JP2000318303A - Ink-jet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet recording medium recordable in ink which has a high ink absorbing capacity, and an excellent image coloring capacity, and is excellent in giving an artistic feeling by an uneven pattern formed by embossing a support when printed. SOLUTION: This ink-jet recording medium comprises a water-resistant opaque support, and an ink receiving layer which is provided on the water- resistant opaque support. The side where the ink receiving layer is provided of the water-resistant opaque support is embossed, and the ink receiving layer which is provided on the water-resistant opaque support is a porous layer mainly containing inorganic ultra-fine particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording medium for recording using ink, and further has high ink absorbency, excellent image color, and is provided with a pattern when printed. The present invention relates to an ink jet recording medium having excellent aesthetic sensation due to the formed uneven pattern.

[0002]

2. Description of the Related Art Ink-jet recording is a method in which fine droplets of ink are made to fly and adhere to a recording medium such as paper by various operating principles to record images and characters. It has features such as easy multi-coloring, great flexibility in recording patterns, and no need for development-fixing. It has rapidly spread in various uses as a recording device for various figures and color images including Chinese characters. I have. Further, an image formed by the multi-color ink jet system can obtain a record comparable to multi-color printing by a plate making system or printing by a color photographic system. In addition, in applications requiring a small number of copies, it is being widely applied to the field of full-color image recording because it is less expensive than the photographic technique.

In addition, the cost of the ink jet recording apparatus has been reduced,
Because it is possible to easily obtain an image with excellent image reproducibility and color reproducibility such as sharpness and color at the level of a personal computer, an ink jet recording device can be used from a special recording device used for a specific person to a general-purpose one. In recent years, the recording apparatus has been changed, and in recent years, in particular, the ink jet recording apparatus has been further improved in definition, and the ratio of possession by an individual has been greatly increased due to the appearance of an ink jet recording apparatus that claims photographic quality at a low price. I have.

[0004] Further, with diversification of uses, they are increasingly used for large-sized posters, POP arts, and drafting applications. In these applications, the high sharpness of the ink jet can be utilized and excellent color can be obtained, so that a good image can be obtained, and the advertising effect is large. Application to these is because it is possible to easily obtain an image excellent in image reproducibility and color reproducibility such as sharpness and color at the level of a personal computer, which is also a reason for frequently using an ink jet recording medium. .

[0005] Due to the high performance and diversification of applications of these ink jet recording apparatuses, the characteristics and demands required of the ink jet recording medium have been considerably increased. In particular, in a recording device that claims high definition of an image or a recording device capable of large-format printing, the amount of ink used to form an image is considerably increased, and an ink receiving layer for absorbing the ink is used. Is improving.

[0006] Further, diversification of uses has also occurred with respect to the appearance of ink jet recording media. In addition to the conventional glossy or low gloss appearance of plain paper and matte paper, art paper, coated paper, cast paper and cast paper have been developed. There is a demand for an appearance having gloss similar to paper, photographic paper, and the like. This is because ink jet recording can reproduce image quality comparable to printing or photography, and there is a demand for a similar appearance.

Therefore, as an ink jet recording medium having a glossy surface, a cast coated paper obtained by performing a cast finish while the coating layer is in a wet state is disclosed in JP-A-6-320.
No. 857, the surface gloss is extremely low as compared with silver halide photographic printing paper, and the texture of silver halide photography cannot be obtained.

On the other hand, as an ink jet recording medium having improved surface glossiness, a medium in which an ink receiving layer made of a resin is provided on a support has been proposed. Examples of resins used in such applications include, for example, JP-A-57-3818.
No. 5, No. 62-184879, polyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymer, JP-A-60-168651, and JP-A-60-16865.
Nos. 171143 and 61-134290, resin compositions mainly comprising polyvinyl alcohol, and vinyl alcohol and olefin or styrene and anhydride as described in JP-A-60-234879. Copolymer with maleic acid, JP-A-61-748
No. 79, a cross-linked product of polyethylene oxide and isocyanate.
No. 79, a mixture of carboxymethylcellulose and polyethylene oxide.
A polymer in which methacrylamide is grafted onto polyvinyl alcohol as shown in JP-A-1-132377; an acrylic polymer having a carboxyl group as shown in JP-A-62-220383; Polyvinyl acetal-based polymer as disclosed in JP 214382, JP-A-4-28228
Various ink-absorbing polymers such as a crosslinkable acrylic polymer as described in JP-A Nos. 2 and 4-285650 have been proposed. Also, JP-A-4-282282
And JP-A-4-285650 have proposed an ink jet recording medium using a polymer matrix composed of a crosslinkable polymer and an absorbent polymer together.
However, the ink receiving layer made of such a resin has the disadvantage that although it has high surface gloss, it has a low absorption rate and a small amount of absorption, as compared with an ink receiving layer made of fine pigment particles such as silica.

As an ink jet recording medium having a high ink absorption speed and a high surface gloss, an ink jet recording material using alumina hydrate (cationic alumina hydrate) has recently been proposed. JP-A-60-
As described in JP-A-232990, JP-A-60-245588, JP-B-3-24906, JP-A-6-199035 and JP-A-7-82694, fine quasi-boehmite-type alumina hydrate is dissolved in water. An ink jet recording medium coated on a support surface together with a binder is disclosed. However, an ink jet recording medium using pseudo-boehmite-type alumina hydrate has very high surface gloss, but has a small pore volume, and as described in JP-A-5-24335, for example. In addition, the ink absorption capacity is small, and thick film coating is necessary to obtain a sufficient ink absorption capacity.

[0010] For example, Japanese Patent Application Laid-Open No. Hei 10-203006 proposes an ink jet recording medium having a primary particle diameter of 3 nm to 30 nm and mainly using synthetic silica obtained by a gas phase method. Also in this case, in order to obtain a sufficient absorption capacity, a film thickness of 30 μm or more is required.

On the other hand, Japanese Patent Application Laid-Open No. Hei 7-89217 discloses an ink jet recording medium in which a base paper provided with an ink receiving layer has an uneven pattern. This is characterized in that an irregular pattern is formed on the surface of a base paper mainly composed of cellulose pulp, and an ink receiving layer mainly composed of a white pigment and a binder resin is provided thereon. However, in this method, since the base paper is a paper containing cellulose pulp as a main component, the ink receiving layer made of a forming material requiring a thick film coating such as alumina hydrate or fumed silica as described above is used. In this case, the effect is hardly exhibited, and a sufficient aesthetic effect cannot be obtained.

