JP4291785B2 - Inkjet recording medium and method for producing the same - Google Patents

Description

The present invention relates to a recording medium to be used for ink jet recording using liquid ink such as water-based ink and oil-based ink, or solid ink that is solid at room temperature and is melted and liquefied and used for printing. The present invention relates to a high-quality ink jet recording medium in which aging blur of an image is improved while suppressing the above and a method for producing the same .

In recent years, with the rapid development of the information technology (IT) industry, a wide variety of information processing systems have been developed, and recording methods and recording apparatuses suitable for each information processing system have been developed and put into practical use one after another.
Among these recording methods, the inkjet recording method is capable of recording on a variety of recording materials, has advantages such as being relatively inexpensive and compact in hardware (device), and excellent in quietness. It is also widely used in so-called home use.

In addition, with the recent evolution of the resolution of inkjet printers, it has become possible to obtain so-called photographic-like high-quality recorded matter. With the advancement of such hardware (device), inkjet recording Many types of recording media have been developed.
The characteristics required for the above-mentioned recording medium for ink jet recording are generally (1) fast drying (high ink absorption speed), and (2) ink dot diameter is appropriate and uniform. (No blurring), (3) good graininess, (4) high dot roundness, (5) high color density, (6) high chroma (dullness) (7) The water resistance, light resistance, and ozone resistance of the recorded image are good, (8) the whiteness of the recording medium is high, and (9) the storage stability of the recording medium is good. (No yellowing coloring even after long-term storage, no bleeding of images over time), (10) Difficult to deform and good dimensional stability (curl is sufficiently small), (11) Hard running performance It is good.
Furthermore, in the use of photo glossy paper used for the purpose of obtaining so-called photographic-like high-quality recorded matter, in addition to the above properties, gloss, surface smoothness, and photographic paper-like texture similar to silver salt photography. Etc. are also required.

  In recent years, an ink jet recording medium having a porous structure in an ink receiving layer has been developed and put into practical use for the purpose of improving the above-mentioned various characteristics. Such an ink jet recording medium has a high glossiness with excellent ink receptivity (fast drying property) by obtaining a porous structure.

  For example, Patent Documents 1 and 2 below propose an ink jet recording medium that includes fine inorganic pigment particles and a water-soluble resin and has an ink receiving layer having a high porosity on a support. These recording media, in particular, inkjet recording media provided with an ink-receiving layer having a porous structure using silica as inorganic pigment fine particles have excellent ink absorbability due to the structure, and can form high-resolution images. In addition, it is possible to exhibit high gloss.

  Also disclosed is an inkjet recording paper having a porous structure ink-receiving layer in which a liquid transfer amount measured by the Bristow method is specified using a mixed solvent (diethylene glycol / triethyl monobutyl ether / water = 15/15/70) ( For example, it is described that it is excellent in ink absorptivity and cockling resistance. An ink-receiving layer in which a thermoplastic resin dispersion is applied to the surface of a paper substrate to form a water-permeable intermediate layer, and a coating liquid containing a pigment and a binder is applied to the surface of the water-permeable intermediate layer Inkjet recording papers having a high ink absorption and image definition are also disclosed (for example, see Patent Document 4), and it is described that there is no printing failure due to cockling.

  Also, an ink jet recording in which a first ink receiving layer containing polyvinyl alcohol having a saponification degree of 90% or less and a second ink receiving layer containing amorphous silica, a cationic resin, and an aqueous polymer binder are sequentially provided. (For example, refer to Patent Document 5), there is a description that an image with high color development and no bleeding can be recorded at high speed and the coating film strength is excellent. An ink jet recording sheet in which a plurality of ink receiving layers containing a white pigment having a specific refractive index and specific surface area is provided on a support is also disclosed (see, for example, Patent Document 6), which has excellent ink absorbability and high density. It is described that a high-definition image can be recorded.

Further, an ink jet recording sheet provided with an ink receiving layer containing specific fine particles, a cationic polymer, and a water-soluble resin is presented (see, for example, Patent Document 7), which is quick-drying and has a high print density and resembles a silver salt photograph. It is described that glossiness can be obtained.
However, none of the above measures is still inadequate level in the effect of suppressing the aging blur of the recorded image. When trying to further improve the aging blur, when applying the ink receiving layer coating liquid, The problem remains that the occurrence of rings (wrinkles) cannot be avoided.

JP 10-119423 A Japanese Patent Laid-Open No. 10-217601 JP 2002-144720 A JP 2002-103787 A Japanese Patent Laid-Open No. 11-221961 Japanese Patent Publication No. 04-055395 Japanese Patent Application No. 2002-098662

Accordingly, the object of the present invention is that when printed with an ink jet printer, it is quick-drying, excellent in ink absorbability, sufficiently suppresses aging of recorded images, and cockling (close to wrinkles) when applying an ink receiving layer. It is an object of the present invention to provide an ink jet recording medium capable of avoiding the occurrence of the above and a manufacturing method thereof .

In view of such a situation, as a result of intensive studies, the present inventors have found that the support is a paper base material and at least one of the particles of the acrylic silicon resin on the surface of the paper base material on which at least the ink receiving layer is formed. And an undercoat layer containing seeds, and found that the above-mentioned problems can be solved when the coating amount of the acrylic silicon-based resin is 1 to 30 g / m ² , thereby completing the present invention. .

That is, the present invention provides the following inkjet recording medium.
<1> In the ink-jet recording medium having an ink-receiving layer on a support, wherein the support is (1) a paper substrate, as the thermoplastic resin particles to form surface side of at least the ink-receiving layer of the paper substrate is composed of a subbing layer comprising at least one particle of an acrylic silicone resin, (2) coating amount of the acryl silicone resin is 1 to 30 g / m ^2, the ink jet recording medium, characterized in that body.

<2> in the undercoat layer, the ink-jet recording medium body according to <1>, wherein the further contains a pigment.
< 3 > The inkjet according to <1> or <2>, wherein the thermoplastic resin particles have an average particle diameter of 10 to 200 nm and a minimum film-forming temperature (MFT) of 5 to 60 ° C. Recording medium.
< 4 > The ink receiving layer according to any one of <1> to < 3 >, further comprising a water-soluble resin, a crosslinking agent capable of crosslinking the water-soluble resin, fine particles, and a mordant. Inkjet recording medium.
< 5 > The water-soluble resin is at least one selected from a polyvinyl alcohol resin, a cellulose resin, a resin having an ether bond, a resin having a carbamoyl group, a resin having a carboxyl group, and gelatins, and The inkjet recording medium according to < 4 >, wherein the fine particles are at least one selected from silica fine particles, colloidal silica, alumina fine particles, and pseudoboehmite.
< 6 > The ink receiving layer is a layer obtained by crosslinking and curing a coating layer coated with a coating solution containing at least fine particles and a water-soluble resin, and the crosslinking and curing is applied to the coating solution and / or the following basic solution. A cross-linking agent is added and (1) the coating layer is formed by coating the coating solution, or (2) the coating layer formed by coating the coating solution is in the process of being dried. Any one of the above <1> to < 5 >, which is carried out by applying a basic solution having a pH of 7.1 or higher to the coating layer at any time before the is reduced-rate drying An ink jet recording medium according to claim 1.
<7> A composition containing at least one kind of acrylic silicon latex as thermoplastic resin particles on at least the ink receiving layer forming surface side of the paper base, and the coating amount of the acrylic silicon resin is 1 to 30 g / The step of forming an undercoat layer by adhering to m ² to produce a support, and forming the ink receiving layer by applying a coating solution for an ink receiving layer on the undercoat layer on the support. And a process for producing an ink jet recording medium.

According to the present invention, when the ink-receiving layer coating solution is applied, there is no production trouble such as cockling, and when printing is performed with an ink jet printer, the ink absorption is excellent and the recorded image is faded over time. It is possible to provide a high-quality inkjet recording medium with improved quality and a method for producing the same .

[Inkjet recording medium]
First, the ink jet recording medium of the present invention will be described. Ink jet recording medium of the present invention has a formed by providing a certain subbing layer configuration paper substrate surface, and coating amount of the acrylic silicon resin of the undercoat layer is 1 to 30 g / m ² der It has the support body which is characterized by the above-mentioned. First, the support will be described in detail.
The ink jet recording medium of the present invention is an ink jet recording medium having an ink receiving layer on a support, wherein the support is heated to a paper base and at least a surface of the paper base on which the ink receiving layer is formed. A first feature is that it is composed of an undercoat layer containing at least one kind of acrylic silicon resin particles as plastic resin particles. The support of the present invention has a paper base material and an undercoat layer containing at least one kind of acrylic silicon resin particles as thermoplastic resin particles on at least the ink receiving layer forming surface side of the paper base material. Due to the construction, the ink jet recording medium according to the present invention is rich in ink absorbability and can effectively suppress the aging of recorded images. Hereinafter, the support for the inkjet recording medium of the present invention having such a configuration and physical properties is appropriately referred to as “the support of the present invention” or “the support with an undercoat layer of the present invention”.

Furthermore, as the above-mentioned support of the present invention, glycerin, 2 in the water absorption test (contact time is 2 minutes) specified in JIS P8140 in order to effectively suppress blurring of images while preventing cockling. -Cobb water absorption measured using an aqueous solution containing at least one of pyrrolidone, isopropyl alcohol, ethylene glycol, diethylene glycol and diethylene glycol monobutyl ether is 10 g / m ² or more, and the ink receiving layer forming coating solution is The second feature is that the Cobb water absorption measured using the ink receiving layer coating solution first applied to the undercoat layer is 10 g / m ² or less. Here, the ink receiving layer coating liquid used for the latter cup water absorption is the coating liquid for the ink receiving layer which is provided closest to the support and is directly applied to the surface of the ink receiving layer. When the layer is composed of only one layer, the coating solution may be used. In the case of a structure in which a plurality of ink receiving layers are provided by being laminated, the surface provided on the support, specifically, the above-mentioned provided on the support. The measurement is performed using a coating solution for forming an ink receiving layer closest to the support to be coated first directly on the undercoat layer.
In order to more effectively suppress blurring of images over time, the water absorption test (contact time is 2 minutes) prescribed in JIS P8140 includes glycerin, 2-pyrrolidone, isopropyl alcohol, ethylene glycol, diethylene glycol. It is desirable to measure using an aqueous solution containing 5 to 30% by mass of at least one of diethylene glycol monobutyl ether.

