JP2014087978A - Recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium that has high ink absorption and high fold-crack resistance.SOLUTION: The recording medium has a substrate, a first ink-receiving layer and a second ink-receiving layer as an outermost surface in this order. The first ink-receiving layer contains an inorganic particle, a polyvinyl alcohol having an acetoacetyl group and at least one kind of compound selected from among a dihydrazide compound, a water-soluble metal salt and a dialdehyde compound and the second ink-receiving layer contains an alumina hydrate and a polyvinyl alcohol having no acetoacetyl group.

Description

  The present invention relates to a recording medium.

  In recent years, inkjet recording methods are being applied in the field of commercial printing. In commercial printing, since recording is performed on a recording medium at a high speed, the recording medium to be used is required to have high ink absorbability.

  In the commercial printing field, there is a growing demand for photo books and photo albums. Photo books and photo albums can be spread by folding a recording medium on which an image is recorded in two. In this photobook or photo album manufacturing process, there is a known phenomenon (folding phenomenon) in which an image breaks along a fold when a recording medium on which an image is recorded is folded in half.

  As a method for suppressing the phenomenon that the surface of the recording medium breaks, Patent Document 1 discloses a recording medium having an ink receiving layer containing inorganic particles and polyvinyl alcohol having an acetoacetyl group.

JP 2006-239920 A

  However, according to the study by the present inventors, the recording medium described in Patent Document 1 has insufficient ink absorbability. Further, Patent Document 1 has been studying the cracking of the surface of the recording medium under the condition that the recording medium is wound around a cylinder having a diameter of 1 inch. Accordingly, it has been found that when the recording medium described in Patent Document 1 is folded in half as in the case of using it in a photobook or a photo album, a cracking phenomenon occurs.

  Accordingly, an object of the present invention is to provide a recording medium having high ink absorbability and high resistance to cracking.

  The above object is achieved by the present invention described below. That is, the recording medium according to the present invention includes a base material, a first ink receiving layer, and a second ink receiving layer which is the outermost ink receiving layer in this order, and the first ink receiving layer. Contains inorganic particles, polyvinyl alcohol having an acetoacetyl group, and at least one compound selected from a dihydrazide compound, a water-soluble metal salt, and a dialdehyde compound, and the second ink receiving layer comprises an alumina water solution. It contains a hydrate and polyvinyl alcohol having no acetoacetyl group.

  According to the present invention, it is possible to provide a recording medium having high ink absorbability and high crack resistance.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments.

[recoding media]
The recording medium of the present invention includes the base material, the first ink receiving layer, and the second ink receiving layer in this order. In the present invention, an inkjet recording medium used in the inkjet recording method is preferable. Hereinafter, each component constituting the recording medium of the present invention will be described.

<Base material>
As a base material, what is comprised only from a base paper, and the thing which has a base paper and a resin layer, ie, the thing by which the base paper is coat | covered with resin, are mentioned. In the present invention, it is preferable to use a base material having a base paper and a resin layer. In that case, the resin layer may be provided only on one side of the base paper, but is preferably provided on both sides.

  The base paper is made with wood pulp as a main raw material, and if necessary, synthetic pulp such as polypropylene and synthetic fibers such as nylon and polyester are added. Wood pulp includes hardwood bleached kraft pulp (LBKP), hardwood bleached sulfite pulp (LBSP), softwood bleached kraft pulp (NBKP), softwood bleached sulfite pulp (NBSP), hardwood bleached pulp (LDP), coniferous melted pulp (NDP) ), Hardwood unbleached kraft pulp (LUKP), and softwood unbleached kraft pulp (NUKP). These can use 1 type (s) or 2 or more types as needed. Among wood pulp, it is preferable to use LBKP, NBSP, LBSP, NDP, and LDP having a large amount of short fiber components. The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities. Moreover, the pulp which performed the bleaching process and improved the whiteness is also preferable. In the paper base material, a sizing agent, a white pigment, a paper strength enhancing agent, a fluorescent whitening agent, a moisture retention agent, a dispersing agent, and a softening agent may be appropriately added.

In the present invention, the paper density defined by JIS P 8118 of the base paper is preferably 0.6 g / cm ³ or more and 1.2 g / cm ³ or less. Further, it is more preferably 0.7 g / cm ³ or more and 1.2 g / cm ³ or less.

  In this invention, when a base material has a resin layer, it is preferable that the film thickness of a resin layer is 50 micrometers or more and 60 micrometers or less. In the present invention, the thickness of the resin layer is calculated by the following method. First, a cross section of the recording medium is cut out with a microtome, and the cross section is observed with a scanning electron microscope. And the film thickness of arbitrary 100 points | pieces or more of a resin layer is measured, and let the average value be the film thickness of a resin layer. The film thicknesses of the other layers in the present invention are calculated by the same method.

  The resin used for the resin layer is preferably a thermoplastic resin. Examples of the thermoplastic resin include acrylic resin, acrylic silicone resin, polyolefin resin, and styrene-butadiene copolymer. Among these, it is preferable to use a polyolefin resin. In the present invention, the polyolefin resin means a polymer using olefin as a monomer. Specific examples include a homopolymer and a copolymer such as ethylene, propylene, and isobutylene. The polyolefin resin can use 1 type (s) or 2 or more types as needed. Among these, it is preferable to use polyethylene. As the polyethylene, it is preferable to use low density polyethylene (LDPE) or high density polyethylene (HDPE). The resin layer may contain a white pigment, a fluorescent brightening agent, and ultramarine blue in order to adjust opacity, whiteness, and hue. Among them, it is preferable to contain a white pigment because opacity can be improved. Examples of the white pigment include rutile type or anatase type titanium oxide.