Japanese Patent Application Laid-Open No. 9-86034 discloses an ink jet recording medium having a glossy and molded pattern by forming a glossy ink receiving layer and then applying an emboss calender. However, in this method, it is necessary to first form a glossy ink receiving layer by a casting method or the like, and then mold the surface with an embossing machine or the like, so that the manufacturing process becomes complicated. In addition, since there is a gloss imparting step by a casting method, the support needs to have air permeability, and a film or synthetic paper without air permeability,
Alternatively, there is a drawback that it cannot be produced with resin-coated paper.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording medium for recording using ink.
It is an object of the present invention to provide an ink jet recording medium having high ink absorbency, excellent image color properties, and an excellent aesthetic feeling due to a concave-convex pattern formed on the surface of a support when printed.

[0014]

In view of this situation, the present inventors have conducted intensive studies on recording paper having an uneven pattern on the surface. As a result, a water-resistant opaque support was used as a support, Various irregularities such as silk, mesh, canvas, and fine-grained surfaces are preliminarily applied to the substrate, and a porous ink receiving layer mainly composed of inorganic ultra-fine particles is provided on the support, so that high ink jet recording is possible. An ink jet recording medium having high absorbency and high-quality image color, and having a high aesthetic effect due to the concavo-convex pattern formed on the support was completed.

That is, the ink jet recording medium of the present invention is a recording medium comprising a water-resistant opaque support and an ink receiving layer provided thereon, wherein the side of the water-resistant opaque support on which the ink receiving layer is provided. Is typed,
In addition, the ink jet recording medium is characterized in that the ink receiving layer provided thereon is a porous layer mainly containing inorganic ultrafine particles.

The ink receiving layer has a primary particle diameter of 3 nm.
It is more preferable that the layer contains at least one kind of inorganic ultrafine particles selected from the group consisting of fumed silica fine particles, colloidal silica, alumina hydrate, and γ-type aluminum oxide having a thickness of 100 nm. Further, the coating amount of the ink receiving layer containing these is more preferably 20 g / m ² or more.

The water-resistant opaque support is preferably a resin-coated paper provided with a coating layer of a thermoplastic resin on paper, and more preferably the thermoplastic resin is a polyethylene resin or a polypropylene resin. It is also a preferred embodiment to include a pigment in the coating layer of the thermoplastic resin.

By forming the coated thermoplastic resin coating layer by pressing against a desired molded cooling roll at the time of melt extrusion coating of the thermoplastic resin, the molded die becomes clearer. preferable.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The ink jet recording medium of the present invention will be described below in detail.

The water-resistant opaque support used in the present invention is preferably, for example, synthetic paper, resin-coated paper, opaque film containing pigment, or foamed film. Resin-coated paper similar to a photographic support is more preferred from the viewpoint of feel, luxury, and ease of molding.

The base paper for resin-coated paper preferably used in the present invention is not particularly limited, and generally used paper can be used. Preferably, for example, a base paper used for a photographic support is used. Smooth and dense base paper. As the pulp constituting the base paper, a natural pulp, a recycled pulp, a synthetic pulp, or the like is used alone or in combination of two or more. As the natural pulp, bleached chemical pulp such as pulp usually used for papermaking, that is, softwood kraft pulp, hardwood kraft pulp, softwood sulphite pulp, hardwood sulphite pulp and the like can be used. Further, mechanical pulp having high whiteness may be used. Further, non-wood pulp manufactured from grass fibers such as straw, esparto, bagasse, and kenaf, bast fibers such as hemp, mulberry, ganpi, mitsumata, and cotton may be used. Of these, bleached chemical pulp, such as softwood kraft pulp, hardwood kraft pulp, softwood sulphite pulp, and hardwood sulphite pulp, which is usually most frequently used industrially, is particularly preferred.

Pulp is used to improve papermaking suitability and various paper properties such as strength, smoothness, and uniformity of formation.
It is usually beaten by a beater such as a double disc refiner. The degree of beating can be selected according to the purpose in the normal range of 250 ml to 450 ml in Canadian Standard Freeness.

The beaten pulp slurry is made by a paper machine such as a fourdrinier paper machine, a twin wire paper machine, or a round net paper machine. In this case, in the present invention, the pulp slurry usually used in papermaking is used. Various additives such as a dispersing aid, a dry paper strength enhancer, a wet paper strength enhancer, a filler, a sizing agent, and a fixing agent can all be added as needed. Further, if necessary, a pH adjuster, a dye, a colored pigment, an optical brightener and the like can be added.

The dispersing aids include, for example, polyethylene oxide, polyacrylamide, smelt, and the like. The paper-strength enhancers include, for example, vegetable gums, starch, anionic paper-strength enhancers such as carboxy-modified polyvinyl alcohol, cationized starch, and the like. Cationic polyacrylamide, a cationic paper strength enhancer such as polyamide polyamine epichlorohydrin resin, as a filler, for example, clay, kaolin,
Talc, calcium carbonate, barium sulfate, titanium oxide,
Aluminum hydroxide, magnesium hydroxide and the like, as sizing agents, for example, higher fatty acid salts, rosin, rosin derivatives such as maleated rosin, dialkyl ketene dimer, alkenyl or alkyl succinate, epoxidized fatty acid amide, polysaccharide ester and the like Examples of the fixing agent include polyvalent metal salts such as aluminum sulfate and aluminum chloride, cationic polymers such as cationized starch and polyamide polyamine epichlorohydrin resin, and examples of the pH adjusting agent include hydrochloric acid, caustic soda, and sodium carbonate.

The base paper for resin-coated paper used in the present invention can be tab-sized or size-pressed with a liquid containing various additives including a water-soluble polymer additive. .

Examples of the above-mentioned water-soluble polymer additives include starch derivatives such as starch, cationized starch, oxidized starch, etherified starch and phosphate esterified starch; polyvinyl alcohol derivatives such as polyvinyl alcohol and carboxy-modified polyvinyl alcohol; Carboxymethyl cellulose,
Hydroxymethyl cellulose, hydroxyethyl cellulose, cellulose derivatives such as cellulose sulfate,
Gelatin, casein, water-soluble natural polymers such as soy protein,
Sodium polyacrylate, sodium salt of styrene-maleic anhydride copolymer, water-soluble polymer such as maleic anhydride resin such as sodium polystyrene sulfonate, and aqueous polymer such as thermosetting synthetic resin such as melamine resin and urea resin Adhesives and the like are used. In addition, petroleum resin emulsions, ammonium salts of styrene-maleic anhydride copolymer alkyl esters, alkyl ketene dimer emulsions, styrene-butadiene copolymers, ethylene-vinyl acetate copolymers are used as sizing agents. Dispersions of polymers, polyethylene, polyvinylidene chloride and the like can be mentioned. Other additives include an inorganic electrolyte such as sodium chloride, calcium chloride, and boa nitrate as antistatic agents, glycerin and polyethylene glycol as hygroscopic substances, and clay, kaolin, talc, barium sulfate, and oxidized as pigments. Titanium or the like is used as a pH adjusting agent such as hydrochloric acid, caustic soda, or sodium carbonate, and other additives such as a dye, a fluorescent whitening agent, an antioxidant, and an ultraviolet absorber can be used in combination.