Furthermore, the support according to the present invention has a water absorption test (contact time of 2 minutes) specified in JIS P8140 in order to improve both the prevention of cockling and the suppression of image blurring at a high level. ,
(1) Solution A1 (diethylene glycol monobutyl ether 11 parts / glycerin 11 parts / 2-pyrrolidone 4 parts / water 75 parts),
(2) Solution A2 (diethylene glycol monobutyl ether 11 parts / water 89 parts), (3) Solution A3 (isopropyl alcohol 3 parts / ethylene glycol 4 parts / diethylene glycol 4 parts / glycerin 10 parts / 2-pyrrolidone 1 part / water 78 parts) ),
At least one of the Cobb water absorption measured using a coating is 10 g / m ² or more, and the Cobb water absorption measured using the coating liquid forming the ink receiving layer is 10 g / m ² or less. Is more preferable. Here, in said solution composition A1-A3, the number of parts of a composition represents a mass part. Further, the ink receiving layer forming coating solution used in this case is an ink receiving layer coating solution formed at a position closest to the support, as described above.

With the support with an undercoat layer of the present invention, when the Cobb water absorption measured using an aqueous solution as described above is 10 g / m ² or more, the ink jet recording medium according to the present invention is rich in ink absorbability. It is possible to effectively suppress blurring of images over time.
Here, the Cobb water absorption measured using the above aqueous solution is more preferably 15 g / m ² or more, particularly 25 g / m ² or more from the viewpoint of further improving ink absorbency and aging blur. Is most preferred. In addition, there is no restriction | limiting in particular in the upper limit of this Cobb water absorption.

In addition, the ink-jet recording medium of the present invention is particularly suitable for a support with an undercoat layer of the present invention by setting the Cobb water absorption measured with an ink receiving layer coating solution to 10 g / m ² or less. Thus, it is possible to satisfactorily apply the coating liquid for the ink receiving layer without causing cockling (that is, near wrinkles), and to obtain a high-quality ink jet recording medium. In order to predict the state of cockling generation, in the present invention, when there are a plurality of ink-receiving layer coating solutions that are directly applied to the support, that is, when there are a plurality of ink-receiving layers, the undercoat is applied. An ink receiving layer coating solution that is directly coated on the layer is used. Measured Cobb water absorption as described above is even more the viewpoint of suppressing cockling, more preferably 8 g / m ² or less, and most preferably 6 g / m ² or less. In addition, there is no restriction | limiting in particular in the minimum of this Cobb water absorption.

In this specification, the above-mentioned Cobb water absorption (g / m ² ) is obtained by preparing a test piece of a support with an undercoat layer under the conditions specified in JIS P8140, and making “Garle” manufactured by Toyo Seiki Seisakusho Co., Ltd. The water absorbency measured using a sizing degree tester according to the procedure specified in the above standard with a contact time of 2 minutes. Here, as the solution used in this test, an aqueous solution having the above composition and a coating solution for forming the ink receiving layer of the ink jet recording medium of the present invention are used.
Hereinafter, although the main structural requirements of this invention are demonstrated in detail, this invention is not limited to these explanatory items and an illustration.

(Support)
The support of the present invention comprises a paper base material and an undercoat layer containing at least one kind of acrylic silicon resin particles as thermoplastic resin particles on at least the ink receiving layer forming surface side of the paper base material. Yes.
As the paper base of the present invention, a paper base made of raw paper or synthetic paper is used. As the base paper used for this paper base material, both softwood pulp and hardwood pulp can be used. However, it is preferable to use a lot of hardwood pulp having short fibers and high smoothness. For example, pulp constituting the base paper Of these, 60% by mass or more is preferably hardwood pulp. Specifically, as wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, and NUKP can be used, and more LBKP, NBSP, LBSP, NDP, and LDP with more short fibers are used. It is preferable.
The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities, and a pulp having a whiteness improved by bleaching is also useful.

As a paper base material, instead of the above-mentioned natural pulp, it may be replaced with synthetic pulp made of polyethylene, polypropylene, etc., and synthetic fiber made of polyester, polyvinyl alcohol, nylon, etc., and natural pulp and synthetic pulp are mixed in any ratio You may use what you did.
In addition, as for the freeness of the pulp material to be used, what is 200-500 ml is preferable by the CSF standard, and what is 300-400 ml is more preferable. The fiber length after beating is preferably such that the (24 + 42) mesh residue defined by JIS P8207 is 40% by mass or less.

The above base paper usually contains a sizing agent, for example, epoxidized fatty acid amide, fatty acid anhydride, rosin acid anhydride, alkenyl succinic anhydride, succinic acid amide, isopropenyl stearate, aziridine compound, alkyl ketene. A neutral sizing agent such as dimer can be preferably used.
In addition, a sizing agent is generally added to the base paper, and a medium such as sulfate band (aluminum sulfate), cationized starch, polyamide polyamine epichlorohydrin, polyacrylamide, and polyacrylamide derivatives, which are commonly used as the fixing agent. It is preferable to use a neutral or weak alkaline fixing agent or neutralize with an alkali after adding a sulfuric acid band.

Furthermore, for the purpose of improving the smoothness, a filler such as calcium carbonate, talc, clay, kaolin, titanium dioxide, urea resin fine particles and the like can be internally added to the base paper.
Examples of internal chemicals other than the above internal sizing agent, fixing agent and filler include paper strength enhancers such as polyacrylamide, starch, and polyvinyl alcohol, reaction products of maleic anhydride copolymer and polyalkylene polyamine, and higher grades. Softening agents such as quaternary ammonium salts of fatty acids, colored dyes, fluorescent dyes and the like may be added to the base paper as necessary.

The base paper used for the paper base of the present invention can be made using the raw materials as described above and using a long net paper machine or a circular net paper machine. Weighing of the base paper is preferably 20 to 300 g / m ^2, and more preferably 50 to 200 g / m ^2. The thickness of the base paper is preferably 25 to 350 μm, more preferably 40 to 250 μm.
The base paper can be given a high smoothness by calendering at the paper making stage or after paper making. The density of the base paper is generally 0.7 to 1.2 g / m ² (conforming to JIS P-8118). Furthermore, the base paper stiffness is preferably 20 to 200 g under the conditions specified in JIS P-8143.

  Further, the surface of the support of the present invention may be subjected to surface treatment such as corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment in order to improve wettability and adhesion. Good.

The support used in the recording material of the present invention can be provided with a backcoat layer. Examples of components that can be added to the backcoat layer include white pigments, aqueous binders, and other components.
Examples of the white pigment contained in the backcoat layer include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, and silicic acid. White inorganic pigments such as aluminum, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, Examples thereof include organic pigments such as styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin, and melamine resin.

Examples of the aqueous binder used in the back coat layer include styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, Examples thereof include water-soluble polymers such as carboxymethyl cellulose, hydroxyethyl cellulose and polyvinyl pyrrolidone, and water-dispersible polymers such as styrene butadiene latex and acrylic emulsion.
The backcoat layer may contain other components such as an antifoaming agent, an antifoaming agent, a dye, a fluorescent brightening agent, a preservative, and a water resistant agent.

(Thermoplastic resin particles)
The support used in the present invention has an undercoat layer containing at least one kind of acrylic silicon resin particles as thermoplastic resin particles on at least the ink receiving layer forming surface side of the paper substrate.
There is no restriction | limiting in particular as said thermoplastic resin particle, All the particles of a conventionally well-known thermoplastic resin are included. Examples of such known thermoplastic resins include general-purpose thermoplastic polymers such as polyolefins such as polyethylene, polypropylene and polyvinyl chloride; polyamides and polyimides; polyesters such as polyethylene terephthalate; Α-methylene aliphatic monocarboxylic acid esters such as methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, dodecyl (meth) acrylate, octyl (meth) acrylate and phenyl (meth) acrylate Styrenes such as styrene, chlorostyrene and vinyl styrene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; vinyl methyl ketone , Bini Hexyl ketone, homopolymer consisting of vinyl ketones such as vinyl isopropenyl ketone, or any copolymers including these structural units, and the like.

The said thermoplastic resin particle used for this invention may be used individually by 1 type, and may use 2 or more types together.
The thermoplastic resin particles preferably have an average particle diameter of 10 to 200 nm. Here, the value measured by the laser diffraction / dynamic light scattering method (apparatus name: Otsuka Electronics Co., Ltd. ELS-800) is employ | adopted for the average particle diameter of the resin particle. Moreover, as a thermoplastic resin which comprises resin fine particles, the thing whose minimum film forming temperature (MFT) is 5-60 degreeC is preferable.
The coating amount of the thermoplastic resin in the undercoat layer is preferably ¹ to 30 g / m2.

As the thermoplastic resin particles used in the undercoat layer of the present invention, those containing water-dispersible latex-dispersed particles are preferred from the viewpoints of suppression of cockling, improvement of aging blurring, and production suitability.
The water-dispersible latex is obtained by dispersing a hydrophobic polymer insoluble or hardly soluble in water as fine particles in an aqueous phase dispersion medium. As the dispersion state, the polymer is emulsified in a dispersion medium, emulsion-polymerized, micelle-dispersed, or partly hydrophilic in the polymer molecule and the molecular chain itself is molecularly dispersed. Any of these may be used. For such polymer latexes, edited by Taira Okuda and Hiroshi Inagaki “Synthetic Resin Emulsion” (published by Kobunshi Publishing Co., Ltd., 1978), Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki and Keiji Kasahara “Application of Synthetic Latex” ( Published by Kobunshi Shuppankai, 1993) and Soichi Muroi, “Chemistry of Synthetic Latex” (published by Shubunshi Shuppankai, 1970).

Specific examples of the water-dispersible latex used in the undercoat layer of the present invention include acrylic latex, acrylic silicon latex, acrylic epoxy latex, acrylic styrene latex, acrylic urethane latex, styrene-butadiene latex, acrylonitrile - butadiene latex, and at least one is preferably mentioned are selected from vinyl acetate-based latex, in the present invention Ru using an acrylic silicone latex.

The molecular weight of the water-dispersible latex is preferably 3,000 to 1,000,000, and more preferably about 5,000 to 100,000 in terms of number average molecular weight. If the molecular weight is too small, the mechanical strength of the undercoat forming layer may be insufficient, and if it is too large, it may be disadvantageous in terms of production suitability such as dispersion stability and viscosity.
Among the above water-dispersible latexes, the undercoat layer of the present invention is more effective than the acrylic silicone latex and the acrylic styrene latex from the viewpoint that the ink solvent permeability and the cockling suppression effect are high and can be economical and suitable for production. Most preferred is at least one selected.
Hereinafter, various water-dispersible latexes suitably used for the undercoat layer of the support in the present invention will be described.