<Ink receiving layer>
The recording medium of the present invention has a first ink receiving layer and a second ink receiving layer. The second ink receiving layer is the outermost ink receiving layer. As long as the effects of the present invention are not impaired, other ink receiving layers are provided between the substrate and the first ink receiving layer or between the first ink receiving layer and the second ink receiving layer. It may be. Further, the ink receiving layer may be provided on only one side of the base material or on both sides. When the ink receiving layer is provided on both sides, it is preferable that both sides have a first ink receiving layer and a second ink receiving layer that satisfy the configuration of the present invention.

  In the present invention, the total thickness of the first ink receiving layer and the second ink receiving layer is preferably 15 μm or more and 30 μm or less. The film thickness of the first ink receiving layer is more preferably 1.0 times or more and 14.0 times or less with respect to the film thickness of the second ink receiving layer, and 2.0 times or more and 9. More preferably, it is 0 times or less. If it is less than 2.0 times, the effect of improving the cracking resistance of the recording medium may not be sufficiently obtained, and if it is more than 9.0 times, the effect of improving the ink absorbability may not be sufficiently obtained. is there. In the present invention, the film thickness of the ink receiving layer is a film thickness at the time of drying. Arbitrary 10 points of the ink receiving layer are selected, and the film thickness at each point is measured with an electron microscope and is an average value. is there.

(1) Material used for first ink receiving layer In the present invention, the first ink receiving layer comprises inorganic particles, polyvinyl alcohol having an acetoacetyl group as a binder, a dihydrazide compound, a water-soluble metal salt, and a dialdehyde. And at least one compound selected from compounds.

  The film thickness of the first ink receiving layer is preferably 8 μm or more and 32 μm or less, and more preferably 10 μm or more and 27 μm or less.

(Inorganic particles)
In the present invention, examples of the inorganic particles used in the first ink receiving layer include alumina hydrate, alumina, silica, colloidal silica, titanium dioxide, zeolite, kaolin, talc, hydrotalcite, zinc oxide, and zinc hydroxide. , Aluminum silicate, calcium silicate, magnesium silicate, zirconium oxide, and zirconium hydroxide. These inorganic particles can be used alone or in combination of two or more as required. Among the inorganic particles, it is preferable to use alumina hydrate, alumina, or silica that can form a porous structure with high ink absorbability. Furthermore, it is more preferable to use alumina hydrate.

(Polyvinyl alcohol having an acetoacetyl group)
Polyvinyl alcohol having an acetoacetyl group can be synthesized by a known method. For example, the method of reacting polyvinyl alcohol and diketene is mentioned. The amount of acetoacetyl groups in polyvinyl alcohol having acetoacetyl groups can be expressed by the degree of acetoacetylation. The degree of acetoacetylation is determined by using nuclear magnetic resonance spectroscopy ( ¹ H-NMR), and the peak intensity of protons derived from CH ₃ in the acetoacetyl group and the peak intensity of protons derived from CH ₂ in the polyvinyl alcohol main chain. Can be calculated by comparing. In the present invention, the degree of acetoacetylation is preferably from 0.1 mol% to 20.0 mol%, more preferably from 1.0 mol% to 15.0 mol%.

  In the present invention, the saponification degree of polyvinyl alcohol having an acetoacetyl group is preferably 80 mol% or more and 100 mol% or less, and more preferably 85 mol% or more and 100 mol% or less. The degree of saponification is the ratio of the number of moles of hydroxyl groups produced by the saponification reaction when polyvinyl alcohol is obtained by saponifying polyvinyl acetate. In the present invention, the value measured by the method of JIS-K6726. Shall be used.

  Moreover, the average polymerization degree of polyvinyl alcohol having an acetoacetyl group is preferably 500 or more and 5,000 or less, and more preferably 1,000 or more and 4,500 or less. In the present invention, the average degree of polymerization is the viscosity average degree of polymerization determined by the method of JIS-K6726.

  The content of polyvinyl alcohol having an acetoacetyl group in the first ink receiving layer is preferably 3.0% by mass or more and 30.0% by mass or less with respect to the content of inorganic particles. It is more preferable that the content is not less than 2% by mass and not more than 20.0% by mass. If it is less than 3.0% by mass, the effect of improving the crack resistance of the recording medium may not be sufficiently obtained. If it is larger than 30.0% by mass, the ink absorption improvement effect may not be sufficiently obtained.

(At least one compound selected from dihydrazide compounds, water-soluble metal salts and dialdehyde compounds)
In the present invention, at least one compound selected from a dihydrazide compound, a water-soluble metal salt, and a dialdehyde compound functions as a crosslinking agent for polyvinyl alcohol having an acetoacetyl group. These content is preferably 0.01 g / ^{m 2} or more 3.00 g / ^{m 2} or less, 0.05 g / ^{m 2} or more 2.00 g / ^{m 2} or less is more preferable.