The base paper for resin-coated paper used in the present invention preferably has good surface smoothness such as compression by applying pressure with a calendar or the like during or after papermaking.
Beck's smoothness measured by JIS-P-8119 is 20
Those having 0 seconds or more are particularly preferable. The basis weight is 30
~250g / m ² is preferred.

As the resin of the resin-coated paper, a thermoplastic resin or a resin which is cured by an electron beam can be used. Examples of the thermoplastic resin include a polyolefin resin and a polyester resin. Polyolefin resins include low-density polyethylene, high-density polyethylene, polypropylene,
It is a homopolymer of an olefin such as polybutene or polypentene, or a copolymer composed of two or more olefins such as an ethylene-propylene copolymer, and a mixture thereof. Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. These thermoplastic resins having various densities and melt viscosity indices (melt index) can be used alone or in combination. Preferably, polyethylene resin and polypropylene resin are used.

In the resin of the resin-coated paper, white pigments such as titanium oxide, zinc oxide, talc and calcium carbonate; fatty acid amides such as stearamide and arachidic amide; zinc stearate; calcium stearate; Aluminum, metal salts of fatty acids such as magnesium stearate, pigments and dyes of blue such as cobalt blue, ultramarine blue, cecilian blue, and phthalocyanine blue; pigments and dyes of magenta such as cobalt violet, fast violet, and manganese purple; fluorescent brighteners; It is preferable to add various additives such as an ultraviolet absorber and an antioxidant in an appropriate combination.

The resin-coated paper, which is preferably used in the present invention, is a so-called extrusion coating method in which, in the case of a thermoplastic resin such as a polyolefin resin or a polyester resin, a heat-melted resin is cast on a running base paper. And the side or both sides on which the ink receiving layer is provided is covered with a resin. In the case of a resin that is cured by an electron beam, the resin is applied by a commonly used coater such as a gravure coater or a blade coater, and then irradiated with an electron beam to cure and coat the resin. Further, before coating the resin on the base paper, the base paper is preferably subjected to an activation treatment such as a corona discharge treatment or a flame treatment.
The surface of the support on which the ink receiving layer is applied may be a glossy surface, a matte surface, or the like, depending on the intended use. A pattern in which a pattern is formed on the surface is used.

Although it is not necessary to coat the back surface with a resin, it is preferable to coat the resin from the viewpoint of preventing curling. The back surface is usually a matte surface, and the front surface or both front and back surfaces can be subjected to an activation treatment such as a corona discharge treatment or a flame treatment as required. The thickness of the coating resin layer is not particularly limited, but is generally 5 to 50 μm on the surface or both surfaces on which the ink receiving layer is applied.

In the production of the resin-coated paper used in the present invention, the surface of which is impressed with various uneven patterns such as silk, mesh, canvas, and fine-grained surfaces, a polyolefin resin or the like is extruded. Extruded into a film between a sheet-like substrate such as paper and a cooling roll, pressure bonding,
It is manufactured by cooling. The cooling roll is used to form the surface shape of the resin coating layer, and the surface of the resin-coated paper is formed to be high gloss, matte, or patterned, for example, silk or mat, depending on the shape of the cooling roll surface. You can do it. In the present invention, a mirror-finished or fine-roughened cooling roll is used to form a resin coating layer on the side on which the ink receiving layer is provided, and thereafter, a variety of silk-like, mesh-like, canvas-like, fine-grain-like, etc. By embossing a machine with an embossed pattern on the surface, a method of making the desired pattern and, in the production of resin-coated paper, by copying the mold with a cooling roll engraved with the desired pattern on the surface in advance. There is a method of making a desired type. Resin-coated paper preferably used in the present invention,
A resin-coated paper having a finely roughened surface having a surface glossiness of 70% or less is prepared, and a resin-coated paper on which a desired shaping is performed by an embossing machine, or more preferably, a desired shaping is applied to a cooling roll. This is a resin-coated paper that is simultaneously molded when a pattern is engraved to produce the resin-coated paper.

The ultrafine inorganic particles in the ink jet recording medium of the present invention are inorganic fine particles having a primary particle diameter of 100 nm or less. For example, JP-A-1-97678,
JP-A-2-275510, JP-A-3-281383, JP-A-3-285814, JP-A-3-285815, JP-A-4-92183, JP-A-4-267180, JP-A-4-275917 and the like. Proposed pseudo-boehmite sol, JP-A-60-219083,
JP-A-61-19389, JP-A-61-188183, JP-A-63-178074, and JP-A-5-5147.
No. 0, etc., colloidal silica, Japanese Patent Publication No. 4-19037, and Japanese Patent Application Laid-Open No. 62-286.
No. 787, silica / alumina hybrid sol, JP-A-10-119423,
Silica sol in which ultrafine silica particles are dispersed by a high-speed homogenizer as described in JP-A-10-217601, smectite clay such as hectite and montmorillonite (JP-A-7-81210), zirconia sol , Chromia sol, yttria sol, ceria sol, iron oxide sol, zircon sol, antimony oxide sol, and the like.

