaluminum chloride in cationic silica dispersion B was changed to 217 g in layer A of recording paper 3.

[Evaluation]
Color developability A black 100% output solid image is printed on each recording paper by using an ink jet printer PM-G800 manufactured by Seiko Epson Corporation and genuine dye ink, and the reflection density (Visal) of the black solid image is measured by an optical reflection densitometer. (X-Rite 938, manufactured by X-Rite).

A: 2.1 or more B: 2.0 or more and less than 2.1 Δ: 1.9 or more and less than 2.0 ×: less than 1.9.

Bleeding Under an environment of 23 ° C and 55% RH, using a Seiko Epson ink jet printer PM-950C, print a black line with a line width of about 0.3mm against a solid blue image using genuine ink. After natural drying for 1 hour, it was inserted into a transparent clear file. This is left as a clear file in an environment of 40 ° C. and 80% RH for one week, and the line width of the black line is measured with a microdensitometer before and after storage (the reflection density is 50% of the maximum density). The width was defined as the line width), and the rate of change in the line width represented by the following equation was determined. This value was used as a measure of bleeding after long-term storage, and bleeding was determined as follows. The smaller this value is, the better the bleeding is, and the level at which there is no practical problem is 130 or less.

Line width change rate =
(Line width of the black line after saving / line width of the black line before saving) × 100
A: The line width change rate is 110 or less. O: The line width change rate is more than 110 and 120 or less. Δ: The line width change rate is more than 120 and 130 or less (no problem in practical use).
X: The line width change rate exceeds 130 (practically problematic).

Absorptivity In a 23 ° C. and 80% RH environment, a chart with a blue density change was printed with EPSON PM950C and judged visually.

A: No mottle or overflow is observed. O: Slight mottle or overflow is observed in a portion with a large amount of ink. Δ: Clear mottle or overflow is observed in a portion with a large amount of ink.
X: Overflow is clearly observed even in a portion with a small amount of ink (practically problematic).

Turbidity Using a turbidimeter SEP-PT-706D (manufactured by Mitsubishi Chemical Corporation), the coating solution was put into a quartz cell having a width of 5 mm and measured. The obtained results are shown in Table 1.

  From Table 1, it can be seen that the ink jet recording paper of the present invention has little occurrence of bleeding, a high image density, and good ink absorbability. In Table 1, the coating liquid turbidity of the recording paper 8 was not measured because it was impossible to prepare the liquid as shown in the table.

Claims (7)

An ink jet recording sheet provided with at least three ink absorbing layers laminated in the order of A layer, B layer, and C layer, as viewed from the surface side on which ink is printed, on a non-water absorbent support, Each ink absorbing layer contains inorganic fine particles and a binder, and the A layer is a recording paper formed by containing an inorganic fine particle dispersion dispersed in the presence of a water-soluble polyvalent metal compound and drying it. J. et al. TAPPI paper pulp test method no. In accordance with 51-87, the liquid transition amount at a contact time of 0.04 seconds measured by the Bristow method with a liquid mixed at a mass ratio of diethylene glycol / triethylene glycol monobutyl ether / water = 15/15/70 is B layer < An ink jet recording paper, wherein C layer is less than A layer. The inkjet recording paper according to claim 1, wherein the A layer is an outermost layer, and a dry film thickness thereof is 5% or more and 20% or less of a total dry film thickness. The inkjet recording paper according to claim 1 or 2, wherein the dry film thickness of the B layer is 10% or more and 20% or less of the total dry film thickness. 3. The ink jet recording paper according to claim 1, wherein the water-soluble polyvalent metal compound is 10% by mass or more and 50% by mass or less with respect to the oxide equivalent value of the inorganic fine particles as an oxide equivalent value. The inkjet recording paper according to any one of claims 1 to 4, wherein the turbidity of the coating liquid for the A layer is 50 ppm or less. The inkjet recording paper according to claim 4, wherein the polyvalent metal of the water-soluble polyvalent metal compound is aluminum or zirconium. The inkjet recording paper according to any one of claims 1 to 6, wherein the inorganic fine particles are vapor-phase method silica fine particles.