  Examples of the dihydrazide compound that can be used in the present invention include carbodihydrazide, oxalic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, isophthalic acid dihydrazide, and terephthalic acid dihydrazide. Among these, succinic acid dihydrazide, adipic acid dihydrazide, and sebacic acid dihydrazide are preferable, and adipic acid dihydrazide is more preferable.

  Examples of water-soluble metal salts that can be used in the present invention include zirconium salts, aluminum salts, and titanium salts. Of these, zirconium salts are preferred. Zirconium salts include zirconium nitrate, basic zirconium carbonate, zirconium acetate, zirconium sulfate, zirconium oxychloride, basic zirconium chloride, hydroxy zirconium chloride, zirconium carbonate, ammonium zirconium carbonate, and potassium zirconium carbonate. Among these, zirconium nitrate, basic zirconium chloride, and ammonium zirconium carbonate are more preferable, and zirconium nitrate and basic zirconium chloride are particularly preferable.

  Examples of the dialdehyde compound that can be used in the present invention include glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, and maleindialdehyde. Of these, glyoxal is preferable.

(2) Material used for second ink receiving layer In the present invention, the second ink receiving layer contains alumina hydrate as inorganic particles and polyvinyl alcohol having no acetoacetyl group as a binder. The film thickness of the second ink receiving layer is preferably 2 μm or more and 13 μm or less, and more preferably 3 μm or more and 10 μm or less. If it is smaller than 2 μm, the ink absorption improvement effect may not be sufficiently obtained. If it is larger than 13 μm, the effect of improving the crack resistance of the recording medium may not be sufficiently obtained.

(Alumina hydrate)
In the present invention, the alumina hydrate is
Formula _{(X): Al 2 O 3} -n (OH) 2n · mH 2 O
(In general formula (X), n is 0, 1, 2, or 3, m is 0 or more and 10 or less, preferably 0 or more and 5 or less. However, m and n are not 0 at the same time.)
What is represented by these can be used suitably. In many cases, mH ₂ O represents a detachable aqueous phase that does not participate in the formation of a crystal lattice, and therefore m may not be an integer. Also, m can be zero when the alumina hydrate is heated.

  In the present invention, the alumina hydrate can be produced by a known method. Specifically, a method of hydrolyzing aluminum alkoxide, a method of hydrolyzing sodium aluminate, and a method of neutralizing an aqueous solution of sodium aluminate by adding an aqueous solution of aluminum sulfate or aluminum chloride.

  In the present invention, the volume average particle diameter of the alumina hydrate is preferably 1.0 mm or less.

  As the crystal structure of the alumina hydrate, amorphous, kibsite type, and boehmite type are known depending on the heat treatment temperature. The crystal structure of alumina hydrate can be analyzed by an X-ray diffraction method. Of these, boehmite type alumina hydrate or amorphous alumina hydrate is preferable in the present invention. Specific examples include alumina hydrates described in JP-A-7-232473, JP-A-8-132731, JP-A-9-66664, JP-A-9-76628, and commercially available alumina water. Examples of Japanese products include Dispersal HP14 and HP18 (above, manufactured by Sasol). These alumina hydrates can be used alone or in combination of two or more as required.

In the present invention, the specific surface area of the alumina hydrate determined by the BET method is preferably 100 m ² / g or more and 200 m ² / g or less, more preferably 125 m ² / g or more and 175 m ² / g or less. preferable. Here, the BET method is a method in which a specific surface area of a sample is measured from an adsorbed amount by adsorbing molecules and ions of a known size on the sample surface. In the present invention, nitrogen gas is used as the gas adsorbed on the sample.

  In the present invention, by using alumina hydrate as the inorganic particles of the second ink receiving layer which is the outermost ink receiving layer, the ink can be favorably absorbed immediately after the ink is applied to the recording medium. Can do. This is presumably because alumina hydrate has a higher surface energy than other inorganic particles. In the present invention, the inorganic particles used in the second ink receiving layer are preferably only alumina hydrate, but may be 10% by mass or less based on the total content of the inorganic particles in the second ink receiving layer. For example, other inorganic particles may be used in combination.

(Polyvinyl alcohol without acetoacetyl group)
Examples of polyvinyl alcohol having no acetoacetyl group include polyvinyl alcohol synthesized by saponifying polyvinyl acetate.

  The saponification degree of polyvinyl alcohol is preferably 80 mol% or more and 100 mol% or less, and more preferably 85 mol% or more and 100 mol% or less. Moreover, 1,500 or more and 5,000 or less are preferable and, as for the average degree of polymerization of polyvinyl alcohol, 2,000 or more and 5,000 or less are more preferable.

  The content of polyvinyl alcohol having no acetoacetyl group in the second ink receiving layer is preferably 3.0% by mass or more and 20.0% by mass or less with respect to the content of alumina hydrate. More preferably, it is 5.0 mass% or more and 14.0 mass% or less. If it is less than 5.0% by mass, the effect of improving the crack resistance of the recording medium may not be sufficiently obtained. If it is greater than 14.0% by mass, the ink absorption improvement effect may not be sufficiently obtained.

(3) Materials that can be used in common for the first and second ink receiving layers (boric acid and borate)
In the present invention, the first and second ink receiving layers preferably further contain at least one selected from boric acid and borates. By containing boric acid or borate, the water resistance of the ink receiving layer is increased, and the binder absorbs the ink and swells, so that the capillary force is weakened and the ink absorbability can be prevented from being lowered. .