  Specific examples of the acrylic latex that can be used in the present invention include methyl (meth) acrylate / ethyl (meth) acrylate / (meth) acrylic acid copolymer latex, methyl (meth) acrylate / 2-ethylhexyl (meth) acrylate. / Styrene / (meth) acrylic acid copolymer latex, styrene / butadiene / (meth) acrylic acid copolymer latex, styrene / butadiene / divinylbenzene / (meth) acrylic acid copolymer latex, methyl (meth) acrylate / vinyl chloride / Examples thereof include latex of (meth) acrylic acid copolymer, latex of vinylidene chloride / ethyl (meth) acrylate / (meth) acrylonitrile / (meth) acrylic acid copolymer, and the like. In addition, in the acrylic latex, a water-modified latex modified with silicon or a water-dispersible latex containing a silicon-based structural unit can be suitably used.

Some of these acrylic latexes are available as commercial products. For example, the following commercially available water-dispersible latexes can be used in the present invention. For example, examples of acrylic resins include “Cebian A4635, 46583, 4601” manufactured by Daicel Chemical Industries, Ltd., and “Nipol Lx811, 814, 821, 820, 857” manufactured by Nippon Zeon Co., Ltd. .
Furthermore, cationic acrylic emulsions of acrylic silicon latex described in JP-A-10-264511, JP-A-2000-43409, JP-A-2000-343811, and JP-A-2002-120452 can be suitably used.

  Examples of styrene-butadiene latex usable in the present invention include styrene and styrene derivatives such as vinyltoluene, p-tertbutylstyrene, vinylbenzoic acid, methyl vinylbenzoate, α-methylstyrene, and p-chloromethylstyrene. , Latexes of copolymers with butadiene and butadiene derivatives with optional substitution.

  As the vinyl acetate latex, for example, α, β-unsaturated carboxylic acid and derivatives thereof, polymers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, sodium acrylate, ammonium methacrylate, potassium itaconate, and the like Copolymer latex may be mentioned.

  Examples of the vinylidene chloride latex include latexes of polymers of vinylidene chloride and substituted vinylidene chloride and arbitrary copolymers containing these structural units.

  Examples of the styrene latex include styrene, vinyl toluene, p-tertbutyl styrene, vinyl benzoic acid, methyl vinyl benzoate, α-methyl styrene, p-chloromethyl styrene, vinyl naphthalene, p-hydroxymethyl styrene, p- Examples thereof include polymers and copolymer latexes such as sodium styrenesulfonate, potassium p-styrenesulfinate, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, and the like.

  Examples of the vinyl chloride latex include vinyl chloride homopolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, vinyl chloride-vinyl alcohol copolymer, etc. Of latex.

  Examples of the polyethylene-based latex include ethylene, propylene, isoprene, butadiene, 6-hydroxy-1-hexene, cyclopentadiene, 4-pentenoic acid, methyl 8-nonenoate, vinyl sulfonic acid, trimethylvinylsilane, trimethoxyvinylsilane, and pentadiene. 1,4-divinylcyclohexane, 1,2,5-trivinylcyclohexane, and other polymer latexes.

  Examples of the polyester-based latex include latexes such as polyester resins that are composed of polyvalent carboxylic acids and polyhydric alcohols and are condensation-polymerized singly or in combination of two or more.

  In the present invention, the binder used for forming the ink solvent-permeable undercoat layer includes polyvinyl alcohol, starch, polyvinylpyrrolidone, gelatin, carboxymethylcellulose (CMC), hydroxypropylcellulose (HPC), methylcellulose (MC) together with the water-dispersible latex. ) And the like, and may further contain pigments, thickeners, fluorescent brighteners, surfactants, crosslinking agents, bluing agents, and the like.

In the undercoat layer of the present invention, the water-dispersible latex is preferably used as 50% by mass or more of the total binder, and more preferably 70% by mass or more of the water-dispersible latex.
In the undercoat layer of the present invention, the total coating amount of the water-dispersible latex is preferably 1 to 30 g / m ^2, the range of 3 to 20 g / m ² is more preferable. When the total coating amount of the water-dispersible latex is less than 1 g / m ² , cockling may occur when forming the ink receiving layer, and when the total coating amount exceeds 30 g / m ^2. The permeability of the ink solvent may be insufficient.

The water-dispersible latex used in the present invention, particularly as an acrylic latex, has an average particle size of dispersed particles of preferably 10 to 200 nm, and more preferably 15 to 150 nm. If the average particle diameter is less than 10 nm, the ink absorbability of the recording medium may be reduced, and if the average particle diameter exceeds 200 nm, cockling may occur when forming the ink receiving layer. .
The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.

The undercoat layer of the present invention is an ink solvent-permeable resin layer formed by applying a coating agent composed of a binder containing acrylic silicon latex as a composition containing thermoplastic resin particles. As used herein, an acrylic silicone-based latex (water-dispersible latex) has the specific particle size range, a water-dispersible latex of an acrylic resin having a minimum film-forming temperature of 5 to 60 ° C. (MFT). Here, the minimum film-forming temperature (MFT) of the water-dispersible latex refers to a temperature at which the undercoat layer coating solution is applied and dried or heat-treated to form a film, and is preferably 5 in the present invention. C. to 60.degree. C., more preferably 10 to 50.degree. When the minimum film-forming temperature (MFT) of the water-dispersible latex is less than 5 ° C., the latex surface may cause problems such as adhesion or adhesion in a state where the undercoat layer coating solution is applied and dried. In addition, when the minimum film-forming temperature (MFT) exceeds 60 ° C., it may be insufficient under normal drying conditions to form a transparent undercoat layer coating solution by drying and heat treatment. .
In order to control this minimum film forming temperature, a film forming aid may be added. The film-forming aid, also called a plasticizer, is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature of the water-dispersible latex, and is described in detail in the above-mentioned book "Synthetic Latex Chemistry". Yes.

The undercoat layer in the present invention is preferably an embodiment further containing a pigment.
The pigment used in the present invention preferably has an average particle size of 0.05 to 20 [mu] m, more preferably 0.1 to 10 [mu] m, from the viewpoint of enhancing ink absorbency and suppressing aging blur. Here, the above-mentioned “average particle diameter” means an area average particle diameter, and is regarded as the diameter of the particle with a circle equivalent to the projected area of each particle, and is calculated from the number average. Point to.

  Specific examples of the pigment are not particularly limited, but titanium dioxide, kaolin, clay, calcined clay, amorphous silica (also referred to as amorphous silica), zinc oxide, aluminum oxide, aluminum hydroxide, heavy carbonate Calcium, light calcium carbonate, satin white, aluminum silicate, alumina, colloidal silica, zeolite, synthetic zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene resin pigment, benzoguanamine resin pigment, etc. In the general coated paper manufacturing field, various publicly known pigments can be used alone or in combination of two or more.

Among the above pigments, it is preferable to use titanium dioxide from the viewpoint of whiteness and shielding properties, and as the titanium dioxide, sulfuric acid method, chlorine method, rutile type, anatase type, Various titanium dioxide pigments such as those subjected to surface treatment with a hydrous metal oxide and those coated with an organic compound can be used.
The pigment is preferably dispersed in combination with a dispersant, and as the dispersant, a known one such as a sodium salt of a polycarboxylic acid type polymer can be used.

  The undercoat layer in the present invention is preferably prepared by applying an aqueous coating solution and drying it. The “aqueous” means that about 60% by mass or more of the solvent (dispersion medium) of the coating solution is water. As the solvent other than water in the coating solution, a water-miscible organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate can be used.

  The above-mentioned water-dispersible polymer is mixed with an aqueous solvent, additives are mixed as necessary, and the mixture is finely divided using a high-speed stirrer, thereby dispersing water in an average particle size of 200 nm or less. A liquid can be obtained. Examples of the high-speed stirrer used to obtain the aqueous dispersion include a high-speed rotary disperser, a medium stirring disperser (such as a ball mill, a sand mill, and a bead mill), an ultrasonic disperser, a colloid mill disperser, and a high-pressure disperser. Various conventionally known dispersers can be used, but a medium stirring type disperser, a colloid mill disperser, or a high pressure disperser is preferable from the viewpoint of efficiently dispersing the formed fine particles.

  The high-pressure disperser (homogenizer) is described in detail in US Pat. No. 4,533,254, JP-A-6-47264, etc., but as a commercially available apparatus, a Gorin homogenizer (APV GAULIN) is used. INC.), A microfluidizer (MICROFLUIDEX INC.), An optimizer (Sugino Machine Co., Ltd.) and the like can be used. In recent years, a high-pressure homogenizer having a mechanism for atomizing in an ultrahigh-pressure jet stream as described in US Pat. No. 5,720,551 is particularly effective for emulsification dispersion of the present invention. DeBEE2000 (BEE INTERNIONAL LTD.) Is an example of an emulsifying apparatus using this ultra-high pressure jet stream.

  Water, an organic solvent, or a mixed solvent thereof can be used as the aqueous solvent in the dispersion step. Examples of the organic solvent that can be used for the dispersion include alcohols such as methanol, ethanol, n-propanol, i-propanol, and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate, and toluene. It is done.

  The support of the present invention composed of a paper base and an undercoat layer as described above is not only an inkjet recording medium, but also a thermal transfer image receiving recording medium, a sublimation transfer image receiving recording medium, an electrophotographic image receiving medium, Further, it is also suitably used for a thermosensitive color recording medium.

(Ink receiving layer)
Next, the ink receiving layer will be described.
The ink jet recording medium of the present invention is obtained by forming an ink receiving layer on a support having the undercoat layer, and the ink receiving layer contains a fine particle dispersion and a water-soluble resin. The fine particles therein are components of the ink receiving layer of the ink jet recording medium.
The ink receiving layer of the ink jet recording medium has a porous structure by containing fine particles, thereby improving the ink absorption performance. In particular, when the solid content of the fine particles in the ink receiving layer is 50% by mass or more, more preferably more than 60% by mass, it becomes possible to form a more favorable porous structure, and sufficient ink absorptivity. This is preferable because an ink jet recording medium having the above can be obtained. Here, the solid content in the ink receiving layer of fine particles is a content calculated based on components other than water in the composition constituting the ink receiving layer.
The fine particles used in the present invention may be either organic fine particles or inorganic fine particles, but inorganic fine particles are preferred from the viewpoint of ink absorbability and image stability.