For the ink jet recording medium of the present invention, commercially available inorganic ultrafine particles can also be suitably used. An example is described below, but the present invention is not limited to this. For example, as the alumina hydrate, Cataloid AS-1, Cataloid AS-2, Cataloid AS-3
Alumina sol 100, Alumina sol 200, Alumina sol 520 (More than Nissan Chemical Industry), M-200 (More than Mizusawa Chemical Industry), Aluminum sol 10, Aluminum sol 20, Aluminum sol 132, Aluminum sol 132S, Aluminum sol SH5, aluminum sol CSA5
5. Aluminum sol SV102, aluminum sol SB52 (all manufactured by Kawaken Fine Chemical), and as colloidal silica, Snowtex 20, Snowtex 3
0, Snowtex 40, Snowtex S, Snowtex O, Snowtex C, Snowtex N, Snowtex 20L, Snowtex UP, Snowtex OL, Snowtex AK, Snowtex PST-
1. Snowtex K, Snowtex XS, Snowtex SS, Snowtex XL, Snowtex Y
L, Snowtex ZL, Snowtex PST-1,
Snowtex PST-3, Snowtex PST-
5, MA-ST, IPA-ST, NBA-ST, IBA
-ST, EG-ST, XBA-ST, ETC-ST, D
MAC-ST (all manufactured by Nissan Chemical Industries), Cataloid S
-20L, Cataloid S-20H, Cataloid S-30
L, Cataroid S-30H, Cataloid SI-30, Cataloid SI-40, Cataloid SI-50, Cataloid SI-350, Cataloid SI-45P, Cataloid SI-80P, Cataloid SN, Cataloid SA, Cataloid SB, USB-1, USB-2, USB-3, O
SCAL1132, OSCAL1232, OSCAL1
332, OSCAL1432, OSCAL1532, O
Examples of SCAL1622, OSCAL1722 (both manufactured by Kasei Kasei Kogyo) and silica / alumina hybrid sol include Snowtex UP-AK1 and Snowtex UP
-AK2, Snowtex UP-AK3 (all manufactured by Nissan Chemical Industries, Ltd.) and A-153 as antimony oxide sol
0, A-1550, A-2550 (all manufactured by Nissan Chemical Industries, Ltd.), and the thylium silicate include thylium silicate 35, thylium silicate 45, and thylium silicate 75 (all manufactured by Nissan Chemical Industries). be able to.

Among these inorganic ultrafine particles, colloidal silica or fumed silica ultrafine particles (both are collectively referred to as synthetic silica ultrafine particles in the present invention), alumina hydrate, and γ-type aluminum oxide fine particles are preferable. Can be used.

The shape of colloidal silica, one of the inorganic ultrafine particles, is generally spherical or nearly spherical. The colloidal silica according to the present invention is preferably an elongated shape in which small silica particles are connected in a chain, or a non-spherical shape having a three-dimensional network structure. Elongated particles mean particles that have no extension in the three-dimensional direction but extend in the same plane. Elongated particles include those that are substantially straight, bent, branched, ringed, and the like. On the other hand, a particle having a three-dimensional network structure refers to a particle having a network structure in which these elongated particles are literally three-dimensionally entangled.

The non-spherical silica particles preferably used in the present invention can be obtained by various methods. In the present invention, the silica particles having a non-spherical shape are obtained by any method. Then, it can be preferably used in the present invention. As a method for forming non-spherical silica particles, for example, alkali is removed from general water glass to form active silicic acid, and the silica is linked to non-spherical (chain).
It is obtained by growing particles by adding a cation of a valence or higher.

Here, activated silicic acid means silicic acid and a particle diameter of 3n.
m colloidal particles in which a polymer of silicic acid less than
It can be easily obtained by a known method. Colloidal aqueous solution of preferred active silicic acid, water-soluble silicate, for example, SiO ₂ / M ₂ O
(However, M represents an alkali metal atom)
It is obtained by subjecting a diluent of about 4.5 water glass to a cation exchange treatment, and is usually 6% by weight or less in terms of SiO ₂ .
It preferably contains 1 to 6% by weight and usually has a pH of 5 or less, preferably 2 to 5. This pH may be adjusted by leaving a part of the cations in the water glass diluent during the cation exchange treatment, or by removing all or a part of the cations therein. It can also be easily prepared by adding a small amount of an alkali metal oxide, a water-soluble organic base or the like to the aqueous colloid solution of the above. This colloidal solution of activated silicic acid is unstable and has a property of easily gelling. Therefore, it is preferable that the colloidal solution promotes the gelation but contains as little impurities as possible, and preferably the one immediately after the preparation. A more preferred aqueous colloidal solution of activated silicic acid is SiO ₂ /
It is obtained by passing a diluted aqueous solution of sodium water glass, which is a commercially available industrial product having a Na ₂ O molar ratio of about 2 to 4, through a hydrogen-type cation exchange resin.

Divalent or higher cations are added to the aqueous colloidal solution of activated silicic acid so as to form a non-spherical (chain-like) connection, thereby growing particles. As the divalent or higher cation, a calcium ion and a magnesium ion are preferable, and a calcium salt, a magnesium salt, or a mixture thereof is preferably added as an aqueous solution. The total amount of the calcium salt, the magnesium salt, or a mixture thereof is expressed as a weight ratio [(CaO + MgO) / SiO ₂ ] calculated as each oxide with respect to the active silicic acid.
In this case, the amount is preferably from 1500 to 25000 ppm, and particularly in the case of elongated particles, it is preferably from 1500 to 8500 ppm.

The addition of these salts is preferably carried out while stirring the colloidal solution of activated silicic acid. In this case, the mixing temperature and the mixing time are not particularly limited, but are preferably from 2 to 50 ° C. for about 5 to 30 minutes. Is preferred. Examples of calcium and magnesium salts which may be added include calcium or magnesium chloride, nitrate, sulfate, sulfamate, formate,
And inorganic acid salts such as acetates and organic acid salts. These calcium salts and magnesium salts may be used as a mixture. The concentration of these salts at the time of addition is not particularly limited, and may be about 2 to 20% by weight.

When a polyvalent metal component other than calcium and magnesium is contained in the above-mentioned colloidal solution of activated silicic acid together with the calcium salt and magnesium salt, a silica sol can be produced more preferably. Examples of polyvalent metals other than calcium and magnesium include:
Sr, Ba, Zn, Sn, Pb, Cu, Fe, Ni, C
Examples thereof include divalent, trivalent or tetravalent metals such as o, Mn, Al, Cr, Y, and Ti. When the amounts of the calcium salt and the magnesium salt are converted into the amounts of CaO and MgO, respectively,
The polyvalent metal oxide is preferably about 10 to 80% by weight with respect to MgO.

When the above polyvalent metal component remains in the colloidal solution of activated silicic acid obtained by subjecting the diluted solution of water glass to cation exchange treatment, the polyvalent metal component is added to the colloidal solution of 10 to 80%. Included as part of weight%. The remaining polyvalent metal component is preferably added as an aqueous solution of the polyvalent metal together with the calcium salt and magnesium salt to be added. Preferred examples of the polyvalent metal include inorganic and organic acid salts such as chloride, nitrate, sulfate, sulfamate, formate, and acetate. Further, salts such as zincate, stannate, aluminate, and plumbate, such as sodium aluminate and sodium stannate, can also be used. The calcium salt, magnesium salt, polyvalent metal salt and the like to be added are preferably mixed uniformly with a colloidal solution of activated silicic acid, and are usually added as an aqueous solution.

An alkali metal hydroxide, a water-soluble organic base, or a water-soluble silicate thereof is added to the aqueous solution obtained by the above steps. This addition is preferably carried out as soon as possible after the end of the process and with stirring. The temperature and time for mixing these are not particularly limited,
The temperature is preferably about 5 to 30 minutes at about 50 ° C. The added alkali metal hydroxide, water-soluble organic base, or water-soluble silicate thereof is preferably uniformly mixed with the aqueous liquid obtained in the above step, and is added directly or as an aqueous solution.

As the alkali metal hydroxide, for example,
Hydroxides such as sodium, potassium, and lithium. As the organic base, for example, quaternary ammonium hydroxides such as tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, tetramethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine,
Examples thereof include amines such as N, N-dimethylethanolamine, N- (β-aminoethyl) ethanolamine, N-methylethanolamine, monopropanolamine, and morpholine, and other organic compounds containing a basic nitrogen atom. Examples of the water-soluble silicates include sodium silicate, potassium silicate, quaternary ammonium silicate, and amine silicate.

Further, aluminates, formates, zincates, and plumbates of alkali metals or organic bases can also be used. These alkali metal hydroxides, organic bases, silicates, metal salts and the like may be used as a mixture.
If the alkali metal atom or organic base molecule of the alkali metal hydroxide is represented by M, the amount of alkali metal hydroxide, organic base or water-soluble silicate thereof added is
SiO ₂ / M ₂ O is 20 to 200, where the total of the silica content derived from the activated silicic acid and the silica content of the silicate is SiO ₂ ,
Preferably, the amount is such that the molar ratio is 60 to 100. By this addition, the solution reaches a pH of about 7 to 10.

The mixture obtained by the above steps is
30 minutes to 40 hours at 300 ° C., preferably 90 to 150 hours
SiO ₂ concentration 1 by heating 2 to 12 hours at ℃
6% by weight of a silica sol having a non-spherical shape is obtained. By concentrating this sol if desired, a higher concentration sol can be obtained. Incidentally, the non-spherical silica particles obtained by the above method have a secondary particle diameter in the range of 40 to 300 nm as measured by the dynamic light scattering method. It has a shape grown in a plane or three-dimensionally.

The non-spherical silica particles according to the present invention only need to be present in a non-spherical shape at least in the coating liquid for forming the ink receiving layer in the ink jet recording medium of the present invention. Prior to the preparation of the coating liquid for the preparation, the non-spherical silica particles according to the present invention including the above-described method are prepared, and the coating liquid for forming the ink receiving layer may be prepared using the silica particles. At the time of preparing the coating liquid for forming, the coating liquid may be prepared while preparing the non-spherical silica particles according to the present invention including the above method in the coating liquid.
As long as the non-spherical silica particles according to the present invention are prepared before preparing the coating liquid, commercially available ones can also be used. Examples of commercially available non-spherical silica particles include Snowtex UP and Snowtex OU manufactured by Nissan Chemical Industries.
P and the like.

The silica fine particles other than colloidal silica are:
93% or more of SiO _{2 and} about 5% or less of Al ₂ O _{3 on a} dry basis,
Fine particles composed of about 5% or less of Na ₂ O, such as so-called white carbon, amorphous silica such as silica gel and fine powder silica. Methods for producing amorphous silica fine particles include a liquid phase method, a pulverized solid phase method, a crystallization solid phase method, and a gas phase method. The liquid phase method is a method for producing fine particles in which a silicate compound or the like existing in a liquid is precipitated in a solid state by a chemical or physical change. The pulverized solid phase method is a method for mechanically pulverizing silica solids, and the crystallization solid phase method is a method for producing fine particles utilizing melting, phase transition of a solid, or the like. The gas phase method means the thermal decomposition of volatile metal compound vapor,
This is a method for producing fine particles by heating and evaporating raw materials, cooling and condensing generated gas phase species.

The silica fine particles used in the present invention are amorphous silica fine particles synthesized by a gas phase method. Among them, ultrafine silica having an average primary particle diameter of 3 nm to 100 nm is preferable. Particularly preferred primary particle size is 4
nm to 50 nm. Further, the secondary particles to which these are connected are preferably 10 nm to 200 nm, more preferably 15 nm to 100 nm. Aerosil (Texa) corresponds to a commercially available product as amorphous silica fine particles synthesized by the gas phase method.

The sol of the gas phase method silica fine particles used in the present invention is prepared by adding silica fine particles having the above-mentioned primary particle size to water and dispersing the same with a high-speed homogenizer or the like so that the average secondary particle size is 200 nm or less, preferably 100 nm. It is distributed to the following.

The alumina hydrate used in the present invention can be represented by the following general formula. Al ₂ O ₃ .nH ₂ O alumina hydrate is classified into gypsite, vialite, norstrandite, boehmite, boehmite gel (pseudo boehmite), diaspore, amorphous amorphous, etc. according to the difference in composition and crystal form. You. Among them, in the above formula, when the value of n is 1, it represents an alumina hydrate having a boehmite structure, and when n is more than 1 and less than 3, it represents an alumina hydrate having a pseudo-boehmite structure; When it is 3 or more, it represents an alumina hydrate having an amorphous structure. In particular, alumina hydrates preferred for the present invention are those having a pseudo-boehmite structure in which at least n is more than 1 and less than 3.

In order for the alumina hydrate to have a sufficient ink absorption rate, the average pore radius of the alumina hydrate should be 1 to 1
The thickness is preferably 0 nm, particularly preferably 3 to 7 nm. If the pore radius is too small, it becomes difficult to absorb the ink. If the pore radius is too large, fixation of the dye in the ink is deteriorated, and image bleeding occurs.

In order for the alumina hydrate to have a sufficient ink absorption capacity, the pore volume of the alumina hydrate is preferably in the range of 0.3 to 0.8 ml / g.
It is preferably in the range of 0.4 to 0.6 ml / g. When the pore volume of the ink receiving layer is large, cracks and powder fall occur in the ink receiving layer, and when the pore volume is small, absorption of the ink becomes slow. Further, the solvent absorption amount of the ink receiving layer per unit area is preferably 5 ml / m ² or more, particularly preferably 10 ml / m ² or more. When the amount of solvent absorption per unit area is small, ink may overflow especially when multicolor printing is performed.

In order for the alumina hydrate to sufficiently absorb and fix the dye in the ink, the BET specific surface area should be 70 to 300.
It is preferably in the range of m ² / g. If the BET specific surface area is too small, the pore size distribution tends to be large, and the fixing efficiency of the dye in the ink is deteriorated, and image bleeding occurs. Conversely, if the BET specific surface area is too large, it becomes difficult to disperse the alumina hydrate.

The shape of the alumina hydrate used in the present invention may be any of a plate shape, a fiber shape, a needle shape, a spherical shape, a rod shape and the like, and a preferable shape is a plate shape from the viewpoint of ink absorption. The plate-like alumina hydrate has an average aspect ratio of 3
-8, preferably an average aspect ratio of 3-6. Aspect ratio is the "diameter" of the particle "thickness"
It is expressed by the ratio of Here, the diameter of the particle means the diameter of a circle equal to the projected area of the particle when the alumina hydrate is observed with an electron microscope. When the aspect ratio is smaller than the above range, the pore size distribution of the ink receiving layer becomes narrow, and the ink absorbency decreases. On the other hand, when the aspect ratio exceeds the above range, it becomes difficult to prepare alumina hydrate by aligning the particles.

The alumina hydrate used in the present invention can be produced by a known method such as hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali, and hydrolysis of aluminate. . The physical properties of alumina hydrate, such as particle diameter, pore diameter, pore volume, and specific surface area, should be controlled by conditions such as precipitation temperature, aging temperature, aging time, liquid pH, liquid concentration, and coexisting compounds. Can be.

As a method for obtaining an alumina hydrate from an alkoxide, JP-A-57-88074, JP-A-57-88074,
No. 56321, JP-A-4-275917, JP-A-6-64918, JP-A-7-10535,
-267633, U.S. Pat. No. 2,656,321
Patent Document 1 discloses a method for hydrolyzing aluminum alkoxide. These aluminum alkoxides include isopropoxide, 2-butoxide and the like.

Also, Japanese Patent Application Laid-Open No. 54-116398,
JP-A-55-23034, JP-A-55-27824 and JP-A-56-120508 disclose a method using an aluminum inorganic salt or a hydrate thereof as a raw material. Examples of the raw material include inorganic salts such as aluminum chloride, aluminum nitrate, aluminum sulfate, polyaluminum chloride, ammonium alum, sodium aluminate, potassium aluminate, and aluminum hydroxide, and hydrates thereof.

As still another method, Japanese Patent Application Laid-Open No. 56-120
No. 508, a method in which the pH is alternately changed from an acidic side to a basic side to grow alumina hydrate crystals, and aluminum as described in Japanese Patent Publication No. 4-33728. There is also a method of mixing alumina hydrate obtained from an inorganic salt of the above with alumina obtained by the Bayer method, and rehydrating the alumina.

In the present invention, the γ-type aluminum oxide fine particles are γ-type crystals of aluminum oxide, and when crystallographically classified, they can be further divided into a γ group and a δ group. Fine particles having a crystal form of the δ group are more preferable.

The alumina of the γ-type crystal fine particles can reduce the average particle size of the primary particles to about 10 nm.
(Hereinafter referred to as “secondary particles”), and the particle diameter increases from several thousand to tens of thousands of nm. When such γ-type alumina crystal fine particles having such a large particle diameter are used, the printability and the absorbability of the ink receiving layer are good, but the ink lacks transparency and the coating film defects are liable to occur. The average particle size of the primary particles is preferably less than 80 nm. When secondary particles composed of primary particles of 80 nm or more are used, fragility is increased and coating film defects are very likely to occur.

To obtain γ-type alumina crystal fine particle sol,
Normally, ultrafine particles having an average particle diameter of 200 nm or less, preferably 100 nm or less, are obtained by milling γ-type alumina crystals, which are secondary particles of several thousands to tens of thousands of nm, using a bead mill, an ultrasonic homogenizer, or a high-pressure homogenizer. Crush until it becomes When the average particle size exceeds 200 nm, the ink absorbency increases, but the coating is brittle and the transparency decreases. As the pulverizing means, a method using an ultrasonic homogenizer or a high-pressure homogenizer is preferable.In other pulverizing methods such as a bead mill, since the γ-type alumina crystal is a hard crystal, foreign matter is easily mixed in from the pulverizing container, and the transparency is high. Causes a decrease in the number of defects and the generation of defects. γ-type alumina crystal fine particles are excellent in ink absorbency, good in printing quality such as drying property and ink fixing property, and are excellent in transparency by making them ultra-fine particles even if they are contained in the ink receiving layer at a high ratio. A recording medium can be obtained.

The γ-type alumina crystal fine particles are commercially available as aluminum oxide C belonging to the δ group (manufactured by Nippon Aerosil Co., Ltd.) and AKP-G01 belonging to the γ group.
5 (manufactured by Sumitomo Chemical Co., Ltd.).

A water-soluble or water-insoluble polymer compound may be added as a binder for the inorganic ultrafine particles used in the present invention. The polymer compound used in the present invention is
A compound having an affinity for ink as a component of the ink receiving layer. For example, as the water-soluble polymer compound, polyvinyl alcohol, acrylic resin, styrene-acrylic copolymer, maleic anhydride polymer, styrene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer,
Starch, polyvinyl butyral, gelatin, casein, ionomer, gum arabic, carboxymethylcellulose, alginic acid, sodium alginate, pullulan, polyvinylpyrrolidone, polyacrylamide, polyethylene glycol, polypropylene glycol and the like. Preferably, it is polyvinyl alcohol.

As the water-insoluble polymer compound, alcohols such as ethanol and 2-propanol and a water-insoluble binder dissolved in a mixed solvent of these alcohols and water can stabilize the dispersion of aluminum oxide. Is particularly preferred. Examples of such a water-insoluble binder include acetal resins such as a vinylpyrrolidone / vinyl acetate copolymer, polyvinyl butyral, and polyvinyl formal. Particularly, the degree of acetalization is 5 mol%.
The acetal resin in the range of not less than 20 mol% is particularly preferable because it can contain water to some extent and can easily disperse the inorganic ultrafine particles.

These polymer compounds may be used alone or in combination of two or more.
Is added. Preferably, 5 to 20% by weight is added.
If the amount is less than the above range, the strength of the coating film becomes weak, and if the amount is too large, the ink absorbency decreases.

The method for applying the coating liquid in the present invention is as follows.
E-bar coating, curtain coating, strado hopper coating, extrusion coating, roll coating, air knife coating,
Various coating methods such as gravure coating and rod bar coating can be adopted.

In the present invention, the ink receiving layer may have a single layer structure or a multilayer structure. In the case of a laminated structure, all layers may be layers having the same composition, or may be a laminated structure with a layer composed of other components.