  The ratio A of the content of boric acid and borate to the content of polyvinyl alcohol having an acetoacetyl group in the first ink receiving layer is preferably 0% by mass or more and 15% by mass or less. More preferably, it is 12 mass% or less. Further, the ratio B of the content of boric acid and borate to the content of polyvinyl alcohol having no acetoacetyl group in the second ink receiving layer is 5% by mass or more and 35% by mass or less. Preferably, it is 10 mass% or more and 30 mass% or less. Moreover, it is preferable that the ratio A and the ratio B satisfy the relationship of 0 <B / A <1.

Examples of boric acid include orthoboric acid (H ₃ BO ₃ ), metaboric acid, and diboric acid. As the borate, the water-soluble salt of boric acid is preferable. Examples thereof include alkali metal salts of boric acid such as sodium salt and potassium salt of boric acid; alkaline earth metal salts of boric acid such as magnesium salt and calcium salt of boric acid; ammonium salt of boric acid. Among these, it is preferable to use orthoboric acid from the viewpoint of the temporal stability of the coating liquid and the effect of suppressing the occurrence of cracks.

(Other binders)
The first and second ink receiving layers may further contain other binders in addition to the above binder. In the present invention, the binder means a material that can bind inorganic particles and form a film.

  Examples of the binder include starch derivatives such as oxidized starch, etherified starch and phosphate esterified starch; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; casein, gelatin, soybean protein, and derivatives thereof; polyvinylpyrrolidone, maleic anhydride Resin, conjugated polymer latex such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer; acrylic polymer latex such as polymer of acrylic acid ester and methacrylic acid ester; such as ethylene-vinyl acetate copolymer Vinyl polymer latex; functional group-modified polymer latex with a functional group-containing monomer such as a carboxyl group of the above polymer; a product obtained by cationizing the polymer with a cationic group; using a cationic surfactant Above The polymer surface is cationized; the monomer constituting the polymer is polymerized under cationic polyvinyl alcohol, and the polyvinyl alcohol is distributed on the surface of the polymer; in a suspension dispersion of cationic colloidal particles The monomer constituting the polymer is polymerized and cationic colloidal particles are distributed on the surface of the polymer; an aqueous binder such as a thermosetting synthetic resin such as a melamine resin or a urea resin; an acrylic ester such as polymethyl methacrylate And polymers and copolymers of methacrylic acid ester; synthetic resins such as polyurethane resin, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, alkyd resin. These binders can use 1 type (s) or 2 or more types as needed.

(Additive)
Each of the first and second ink receiving layers has various additives as necessary, for example, fixing agents such as various cationic resins, flocculants such as polyvalent metal salts, surfactants, fluorescent whitening agents, brightening agents. Adhesives, antifoaming agents, antifoaming agents, mold release agents, penetrating agents, lubricants, UV absorbers, antioxidants, leveling agents, preservatives, pH regulators, and other various auxiliary agents known in the technical field Can be added.

  Among these, it is preferable to contain a cationic resin. Examples of cationic resins that can be used in the present invention include polyethyleneimine resins, polyamine resins, polyamide resins, polyamide epichlorohydrin resins, polyamine epichlorohydrin resins, polyamide polyamine epichlorohydrin resins, polydiallylamine resins, dicyandiamide condensates, etc. Is mentioned. These cationic resins can use 1 type (s) or 2 or more types as needed.

  Further, it is preferable to contain a pH adjusting agent in order to adjust the surface pH of the recording medium. In the present invention, the surface pH of the recording medium is preferably 4.5 or more, 5.5 or less, more preferably 4.8 or more and 5.3 or less, and particularly preferably 5.0 or more and 5.2 or less. An acid is mentioned as a pH adjuster. As the acid, alkylsulfonic acid is preferable. When the first and second ink receiving layers contain alkylsulfonic acid, the content thereof is preferably 1.3% by mass or more and 2.1% by mass or less, respectively, with respect to the inorganic particles. It is more preferable that the content is 4% by mass or more and 1.9% by mass or less. Examples of the alkyl sulfonic acid include methane sulfonic acid, ethane sulfonic acid, butane sulfonic acid, and isopropane sulfonic acid. Of these, methanesulfonic acid is preferably used. In addition to the alkylsulfonic acid, a strong acid such as hydrochloric acid or nitric acid may be used in combination.

[Method of manufacturing recording medium]
In the present invention, the method for producing a recording medium is not particularly limited, but the recording medium includes a step of preparing a coating liquid for the ink receiving layer and a step of coating the base material with the coating liquid for the ink receiving layer. A method for producing the medium is preferred. Hereinafter, a method for manufacturing the recording medium will be described.

<Method for producing substrate>
In the present invention, a generally used paper making method can be applied as a method for producing the base paper. Examples of the paper machine include a long paper machine, a round paper machine, a cylinder, and a twin wire. In order to improve the surface smoothness of the base paper, surface treatment may be performed by applying heat and pressure during the paper making process or after the paper making process. Specific surface treatment methods include calendar processing such as machine calendar and super calendar.