  Preferred examples of the organic fine particles include polymer fine particles obtained by, for example, emulsion polymerization, microemulsion polymerization, soap-free polymerization, seed polymerization, dispersion polymerization, suspension polymerization and the like. Specifically, polyethylene, polypropylene, polystyrene , Polyacrylate, polyamide, silicone resin, phenol resin, natural polymer powder, latex or emulsion polymer fine particles, and the like.

  Examples of the inorganic fine particles include silica fine particles, colloidal silica, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, pseudoboehmite, zinc oxide, and hydroxide. Examples thereof include zinc, alumina, aluminum silicate, calcium silicate, magnesium silicate, zirconium oxide, zirconium hydroxide, cerium oxide, lanthanum oxide, and yttrium oxide. Among these, silica fine particles, colloidal silica, alumina fine particles, or pseudoboehmite are preferable from the viewpoint of forming a good porous structure.

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

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

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

  The average primary particle size of the vapor phase silica is 50 nm or less, more preferably 20 nm or less, particularly preferably 10 nm or less, and most preferably 3 to 10 nm. The above-mentioned vapor phase silica is easy to adhere to each other by hydrogen bonding due to silanol groups. Therefore, when the average primary particle diameter is 50 nm or less, a structure having a large porosity can be formed, and the ink absorption characteristics can be effectively improved. Can be improved.

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

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

About the pore structure of pseudo boehmite, the average pore radius is preferably 1 to 25 nm, and more preferably 2 to 10 nm. The pore volume is preferably 0.3 to 2.0 cc / g, more preferably 0.5 to 1.5 cc / g. Here, the pore radius and pore volume are measured by a nitrogen adsorption / desorption method, and can be measured by, for example, a gas adsorption / desorption analyzer (for example, trade name “Omni Soap 369” manufactured by Coulter). .
Among alumina fine particles, vapor-phase method alumina fine particles are preferable because of their large specific surface area. The average primary particle size of the vapor phase alumina is 50 nm or less, and more preferably 20 nm or less.
Furthermore, colloidal silica having an average primary particle size of 50 nm or less is also preferable.
That is, the inorganic fine particles used in the present invention are preferably silica fine particles, colloidal silica, alumina fine particles, and pseudoboehmite.

  When the above-mentioned fine particles are used in an inkjet recording medium, for example, JP-A-10-81064, JP-A-10-119423, JP-A-10-157277, JP-A-10-217601, JP-A-11-348409, JP-A-2001-2001. 138621, 2000-43401, 2000-21235, 2000-309157, 2001-96897, 2001-138627, JP-A-11-91242, 8-2087, 8-2090 No. 8-2091, No. 8-2093, No. 8-174992, No. 11-192777, JP-A No. 2001-301314, etc. can be preferably used.

  In the ink jet recording medium of the present invention, the ink receiving layer contains a dispersion of organic or inorganic fine particles as described above, a water-soluble resin, and if necessary, a crosslinking agent and a mordant, etc. Various excellent characteristics such as high printing density and high glossiness are exhibited.

Hereinafter, components of the ink receiving layer other than the fine particles will be described.
(Water-soluble resin)
Examples of the water-soluble resin used in the present invention include a polyvinyl alcohol resin (polyvinyl alcohol (PVA), acetoacetyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, and anion-modified polyvinyl) that is a resin having a hydroxy group as a hydrophilic structural unit. Alcohol, silanol-modified polyvinyl alcohol, polyvinyl acetal, etc.], cellulosic resins [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl methyl cellulose, hydroxy Propylmethylcellulose, etc.], chitins, chitosans, starch, resins having an ether bond (polyethylene oxide) PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), polyvinyl ether (PVE), etc.], resins having a carbamoyl group [polyacrylamide (PAAM), polyvinylpyrrolidone (PVP), polyacrylic acid hydrazide, etc.), etc. It is done.
Moreover, the polyacrylic acid salt which has a carboxyl group as a dissociable group, maleic acid resin, alginate, gelatins, etc. can be mentioned.

Among these, polyvinyl alcohol resin is particularly preferable. Examples of the polyvinyl alcohol include Japanese Patent Publication No. 4-52786, Japanese Patent Publication No. 5-67432, Japanese Patent Publication No. 7-29479, Japanese Patent No. 2537827, Japanese Patent Publication No. 7-57553, Japanese Patent No. 2502998, and Japanese Patent No. 3053231. JP-A-63-176173, JP-A-2604367, JP-A-7-276787, JP-A-9-207425, JP-A-11-58941, JP-A-2000-135858, JP-A-2001-205924, JP 2001-287444, JP 62-278080, JP 9-39373, JP 2750433, JP 2000-18801, JP 2001-213045, JP 2001-328345, JP 8 -324105, JP-A-11-348417, etc. It is below.
Examples of water-soluble resins other than polyvinyl alcohol resins include compounds described in “0011” to “0014” of JP-A No. 11-165461.
These water-soluble resins may be used alone or in combination of two or more.

  As content of the water-soluble resin of this invention, 9-40 mass% is preferable with respect to the total solid content mass of an ink receiving layer, and 12-33 mass% is more preferable.

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

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

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

<Content ratio of fine particles and water-soluble resin>
The mass content ratio [PB ratio (x / y)] between the fine particles (x) and the water-soluble resin (y) greatly affects the film structure and film strength of the ink receiving layer. That is, as the mass content ratio [PB ratio] increases, the porosity, pore volume, and surface area (per unit mass) increase, but the density and strength tend to decrease.

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

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

For example, a coating solution in which vapor-phase method silica fine particles having an average primary particle size of 20 nm or less and a water-soluble resin are completely dispersed in an aqueous solution at a mass ratio (x / y) of 2 to 5 is applied onto a support. When the coating layer is dried, a three-dimensional network structure is formed in which the secondary particles of silica fine particles are network chains, the average pore diameter is 25 nm or less, the porosity is 50 to 80%, and the pore specific volume is 0.00. A translucent porous film having a specific surface area of 5 ml / g or more and a specific surface area of 100 m ² / g or more can be easily formed.

(Crosslinking agent)
The ink receiving layer of the ink jet recording medium of the present invention includes a coating layer containing fine particles and a water-soluble resin, and further includes a cross-linking agent capable of cross-linking the water-soluble resin, and a cross-linking reaction between the cross-linking agent and the water-soluble resin. An embodiment that is a cured porous layer is preferred.

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

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

Isocyanate compounds such as 1,6-hexamethylene diisocyanate; Aziridine compounds described in US Pat. Nos. 3,017,280 and 2,983611; Carboximide compounds described in US Pat. No. 3,100,704; Glycerol triglycidyl Epoxy compounds such as ether; Ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; Halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; 2,3-dihydroxy Dioxane-based compounds such as dioxane; titanium-containing aluminum sulfate, chromium alum, potassium alum, metal-containing compounds such as zirconyl acetate, chromium acetate, polyamine compounds such as tetraethylenepentamine, hydrazide compounds such as adipic acid dihydrazide, A low molecule or polymer containing two or more oxazoline groups.
The above crosslinking agents may be used singly or in combination of two or more.

In the crosslinking and curing, a crosslinking agent is added to a coating solution containing fine particles, a water-soluble resin or the like (hereinafter sometimes referred to as “coating solution A”) and / or the following basic solution, and (1) the coating At the same time as the coating layer is formed by applying the liquid, or (2) at any time during the drying of the coating layer formed by applying the coating liquid and before the coating layer exhibits reduced-rate drying It is preferable to carry out by applying a basic solution having a pH of 7.1 or higher (hereinafter sometimes referred to as “coating liquid B”) to the coating layer. The application of the cross-linking agent is preferably performed as described below when a boron compound is taken as an example. That is, when the ink receiving layer is a layer obtained by crosslinking and curing a coating layer coated with a coating solution (coating solution A) containing a water-soluble resin containing fine particles and polyvinyl alcohol, crosslinking curing is performed by (1) the coating described above. Simultaneously with application of the liquid, (2) at any time during the dry coating of the coating layer formed by coating the coating liquid and before the coating layer exhibits reduced-rate drying, the pH is 7.1. The above basic solution (coating solution B) is applied to the coating layer. The boron compound as a cross-linking agent may be contained in either the coating liquid A or the coating liquid B, and may be contained in both the coating liquid A and the coating liquid B.
1-50 mass% is preferable with respect to water-soluble resin, and, as for the usage-amount of a crosslinking agent, 5-40 mass% is more preferable.

(mordant)
In the present invention, a mordant is preferably contained in the ink receiving layer in order to improve the water resistance and aging resistance of the formed image.
As the mordant, as the organic mordant, the above-described cationic polymer (cationic mordant) or inorganic mordant is preferable, and a liquid ink having an anionic dye as a colorant by allowing the mordant to be present in the ink receiving layer; Can stabilize the coloring material and improve water resistance and aging resistance. The organic mordant and the inorganic mordant may be used alone or in combination with the organic mordant and the inorganic mordant.

  The mordant is added to a coating liquid (coating liquid A) containing fine particles and a water-soluble resin, or is contained in the coating liquid B and applied when there is a concern of causing aggregation between the fine particles.

An inorganic mordant can also be used as the mordant of the present invention, and examples of the inorganic mordant include polyvalent water-soluble metal salts and hydrophobic metal salt compounds.
Specific examples of the inorganic mordant include, for example, magnesium, aluminum, calcium, scandium, titanium, vanadium, manganese, iron, nickel, copper, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, indium, barium, lanthanum, Examples thereof include salts or complexes of metals selected from cerium, praseodymium, neodymium, samarium, europium, gadolinium, dysproprosium, erbium, ytterbium, hafnium, tungsten, and bismuth.

  Specifically, for example, calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, chloride chloride Dicopper, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel sulfate Ammonium hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum alum, basic polyaluminum hydroxide, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate Products, ferrous bromide, ferrous chloride, ferric chloride, Ferrous acid, ferric sulfate, zinc phenolsulfonate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, titanium tetrachloride, tetraisopropyl titanate, titanium acetylacetonate, titanium lactate, zirconium acetyl Acetonate, zirconyl acetate, zirconyl sulfate, ammonium zirconium carbonate, zirconyl stearate, zirconyl octylate, zirconyl nitrate, zirconium oxychloride, zirconium zirconium chloride, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, citric acid Magnesium nonahydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphoric acid n hydrate, gallium nitrate Germanium nitrate, strontium nitrate, yttrium acetate, yttrium chloride, yttrium nitrate, indium nitrate, lanthanum nitrate, lanthanum chloride, lanthanum acetate, lanthanum benzoate, cerium chloride, cerium sulfate, cerium octylate, praseodymium nitrate, neodymium nitrate, nitric acid Examples include samarium, europium nitrate, gadolinium nitrate, dysprosium nitrate, erbium nitrate, ytterbium nitrate, hafnium chloride, and bismuth nitrate.