The coating amount of the ink receiving layer containing the inorganic ultrafine particles of the present invention must be 15 g or more per square meter in terms of solid content. 20 g or more and 60 g or less.

As a means for drying after coating, a general known method can be used and is not limited. For example,
There are a method of transporting the heated air generated by the heat source into the heated heater, and a method of passing the air near the heat source such as a heater.

Further, the coating liquid for forming an ink receiving layer containing the inorganic ultrafine particles of the present invention and, if necessary, a binder may contain, if necessary, a surfactant, an inorganic pigment, a coloring dye,
Color pigment, ink dye fixing agent (cationic resin), ultraviolet absorber, antioxidant, pigment dispersant, defoamer, leveling agent, preservative, fluorescent brightener, viscosity stabilizer, pH adjuster, hard Various known additives such as a film agent can be added.

As described above, when an ink receiving layer mainly composed of inorganic ultrafine particles is provided on the water-resistant opaque support having been formed thereon, the transparency of the ink receiving layer is excellent. An ink jet recording medium that is clearly visible from the surface and has excellent ink jet suitability and aesthetic sensation. If the inorganic pigment in the ink receiving layer is other than the present invention, the ink receiving layer becomes opaque, and the molding pattern applied to the support becomes unclear, resulting in poor aesthetic feeling. In particular, when the ink receiving layer is a thick coat of 20 g / m ² or more, the mold pattern applied to the support is hardly seen from the surface and becomes extremely unclear.

[0073]

EXAMPLES The present invention will be described below with reference to examples, but is of course not limited thereto.

<Preparation of base paper for resin-coated paper> A 1: 1 mixture of bleached hardwood kraft pulp (LBKP) and softwood bleached sulphite pulp (NBSP) was beaten to 300 ml with Canadian Standard Freeness to prepare a pulp slurry. . As a sizing agent, alkyl ketene dimer to pulp is 0.5% by weight, polyacrylamide is 1.0% by weight to pulp, cationized starch is 2.0% by weight to pulp, and polyamide epichlorohydrin resin is a sizing agent. 0.5% by weight of pulp was added and diluted with water to obtain a 1% slurry. The slurry was paper-made to have a basis weight of 170 g / m ² by a Fourdrinier paper machine, and used as a base paper for polyolefin resin-coated paper.

<Preparation of Support A> On the surface of the base paper for resin-coated paper (the side on which the ink receiving layer is provided), a resin having a density of 0.918 g / cm ^{3 and} a low-density polyethylene of 100% by weight was applied. A polyethylene resin composition in which 10% by weight of anatase type titanium is uniformly dispersed is melted at 320 ° C., extrusion-coated to a thickness of 30 μm at 200 m / min, and glossed using a fine-roughened cooling roll. A 60% resin coating was applied. On the other surface, a high-density polyethylene resin having a density of 0.962 g / cm ³ was melted at 320 ° C., extrusion-coated so as to have a thickness of 30 μm, and a glossiness of 5% using a rough cooling roll.
Was covered with a resin. Next, the resin-coated paper was applied to a silk-patterned embossing machine to prepare a water-resistant opaque support A having a silk-patterned surface.

<Preparation of Support B> On the surface of the resin-coated paper base paper (the side on which the ink receiving layer is provided), a resin having a density of 0.918 g / cm ^{3 and} a low-density polyethylene of 100% by weight was applied. A polyethylene resin composition in which 10% by weight of anatase type titanium is uniformly dispersed is melted at 320 ° C., extrusion-coated to a thickness of 30 μm at a rate of 200 m / min, and cooled using a cooling roll engraved with a silk pattern. Coated. The other surface has a density of 0.96
2 g / cm ³ of high density polyethylene resin is melted at 320 ° C. and extrusion coated to a thickness of 30 μm.
Backside resin coating with a gloss of 5% was performed using a rough cooling roll. This is referred to as a water-resistant opaque support B.

<Preparation of Support C> Synthetic paper (Yupo FPG # 200, manufactured by Oji Oil Chemicals Co., Ltd.) produced by blending a polypropylene resin with an inorganic filler and subjecting it to a biaxial stretching film forming method was used. A water-resistant opaque support having a pattern embossed on the surface (the side on which the ink receiving layer is provided) was prepared by embossing with a pattern embossing machine. This is referred to as a water-resistant opaque support C.

<Preparation of Support D> The base paper for resin-coated paper was not coated with the resin, but was directly applied to a silk embossing machine to form a silk pattern on the surface. This is designated as support D.

<Synthesis of Alumina Hydrate> Ion-exchanged water 1
200 g and isopropyl alcohol 900 g were charged into a 3 L reactor and heated to 75 ° C. 408 g of aluminum isopropoxide were added, and 75 g for 24 hours, followed by 9 g
Hydrolysis was performed at 5 ° C. for 10 hours. After hydrolysis, acetic acid 2
4 g was added and the mixture was stirred at 95 ° C. for 48 hours. Next, the mixture was concentrated so that the solid content concentration became 15% by weight to obtain a white alumina hydrate dispersion. The sol was dried at room temperature and measured for X-ray diffraction, which showed a pseudo-boehmite structure. When the average particle size was measured with a transmission electron microscope,
It was 0 nm, and it was a plate-like alumina hydrate having an aspect ratio of 6.0. When the average pore radius, pore volume and BET specific surface area were measured by the nitrogen adsorption / desorption method, 7.1 nm, 0.65 ml / g and 2
00 m ² / g.

<Ink Receiving Layer Coating Liquid A> 10% by weight of polyvinyl alcohol (manufactured by Kuraray Co., Ltd.) was added to 100 parts of the alumina hydrate dispersion using the 15% by weight alumina hydrate dispersion. PVA235) 15 parts of an aqueous solution were mixed. After mixing, the mixture was uniformly dispersed in a homomixer at 10,000 rpm for 10 minutes. The dispersion was concentrated by an evaporator to a predetermined concentration to obtain a coating liquid A.

<Ink receiving layer coating liquid B> As alumina fine particles, 600 g of aerosil aluminum oxide C (manufactured by Nippon Aerosil Co., Ltd.) having a primary particle diameter of 13 nm, which is a γ-type alumina crystal powder of the δ group, was placed in 2400 g of ion-exchanged water. The mixture was dispersed by a stirrer to prepare a 20% by weight slurry-like viscous liquid. Using this 20 wt% γ-type alumina dispersion, 10 wt% was added to 100 parts of the alumina dispersion.
30 parts of an aqueous solution of polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.) was mixed. After mixing, 10,000 r into a homomixer
The mixture was uniformly dispersed at pm for 10 minutes. The dispersion was concentrated by an evaporator to a predetermined concentration to obtain a coating liquid B.

<Ink Receiving Layer Coating Liquid C> The coating composition for the ink receiving layer is a gas-phase fine particle silica having a primary particle diameter of 7 nm (AEROSIL300: manufactured by Nippon Aerosil Co., Ltd.).
g in 500 g of ion-exchanged water with a stirrer,
10% by weight of polyvinyl alcohol (Kuraray PVA)
235) A coating solution C was prepared by mixing 80 g of the aqueous solution.

<Ink receiving layer coating liquid D> The coating composition for the ink receiving layer is a commercially available non-spherical colloidal silica.
Snowtex UP (Nissan Chemical Industries, Ltd., primary particle diameter 10 to 20 nm, average secondary particle diameter about 70 nm, SiO
₂ concentration 20 to 21% by weight) 200 parts, 10 parts by weight of polyvinyl alcohol (Kuraray PVA117) 30 parts,
20 parts of a cationic dye fixing agent (Smileds Resin 1001: manufactured by Sumitomo Chemical Co., Ltd.) was mixed to obtain a coating liquid D.

<Ink receiving layer coating liquid E> 100 parts of synthetic amorphous silica (Fine Seal X-37B: manufactured by Tokuyama Co.) having a BET specific surface area of 270 m ² / g was used. Alcohol (PVA117:
30 parts of Kuraray Co., Ltd.) and 20 parts of a cationic dye fixing agent (Smileds Resin 1001: Sumitomo Chemical Co., Ltd.) were mixed to prepare a coating liquid E.

The coating was carried out on the surface of the support having been subjected to molding so as to have a coating amount shown in Table 1 using a wire bar. After the application, the coating was left at 90 ° C. for 10 minutes and dried.

<Evaluation of Imprinting Clarity> The evaluation of imprinting clarity was performed by using an ink jet printer PM-770C manufactured by Seiko Epson Corporation to print a person image and to see an image in which the imprinting pattern applied to the support was very clearly visible. A, B was clearly seen, C was blurred, and D was hardly seen. As for evaluation, A and B are good, and C and
D has a problem in use.

<Evaluation of ink absorptivity> On the other hand, the evaluation of the ink absorptivity was carried out by printing a double-colored rectangular pattern with cyan ink and magenta ink using BJC-420J manufactured by Canon Inc. which is an ink jet recording apparatus. The boundary between the print pattern and the unprinted area is defined according to the following criteria.
It was evaluated visually. A: No bleeding was observed at the boundary part B: Slight bleeding was partially detected at the boundary part C: Slight bleeding was observed at the boundary part D: Remarkable bleeding was observed at the boundary part The evaluations of A and B show that the ink absorbability is excellent.

<Evaluation of Image Color> Canon BJC-42
Solid printing of magenta and cyan was performed using 0J. The color was visually evaluated as follows. ：: Good color and no dullness. Δ: Somewhat dull. ×: The color is rough and dull.

[0089]

[Table 1]

From Table 1, it can be seen that Examples 1 to 11 in which a porous ink receiving layer containing inorganic ultrafine particles were provided on a water-resistant opaque support were not Comparative Examples 1 and 2, which were not water-resistant supports. In comparison with Comparative Example 2 in which an ink receiving layer lacking the transparency of the inorganic pigment was provided, the ink absorption and the image coloration were better, and the mold applied to the support was clearly seen. Comparative Example 3 was inferior in the color of the image, probably because the ink receiving layer for increasing the transparency was provided on the support absorbing the ink. When the coating amount was 20 g / m ² or more, the ink absorption was particularly good.

[0091]

As described above, the ink jet recording medium in which the highly transparent ink receiving layer made of inorganic ultrafine particles is provided on the imprinted water-resistant opaque support of the present invention has a high ink absorbing property. It has high image aesthetics and a clear appearance of the typed pattern. In particular, when the water-resistant opaque support is a resin-coated paper, the production is easy. Furthermore, the coating amount of the ink receiving layer is 20 g /
When it is at least m ^2, it is more preferable.

 ──────────────────────────────────────────────────の Continued on the front page F-term (reference) 2C056 FC06 2H086 BA15 BA33 BA34 BA46 4F100 AA00B AA19B AA20B AK01A AK03A AK04A AK07A AR00A AR00B BA03 BA07 BA10A BA10C CA13A CC00B DE01B DG10JJBBJJBJJBJJBJJBJJBJJBGB

Claims (14)

[Claims] 1. A recording medium comprising a water-resistant opaque support and an ink receiving layer provided thereon, wherein the water-resistant opaque support is subjected to molding on a side on which the ink receiving layer is provided, and An ink jet recording medium, wherein the ink receiving layer provided thereon is a porous layer mainly containing inorganic ultrafine particles. 2. The method according to claim 1, wherein the inorganic ultrafine particles have a primary particle size of 3 nm or more.
2. The ink jet recording medium according to claim 1, which is 100 nm synthetic silica fine particles. 3. The ink jet recording medium according to claim 2, wherein said synthetic silica fine particles are colloidal silica. 4. The ink jet recording medium according to claim 2, wherein said synthetic silica fine particles are ultrafine silica synthesized by a gas phase method. 5. The ink jet recording medium according to claim 1, wherein said inorganic ultrafine particles are hydrated alumina. 6. The ink jet recording medium according to claim 5, wherein said alumina hydrate has a pseudo-boehmite structure. 7. The ink jet recording medium according to claim 1, wherein said inorganic ultrafine particles are γ-type aluminum oxide fine particles. 8. The ink jet recording medium according to claim 7, wherein the average primary particle diameter of the γ-type aluminum oxide is 80 nm or less. 9. The ink jet recording medium according to claim ² , wherein the coating amount of the ink receiving layer containing the inorganic ultrafine particles is 20 g / m ² or more. 10. The paper according to claim 1, wherein the imprinted water-resistant opaque support is a resin-coated paper provided with a coating layer of a thermoplastic resin on paper. Ink jet recording medium. 11. The ink jet recording medium according to claim 10, wherein said thermoplastic resin is a polyolefin resin. 12. The ink jet recording medium according to claim 11, wherein said polyolefin resin is a polyethylene resin or a polypropylene resin. 13. The ink jet recording medium according to claim 10, wherein the coating layer of the thermoplastic resin contains a pigment. 14. The molded thermoplastic resin coating layer is formed by being pressed against a desired molded cooling roll during melt extrusion coating of the thermoplastic resin. The inkjet recording medium according to any one of claims 1 to 4.