  Examples of a method of providing a resin layer on the base paper, that is, a method of coating the base paper with a resin include a melt extrusion method, wet lamination, and dry lamination. Among these, a melt extrusion method in which a molten resin is applied to one side or both sides of a base paper by extrusion coating is preferable. For example, a method of laminating a resin layer on a base paper by bringing the conveyed base paper into contact with the resin extruded from an extrusion die at a nip point between a nip roller and a cooling roller and pressing the nip at the nip (extrusion). (Also called coating method) is widely adopted. When the resin layer is provided by melt extrusion, pretreatment may be performed so that the adhesion between the base paper and the resin layer becomes stronger. Examples of the pretreatment include acid etching treatment using a mixed solution of chromic sulfate, flame treatment using a gas flame, ultraviolet irradiation treatment, corona discharge treatment, glow discharge treatment, and anchor coat treatment such as alkyl titanate. Among these, corona discharge treatment is preferable.

  In the case of forming an undercoat layer or a backcoat layer, an undercoat layer coating solution or a backcoat layer coating solution may be prepared in advance and applied to a substrate.

<Method for forming ink receiving layer>
In the recording medium of the present invention, examples of the method for forming the ink receiving layer on the substrate include the following methods. First, an ink receiving layer coating solution is prepared. And the recording medium of this invention can be obtained by apply | coating and drying the said coating liquid on a base material. As a coating method of the coating liquid, a curtain coater, a coater using an extrusion method, or a coater using a slide hopper method can be used. In addition, you may heat a coating liquid at the time of coating. In addition, as a drying method after coating, a method using a hot air dryer such as a straight tunnel dryer, an arch dryer, an air loop dryer, a sine curve air float dryer, a drying using infrared rays, a heating dryer, or a microwave. The method using a machine is mentioned.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited in any way by the following examples as long as the gist thereof is not exceeded. In the description of the following examples, “part” is based on mass unless otherwise specified.

<Example 1>
(Preparation of base material)
Canada Standard Freeness 450 mLCSF LBKP 80 parts, Canada Standard Freeness 480 mLCSF NBKP 20 parts, Cationic Starch 0.60 parts, Heavy Calcium Carbonate 10 parts, Light Calcium Carbonate 15 parts, Alkylketene Dimer 0.10 parts Then, 0.030 parts of cationic polyacrylamide was mixed, and water was added so that the solid content was 3.0% by mass to obtain a paper stock. Next, the stock was made with a long paper machine, subjected to a three-stage wet press, and then dried with a multi-cylinder dryer. Thereafter, an aqueous solution of oxidized starch is impregnated and dried so that the solid content after drying with a size press machine is 1.0 g / m ^2, and further machine calendering is performed, and the basis paper has a basis weight of 155 g / m ² . Was made. Next, a resin composition consisting of 70 parts of low density polyethylene, 20 parts of high density polyethylene and 10 parts of titanium oxide was applied to one side of the base paper so that the dry coating amount was 25 g / m ² . . This surface is the surface of the substrate. Furthermore, the base material was obtained by applying the resin composition which consists of 50 parts of low density polyethylene and 50 parts of high density polyethylene to the other surface (back surface) of a base paper.

(Preparation of crosslinking agent coating solution 1)
Adipic acid dihydrazide was added to ion-exchanged water so as to have a concentration of 10%, and stirred and dissolved to obtain a crosslinking agent coating solution 1.

(Preparation of the first ink receiving layer coating solution 1)
Alumina hydrate (trade name: Disspiral HP14, manufactured by Sasol) was added to the ion-exchanged water so that the concentration was 30% by mass. Next, 1.4% by mass of methanesulfonic acid was added to the alumina hydrate and stirred to obtain a colloidal sol. The obtained colloidal sol was diluted with ion-exchanged water so that the alumina hydrate concentration was 27% by mass to obtain a colloidal sol.

  On the other hand, polyvinyl alcohol having an acetoacetyl group (trade name: Z210, manufactured by Nippon Synthetic Chemical) is added to ion-exchanged water so as to have a concentration of 8%. Obtained.

  The obtained polyvinyl alcohol aqueous solution having an acetoacetyl group and the colloidal sol were mixed so that the polyvinyl alcohol having an acetoacetyl group was 10% by mass with respect to the alumina hydrate. To this, a 3.0% by mass boric acid aqueous solution is mixed so that boric acid is 8% by mass with respect to polyvinyl alcohol having an acetoacetyl group to obtain a first ink-receiving layer coating solution 1. It was.

(Preparation of second ink-receiving layer coating solution 1)
Alumina hydrate (trade name: Disspiral HP14, manufactured by Sasol) was added to the ion-exchanged water so that the concentration was 30% by mass. Next, 1.4% by mass of methanesulfonic acid was added to the alumina hydrate and stirred to obtain a colloidal sol. The obtained colloidal sol was diluted with ion-exchanged water so that the alumina hydrate concentration was 27% by mass to obtain a colloidal sol.

  On the other hand, polyvinyl alcohol having no acetoacetyl group (trade name: PVA235, manufactured by Kuraray Co., Ltd., polymerization degree 3,500, saponification degree 88 mol%) is added to ion-exchanged water so as to have a concentration of 8%, followed by stirring and dissolution. Thus, an aqueous polyvinyl alcohol solution was obtained.