The inorganic mordant of the present invention is preferably an aluminum-containing compound, a titanium-containing compound, a zirconium-containing compound, or a metal compound (salt or complex) of Group IIIB series of the periodic table of elements.
Mordant amount contained in the ink receiving layer in the present invention is preferably from ^{0.01g / m 2 ~5g / m 2} , 0.1g / m 2 ~3g / m 2 is more preferable.

(Other ingredients)
The ink jet recording medium of the present invention may further contain various known additives, for example, acids, ultraviolet absorbers, antioxidants, fluorescent brighteners, monomers, polymerization initiators, polymerization inhibitors, and bleeding inhibitors as necessary. Agents, preservatives, viscosity stabilizers, antifoaming agents, surfactants, antistatic agents, matting agents, anti-curling agents, water-proofing agents, and the like.

  In the present invention, the ink receiving layer may contain an acid. By adding an acid, the surface pH of the ink receiving layer is adjusted to 3 to 8, preferably 5 to 7.5. This is preferable because yellowing resistance of the white background portion is improved. The surface pH is measured by the A method (coating method) of the surface PH measurement defined by the Japan Paper Pulp Technology Association (J.TAPPI). For example, the measurement can be performed by using a paper PH measurement set “Type MPC” manufactured by Kyoritsu Riken Co., Ltd. corresponding to the method A.

Specific examples of acids include formic acid, acetic acid, glycolic acid, oxalic acid, propionic acid, malonic acid, succinic acid, adipic acid, maleic acid, malic acid, tartaric acid, citric acid, benzoic acid, phthalic acid, isophthalic acid , Glutaric acid, gluconic acid, lactic acid, aspartic acid, glutamic acid, salicylic acid, salicylic acid metal salts (salts such as Zn, Al, Ca, Mg), methanesulfonic acid, itaconic acid, benzenesulfonic acid, toluenesulfonic acid, trifluoromethanesulfone Acid, styrenesulfonic acid, trifluoroacetic acid, barbituric acid, acrylic acid, methacrylic acid, cinnamic acid, 4-hydroxybenzoic acid, aminobenzoic acid, naphthalenedisulfonic acid, hydroxybenzenesulfonic acid, toluenesulfinic acid, benzenesulfinic acid, Sulfanilic acid, sulfamic acid, α-le Examples include ricinic acid, β-resorcinic acid, γ-resorcinic acid, gallic acid, phloroglicin, sulfosalicylic acid, ascorbic acid, erythorbic acid, bisphenolic acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, boric acid, boronic acid, etc. It is done. What is necessary is just to determine the addition amount of these acids so that the surface PH of an ink receiving layer may be set to 3-8.
The above acids can be metal salts (eg sodium, potassium, calcium, cesium, zinc, copper, iron, aluminum, zirconium, lanthanum, yttrium, magnesium, strontium, cerium, etc.) or amine salts (eg ammonia, triethylamine, tri Butylamine, piperazine, 2-methylpiperazine, polyallylamine, etc.).

In the present invention, it is preferable that a preservability improving agent such as an ultraviolet absorbent, an antioxidant, or a bleeding inhibitor is contained in the ink receiving layer.
These ultraviolet absorbers, antioxidants and anti-bleeding agents include alkylated phenol compounds (including hindered phenol compounds), alkylthiomethylphenol compounds, hydroquinone compounds, alkylated hydroquinone compounds, tocopherol compounds, thiodiphenyl ether compounds, 2 Compounds having the above thioether bonds, bisphenol compounds, O-, N- and S-benzyl compounds, hydroxybenzyl compounds, triazine compounds, phosphonate compounds, acylaminophenol compounds, ester compounds, amide compounds, ascorbic acid, amine antioxidants Agent, 2- (2-hydroxyphenyl) benzotriazole compound, 2-hydroxybenzophenone compound, acrylate, water-soluble or hydrophobic metal salt, organometallic compound, metal complex, Ndardamine compounds (including TEMPO compounds), 2- (2-hydroxyphenyl) 1,3,5, -triazine compounds, metal deactivators, phosphite compounds, phosphonite compounds, hydroxyamine compounds, nitrone compounds, peroxidation Scavenger, polyamide stabilizer, polyether compound, basic auxiliary stabilizer, nucleating agent, benzofuranone compound, indolinone compound, phosphine compound, polyamine compound, thiourea compound, urea compound, hydrazide compound, amidine compound, sugar compound, hydroxybenzoic acid Acid compounds, dihydroxybenzoic acid compounds, trihydroxybenzoic acid compounds and the like can be mentioned.

  Among these, alkylated phenol compounds, compounds having two or more thioether bonds, bisphenol compounds, ascorbic acid, amine-based antioxidants, water-soluble or hydrophobic metal salts, organometallic compounds, metal complexes, hindered amine compounds, Hydroxyamine compounds, polyamine compounds, thiourea compounds, hydrazide compounds, hydroxybenzoic acid compounds, dihydroxybenzoic acid compounds, trihydroxybenzoic acid compounds and the like are preferable.

  Specific examples of the compound include Japanese Patent Application Nos. 2002-13005, 10-182621, 2001-260519, 4-34953, 4-34513, 11-170686, JP-B-4-34512, EP1138509, JP-A-60-67190, JP-A-7-276808, JP-A-2001-94829, JP-A-47-10537, JP-A-58-111942, and JP-A-58-212844. No. 59-19945, 59-46646, 59-109055, 63-53544, Sho 36-10466, 42-26187, 48-30492, 48-31255 48-41572, 48-54965, 50-10726, US Pat. No. 2,719,086, 3,707,375, 3,754,919, 4,220,711,

  Japanese Patent Publication Nos. 45-4699, 54-5324, European Published Patent Nos. 223739, 309401, 309402, 3105301, 310552, 459416, German Published Patent No. 3435443, Kaisho 54-48535, 60-107384, 60-107383, 60-125470, 60-125471, 60-125472, 60-287485, 60-287486, 60-287487, 60-287488, 61-160287, 61-18854, 61-2111079, 62-146678, 62-146680, 62-146679, 62- No. 282885, No. 62-262047, No. 63-051174, Nos. 63-89877, 63-88380 same issue, same 66-88381 JP, same 63-113536 issue,

  63-163351, 63-203372, 63-224989, 63-251282, 63-267594, 63-182484, JP-A-1-239282, JP-A-2-262654, 2-71262, 3-121449, 4-291865, 4-291684, 5-611166, 5-119449, 5-188687, 5-188686, 5 No. 110490, No. 5-110437, No. 5-170361, No. 48-43295, No. 48-33212, US Pat. Nos. 4,814,262, No. 4,980,275, and the like. .

The other components may be used alone or in combination of two or more. These other components may be added after being water-solubilized, dispersed, polymer-dispersed, emulsified or oil-dropped, or may be encapsulated in microcapsules. In the ink jet recording medium of the present invention, the addition amount of the other components is preferably 0.01 to 10 g / m ² .

  Further, the surface of the inorganic fine particles may be treated with a silane coupling agent for the purpose of improving the dispersibility of the inorganic fine particles. Examples of the silane coupling agent include an organic functional group (for example, vinyl group, amino group (primary to tertiary amino group, quaternary ammonium base), epoxy group, mercapto, in addition to the site for coupling treatment. A group having a group, a chloro group, an alkyl group, a phenyl group, an ester group, or the like).

In the present invention, the ink receiving layer coating solution (coating solution A) preferably contains a surfactant. As the surfactant, any of cationic, anionic, nonionic, amphoteric, fluorine and silicon surfactants can be used.
Nonionic surfactants include polyoxyalkylene alkyl ethers and polyoxyalkylene alkyl phenyl ethers (for example, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene). Nonylphenyl ether, etc.), oxyethylene / oxypropylene block copolymers, sorbitan fatty acid esters (eg, sorbitan monolaurate, sorbitan monooleate, sorbitan trioleate, etc.), polyoxyethylene sorbitan fatty acid esters (eg, polyoxyethylene sorbitan) Monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan tri ), Polyoxyethylene sorbitol fatty acid esters (for example, polyoxyethylene sorbitol tetraoleate), glycerin fatty acid esters (for example, glycerol monooleate), polyoxyethylene glycerin fatty acid esters (polyoxymonostearate) Ethylene glycerol, monooleic acid polyoxyethylene glycerin, etc.), polyoxyethylene fatty acid esters (polyethylene glycol monolaurate, polyethylene glycol monooleate, etc.), polyoxyethylene alkylamine, acetylene glycols (eg, 2, 4, 7) , 9-tetramethyl-5-decyne-4,7-diol, and ethylene oxide adducts, propylene oxide adducts and the like of these diols), among others, polyoxy Ruki alkylene alkyl ethers are preferable. The nonionic surfactant can be used in the coating liquid A and the coating liquid B. Moreover, the said nonionic surfactant may be used independently and may use 2 or more types together.

  Examples of amphoteric surfactants include amino acid type, carboxyammonium betaine type, sulfoneammonium betaine type, ammonium sulfate betaine type, imidazolium betaine type, and the like. For example, US Pat. No. 3,843,368, Those described in JP-A-59-49535, JP-A-63-236546, JP-A-5-303205, JP-A-8-262742, and JP-A-10-282619 can be suitably used. As the amphoteric surfactant, an amino acid type amphoteric surfactant is preferable, and as the amino acid type amphoteric surfactant, as described in JP-A-5-303205, for example, an amino acid (glycine, glutamic acid, Derivatized from histidine acid and the like, and specifically, N-aminoacyl acids and salts thereof into which a long-chain acyl group has been introduced. The amphoteric surfactants may be used alone or in combination of two or more.

Examples of the anionic surfactant include fatty acid salts (for example, sodium stearate, potassium oleate), alkyl sulfate esters (for example, sodium lauryl sulfate, triethanolamine lauryl sulfate), and sulfonates (for example, sodium dodecylbenzenesulfonate). Alkyl sulfosuccinate (for example, sodium dioctyl sulfosuccinate), alkyl diphenyl ether disulfonate, alkyl phosphate, and the like.
Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, pyridinium salts, imidazolium salts, and the like.

Examples of the fluorosurfactant include compounds derived via an intermediate having a perfluoroalkyl group using a method such as electrolytic fluorination, telomerization, or oligomerization.
Examples thereof include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl trialkyl ammonium salts, perfluoroalkyl group-containing oligomers, and perfluoroalkyl phosphate esters.

  The silicone surfactant is preferably silicone oil modified with an organic group, which has a structure in which the side chain of the siloxane structure is modified with an organic group, a structure in which both ends are modified, and a structure in which one end is modified. obtain. Examples of the organic group modification include amino modification, polyether modification, epoxy modification, carboxyl modification, carbinol modification, alkyl modification, aralkyl modification, phenol modification, and fluorine modification.

  In the present invention, the content of the surfactant is preferably 0.001 to 2.0%, more preferably 0.01 to 1.0% with respect to the ink receiving layer coating liquid (coating liquid A). Further, when coating is performed using two or more liquids as the ink receiving layer coating liquid, it is preferable to add a surfactant to each coating liquid.

In the present invention, the ink receiving layer preferably contains a high boiling point organic solvent for curling prevention. The high-boiling organic solvent is an organic compound having a boiling point of 150 ° C. or higher at normal pressure, and is a water-soluble or hydrophobic compound. These may be liquid or solid at room temperature, and may be low molecules or polymers.
Specifically, aromatic carboxylic acid esters (for example, dibutyl phthalate, diphenyl phthalate, phenyl benzoate, etc.), aliphatic carboxylic acid esters (for example, dioctyl adipate, dibutyl sebacate, methyl stearate, dibutyl maleate) , Dibutyl fumarate, triethyl acetyl citrate, etc.), phosphate esters (eg, trioctyl phosphate, tricresyl phosphate, etc.), epoxies (eg, epoxidized soybean oil, epoxidized fatty acid methyl, etc.), alcohols (eg, stearyl) Alcohol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerol, diethylene glycol monobutyl ether (DEGMBE), triethylene glycol monobutyl ether, glycerol Methyl ether, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,4-pentanetriol, 1,2,6-hexanetriol, thiodiglycol, triethanolamine, polyethylene glycol, etc. ), Vegetable oils (eg, soybean oil, sunflower oil, etc.) and higher aliphatic carboxylic acids (eg, linoleic acid, oleic acid, etc.).

(Preparation of inkjet recording medium)
The ink receiving layer of the ink jet recording medium of the present invention is formed, for example, by applying a coating liquid A containing at least fine particles and a water-soluble resin on the surface of a support and (1) simultaneously with the coating or (2) formed by the coating. The coating layer to which the coating solution B is applied after the coating solution B having a pH of 7.1 or more is applied to the coating layer in the middle of drying and before the coating layer exhibits a reduced rate of drying. It is preferably formed by a method of crosslinking and curing (Wet-on-Wet method). Here, the crosslinking agent capable of crosslinking the water-soluble resin is preferably contained in at least one or both of the coating liquid A and the coating liquid B.
Providing an ink receiving layer that has been crosslinked and cured in this manner is preferable from the viewpoints of ink absorptivity and prevention of film cracking.

  It is preferable to add a mordant to the coating liquid B because a large amount of mordant is present near the surface of the ink receiving layer, so that the ink-jet coloring material is sufficiently mordanted and the water resistance of characters and images after printing is improved. A part of the mordant may be contained in the coating liquid A. In that case, the mordants of the coating liquid A and the coating liquid B may be the same or different.

In the present invention, an ink-receiving layer coating solution (coating solution A) containing at least fine particles (for example, vapor-phase process silica) and a water-soluble resin (for example, polyvinyl alcohol) is prepared, for example, as follows. be able to. That is,
Fine particles such as gas phase method silica and a cationic polymer dispersant are added to water (for example, silica fine particles in water are 10 to 20% by mass), and a high-speed rotating wet colloid mill (for example, “M Technique Co., Ltd.” “ For example, a dispersion of the present invention is obtained by dispersing for 20 minutes (preferably 10 to 30 minutes) under high-speed rotation conditions of, for example, 10,000 rpm (preferably 5000 to 20000 rpm). (A boron compound or the like may be added to the coating solution A), an aqueous solution of a water-soluble resin such as polyvinyl alcohol (PVA) (for example, PVA having a mass of about 1/3 of the vapor phase silica). In addition, it can be prepared by dispersing under the same rotation conditions as described above. The obtained coating liquid is in a uniform sol state, and a porous ink-receiving layer having a three-dimensional network structure can be formed by coating this on a support by the following coating method and drying it.

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

  The ink receiving layer coating liquid is applied by a known coating method such as, for example, an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, or a bar coater. it can.

  The coating liquid B is applied to the coating layer at the same time as or after the coating of the ink receiving layer coating liquid (coating liquid A), and the coating layer after coating has a reduced drying rate. It may be given before it becomes shown. That is, after the application of the ink receiving layer coating solution (coating solution A), the mordant is preferably introduced while the coating layer exhibits a constant rate of drying.

  Here, “before the coating layer comes to exhibit a decreasing rate of drying” usually refers to a process of several minutes immediately after the coating of the coating liquid for the ink-receiving layer. This shows the phenomenon of “constant rate drying rate” in which the content of the solvent (dispersion medium) in the medium decreases in proportion to time. About the time which shows this "constant rate drying speed", it describes in chemical engineering handbook (pages 707-712, Maruzen Co., Ltd. issue, October 25, 1980), for example.

  As described above, after the coating solution A is applied, the coating layer is dried until the coating layer exhibits a reduced rate of drying. This drying is generally performed at 40 to 180 ° C. for 0.5 to 10 minutes (preferably, 0 .5-5 minutes). The drying time naturally varies depending on the coating amount, but the above range is usually appropriate.

  As a method of giving before the said 1st application layer comes to show a decreasing rate drying rate, (1) The method of further apply | coating the coating liquid B on an application layer, (2) Spraying by methods, such as spraying. And (3) a method of immersing the support on which the coating layer is formed in the coating solution B, and the like.

  In the method (1), examples of the coating method for coating the coating liquid B include a curtain flow coater, an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, and a bar. A known coating method such as a coater can be used. However, it is preferable to use a method in which the coater does not directly contact the already formed first coating layer, such as an extrusion die coater, a curtain flow coater, a bar coater or the like.

  After application of coating liquid B, it is generally heated at 40 to 180 ° C. for 0.5 to 30 minutes, and dried and cured. Especially, it is preferable to heat at 40-150 degreeC for 1 to 20 minutes.

  Further, when the coating liquid B is applied simultaneously with the application of the ink receiving layer coating liquid (coating liquid A), the coating liquid A and the coating liquid B are placed on the support so that the coating liquid A is in contact with the support. The ink receiving layer can be formed by simultaneous application (multilayer application) and then drying and curing.

  The simultaneous coating (multilayer coating) can be performed by a coating method using, for example, an extrusion die coater or a curtain flow coater. After the simultaneous coating, the formed coating layer is dried. In this case, the drying is generally performed by heating the coating layer at 40 to 150 ° C. for 0.5 to 10 minutes, preferably 40 to 100. It is carried out by heating at a temperature of 0.5 to 5 minutes.

  When the above simultaneous coating (multilayer coating) is performed by, for example, an extrusion die coater, the two types of coating liquid discharged at the same time are close to the discharge port of the extrusion die coater, that is, before moving onto the support. A multilayer is formed, and in that state, it is coated on the support. Since the two-layer coating liquid that has been layered before coating is likely to cause a crosslinking reaction at the interface between the two liquids when transferred to the support, the two liquids to be discharged are mixed in the vicinity of the discharge port of the extrusion die coater. As a result, thickening is likely to occur, which may hinder the application operation. Therefore, when applying simultaneously as described above, the barrier layer liquid (intermediate layer liquid) is interposed between the two liquids together with the application of the ink receiving layer coating liquid (coating liquid A) and the mordant solution (coating liquid B). The simultaneous triple layer coating is preferred.

  The barrier layer solution can be selected without particular limitation. For example, an aqueous solution containing a trace amount of water-soluble resin, water, and the like can be given. The water-soluble resin is used in consideration of applicability for the purpose of a thickener and the like. For example, a cellulose resin (for example, hydroxypropylmethylcellulose, methylcellulose, hydroxyethylmethylcellulose) And polymers such as polyvinylpyrrolidone and gelatin. The barrier layer solution may contain the above mordant.

  After the ink receiving layer is formed on the support, the ink receiving layer is subjected to, for example, super calender, gloss calender, etc., and is subjected to calender treatment through the roll nip under heat and pressure, so that surface smoothness, glossiness, It is possible to improve transparency and coating strength. However, the calendar process may cause a decrease in the porosity (that is, the ink absorptivity may be decreased), so it is necessary to set conditions under which the decrease in the porosity is small.

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

In the case of ink jet recording, the thickness of the ink receiving layer needs to have an absorption capacity sufficient to absorb all of the droplets, and therefore needs to be determined in relation to the porosity in the layer. For example, if the ink amount is 8 nL / mm ² and the porosity is 60%, a film having a layer thickness of about 15 μm or more is required.
Considering this point, in the case of ink jet recording, the layer thickness of the ink receiving layer is preferably 10 to 50 μm.

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

The ink receiving layer is preferably excellent in transparency, but as a guide, the haze value when the ink receiving layer is formed on a transparent film support is preferably 30% or less, and 20% The following is more preferable.
The haze value can be measured using a haze meter (for example, “HGM-2DP” of Suga Test Instruments Co., Ltd.).

  A polymer fine particle dispersion may be added to a constituent layer (for example, an ink receiving layer or a back layer) of the ink jet recording medium of the present invention. This polymer fine particle dispersion is used for the purpose of improving film properties such as dimensional stabilization, curling prevention, adhesion prevention, and film cracking prevention. The polymer fine particle dispersion is described in JP-A Nos. 62-245258, 62-1316648, and 62-110066. If a polymer fine particle dispersion having a low glass transition temperature (40 ° C. or lower) is added to the layer containing the mordant, cracking and curling of the layer can be prevented. Further, even when a polymer fine particle dispersion having a high glass transition temperature is added to the back layer, curling can be prevented.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In the examples, “parts” and “%” represent “parts by mass” and “% by mass” unless otherwise specified.

(Preparation of support 1)
Wood pulp composed of 100 parts of LBKP is beaten to 300 ml Canadian freeness with a double disc refiner, 0.5 parts of epoxidized behenamide, 1.0 part of anionic polyacrylamide, 0.1 part of polyamide polyamine epichlorohydrin, 0.5 part of cationic polyacrylamide All parts were added at an absolutely dry mass ratio with respect to the pulp, and weighed with a long net paper machine to produce a base paper of 170 g / m ² .