  The obtained polyvinyl alcohol aqueous solution and the colloidal sol were mixed so that the polyvinyl alcohol was 10% by mass with respect to the alumina hydrate. A 3.0% by mass boric acid aqueous solution was mixed with polyvinyl alcohol so that boric acid was 20% by mass to obtain a second ink-receiving layer coating solution 1.

(Preparation of recording medium)
The cross-linking agent coating liquid 1, the first ink receiving layer coating liquid 1, and the second ink receiving layer coating liquid 1 are applied simultaneously on the base material obtained above using a slide die coater. The recording medium of Example 1 was obtained by drying with warm air of 40 ° C. The dry coating amount of the crosslinking agent was 0.5 g / m ² , the film thickness of the first ink receiving layer was 20 μm, and the film thickness of the second ink receiving layer was 5 μm.

<Example 2>
A recording medium was produced in the same manner as in Example 1 except that the first ink-receiving layer coating solution 1 was changed to the first ink-receiving layer coating solution 2 in Example 1.

(First ink receiving layer coating solution 2)
Silica (trade name: AEROSIL300, manufactured by EVONIK) was added to the ion-exchanged water so that the concentration was 22% by mass. Next, 5.0% by mass of a cationic polymer (trade name: Charol DC902P, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to silica and stirred to obtain a colloidal sol. The obtained colloidal sol was diluted with ion-exchanged water so that the silica concentration was 18% by mass to obtain a colloidal sol.

  On the other hand, polyvinyl alcohol having an acetoacetyl group (trade name: Z210, manufactured by Nippon Synthetic Chemical) is added to ion-exchanged water so as to have a concentration of 8%. Obtained.

  The obtained polyvinyl alcohol aqueous solution having an acetoacetyl group and the colloidal sol were mixed so that the polyvinyl alcohol having an acetoacetyl group was 20% by mass with respect to silica. To this, a 3.0% by mass boric acid aqueous solution is mixed with polyvinyl alcohol having an acetoacetyl group so that boric acid is 8% by mass to obtain a first ink-receiving layer coating solution 2. It was.

<Example 3>
A recording medium was produced in the same manner as in Example 1 except that the crosslinking agent was changed to zirconium nitrate in Example 1.

<Example 4>
A recording medium was produced in the same manner as in Example 1, except that the ratio of polyvinyl alcohol to alumina hydrate in the second ink-receiving layer coating solution was changed to 5% by mass. did.

<Example 5>
A recording medium was obtained in the same manner as in Example 1 except that the ratio of polyvinyl alcohol to alumina hydrate in the second ink-receiving layer coating solution was changed to 7.5% by mass. Was made.

<Example 6>
A recording medium was obtained in the same manner as in Example 1 except that the ratio of polyvinyl alcohol to alumina hydrate in the second ink-receiving layer coating solution was changed to 12.5% by mass. Was made.

<Example 7>
A recording medium was produced in the same manner as in Example 1, except that the ratio of polyvinyl alcohol to alumina hydrate in the second ink-receiving layer coating solution was changed to 14% by mass. did.

<Example 8>
A recording medium was produced in the same manner as in Example 1, except that the ratio of polyvinyl alcohol to alumina hydrate in the second ink-receiving layer coating solution was changed to 3% by mass. did.

<Example 9>
A recording medium was produced in the same manner as in Example 1, except that the ratio of polyvinyl alcohol to alumina hydrate in the second ink-receiving layer coating solution was changed to 17% by mass. did.

<Example 10>
A recording medium was produced in the same manner as in Example 1, except that the ratio of polyvinyl alcohol to alumina hydrate in the second ink-receiving layer coating solution was changed to 20% by mass. did.

<Example 11>
In Example 1, the ratio of boric acid to polyvinyl alcohol in the second ink-receiving layer coating solution was changed to 10% by mass. Further, the ratio of boric acid to polyvinyl alcohol having an acetoacetyl group in the first ink-receiving layer coating solution was changed to 12% by mass. A recording medium was manufactured in the same manner as Example 1 except for these.

<Example 12>
In Example 1, the ratio of boric acid to polyvinyl alcohol in the second ink-receiving layer coating solution was changed to 10% by mass. In addition, the ratio of boric acid to polyvinyl alcohol having an acetoacetyl group in the first ink-receiving layer coating solution was changed to 15% by mass. A recording medium was manufactured in the same manner as Example 1 except for these.

<Example 13>
In Example 1, the ratio of boric acid to polyvinyl alcohol in the second ink-receiving layer coating solution was changed to 5% by mass. Further, the ratio of boric acid to polyvinyl alcohol having an acetoacetyl group in the first ink receiving layer coating solution was changed to 10% by mass. A recording medium was manufactured in the same manner as Example 1 except for these.

<Example 14>
A recording medium was prepared in the same manner as in Example 1 except that the ratio of boric acid to polyvinyl alcohol in the second ink-receiving layer coating solution was changed to 10% by mass.

<Example 15>
A recording medium was produced in the same manner as in Example 1 except that the ratio of boric acid to polyvinyl alcohol in the second ink-receiving layer coating solution was changed to 15% by mass.

<Example 16>
A recording medium was prepared in the same manner as in Example 1 except that the ratio of boric acid to polyvinyl alcohol in the second ink-receiving layer coating solution was changed to 25% by mass.

<Example 17>
A recording medium was produced in the same manner as in Example 1 except that the ratio of boric acid to polyvinyl alcohol in the second ink-receiving layer coating solution was changed to 30% by mass.

<Example 18>
A recording medium was produced in the same manner as in Example 1 except that the ratio of boric acid to polyvinyl alcohol in the second ink-receiving layer coating solution was changed to 5% by mass.

<Example 19>
A recording medium was produced in the same manner as in Example 1, except that the ratio of boric acid to polyvinyl alcohol in the second ink-receiving layer coating solution was changed to 35% by mass.

<Example 20>
In Example 1, recording was performed in the same manner as in Example 1 except that the ratio of boric acid to polyvinyl alcohol having an acetoacetyl group in the first ink-receiving layer coating solution was changed to 1% by mass. A medium was made.

<Example 21>
In Example 1, recording was performed in the same manner as in Example 1 except that the ratio of boric acid to polyvinyl alcohol having an acetoacetyl group in the first ink-receiving layer coating solution was changed to 5% by mass. A medium was made.

<Example 22>
In Example 1, recording was performed in the same manner as in Example 1 except that the ratio of boric acid to polyvinyl alcohol having an acetoacetyl group in the first ink-receiving layer coating solution was changed to 12% by mass. A medium was made.

<Example 23>
In Example 1, recording was performed in the same manner as in Example 1 except that the ratio of boric acid to polyvinyl alcohol having an acetoacetyl group in the first ink-receiving layer coating solution was changed to 15% by mass. A medium was made.

<Example 24>
In Example 1, boric acid was not added to the first ink-receiving layer coating solution. A recording medium was manufactured in the same manner as in Example 1 except for the above.

<Example 25>
In Example 1, the dry film thickness of the second ink receiving layer was changed to 3 μm. Further, the dry film thickness of the first ink receiving layer was changed to 27 μm. A recording medium was manufactured in the same manner as Example 1 except for these.

<Example 26>
In Example 1, the dry film thickness of the second ink receiving layer was changed to 10 μm. Further, the dry film thickness of the first ink receiving layer was changed to 20 μm. A recording medium was manufactured in the same manner as Example 1 except for these.

<Example 27>
In Example 1, the dry film thickness of the second ink receiving layer was changed to 2 μm. The dry film thickness of the first ink receiving layer was changed to 28 μm. A recording medium was manufactured in the same manner as Example 1 except for these.

<Example 28>
In Example 1, the dry film thickness of the second ink receiving layer was changed to 13 μm. Further, the dry film thickness of the first ink receiving layer was changed to 17 μm. A recording medium was manufactured in the same manner as Example 1 except for these.

<Example 29>
In Example 1, the dry film thickness of the second ink receiving layer was changed to 6 μm. Further, the dry film thickness of the first ink receiving layer was changed to 24 μm. A recording medium was manufactured in the same manner as Example 1 except for these.

<Example 30>
In Example 1, the dry film thickness of the second ink receiving layer was changed to 3 μm. Further, the dry film thickness of the first ink receiving layer was changed to 12 μm. A recording medium was manufactured in the same manner as Example 1 except for these.

<Example 31>
In Example 1, the dry film thickness of the second ink receiving layer was changed to 8 μm. Further, the dry film thickness of the first ink receiving layer was changed to 32 μm. A recording medium was manufactured in the same manner as Example 1 except for these.

<Example 32>
In Example 1, the dry film thickness of the second ink receiving layer was changed to 2 μm. Further, the dry film thickness of the first ink receiving layer was changed to 8 μm. A recording medium was manufactured in the same manner as Example 1 except for these.

<Comparative Example 1>
A recording medium was produced in the same manner as in Example 1 except that the polyvinyl alcohol of the second ink receiving layer was changed to polyvinyl alcohol having an acetoacetyl group in Example 1.

<Comparative example 2>
A recording medium was prepared in the same manner as in Example 1 except that the polyvinyl alcohol having an acetoacetyl group in the first ink receiving layer was changed to polyvinyl alcohol.

<Comparative Example 3>
In Example 1, the polyvinyl alcohol of the second ink receiving layer was changed to polyvinyl alcohol having an acetoacetyl group. Further, polyvinyl alcohol having an acetoacetyl group in the first ink receiving layer was changed to polyvinyl alcohol. A recording medium was manufactured in the same manner as Example 1 except for these.

<Comparative Example 4>
A recording medium was produced in the same manner as in Example 2 except that the second ink-receiving layer coating solution 1 was changed to the second ink-receiving layer coating solution 2 in Example 2.

(Second ink-receiving layer coating solution 2)
Silica (trade name: AEROSIL300, manufactured by EVONIK) was added to the ion-exchanged water so that the concentration was 22% by mass. Next, 5.0% by mass of a cationic polymer (trade name: Charol DC902P, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to silica and stirred to obtain a colloidal sol. The obtained colloidal sol was diluted with ion-exchanged water so that the silica concentration was 18% by mass to obtain a colloidal sol.
On the other hand, polyvinyl alcohol (trade name: PVA235, manufactured by Kuraray Co., Ltd., polymerization degree 3500, saponification degree 88%) was added to ion-exchanged water so as to have a concentration of 8%, and stirred and dissolved to obtain an aqueous polyvinyl alcohol solution.

  The obtained polyvinyl alcohol aqueous solution and the colloidal sol were mixed so that acetopolyvinyl alcohol was 20% by mass with respect to silica. To this, a 3.0% by mass boric acid aqueous solution was mixed with polyvinyl alcohol so that boric acid was 20% by mass to obtain a second ink-receiving layer coating solution 2.

<Comparative Example 5>
A recording medium was produced in the same manner as in Example 1 except that the second ink-receiving layer coating solution 1 was changed to the second ink-receiving layer coating solution 2 in Example 1.

<Comparative Example 6>
In Comparative Example 4, the ratio of polyvinyl alcohol to silica in the second ink-receiving layer coating solution was changed to 10% by mass. Moreover, the ratio of the polyvinyl alcohol which has an acetoacetyl group with respect to the silica of the 1st ink receiving layer coating liquid was changed to 10 mass%. Except for these, a recording medium was produced in the same manner as in Comparative Example 4, but the ink-receiving layer coating solution could not be applied.

<Comparative Example 7>
In Comparative Example 5, a recording medium was prepared in the same manner as in Comparative Example 5 except that the ratio of polyvinyl alcohol to silica in the second ink-receiving layer coating solution was changed to 10% by mass. The coating liquid for coating could not be applied.

<Comparative Example 8>
In Example 2, a recording medium was produced in the same manner as in Example 2 except that the ratio of polyvinyl alcohol having an acetoacetyl group to silica in the first ink-receiving layer coating solution was changed to 10% by mass. However, the ink receiving layer coating solution could not be applied.

<Comparative Example 9>
In Example 1, the second ink-receiving layer coating solution was not applied. A recording medium was manufactured in the same manner as in Example 1 except for the above.

<Comparative Example 10>
In Comparative Example 2, the second ink-receiving layer coating solution was not applied. A recording medium was manufactured in the same manner as in Comparative Example 2 except for this.

<Comparative Example 11>
In Example 1, the crosslinking agent coating solution was not applied. A recording medium was manufactured in the same manner as in Example 1 except for the above.

Abbreviations in the table are as follows.
AAPVA: polyvinyl alcohol having an acetoacetyl group ADH: adipic acid dihydrazide nitrate Zr: zirconium nitrate [Evaluation]
The following evaluation was performed using each recording medium obtained above. In the following evaluation criteria, A and B were preferable levels, and C was an unacceptable level. As described above, Comparative Examples 6 to 8 were not evaluated because the ink-receiving layer coating solution could not be applied.

<Fracture resistance>
A black solid image was recorded on the entire surface of each recording medium obtained above using an inkjet printer (trade name: MP990, manufactured by Canon Inc.). The recording medium was folded in half so that the obtained image was on the inside, and a 500 kg load was applied using a press machine for 5 minutes to make a crease. After opening and closing the creased recording medium 20 times, the crease portion was visually observed to evaluate the crease resistance. The evaluation criteria are as follows. The evaluation results are shown in Table 2.
A: Almost no white streak was seen along the crease.
B: Slight white streaks were seen along the crease, but the level was not worrisome.
C: A white streak was clearly seen along the crease.

<Ink absorbability>
A green solid image was recorded on each of the recording media obtained above in the “photo paper glossy gold, no color correction” mode using an inkjet printer (trade name: MP990, manufactured by Canon Inc.). The obtained image was visually observed to evaluate ink absorbency. The evaluation criteria are as follows. The evaluation results are shown in Table 2.
A: Color unevenness was hardly seen.
B: Slight color unevenness was observed but at a level that was not a concern.
C: Color unevenness was considerably observed.

Claims (6)

A recording medium having a substrate, a first ink receiving layer, and a second ink receiving layer which is an outermost ink receiving layer in this order,
The first ink receiving layer contains inorganic particles, polyvinyl alcohol having an acetoacetyl group, and at least one compound selected from a dihydrazide compound, a water-soluble metal salt, and a dialdehyde compound,
The recording medium, wherein the second ink receiving layer contains alumina hydrate and polyvinyl alcohol having no acetoacetyl group.   The content of the polyvinyl alcohol having no acetoacetyl group in the second ink receiving layer is 5.0% by mass or more and 14.0% by mass or less with respect to the content of the alumina hydrate. The recording medium according to claim 1. The first ink receiving layer further contains at least one selected from boric acid and borate; the second ink receiving layer further contains at least one selected from boric acid and borate;
The ratio A of the boric acid and borate content to the content of polyvinyl alcohol having the acetoacetyl group in the first ink receiving layer is 1 to 12% by mass,
The content ratio B of the boric acid and borate to the content of polyvinyl alcohol having no acetoacetyl group in the second ink receiving layer is 10% by mass or more and 30% by mass or less. Item 3. The recording medium according to Item 1 or 2.   The ratio A of the content of boric acid and borate to the content of polyvinyl alcohol having the acetoacetyl group in the first ink receiving layer, and the acetoacetyl group in the second ink receiving layer The ratio B of the content of the boric acid and borate with respect to the content of polyvinyl alcohol that does not have the content satisfies the relationship of 0 <B / A <1. Recording media.   The film thickness of the first ink receiving layer is 2.0 times or more and 9.0 times or less with respect to the film thickness of the second ink receiving layer. Recording media. 6. The recording medium according to claim 1, wherein a total thickness of the first ink receiving layer and a thickness of the second ink receiving layer is 15 μm or more and 30 μm or less.