In order to adjust the surface size of the base paper, 0.04% of a fluorescent whitening agent (“Whiteex BB” manufactured by Sumitomo Chemical Co., Ltd.) is added to a 4% aqueous solution of polyvinyl alcohol, and this is calculated in terms of absolute dry mass. The base paper was impregnated to 0.5 g / m ² , dried, and then subjected to a calendering process to obtain a base paper adjusted to a density of 1.05 g / cc.

On the surface of the base paper obtained above (on the side on which the image forming layer is provided), an ink solvent-permeable undercoat coating solution having the composition shown below is applied so that the coating amount after drying is 10.0 g / m ² . It was applied with a bar coater and dried to form an ink solvent-permeable undercoat layer. Next, an ink solvent permeable undercoat coating liquid having the following composition is applied to the wire surface (back surface) on the side where the ink solvent permeable undercoat layer is not formed, so that the dry coating amount is 20.0 g / m ² . Then, it was coated with a bar coater and dried to form a curl adjusting layer, and the target substrate 1 with an undercoat layer was produced.

<Composition of coating solution for ink solvent permeable undercoat>
Acrylic water-dispersible latex 1 ... 87 parts (Acrylic styrene latex obtained in Synthesis Example 1 described later:
(Non-volatile content 34% by weight, pH 8.0, viscosity 400 mPa · s, average particle size 60 nm)
・ Water ………… 13 parts

(Preparation of support 2)
Instead of “acrylic water-dispersible latex 1” in the <composition of ink solvent-permeable undercoat coating solution> used in the preparation of the support 1, “acrylic water-dispersible latex obtained in Synthesis Example 2 ” 2 (acrylic silicon-based latex: non-volatile content 31% by weight, pH 7.2, viscosity 30 mPa · s, average particle size 50 nm) ”was used to obtain Support 2 in the same manner.

(Preparation of support 3)
Instead of “acrylic water-dispersible latex 1” in the <composition of ink solvent-permeable undercoat coating solution> used in the preparation of the support 1, “acrylic epoxy latex (“ AEA ”manufactured by Daicel Chemical Industries, Ltd.) was used. −61 ”, MFT = 40 ° C., average particle size = 50 nm, solid content concentration = 30%)” was used to obtain Support 3 in the same manner.

(Preparation of support 4)
Instead of “acrylic water dispersible latex 1” in the <composition of ink solvent permeable undercoat coating solution> used in the production of the support 1, “acrylic urethane latex (“ AU- ”manufactured by Daicel Chemical Industries, Ltd.) was used. 124 ”, MFT = 0 ° C., average particle size = 100 nm, solid content concentration = 40%)” was used to obtain Support 4 in the same manner.

(Preparation of support 5)
In <Composition of Ink Solvent-permeable Undercoat Coating Solution> used in the production of the support 1, instead of “acrylic water-dispersible latex 1”, “styrene-butadiene latex (“ Nipol ”manufactured by Nippon Zeon Co., Ltd.) was used. Support 5 was obtained in the same manner except that “LX110”, average particle diameter = 80 nm, solid content concentration = 41%) ”was used.

(Preparation of support 6)
Instead of “acrylic water-dispersible latex 1”, <acrylonitrile-butadiene latex (“Nipol” manufactured by Nippon Zeon Co., Ltd.) was used instead of “acrylic water-dispersible latex 1”. 1561 ”, average particle size = 50 nm, solid content concentration = 40%)” was used to obtain Support 6 in the same manner.

(Preparation of support 7)
Support was performed in the same manner except that the following composition was added to the <composition of the coating solution for ink solvent-permeable undercoat> used in the preparation of the support 1 to add a white pigment dispersion having the following composition. Body 7 was obtained.
<Composition of white pigment dispersion>
・ Titanium dioxide: 100 parts (“Taipeke R-780-2” manufactured by Ishihara Sangyo Co., Ltd.)
・ Na salt of special polycarboxylic acid type polymer ......... 1.2 parts (trade name "Demol EP" manufactured by Kao Corporation)
・ Water ……… 122 parts
<Composition of coating solution for ink solvent permeable undercoat>
-Acrylic water-dispersible latex 2 ... 26 parts (acrylic silicone latex obtained in Example 12 to be described later)
・ The above white pigment dispersion liquid …… 10 parts ・ Water …… 64 parts

(Preparation of support 8)
In the production of the support 1, the support 8 was obtained in the same manner except that the ink solvent-permeable primer coating solution was applied so that the coating amount after drying was 20.0 g / m ² and dried. It was.

(Preparation of support 9)
In the production of the support 1, the support 9 was obtained in the same manner except that the ink solvent-permeable undercoat coating solution was applied and dried so that the coating amount after drying was 35.0 g / m ^2. It was.

(Preparation of support 10)
In <Composition of Ink Solvent-permeable Undercoat Coating Solution> used in the production of the support 2, instead of “Acrylic Water Dispersible Latex 2”, “acrylic styrene latex (“ John Crill ”manufactured by Johnson Polymer Co., Ltd.) was used. 450 ”, MFT <5 ° C., Tg = 16 ° C., average particle size = 60 nm, solid content concentration = 42%)> was used to obtain the support 10 in the same manner.

(Preparation of Comparative Support A)
Comparative support A was obtained in the same manner except that no ink solvent-permeable undercoat layer was formed on the surface of the base paper (side on which the image forming layer was provided) in the production of the support 1.

(Preparation of Comparative Support B)
In the production of the support 1, 9.9% polyvinyl alcohol “PVA-105” (manufactured by Kuraray Co., Ltd., saponification degree 98.5%, polymerization degree 500) instead of the ink solvent-permeable undercoat coating solution. A comparative support B was obtained in the same manner except that an undercoat layer was prepared using

(Evaluation of physical properties of support)
Each support obtained above was subjected to a Cobb water absorption degree and ink water absorption evaluation test as follows, and the results are shown in Table 1 below.
(Cobb water absorption)
Based on the water absorption test method defined in JIS P8140, the contact time was set to 2 minutes, and the water absorption of each support was measured and evaluated according to the following criteria. Here, not the water but the above-mentioned solution (A1) and the ink receiving layer coating liquid (C1) described later were used as the measurement liquid.
[Standard]
-In the case of solution (A1);
AA ... Cobb water absorption was 25 g / m ² or more.
BB ... Cobb water absorption was 10 to 25 g / m ² .
CC: Cobb water absorption was 10 g / m ² or less.
In the case of the ink receiving layer coating liquid (C1);
AA ... Cobb water absorption was 10 g / m ² or less.
BB ... Cobb water absorption was more than 10 g / m ² .

(Ink absorption)
Using an ink jet printer “PM-970C” manufactured by Seiko Epson Corporation, Y (yellow), M (magenta), C (cyan), K (black), B (blue) on each of the above supports. , G (green), and R (red) solid images are printed, and then (after about 1 hour), the paper is brought into contact with the image and pressed, and the degree of transfer of the ink onto the paper is determined as follows. Evaluation was made according to criteria.
[Standard]
AA .... Almost no ink transfer onto the paper (ink absorbability is good).
BB: Some transfer of ink onto paper was recognized (no problem in practical use).
CC ... Many ink transfer on paper was observed.

(Preparation of inkjet recording medium)
Using each of the supports obtained above, an ink jet recording medium was produced according to the following procedure.
[Example 1]
(Preparation of coating liquid C1 for ink receiving layer)
(1) Gas phase method silica fine particles, (2) ion-exchanged water, and (3) a dispersant in the following composition are mixed and rotated using a stirrer “KD-P” manufactured by Shinmaru Enterprises Co., Ltd. After being dispersed at 10000 rpm for 20 minutes, a solution containing (4) polyvinyl alcohol, (5) boric acid, (6) polyoxyethylene lauryl ether, and (7) ion-exchanged water is added to this dispersion. Further, dispersion was carried out at a rotational speed of 10,000 rpm for 20 minutes to prepare a target ink receiving layer coating solution (C1).
Here, the mass ratio between the silica fine particles and the water-soluble resin (PB ratio = (1) / (4)) was 4.5, and the pH of the coating solution for ink receiving layer was 3.5, indicating acidity. .

<Composition of ink receiving layer coating liquid C1>
(1) Gas phase method silica fine particles 10.0 parts ("Reoseal QS-30" manufactured by Tokuyama Corporation, average primary particle size 7 nm)
(2) Ion-exchanged water 51.6 parts (3) Dispersant “Charol DC-902P” 1.0 part (Nittobo Co., Ltd., 51% aqueous solution)
(4) Polyvinyl alcohol (water-soluble resin) 8% aqueous solution 27.8 parts ("PVA124" manufactured by Kuraray Co., Ltd., saponification degree 98.5%, polymerization degree 2400)
(5) Boric acid (crosslinking agent) 0.4 part (6) Polyoxyethylene lauryl ether (surfactant) 1.2 part ("Emulgen 109P" manufactured by Kao Corporation), 10% aqueous solution, HLB value 13.6 )
(7) Ion exchange water 33.0 parts

(Preparation of inkjet recording medium)
After the front surface of the support 1 is subjected to corona discharge treatment, the ink receiving layer coating liquid (C1) obtained above is applied to the front surface of the support at 200 ml / m ² using an extrusion die coater. The coating layer was dried at a temperature of 80 ° C. (wind speed of 3 to 8 m / sec) with a hot air dryer until the solid content concentration of the coating layer reached 20%. This coating layer exhibited a constant rate of drying during this period. Immediately after that, it was immersed in a mordant solution (D) having the following composition for 30 seconds to deposit 20 g / m ² on the coating layer (step of applying a mordant solution), and further dried at a temperature of 80 ° C. for 10 minutes. (Drying process). This produced the ink jet recording medium of the present invention provided with an ink receiving layer having a dry film thickness of 32 μm.

<Composition of mordant coating liquid D>
(1) Boric acid (crosslinking agent) 0.65 parts (2) Polyallylamine “PAA-10C” 20% aqueous solution 12.5 parts (Mordant, manufactured by Nittobo Co., Ltd.)
(3) Ion-exchanged water 72.0 parts (4) Ammonium chloride (surface pH adjusting agent) 0.8 parts (5) Polyoxyethylene lauryl ether (surfactant) 10 parts (Emulgen 109P manufactured by Kao Corporation) ”2% aqueous solution, HLB value 13.6)
(6) MegaFac "F1405" 10% aqueous solution 2.0 parts (Fluorine surfactant manufactured by Dainippon Ink & Chemicals, Inc.)

[Examples 2 , 7 and 8, Reference Examples 1 to 6 ]
An inkjet recording medium of the present invention was produced in the same manner as in Example 1 except that the supports 2 to 10 were used instead of the support 1 used in Example 1.

[Comparative Examples 1-2]
In Example 1, ink jet recording media of Comparative Examples 1 and 2 were produced in the same manner as in Example 1 except that Comparative Support A and Comparative Support B were used instead of Support 1. .

[Comparative Example 3]
(Preparation of inkjet recording medium)
After performing corona discharge treatment on the wire surface (back surface) side of the base paper obtained above, a high-density polyethylene is coated to a thickness of 19 μm using a melt extruder, and a resin layer comprising a mat surface is formed. (Hereinafter, the resin layer surface is referred to as “back surface”). The resin layer on the back side is further subjected to corona discharge treatment, and thereafter, as an antistatic agent, aluminum oxide (“Alumina sol 100” manufactured by Nissan Chemical Industries, Ltd.) and silicon dioxide (“Nissan Chemical Industry Co., Ltd.” “ Snowtex O ") to 1: the dispersion was dispersed in water at 2 weight ratio, dry mass was applied as a 0.2 g / m ^2.

Furthermore, after the corona discharge treatment is performed on the felt surface (surface surface) side where the resin layer is not provided, anatase-type titanium dioxide 10%, a trace amount of ultramarine blue, and a fluorescent brightening agent 0.01% (against polyethylene) ) And MFR (melt flow rate) 3.8 low-density polyethylene is extruded to a thickness of 29 μm using a melt extruder, and a high gloss thermoplastic resin layer is formed on the surface side of the base paper. (Hereinafter, this highly glossy surface is referred to as “front side”) to obtain a target support C for comparison.
After the corona discharge treatment was performed on the front surface resin layer having a glossy surface on which the resin layer of the support was not formed, an ink receiving layer was formed in the same manner as in Example 1, and the inkjet recording of Comparative Example 3 was performed. A working medium was prepared.

(Evaluation test)
Each ink jet recording medium obtained above was subjected to the following evaluation test, and the results of the test are shown in Table 2 below.
(1) Cock ring The cock ring when the coating liquid for ink receiving layer was applied to each support was evaluated according to the following criteria.
[Standard]
AA ......... cooking was hardly seen.
BB ...... a little cock ring was seen.
CC: The coating liquid for the ink receiving layer could not be applied because cockling was observed over the entire surface.

(2) Evaluation of image quality Using an ink jet printer “PM-970C” manufactured by Seiko Epson Corporation, images of people and scenery were printed and visually observed, and image quality was evaluated according to the following criteria.
[Standard]
AA ... The image quality was quite good.
BB: The image quality was generally good.
CC: The image quality was normal.
DD ... The image quality was bad.

(3) Time-lapse rainbows Using an inkjet printer “PM-970C” manufactured by Seiko Epson Corporation and ink, a grid-like linear pattern in which magenta ink and black ink are adjacent to each other on each inkjet recording medium ( A line width of 0.28 mm) was printed, and the visual density (OD ₀ ) was measured using “X Light 310TR” manufactured by X Light Corporation. Next, after leaving for 3 hours after printing, after storing in a constant temperature and humidity chamber at a temperature of 40 ° C./90% relative humidity for 1 day, the visual density (OD ₁ ) was measured again, and the difference in density (ΔOD) ) Was evaluated according to the following criteria.
[Standard]
AA .... DELTA.OD was 0.15 or less.
BB .... DELTA.OD was 0.15 to 0.25.
CC .... DELTA.OD was 0.25 or more.

From the results of Tables 1 and 2 above, the present invention satisfying the “Cobb water absorbency of the solution (A1) and the ink receiving layer coating liquid (C1)” defined by the present invention as the support with an undercoat layer. The ink jet recording medium of the present invention using such a support (Examples 1 , 2 , 7 and 8 ) does not cause cockling when the ink receiving layer coating solution is applied, and the recorded image is not blurred over time. It was found to be a suppressed high-quality recording medium.
On the other hand, the ink absorption layer coating liquid (C1) has a Cobb water absorption exceeding the specified value, and the ink jet recording media of Comparative Examples 1 to 3 using a support outside the scope of the present invention show cockling. The ink jet recording medium of Comparative Example 3, which has poor image quality and does not have an undercoat layer to which a composition containing thermoplastic resin particles is adhered, does not show cockling but is poor in aging over time. There was a defect or inferior quality.

[ Synthesis Example 1 ]
(Preparation of acrylic water-dispersible latex 1)
In a reaction vessel equipped with a stirrer, reflux condenser, dropping funnel, nitrogen introduction tube and thermometer, 583 parts of ion-exchanged water, anionic reactive emulsifier [trade name “SE-10N”, manufactured by Asahi Denka Co., Ltd.] The copolymer component A was charged with 162 parts of a 10% aqueous solution, heated to 80 ° C., charged with a catalyst aqueous solution in which 0.4 parts of potassium persulfate was dissolved in 9 parts of ion-exchanged water, and pre-emulsified. (54 parts of styrene, 54 parts of methyl methacrylate, 90 parts of 2-ethylhexyl acrylate, 3 parts of 2-hydroxyethyl methacrylate, 2 parts of methacrylic acid, 22 parts of acrylonitrile, 150 parts of ion-exchanged water, anionic reactive emulsifier [product (Emulsion of 62 parts of 10% aqueous solution of “SE-10N” manufactured by Asahi Denka Co., Ltd.) was added dropwise over 1 hour, and then the reaction was continued for another 1 hour.
Subsequently, copolymerization component B (97 parts of styrene, 97 parts of methyl methacrylate, 10 parts of 2-ethylhexyl acrylate, 7 parts of 2-hydroxyethyl methacrylate, 10 parts of methacrylic acid, trimethoxysilylpropyl methacrylate (= γ-methacrylic acid). Roxypropyltrimethoxysilane) (4 parts) and an anionic reactive emulsifier (trade name “SE-10N”, manufactured by Asahi Denka Co., Ltd.) (0.4 part mixed solution) were added dropwise over 1 hour, and then 1 more The reaction continued for hours. During the reaction, an aqueous catalyst solution prepared by dissolving 1 part of potassium persulfate in 73 parts of ion-exchanged water was added dropwise over 3 hours. After completion of the reaction, the liquid temperature was returned to room temperature, adjusted to pH 8 with a 28% aqueous ammonia solution, acrylic styrene latex (acrylic water-dispersible latex 1 used in Example 1 above (non-volatile content 34 wt%, pH 8). 0.0, viscosity 400 mPa · s, I value 50, O value 135, glass transition temperature 44 ° C., minimum film-forming temperature 5 ° C., average particle size 60 nm).

[ Synthesis Example 2 ]
(Preparation of acrylic water-dispersible latex 2)
In a reaction vessel equipped with a stirrer, reflux condenser, dropping funnel, nitrogen inlet tube and thermometer, 216 parts of isopropyl alcohol and 1.5 parts of azobisisobutyronitrile are stirred and dissolved, and heated to 80 ° C. Warm up. In the reaction vessel, 120 parts of methyl methacrylate, 99 parts of n-butyl acrylate, 16 parts of trimethoxysilylpropyl methacrylate (= γ-methacryloxypropyltrimethoxysilane) and 17 parts of acrylic acid were mixed as copolymerization components. Over 4 hours. After completion of the dropping, a solution prepared by dissolving 0.6 part of azobisisobutyronitrile in 27 parts of isopropyl alcohol was added dropwise as an additional catalyst, and the reaction was further continued for 2 hours to complete the polymerization. After completion of the polymerization, 20 parts of 25% aqueous ammonia was added while stirring, and then 945 parts of ion-exchanged water was added dropwise over about 1 hour. The liquid was applied to a rotary evaporator to distill off isopropyl alcohol, and acrylic silicone latex (acrylic water-dispersible latex 2 used in Example 2 (non-volatile content 31 wt%, pH 7.2, viscosity 30 mPa · s, I Value 71, O value 112, glass transition temperature 25 ° C., minimum film-forming temperature 20 ° C., average particle size 50 nm).

Claims (7)

In the ink jet recording medium having an ink receiving layer on a support, the support includes (1) a paper base, and an acrylic silicon-based thermoplastic resin particle on at least the ink receiving layer forming surface side of the paper base. is composed of a subbing layer comprising at least one resin particle, (2) coating amount of the acryl silicone resin is 1 to 30 g / m ^2, the ink jet recording medium, characterized in that. Wherein the undercoat layer, the ink-jet recording medium according to claim 1, characterized by further containing a pigment. The inkjet recording medium according to claim 1 or 2, wherein the thermoplastic resin particles have an average particle diameter of 10 to 200 nm and a minimum film-forming temperature (MFT) of 5 to 60 ° C. The inkjet according to any one of claims 1 to 3 , wherein the ink receiving layer further contains a water-soluble resin, a cross-linking agent capable of cross-linking the water-soluble resin, fine particles, and a mordant. Recording medium. The water-soluble resin is at least one selected from a polyvinyl alcohol resin, a cellulose resin, a resin having an ether bond, a resin having a carbamoyl group, a resin having a carboxyl group, and gelatin, and the fine particles are The ink jet recording medium according to claim 4 , wherein the medium is at least one selected from silica fine particles, colloidal silica, alumina fine particles, and pseudoboehmite. The ink receiving layer is a layer obtained by crosslinking and curing a coating layer coated with a coating solution containing at least fine particles and a water-soluble resin, and the crosslinking and curing is performed by adding a crosslinking agent to the coating solution and / or the following basic solution. And (1) at the same time when the coating solution is applied to form a coating layer, or (2) during the drying of the coating layer formed by coating the coating solution, the coating layer is reduced. before illustrating the drying, when either the pH is 7.1 or more basic solution to any one of claims 1 to 5, characterized in that is carried out by applying to the coating layer The ink jet recording medium described. A composition containing at least one acrylic silicone latex as thermoplastic resin particles on at least the ink-receiving layer-forming side of the paper substrate, and the coating amount of the acrylic silicone resin is 1 to 30 g / m. ² Forming a subbing layer by adhering so as to form a support, and
Applying an ink-receiving layer coating solution on the undercoat layer on the support to form an ink-receiving layer;
A method for producing an ink jet recording medium, comprising: