JP4002551B2 - Inkjet recording medium - Google Patents

Description

  The present invention relates to a recording material supplied to ink jet recording using liquid ink such as water-based ink and oil-based ink, or solid ink which is solid at room temperature and is melted and liquefied and used for printing. The present invention relates to an ink jet recording medium with less light resistance.

In recent years, with the rapid development of the information technology (IT) industry, various information processing systems have been developed, and a recording method and a recording apparatus suitable for each information processing system have been developed and put into practical use.
Among these recording methods, the inkjet recording method is capable of recording on a variety of recording materials, the hardware (equipment) is relatively inexpensive and compact, and has advantages such as low noise and excellent quietness. It has been widely used not only in offices but also in so-called home use.

In addition, with the recent increase in resolution of inkjet printers, it has become possible to obtain so-called photographic-like high-quality recorded matter. With the advancement of such hardware (equipment), recording for inkjet recording is possible. Various seats have also been developed.
The characteristics required for this recording sheet 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 print portion are good, (8) the whiteness of the recording sheet is high, and (9) the storage stability of the recording sheet is good ( No yellowing coloration even after long-term storage, images do not smear after long-term storage, good aging blur), (10) good deformation and good dimensional stability (curl is sufficiently small), (11) Good hardware (equipment) runnability, etc. And the like.
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, glossiness, surface smoothness, texture of photographic paper similar to silver salt photography, etc. Is also required.

  In recent years, an ink jet recording sheet (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 sheet has a porous structure, so that it has excellent ink receptivity (fast drying property) and high gloss.

For example, an inkjet recording sheet is proposed in which a colorant receiving layer (ink receiving layer) containing inorganic pigment fine particles and a water-soluble resin and having a high porosity is provided on a support (for example, Patent Document 1). Or 2).
These recording sheets, especially ink jet recording sheets provided with a colorant receiving layer having a porous structure using silica as inorganic pigment fine particles, have excellent ink absorbability due to the porous structure, and form high-resolution images. It has a high ink receiving performance and can exhibit high gloss.

An ink jet recording sheet having a porous ink receiving layer containing silica fine particles and water-soluble aluminum is disclosed (see, for example, Patent Document 3), and water resistance and light resistance are maintained while maintaining glossiness and ink absorption. And that surface cracks are improved. Furthermore, examples using various sulfur-containing compounds are described (for example, see Patent Document 4), and there is a description that light resistance and surface cracking are improved while maintaining ink absorbability. Also disclosed is an ink jet recording sheet containing a sulfur-containing compound such as a sulfoxide compound in a porous ink receiving layer containing a silica dispersant, polyallylamine, polyvinylamine and the like (see, for example, Patent Document 5). There is a description that ozone resistance, light resistance, surface cracks, and blemishes are improved while maintaining absorption.
However, in any of the above-described ink jet recording sheets, the ink absorption and the improvement of surface cracks are maintained, but the silver halide photographic material level that can sufficiently satisfy all the image blurring, light resistance, and ozone resistance over a long period of time. It cannot be said that it has reached.
JP 10-119423 A Japanese Patent Laid-Open No. 10-217601 JP 2000-309157 A Japanese Patent No. 3377093 JP 2003-11498 A

An object of the present invention is to solve the conventional problems and achieve the following objects. That is,
The object of the present invention is to have surface smoothness and glossiness of the recording surface, less blur over time, high-resolution and high-density image formation, and image resistance such as light resistance and ozone resistance. Another object of the present invention is to provide an ink jet recording medium that is excellent in color and does not cause coloring of the paper surface.

As a result of intensive studies, the present inventors have found that the above object can be achieved when a sulfoxide compound and a water-soluble polyvalent metal salt are combined and contained in the ink receiving layer. That is, the present invention
<1> In an inkjet recording medium having an ink receiving layer on a support,
An ink jet recording medium, wherein the ink receiving layer contains at least one sulfoxide compound and at least one water-soluble polyvalent metal salt.

<2> The inkjet recording medium according to <1>, wherein the water-soluble polyvalent metal salt is a water-soluble aluminum compound and / or a water-soluble zirconium compound.

<3> The inkjet recording medium according to <1> or <2>, wherein the sulfoxide compound has at least one structure represented by the following general formula (1) in a molecule.

<4> The inkjet recording medium according to any one of <1> to <3>, wherein the sulfoxide-based compound has a hydrophilic group.

<5> The inkjet recording medium according to any one of <1> to <4>, wherein the sulfoxide-based compound is a compound represented by the following general formula (2).

［一般式（２）中、Ｒ¹及びＲ³は、それぞれ独立に、置換又は無置換のアルキル基、置換又は無置換のアリール基、置換又は無置換のヘテロ環基、又はそれらからなるポリマー残基を表し、Ｒ¹とＲ³は同一でも異なってもよく、結合して環を形成していてもよい。Ｒ²は、置換又は無置換の２〜６価の連結基を表し、Ｒ¹及びＲ²、Ｒ²及びＲ³と結合して環を形成していてもよい。ｍは０又は１以上の整数を表し、ｎは０又は１を表す。Ｒ¹、Ｒ²、及びＲ³のうちの少なくともいずれかは、置換又は無置換のアミノ基、置換又は無置換のカルバモイル基、置換又は無置換のスルファモイル基、置換又は無置換のアンモニウム、ヒドロキシル基、スルホン酸、カルボン酸、リン酸、エチレンオキシ基、置換又は無置換の含窒素へテロ環で表される親水性基で置換されたアルキル基、アリール基、ヘテロ環基、及びポリマー残基を表す。］

[In General Formula (2), each of R ¹ and R ³ independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, or a polymer residue comprising them. Represents a group, and R ¹ and R ³ may be the same or different, and may combine to form a ring. R ² represents a substituted or unsubstituted divalent to hexavalent linking group, and may be bonded to R ¹ and R ² , R ² and R ³ to form a ring. m represents 0 or an integer of 1 or more, and n represents 0 or 1. At least one of R ¹ , R ² , and R ³ is a substituted or unsubstituted amino group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted sulfamoyl group, a substituted or unsubstituted ammonium, or a hydroxyl group Sulfonic acid, carboxylic acid, phosphoric acid, ethyleneoxy group, alkyl group substituted with a hydrophilic group represented by a substituted or unsubstituted nitrogen-containing heterocycle, aryl group, heterocyclic group, and polymer residue To express. ]

<6> The inkjet recording medium according to any one of <1> to <5>, wherein the ink receiving layer contains a water-soluble resin.

<7> The water-soluble resin is at least one selected from the group consisting of a polyvinyl alcohol resin, a cellulose resin, a resin having an ether bond, a resin having a carbamoyl group, a resin having a carboxy group, and gelatins. The inkjet recording medium according to <6>, wherein the inkjet recording medium is provided.

<8> The inkjet recording medium according to <6> or <7>, wherein the ink receiving layer contains a crosslinking agent capable of crosslinking the water-soluble resin.

<9> The ink jet recording medium according to any one of <1> to <8>, wherein the ink receiving layer further contains fine particles.

<10> The inkjet recording medium according to <9>, wherein the fine particles are at least one selected from the group consisting of silica fine particles, colloidal silica, alumina fine particles, and pseudoboehmite.

<11> The above-mentioned <10>, wherein the fine particles are vapor-phase method silica fine particles, and used in an ink receiving layer as an aqueous dispersion of vapor-phase method silica containing the vapor-phase method silica fine particles and a dispersant. > Is an ink jet recording medium.

<12> The ink receiving layer is a layer obtained by crosslinking and curing a coating layer to which a coating solution containing at least fine particles and a water-soluble resin is applied, and the crosslinking and curing includes (1) applying the coating solution. Simultaneously with the formation of the coating layer, (2) at any time during the drying of the coating layer formed by coating the coating solution and before the coating layer exhibits reduced drying, the pH is 7.1 or more Any one of <1> to <11>, wherein the basic solution is applied to the coating layer and a crosslinking agent is added to the coating solution and / or the basic solution. Inkjet recording medium.

  According to the present invention, the recording surface has surface smoothness and glossiness, little blur over time, high-resolution and high-density image formation is possible, and image resistance such as light resistance and ozone resistance It is possible to provide an ink jet recording medium that is excellent in color and has no occurrence of coloring on the paper surface.

Hereinafter, the ink jet recording medium of the present invention 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 ink receiving layer contains at least one sulfoxide compound and at least one water-soluble polyvalent metal salt. It is characterized by doing.

The ink jet recording medium of the present invention contains a sulfoxide compound and a water-soluble polyvalent metal salt (especially, a combination of a water-soluble aluminum compound and a zirconium compound) in the ink receiving layer, thereby providing good ink absorbability and glossiness. In addition, blurring of the recorded image is sufficiently suppressed over a long period of time, and the light resistance and ozone resistance of the image are greatly improved.
Hereinafter, the configuration of the ink jet recording medium of the present invention will be described in detail.

<Ink receiving layer>
As described above, the ink receiving layer contains at least one sulfoxide compound and at least one water-soluble polyvalent metal salt.

[Sulphoxide compounds]
The sulfoxide compound preferably has one or more structures represented by the following general formula (1) in the molecule.

  The sulfoxide compound having the structure represented by the general formula (1) may be substituted with a hydrophilic group. Hydrophilic groups include substituted or unsubstituted amino groups, substituted or unsubstituted carbamoyl groups, substituted or unsubstituted sulfamoyl groups, substituted or unsubstituted ammonium, hydroxyl groups, sulfonic acids, carboxylic acids, phosphoric acids, ethylene Examples thereof include oxyacids and substituted or unsubstituted nitrogen-containing heterocycles.

  Furthermore, the sulfoxide compound is preferably a compound represented by the following general formula (2).

［一般式（２）中、Ｒ¹及びＲ³は、それぞれ独立に、置換又は無置換のアルキル基、置換又は無置換のアリール基、置換又は無置換のヘテロ環基、又はそれらからなるポリマー残基を表し、Ｒ¹とＲ³は同一でも異なってもよく、結合して環を形成していてもよい。Ｒ²は、置換又は無置換の２〜６価の連結基を表し、Ｒ¹及びＲ²、Ｒ²及びＲ³と結合して環を形成していてもよい。ｍは０又は１以上の整数を表し、ｎは０又は１を表す。Ｒ¹、Ｒ²、及びＲ³のうちの少なくともいずれかは、置換又は無置換のアミノ基、置換又は無置換のカルバモイル基、置換又は無置換のスルファモイル基、置換又は無置換のアンモニウム、ヒドロキシル基、スルホン酸、カルボン酸、リン酸、エチレンオキシ基、置換又は無置換の含窒素へテロ環で表される親水性基で置換されたアルキル基、アリール基、ヘテロ環基、及びポリマー残基を表す。］

[In General Formula (2), each of R ¹ and R ³ independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, or a polymer residue comprising them. Represents a group, and R ¹ and R ³ may be the same or different, and may combine to form a ring. R ² represents a substituted or unsubstituted divalent to hexavalent linking group, and may be bonded to R ¹ and R ² , R ² and R ³ to form a ring. m represents 0 or an integer of 1 or more, and n represents 0 or 1. At least one of R ¹ , R ² , and R ³ is a substituted or unsubstituted amino group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted sulfamoyl group, a substituted or unsubstituted ammonium, or a hydroxyl group Sulfonic acid, carboxylic acid, phosphoric acid, ethyleneoxy group, alkyl group substituted with a hydrophilic group represented by a substituted or unsubstituted nitrogen-containing heterocycle, aryl group, heterocyclic group, and polymer residue To express. ]

In the general formula (2), the unsubstituted alkyl group represented by R ¹ and R ³ may have a linear, branched, or cyclic structure, and may have an unsaturated bond, for example, carbon An alkyl group having 1 to 22 is preferable, and specifically, methyl group, ethyl group, allyl group, n-butyl group, n-hexyl group, n-octyl group, benzyl group, iso-propyl group, iso-butyl. Group, sec-butyl group, cyclohexyl group, 2-ethylhexyl group and the like. Among them, an alkyl group having 1 to 10 carbon atoms is more preferable, methyl group, ethyl group, allyl group, n-propyl group, iso-butyl. Group, cyclohexyl group and 2-ethylhexyl group are particularly preferred.

As the unsubstituted aryl group represented by R ¹ and R ³ , for example, an aryl group having 6 to 22 carbon atoms is preferable, and specifically, a phenyl group, a 1-naphthyl group, a 2-naphthyl group, and the like. Among them, a phenyl group is particularly preferable.

Examples of the unsubstituted heterocyclic group represented by R ¹ and R ³ include thienyl group, thiazolyl group, oxazolyl group, pyridyl group, pyrazyl group, thiadiazoyl group, triazoyl group, morpholyl group, piperazyl group, pyrimidyl group, triazyl group. Group, indolyl group, benzothiazoyl group, benzoxazoyl group, among which thiazolyl group, oxazoyl group, pyridyl group, thiadiazoyl group, triazoyl group, morpholyl group, pyrimidyl group, triazyl group, benzothiazoyl group, benzo Oxazoyl groups are particularly preferred.

When R ¹ and R ³ represent a polymer residue comprising a substituted or unsubstituted alkyl group, aryl group, or heterocyclic residue, examples of the polymer residue include polymers having the following units.

［Ｒ⁴は、水素原子、又は炭素数１〜４のアルキル基を表し、Ｒ⁵はアルキレン基を表し、Ｑは連結基を表す。Ｒ⁷、Ｒ⁸はアルキレン基を表し、Ｌは１又は２を表し、Ｐは１又は２を表す。Ｒ²、Ｒ³、ｍ、ｎは前記一般式（２）中のＲ²、Ｒ³、ｍ、ｎと同義である］

[R ⁴ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ⁵ represents an alkylene group, and Q represents a linking group. R ⁷ and R ⁸ represent an alkylene group, L represents 1 or 2, and P represents 1 or 2. R ^2, R ^3, m, n are R ^2, R ³ in the general formula (2), m, is synonymous with n]

  In the unit, examples of the linking group represented by Q include the following linking groups.

［Ｒ⁶は水素原子、アルキル基、アリール基を表す。］

[R ⁶ represents a hydrogen atom, an alkyl group, or an aryl group. ]

When R ¹ and R ³ represent an alkyl group, an aryl group, or a heterocyclic residue, the substituent is a substituted or unsubstituted amino group (for example, an amino group having 30 or less carbon atoms, an amino group, an alkylamino group). , Dialkylamino group, arylamino group, acylamino group), substituted or unsubstituted carbamoyl group (for example, carbamoyl group having 30 or less carbon atoms, carbamoyl group, methylcarbamoyl group, dimethylcarbamoyl group, morpholinocarbamoyl group, piperidinocarbamoyl group) Group), substituted or unsubstituted ammonium (for example, ammonium having 30 or less carbon atoms, ammonium, trimethylammonium, triethylammonium, dimethylbenzylammonium, hydroxyethyldimethylammonium), substituted or unsubstituted sulfamoyl group (for example, 30 carbon atoms) Less than Lower sulfamoyl group, sulfamoyl group, methylsulfamoyl group, dimethylsulfamoyl group, morpholinosulfamoyl group, piperidinosulfamoyl group), substituted or unsubstituted nitrogen-containing heterocycle (for example, pyridyl group, A hydrophilic group represented by a pyrimidyl group, morpholino group, pyrrolidino group, piperidino group, piperazyl group), hydroxyl group, sulfonic acid, carboxylic acid, phosphoric acid, ethyleneoxy group, cyano group, halogen atom (for example, fluorine atom) , Chlorine atom, bromine atom), substituted or unsubstituted alkoxycarbonyl group (for example, alkoxycarbonyl group having 30 or less carbon atoms, methoxycarbonyl group, ethoxycarbonyl group, dimethylaminoethoxyethoxycarbonyl group, diethylaminoethoxycarbonyl group, hydroxyethoxy) Carbonyl group A substituted or unsubstituted aryloxycarbonyl group (for example, an aryloxycarbonyl group having 30 or less carbon atoms, a phenoxycarbonyl group), a substituted or unsubstituted alkoxy group (for example, an alkoxy group having 30 or less carbon atoms, a methoxy group, an ethoxy group) Group, phenoxyethoxy group, butoxyethoxy group, hydroxyethoxy group), substituted or unsubstituted aryloxy group (for example, aryloxy group having 30 or less carbon atoms, phenoxy group), substituted or unsubstituted acyloxy group (for example, carbon And a substituted or unsubstituted acyl group (for example, an acyl group having 30 or less carbon atoms, an acetyl group, and a propionyl group).
R ¹ and R ³ may be the same or different and may be combined to form a ring.

R ² represents a substituted or unsubstituted divalent to hexavalent linking group, and may combine with R ¹ and R ² , R ² and R ³ to form a ring. Examples of the sulfur-containing heterocycle formed by bonding R ¹ , R ² and R ³ to each other include thienyl group, thiazoyl group, thiazolidyl group, dithiolan-2-yl group, trithian-2-yl group and dithian-2-yl group. , Etc.

Examples of the divalent to hexavalent linking group represented by R ² include linking groups containing carbon, nitrogen, oxygen, and phosphorus. Specific examples include the following linking groups.

  These linking groups may contain a hetero bond such as an ether bond, an ester bond, an amino bond, an amide bond, or a urethane bond, and may further have a substituent. Moreover, the polymer in which those connection groups are repeated may be sufficient. In that case, the linking groups may be the same or different.

At least one of R ¹ , R ² , and R ³ is a substituted or unsubstituted amino group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted sulfamoyl group, a substituted or unsubstituted ammonium, a hydroxyl group, a sulfone It represents an alkyl group, an aryl group, a heterocyclic group, and a polymer residue substituted with an acid, a carboxylic acid, a phosphoric acid, an ethyleneoxy group, a hydrophilic group represented by a substituted or unsubstituted nitrogen-containing heterocyclic ring. Examples of these hydrophilic groups include the substituents described in the above R ¹ and R ³ .

Since the ink jet recording medium of the present invention is substantially applied by aqueous coating, the sulfoxide compound according to the present invention is preferably water-soluble.
Further, the sulfoxide compound is a Lewis base, has higher water solubility than a thioether compound, and can be added in a larger amount.

When the sulfoxide compound according to the present invention is water-soluble, it is preferably added to a coating solution or a basic solution containing fine particles and a water-soluble resin described later.
Further, when the sulfoxide compound according to the present invention is oil-soluble, it is preferably added to an application solution or a basic solution containing fine particles and a water-soluble resin by adding as an emulsified dispersion or an organic solvent. .

In the ink jet recording medium of the present invention, the content of the sulfoxide compound is preferably 0.01 to 20 g / m ² in order to further improve ozone resistance, image blurring, and glossiness. More preferably, it is 05-7 g / m < ² >.

  In the inkjet recording medium of the present invention, the sulfoxide-based compound generally has a higher oxidation potential than conventional sulfur-containing compounds (thioethers, thioureas), and is more advantageous for the purpose of improving ozone resistance and light resistance. By combining with a dye having a high oxidation potential, higher ozone resistance and light resistance can be expressed.

  The sulfoxide compounds according to the present invention may be used alone or in combination of two or more.

  Specific examples (Exemplary Compounds A-1 to A-75) of the sulfoxide-based compound are shown below, but the present invention is not limited thereto.

[Water-soluble polyvalent metal salt]
Next, the water-soluble polyvalent metal salt will be described. Specific examples of the water-soluble polyvalent metal salt used in combination with the sulfoxide compound include the following.
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, cupric chloride, Ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel ammonium sulfate hexahydrate Japanese products, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum alum, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate, ferrous bromide, ferric chloride Ferrous, ferric chloride, ferrous sulfate, ferric sulfate, phenolsulfone Zinc, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, titanium tetrachloride, tetraisopropyl titanate, titanium acetylacetonate, titanium lactate, zirconium acetylacetonate, zirconyl acetate, zirconyl sulfate, ammonium zirconium carbonate, Zirconyl stearate, zirconyl octylate, zirconyl nitrate, zirconium oxychloride, zirconium hydroxychloride, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate, citric acid Sodium tungsten, 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, samarium nitrate, europium nitrate, gadolinium nitrate, Examples include dysprosium nitrate, erbium nitrate, ytterbium nitrate, hafnium chloride, and bismuth nitrate.

  Among these, aluminum-containing compounds (water-soluble aluminum compounds) such as aluminum sulfate, aluminum alum, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate; zirconium acetylacetonate , Zirconyl acetate, zirconyl sulfate, zirconium ammonium carbonate, zirconyl stearate, zirconyl octylate, zirconyl nitrate, zirconium oxychloride, zirconium zirconium chloride and the like zirconium-containing compounds (water-soluble zirconium compounds); and titanium tetrachloride, tetraisopropyl titanate, Titanium-containing compounds such as titanium acetylacetonate and titanium lactate are preferred, especially polyaluminum chloride, zirconyl acetate, zirconyl carbonate Ammonium, zirconium oxychloride is preferable.

In the inkjet recording medium of the present invention, the content of the water-soluble polyvalent metal salt is preferably 0.1 to 20 g / m ² in order to further improve ozone resistance, image blurring, and glossiness. more preferably 0.4~10g / m ^2, further preferably 0.8~5g / m ^2.

  The water-soluble polyvalent metal salt according to the present invention may be used alone or in combination of two or more.

[Water-soluble resin]
In the ink jet recording medium of the present invention, the ink receiving layer preferably contains a water-soluble resin together with the sulfoxide compound and the water-soluble polyvalent metal salt.

Examples of the water-soluble resin include, for example, a polyvinyl alcohol resin that is a resin having a hydroxyl group as a hydrophilic structural unit [for example, polyvinyl alcohol (PVA), acetoacetyl-modified PVA, cation-modified PVA, anion-modified PVA, silanol-modified PVA, Polyvinyl acetals, etc.], cellulose resins [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.], chitins , Chitosans, starch, resins having an ether bond [eg, polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene Recall (PEG), poly ether (PVE)] and resins having carbamoyl groups [e.g., polyacrylamide (PAAM), polyvinyl pyrrolidone (PVP), polyacrylic acid hydrazide, etc.] and the like.
In addition, polyacrylates having a carboxy group as a dissociable group, maleic acid resins, alginates, gelatins, and the like can also be used.

Among these, polyvinyl alcohol (PVA) 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 can be.
Examples of water-soluble resins other than polyvinyl alcohol resins include compounds described in paragraph numbers [0011 to 0014] of JP-A No. 11-165461.

  These water-soluble resins may be used alone or in combination of two or more. In the ink jet recording medium of the present invention, the content of the water-soluble resin is preferably 9 to 40% by mass, and more preferably 12 to 33% by mass with respect to the total solid content of the ink receiving layer.

  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-based resin are used in combination, the content of the polyvinyl alcohol-based resin in the total water-soluble resin is preferably 50% by mass or more, and more preferably 70% by mass or more.

[Fine particles]
In the ink jet recording medium of the present invention, it is preferable that the ink receiving layer contains fine particles together with a sulfoxide compound and a water-soluble polyvalent metal salt, and it is more preferable to use the fine particles and the water-soluble resin in combination. .
As described above, the ink receiving layer contains fine particles to obtain a porous structure, 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 porous structure having a higher porosity, and sufficient ink. It is preferable because an ink jet recording medium having absorbency 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.
Examples of the fine particles used in the present invention include organic fine particles and inorganic fine particles. From the viewpoint of ink absorbability and image stability, it is preferable to contain inorganic fine particles.

  The organic fine particles are preferably 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, Examples include acrylate, polyamide, silicon resin, phenol resin, natural polymer powder, latex, or emulsion polymer fine particles.

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, water. Examples thereof include zinc oxide, 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 is preferable from the viewpoint of forming a good porous structure. The fine particles may be used as primary particles or in a state where secondary particles are formed. The average primary particle size of these fine particles is preferably 2 μm or less, and more preferably 200 nm or less.
Further, silica fine particles having an average primary particle size of 20 nm or less, colloidal silica having an average primary particle size of 30 nm or less, alumina fine particles having an average primary particle size of 20 nm or less, or pseudoboehmite having an average pore radius of 2 to 15 nm is more preferable. In particular, silica fine particles, alumina fine particles, and pseudoboehmite are preferable.

  Silica fine particles are generally roughly classified into wet method fine particles and dry method (vapor phase method) fine 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 above-mentioned vapor phase method is a method by high-temperature vapor phase hydrolysis of silicon halide (flame hydrolysis method), and silica sand and coke are heated and reduced and vaporized by an arc in an electric furnace and oxidized with air. The method of obtaining anhydrous silica by the method (arc method) is the mainstream, and “gas phase method silica” refers to anhydrous silica fine particles obtained by the gas phase method. As the silica fine particles used in the present invention, the latter “gas phase method silica” fine particles are particularly preferable.

The above-mentioned “gas phase method silica” is different from hydrous silica and the density of silanol groups on the surface or presence / absence of vacancies, etc. and shows different properties, but is suitable for forming a three-dimensional structure with high porosity. ing. 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 silica, the density of silanol groups on the surface of the fine particles is 2 to 3 / nm ² , so that loose soft agglomerates are formed, resulting in a structure with a high porosity. It is estimated to be.

  The above-mentioned “gas phase method silica” has a particularly large specific surface area, so the ink absorbency and retention are high, and the refractive index is low. This is advantageous in that a high color density and good color developability can be obtained. In this way, the receiving layer is transparent, not only for applications that require transparency such as OHP, but also when applied to recording sheets such as photo glossy paper, high color density and good color developability and It is important in that gloss is obtained.

  The average primary particle diameter of the “gas phase method silica” is preferably 30 nm or less, more preferably 20 nm or less, particularly preferably 10 nm or less, and most preferably 3 to 10 nm. Since the vapor phase silica is easily attached to each other by hydrogen bonding with a silanol group, if the average primary particle size is 30 nm or less, a structure with a high porosity can be formed, and ink absorption characteristics are effective. Can be improved.

  Silica fine particles may be used in combination with the other fine particles. 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. The alumina hydrate can be used in various forms, but sol boehmite is preferably used as a raw material from the viewpoint of easily obtaining a smooth layer.

The average pore radius of the pseudoboehmite pore structure is preferably 1 to 30 nm, and more preferably 2 to 15 nm. The pore volume is preferably 0.3 to 2.0 ml / g, more preferably 0.5 to 1.5 ml / g. Here, the pore radius and pore volume are measured by a nitrogen adsorption / desorption method, and can be measured by, for example, a gas adsorption / desorption analyzer (for example, trade name “Omni Soap 369” manufactured by Coulter). .
Among alumina fine particles, vapor-phase method alumina fine particles are preferable because of their large specific surface area. The average primary particle size of the vapor phase alumina is preferably 30 nm or less, and more preferably 20 nm or less.

  When the fine particles are used in an ink jet recording medium, for example, JP-A-10-81064, JP-A-10-119423, JP-A-10-157277, JP-A-10-217601, JP-A-11-348409, JP-A-2001-138621. No. 2000-43401 No. 2000-2111235 No. 2000-309157 No. 2001-96897 No. 2001-138627 No. 11-91242 No. 8-2087 No. 8-2090 No. 8-2091, 8-2093, 8-174992, 11-192777, JP-A-2001-301314, and the like can also be preferably used.

The water-soluble resin and the fine particles, which mainly constitute the ink receiving layer in the present invention, may be a single material or a mixed system of a plurality of materials.
From the viewpoint of maintaining transparency, the type of water-soluble resin to be combined with fine particles, particularly silica fine particles, is important. When the vapor phase silica is used, the water-soluble resin is preferably a polyvinyl alcohol-based resin, more preferably a polyvinyl alcohol-based resin having a saponification degree of 70 to 100%, and particularly a saponification degree of 80 to 99. 5% polyvinyl alcohol resin is preferred.

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 capillary action, and can form dots with good roundness without causing ink “bleeding”. .

(Content ratio of fine particles to water-soluble resin)
In the ink jet recording medium, the mass content ratio [PB ratio (x / y)] between the fine particles (x) in the ink receiving layer and the water-soluble resin (y) depends on the film structure and film strength of the ink receiving layer. It has a big impact. That is, when 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.

  In the ink receiving layer according to the present invention, the mass content ratio [PB ratio (x / y)] prevents a decrease in film strength and cracks during drying caused by the PB ratio being too large, and When the PB ratio is too small, the voids are easily blocked by the resin, and from the viewpoint of preventing the ink absorbency from being lowered due to the decrease in the void ratio, 1.5 / 1 to 10/1 is preferable.

  Since stress may be applied to the recording sheet when passing through the conveyance system of the ink jet recording 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. In consideration of these cases, the PB ratio (x / y) is more preferably 5/1 or less, while it is 2: 1 or more from the viewpoint of ensuring high-speed ink absorbability in an inkjet recording printer. Is more preferable.

Specifically, for example, a gas phase method silica fine particle having an average primary particle diameter of 20 nm or less and a water-soluble resin are completely dispersed in an aqueous solution at a PB ratio (x / y) of 2/1 to 5/1. When the liquid is coated on a support and the coating layer is dried, a three-dimensional network structure is formed in which secondary particles of silica fine particles are network chains, the average pore diameter is 30 nm or less, and the porosity is 50 to 80. %, A translucent porous film having a pore specific volume of 0.5 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 preferably contains a crosslinking agent capable of crosslinking the water-soluble resin in the coating layer containing the water-soluble resin, and in particular, the fine particles and the water-soluble resin are used in combination. Further, an embodiment in which the porous layer is cured by a crosslinking reaction between a crosslinking agent and a water-soluble resin is preferable.

Boron compounds are preferred for crosslinking the water-soluble resin, particularly polyvinyl alcohol. Examples of the boron compound include borax, boric acid, borates (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , 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.

Compounds other than the above boron compounds can also be used as a crosslinking agent for the water-soluble resin. For example,
Aldehyde compounds such as formaldehyde, glyoxal, succinaldehyde, glutaraldehyde, dialdehyde starch, dialdehyde derivatives of plant gum; ketones such as diacetyl, 1,2-cyclopentanedione, 3-hexene-2,5-dione Compounds; active halogen compounds such as bis (2-chloroethyl) urea, bis (2-chloroethyl) sulfone, 2,4-dichloro-6-hydroxy-s-triazine sodium salt; divinylsulfone, 1,3-bis (vinyl) Sulfonyl) -2-propanol, N, N′-ethylenebis (vinylsulfonylacetamide), divinylketone, 1,3-bis (acryloyl) urea, 1,3,5-triacryloyl-hexahydro-s-triazine, etc. Active vinyl compounds; dimethylolurea, methylol N-methylol compounds such as methylhydantoin; melamine compounds such as trimethylol melamine, alkylated methylol melamine, melamine, benzoguanamine, melamine resin; ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diglycerin poly Epoxy compounds such as glycidyl ether, spiroglycol diglycidyl ether, polyglycidyl ether of phenol resin;

Isocyanate compounds such as 1,6-hexamethylene diisocyanate and xylylene diisocyanate; aziridine compounds described in U.S. Pat. Nos. 3,017,280 and 2,983611; and U.S. Pat. No. 3,100,704 Carbodiimide compounds; Ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; Halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; 2,3-dihydroxydioxane and the like Dioxane compounds; metal-containing compounds such as titanium lactate, aluminum sulfate, chromium alum, potash alum, zirconyl acetate and chromium acetate; polyamine compounds such as tetraethylenepentamine; hydrazide compounds such as adipic acid dihydrazide; 2 oxazoline groups Including more than Low molecule or polymer having: anhydride of polyvalent acid, acid described in US Pat. No. 2,725,294, US Pat. No. 2,725,295, US Pat. No. 2,726,162, US Pat. No. 3,834,902, etc. Examples include chloride and bissulfonate compounds; active ester compounds described in US Pat. No. 3,542,558, US Pat. No. 3,251972, and the like.
Said crosslinking agent may be used individually by 1 type, and can also be used in combination of 2 or more type.

In the present invention, the crosslinking and curing described above is performed by adding a crosslinking agent to a coating solution (hereinafter sometimes referred to as “coating solution A”) containing fine particles or a water-soluble resin 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, and the coating layer exhibits a reduced rate of 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 at any time before.
The application of the crosslinking agent is preferably carried out as follows, taking a boron compound 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, the crosslinking curing is performed by (1) Either at the same time as the coating layer is formed by coating the coating solution, or (2) before the coating layer formed by coating the coating solution is dry and before the coating layer exhibits a reduced rate of drying. At that time, it is carried out by applying a basic solution (coating solution B) having a pH of 7.1 or higher to the coating layer. The boron compound as a cross-linking agent may be contained in either the coating solution A or the coating solution B, and may be contained in both the coating solution A and the coating solution B.
The amount of the crosslinking agent used in the ink receiving layer in the invention is preferably from 1 to 50% by mass, more preferably from 5 to 40% by mass, based on the water-soluble resin.

[mordant]
In the ink jet recording medium of 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. The water-soluble polyvalent metal salt can function as a mordant, but may contain a mordant other than the water-soluble polyvalent metal salt together with the water-soluble polyvalent metal salt. As such another mordant, a cationic polymer (cationic mordant) is preferable as an organic mordant, and when the mordant is present in the ink receiving layer, a liquid ink having an anionic dye as a coloring material is used. The interaction works to stabilize the color material and improve water resistance and aging resistance.

As a procedure for using the mordant, a method of adding to the coating liquid A containing fine particles and a water-soluble resin, or a method of adding to the coating liquid B and applying when there is a concern of aggregation between the fine particles. Both are available.
As the cationic mordant, a polymer mordant having a primary to tertiary amino group or a quaternary ammonium base as a cationic group is preferably used, but a cationic non-polymer mordant may also be used. it can. These mordants are preferably compounds having a mass average molecular weight of 500 to 100,000 from the viewpoint of improving the ink absorbability of the ink receiving layer.
Examples of the polymer mordant include a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base (mordant monomer), and the mordant monomer and other monomers (hereinafter, Those obtained as a copolymer or a condensation polymer with "a non-mordant monomer") are preferred. These polymer mordants can be used in any form of water-soluble polymer or water-dispersible latex particles.

  Examples of the monomer (mordant monomer) include trimethyl-p-vinylbenzylammonium chloride, trimethyl-m-vinylbenzylammonium chloride, triethyl-p-vinylbenzylammonium chloride, triethyl-m-vinylbenzylammonium chloride, N , N-dimethyl-N-ethyl-Np-vinylbenzylammonium chloride, N, N-diethyl-N-methyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-Nn-propyl-N -P-vinylbenzylammonium chloride, N, N-dimethyl-Nn-octyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-benzyl-Np-vinylbenzylammonium chloride, N, N-die Ru-N-benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N- (4-methyl) benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-phenyl-N -P-vinylbenzylammonium chloride;

  Trimethyl-p-vinylbenzylammonium bromide, trimethyl-m-vinylbenzylammonium bromide, trimethyl-p-vinylbenzylammonium sulfonate, trimethyl-m-vinylbenzylammonium sulfonate, trimethyl-p-vinylbenzylammonium acetate, trimethyl-m-vinyl Benzylammonium acetate, N, N, N-triethyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N, N-triethyl-N-2- (3-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride Tate;

  N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N- Methyl chloride, ethyl chloride, methyl bromide of dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide , Quaternized products of ethyl bromide, methyl iodide or ethyl iodide, or sulfonates, alkyl sulfonates, acetates or alkyl carboxylates substituted with their anions.

  Specific examples of the compound include monomethyl diallylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium chloride, triethyl-2- (methacryloyloxy) ethylammonium chloride, trimethyl-2- (acryloyloxy) ethylammonium chloride, triethyl. 2- (acryloyloxy) ethylammonium chloride, trimethyl-3- (methacryloyloxy) propylammonium chloride, triethyl-3- (methacryloyloxy) propylammonium chloride, trimethyl-2- (methacryloylamino) ethylammonium chloride, triethyl-2 -(Methacryloylamino) ethylammonium chloride, trimethyl-2- (acryloylamino) ) Ethylammonium chloride, triethyl-2- (acryloylamino) ethylammonium chloride, trimethyl-3- (methacryloylamino) propylammonium chloride, triethyl-3- (methacryloylamino) propylammonium chloride, trimethyl-3- (acryloylamino) propyl Ammonium chloride, triethyl-3- (acryloylamino) propylammonium chloride;

N, N-dimethyl-N-ethyl-2- (methacryloyloxy) ethylammonium chloride, N, N-diethyl-N-methyl-2- (methacryloyloxy) ethylammonium chloride, N, N-dimethyl-N-ethyl- 3- (acryloylamino) propylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium bromide, trimethyl-3- (acryloylamino) propylammonium bromide, trimethyl-2- (methacryloyloxy) ethylammonium sulfonate, trimethyl-3- And (acryloylamino) propylammonium acetate.
In addition, examples of copolymerizable monomers include N-vinylimidazole and N-vinyl-2-methylimidazole.

The non-mordant monomer does not contain a basic or cationic moiety such as a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base, and does not show an interaction with a dye in an inkjet ink. Or the monomer which interaction is substantially small is pointed out.
Examples of the non-mordant monomer include (meth) acrylic acid alkyl ester; (meth) acrylic acid cycloalkyl ester such as cyclohexyl (meth) acrylate; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate; Aralkyl esters such as (meth) benzyl acrylate; aromatic vinyls such as styrene, vinyl toluene and α-methyl styrene; vinyl esters such as vinyl acetate and vinyl propionate; allyl esters such as allyl acetate; vinylidene chloride; Examples thereof include halogen-containing monomers such as vinyl chloride; vinyl cyanides such as (meth) acrylonitrile; olefins such as ethylene and propylene.

The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl moiety, for example, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) Propyl acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, Examples include 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like.
Of these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl methacrylate and the like are preferable.
The non-mordant monomers can also be used alone or in combination of two or more.

Further, as the polymer mordant, polydiallyldimethylammonium chloride, a copolymer of diallyldimethylammonium chloride and other monomers (mordant monomer, non-mordant monomer), a copolymer of diallyldimethylammonium chloride and SO ₂ , polydiallyl Cyclic amine resins represented by methylamine hydrochloride, polydiallyl hydrochloride, and derivatives thereof (including copolymers); polydiethylmethacryloyloxyethylamine, polytrimethylmethacryloyloxyethylammonium chloride, polydimethylbenzylmethacryloyloxyethylammonium chloride, Secondary amino, tertiary amino or quaternary ammonium salt substituted amides represented by polydimethylhydroxyethylacryloyloxyethylammonium chloride, etc. Kill (meth) acrylate polymers and copolymers with other monomers; polyamine resins represented by polyethyleneimine and derivatives thereof, polyallylamine and derivatives thereof, polyvinylamine and derivatives thereof, and the like; polyamide-polyamine resin, polyamide epi Polyamide resins typified by chlorohydrin resins, etc .; polysaccharides typified by cationized starch, chitosan and chitosan derivatives; dicyandiamide formalin polycondensates, dicyandiamide derivatives typified by dicyandiamide diethylenetriamine polycondensates, etc .; polyamidines and polyamidines Derivatives; Dialkylamine epichlorohydrin addition polymers such as dimethylamine epichlorohydrin addition polymers and derivatives thereof; having quaternary ammonium salt-substituted alkyl groups Styrene polymers and copolymers with other monomers may also be preferably exemplified.

  Specific examples of the polymer mordant include JP-A Nos. 48-28325, 54-74430, 54-124726, 55-22766, 55-142339, 60-23850, and 60. -23851, 60-23852, 60-23853, 60-57836, 60-60643, 60-118834, 60-122940, 60-122941, 60-122294 No. 60-235134, JP-A-1-161236, U.S. Pat.Nos. 2,484,430, 2,548,564, 3,148,061, 3,309,690, 4,115,124, 4,124,386, 4,193,800, 4,273,853, JP 4282305, JP 4450224, JP-A-1-16123. No. 10-81064, No. 10-157277, No. 10-217601, JP-A No. 2001-138621, No. 2000-212235, No. 2001-138627, JP-A No. 8-174992, No. 5-B 35162, 5-35163, 5-35164, 5-88846, Japanese Patent Nos. 2648847, 2616677 and the like.

The content of the mordant 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 such as acids, UV absorbers, antioxidants, fluorescent brighteners, monomers, polymerization initiators, polymerization inhibitors, and anti-bleeding agents as required. , Antiseptics, 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) in the surface pH measurement determined by the Japan Paper Pulp Technology Association (J.TAPPI). For example, the measurement can be performed using a paper pH measurement set “Type MPC” manufactured by Kyoritsu Riken Co., Ltd., which corresponds to the above 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 (Zn, Al, Ca, Mg, etc.), 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. The amount of these acids added may be determined so that the surface pH of the ink receiving layer is 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 the ink receiving layer contains a preservability improver such as an ultraviolet absorbent, an antioxidant, and a blurring inhibitor.

  Specific examples of the compound include Japanese Patent Application No. 2002-13005, Japanese Patent Application Laid-Open No. 10-182621, Japanese Patent Application Laid-Open No. 2001-260519, Japanese Patent Application No. 4-34953, Japanese Patent Application No. Hei 4-345513, Japanese Patent Application Laid-Open No. 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, the same 3,754,919 JP, Nos. 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 63-88381 JP, Nos. 63-113536;

  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, U.S. Pat. Nos. 4,814,262, No. 4,980,275, and the like. .

As said other component, 1 type may be individual or 2 or more types may be used together. Such other components may be added after being water-solubilized, dispersed, polymer-dispersed, emulsified or oil-dropped, or may be encapsulated in microcapsules. In the inkjet recording medium of the present invention, the addition amount of the other components is preferably 0.01 to 10 g / m ² .

  Further, for the purpose of improving the dispersibility of the inorganic fine particles, the surface of the inorganic particles may be treated with a silane coupling agent or the like. 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 preferably contains a surfactant. As the surfactant, any of cationic, anionic, nonionic, amphoteric, fluorine and silicon surfactants can be used.
Examples of the nonionic surfactant 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 Ethylene nonylphenyl ether), oxyethylene / oxypropylene block copolymer, sorbitan fatty acid esters (for example, sorbitan monolaurate, sorbitan monooleate, sorbitan trioleate, etc.), polyoxyethylene sorbitan fatty acid esters (for example, polyoxyethylene) Sorbitan monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan Lyolate, etc.), polyoxyethylene sorbitol fatty acid esters (eg, polyoxyethylene sorbitol tetraoleate), glycerin fatty acid esters (eg, 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 the diols), and polyoxy Ruki alkylene alkyl ethers are preferable. The nonionic surfactant can be used in a coating solution (A) and a coating solution (B) described later. Moreover, the said nonionic surfactant may be used independently and may use 2 or more types together.

  Examples of the amphoteric surfactant include amino acid type, carboxyammonium betaine type, sulfoammonium betaine type, ammonium sulfate betaine type, imidazolium betaine type, etc., for example, US Pat. No. 3,843,368, JP, JP-A-59-49535, JP-A-63-236546, JP-A-5-303205, JP-A-8-262742, JP-A-10-282619, JP-A-2514194, JP-A-2759597, JP-A-2000-351269, etc. Can be used preferably. Of the amphoteric surfactants, the amino acid type, carboxyammonium betaine type, and sulfoneammonium betaine type are preferable. 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 salts (for example, sodium lauryl sulfate, triethanolamine lauryl sulfate), and sulfonates (for example, dodecylbenzenesulfone). Acid sodium), alkylsulfosuccinate (for example, sodium dioctylsulfosuccinate), 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 from an intermediate having a perfluoroalkyl group using a method such as electrolytic fluorination, telomerization, or oligomerization.
Examples include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl trialkyl ammonium salts, perfluoroalkyl group-containing oligomers, perfluoroalkyl phosphates, and the like.

  As the silicon surfactant, silicone oil modified with an organic functional group is preferable, and those obtained by modifying the side chain of the siloxane main chain structure with an organic group, those modified at both ends, and those modified at one end are mentioned. It is done. Examples of the organic functional 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 coating liquid for the ink receiving layer. 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, malein) Dibutyl acid, dibutyl fumarate, triethyl acetylcitrate, etc.), phosphate esters (eg, trioctyl phosphate, tricresyl phosphate, etc.), epoxies (eg, epoxidized soybean oil, epoxidized fatty acid methyl, etc.), alcohols (For example, stearyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerin, diethylene glycol monobutyl ether (DEGMBE), triethylene glycol monobutyl ether, glycerin Phosphorus monomethyl 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.).

[Support]
As the support used in the present invention, either a transparent support made of a transparent material such as plastic or an opaque support made of an opaque material such as paper can be used. In order to make use of the transparency of the ink receiving layer, it is preferable to use a transparent support or a highly glossy opaque support. In addition, a read-only optical disk such as a CD-ROM or DVD-ROM, a write-once optical disk such as a CD-R or DVD-R, or a rewritable optical disk is used as a support, and an ink receiving layer is provided on the label surface side. Can do.

As a material that can be used for the transparent support, a material that is transparent and has heat resistance that can withstand radiant heat when used in an OHP or a backlight display is preferable. Examples of such a material include polyesters such as polyethylene terephthalate (PET); polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide, and the like. Of these, polyesters are preferable, and polyethylene terephthalate (PET) is particularly preferable.
Although there is no restriction | limiting in particular as thickness of the said transparent support body, 50-200 micrometers is preferable at the point which is easy to handle.

  As the highly glossy opaque support, one having a glossiness of 40% or more on the surface on which the ink receiving layer is provided is preferable. The glossiness is a value determined according to the method described in JIS P-8142 (75-degree specular gloss test method for paper and paperboard). Specific examples of such a support include the following supports.

For example, high gloss paper support such as art paper, coated paper, cast coated paper, baryta paper used for silver salt photographic support, etc .; polyesters such as polyethylene terephthalate (PET), nitrocellulose, cellulose acetate , Cellulose esters such as cellulose acetate butyrate, and plastic films such as polysulfone, polyphenylene oxide, polyimide, polycarbonate, and polyamide are made opaque by adding a white pigment or the like (surface calendering may be applied). Glossy film; or a support in which a polyolefin coating layer containing or not containing a white pigment is provided on the surface of a highly glossy film containing the various paper supports, the transparent support or the white pigment. Etc.
A white pigment-containing foamed polyester film (for example, foamed PET containing polyolefin fine particles and forming voids by stretching) can also be suitably exemplified. Furthermore, resin-coated paper used for silver salt photographic printing paper is also preferable.

  Although there is no restriction | limiting in particular about the thickness of the said opaque support body, 50-300 micrometers is preferable at the point of the ease of handling.

  Further, it is desirable to use a surface of the support that has been subjected to corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment or the like in order to improve wettability and adhesion.

Next, the base paper used for the resin-coated paper will be described in detail.
As the base paper, wood pulp is used as a main raw material, and paper is made using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp as necessary. As the above-mentioned wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, NUKP can be used, but more LBKP, NBSP, LBSP, NDP, LDP with more short fibers are used. preferable.
However, the content of LBSP and / or LDP is preferably 10% by mass to 70% by mass.

  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 suitable. In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength enhancing agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, polyethylene glycol Moisture retention agents such as varieties, dispersants, softening agents such as quaternary ammonium, and the like can be added as appropriate.

  The freeness of the pulp used for papermaking is preferably 200 to 500 ml as defined by CSF, and the fiber length after beating is a 24 mesh residual mass% and a 42 mesh residual as defined in JIS P-8207. It is preferable that the sum with the mass% of is 30 to 70%. The 4 mesh residue is preferably 20% by mass or less.

The basis weight of the base paper is preferably 30 to 250 g, and particularly preferably 50 to 200 g. The thickness of the base paper is preferably 40 to 250 μm. The base paper can be given a high smoothness by performing a calendar process 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 (JIS P-8118).
Furthermore, the base paper stiffness is preferably 20 to 200 g under the conditions specified in JIS P-8143.

A surface sizing agent may be applied to the surface of the base paper, and as the surface sizing agent, the same sizing agent that can be added to the base paper can be used.
The pH of the base paper is a value measured by a hot water extraction method defined in JIS P-8113, and is preferably 5-9.

  The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but some LLDPE, polypropylene, etc. can also be used.

  In particular, the polyethylene layer on the side that forms the ink-receiving layer is added with rutile or anatase-type titanium oxide and fluorescent brightening agent, ultramarine, in polyethylene, as is often done with photographic papers, What improved opacity, whiteness, and hue is preferable. Here, as titanium oxide content, 3-20 mass% is preferable with respect to polyethylene, and 4-13 mass% is more preferable. Although the thickness of a polyethylene layer is not specifically limited, 10-50 micrometers is suitable for both front and back layers. Further, an undercoat layer can be provided on the polyethylene layer in order to provide adhesion to the ink receiving layer. The undercoat layer is preferably water-based polyester, gelatin, or PVA. Further, the thickness of the undercoat layer is preferably 0.01 to 5 μm.

  Polyethylene-coated paper can be used as glossy paper, or it is a matte surface or silky surface that can be obtained with ordinary photographic printing paper by applying a so-called molding process in the process of extruding molten polyethylene onto the surface of the base paper and coating it. Can also be used.

A back coat layer can also be provided on the support, and examples of components that can be added to the back coat layer include white pigments, water-soluble 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 water-soluble binder used in the backcoat layer include styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, and gelatin. Water-soluble polymers such as carboxymethylcellulose, hydroxyethylcellulose, and polyvinylpyrrolidone, and water-dispersible polymers such as styrene-butadiene latex and acrylic emulsion.
Examples of other components contained in the back coat layer include an antifoaming agent, an antifoaming agent, a dye, a fluorescent brightening agent, a preservative, and a water resistant agent.

(Preparation of inkjet recording medium)
The ink receiving layer of the ink jet recording medium of the present invention is, for example, coated with a coating liquid A containing at least fine particles and a water-soluble resin on the support surface, and (1) simultaneously with coating the coating liquid to form a coating layer. Or (2) a coating solution B (base) having a pH of 7.1 or higher, either during the drying of the coating layer formed by applying the coating solution and before the coating layer exhibits a reduced rate of drying. And a coating layer to which the coating solution B is applied is crosslinked and cured by adding a crosslinking agent to the coating solution A and / or the coating solution B (Wet-on-Wet method). It is preferable that it is formed by. Here, the sulfoxide compound and the water-soluble polyvalent metal salt according to the present invention are contained in at least one of the first coating liquid (coating liquid A) or the second coating liquid (coating liquid B), The first coating solution (coating solution A) contains a sulfoxide-based compound, and the second coating solution (coating solution B) contains a water-soluble polyvalent metal salt, or the first coating solution (coating solution A). It is preferable that the water-soluble polyvalent metal salt is contained in (2) and the sulfoxide compound is contained in the second coating liquid (coating liquid B). Moreover, it is preferable that a crosslinking agent capable of crosslinking the water-soluble resin is also contained in at least one of the coating liquid A and the coating liquid B. As the coating solution B (basic solution), it is preferable to use a solution having a pH of 7.1 or more as described above, and more preferably between pH = 7.5 and 10.0.
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.

  This is preferable because a large amount of mordant is present near the surface of the ink receiving layer, so that the ink-jet coloring material is effectively 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 method silica) and a water-soluble resin (for example, polyvinyl alcohol) is prepared, for example, as follows. be able to. That is,
Vapor phase silica fine particles and a 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, “Clairemix” manufactured by M Technique Co., Ltd.) For example, at a high speed of 10,000 rpm (preferably 5000 to 20000 rpm), for example, after being dispersed for 20 minutes (preferably 10 to 30 minutes), then, a crosslinking agent (boron compound), polyvinyl alcohol (PVA) It can be prepared by adding an aqueous solution (for example, PVA having a mass of about 1/3 of that of the above-mentioned gas phase method silica) and dispersing under the same rotation conditions as described above. The obtained coating solution is in a uniform sol state, and can be formed on a support by the following coating method and dried to form a porous ink receiving layer having a three-dimensional network structure. .

In addition, the preparation of the aqueous dispersion composed of the above-mentioned gas phase method silica and the dispersant may be performed by preparing a gas phase method silica aqueous dispersion in advance and adding the aqueous dispersion to the aqueous dispersant solution. The aqueous solution may be added to the vapor phase silica aqueous dispersion, or may be mixed simultaneously. Further, instead of vapor phase silica aqueous dispersion, powder vapor phase silica may be used and added to the dispersant aqueous solution as described above.
Vapor phase silica is preferably used as an aqueous dispersion using a dispersant because the glossiness of the ink jet recording medium is further improved.
After mixing said vapor phase silica and a dispersing agent, the mixed liquid is refined using a disperser, whereby an aqueous dispersion having an average particle diameter of 50 to 300 nm can be obtained. Dispersers used for obtaining the aqueous dispersion include conventionally known high-speed rotary dispersers, medium stirring dispersers (ball mills, sand mills, etc.), ultrasonic dispersers, colloid mill dispersers, high pressure dispersers, and the like. Various dispersers can be used, but from the viewpoint that the formed fine particles can be efficiently dispersed, a stirring type disperser, a colloid mill disperser, or a high pressure disperser is preferable.

  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 the 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.

In addition, a chaotic polymer can be used as the dispersant. Examples of the chaotic polymer include the aforementioned mordants. It is also preferable to use a silane coupling agent as the dispersant.
In that case, it is preferable to use at least one dispersant selected from dispersant compounds having an I / O value of 2.0 or less in order to prevent aging blur. Here, the above I / O value is a parameter representing the scale of hydrophilicity / lipophilicity of a compound or a substituent, and detailed explanation is given in Yoshio Koda's “Organic Conceptual Diagram” (Sankyo Publishing, 1984). There is. I represents inorganic and O represents organic. The larger the I / O value, the greater the inorganicity (the higher the polarity and the higher the hydrophilicity).
The amount of the dispersant added to the fine particles is preferably 0.1% to 30%, more preferably 1% to 10%.

  In the present invention, the ink receiving layer coating liquid is applied by a known coating method such as 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 be carried out.

  The coating liquid (B) is applied to the coating layer simultaneously with or after the coating of the ink receiving layer coating liquid (coating liquid (A)), and the coating liquid (B) is applied to the coating layer after coating. You may give before (A) comes to show a decreasing rate drying rate. That is, after the application of the ink-receiving layer coating liquid (coating liquid (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 reduced rate of drying” usually refers to a process for several minutes immediately after the coating of the coating liquid for the ink receiving layer, and during this time, the coated coating layer is applied. 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 application of the first coating solution, the coating layer is dried until the coating layer exhibits a decreasing rate of drying. For 0.5 to 5 minutes). The drying time naturally varies depending on the coating amount, but usually the above range is 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 a coating liquid (B) on an application layer, (2) By methods, such as a spray The method of spraying, (3) The method of immersing the support body in which this coating layer was formed in coating liquid (B), etc. are mentioned.

  In the method (1), examples of the application method for applying the coating liquid (B) include curtain flow coaters, extrusion die coaters, air doctor coaters, blade coaters, rod coaters, knife coaters, squeeze coaters, and reverse roll coaters. A known coating method such as a bar 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 the application of the mordant solution (coating liquid (B)), it is generally heated at a temperature of 40 to 180 ° C. for 0.5 to 30 minutes to be dried and cured. Especially, it is preferable to heat at a temperature of 40 to 150 ° C. for 1 to 20 minutes.

  When the mordant solution (coating liquid (B)) is applied simultaneously with the application of the ink receiving layer coating liquid (coating liquid (A)), the ink receiving layer coating liquid (coating liquid (A)) and the mordant solution ( The coating liquid (B)) is simultaneously coated (multilayer coating) on the support so that the ink receiving layer coating liquid (coating liquid (A)) is in contact with the support, and then dried and cured. A receiving layer can be formed.

  The above simultaneous application (multilayer application) can be performed, for example, by an application method using an extrusion die coater or a curtain flow coater. After the simultaneous application, the formed application layer is dried. In this case, the drying is generally carried out by heating the application layer at a temperature of 40 to 150 ° C. for 0.5 to 10 minutes, preferably at a temperature of 40 It is carried out by heating at -100 ° C for 0.5-5 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 move near the discharge port of the extrusion die coater, that is, on the support. A multilayer is formed in advance, and the multilayer is applied on the support in that state. Since the two-layer coating liquid that has been layered before coating tends to cause a crosslinking reaction at the interface between the two liquids when transferred to the support, the two liquids that are discharged near the discharge port of the extrusion die coater. May become mixed and thicken easily, which may hinder the application work. Accordingly, when the simultaneous multi-layer coating is performed as described above, the barrier layer liquid (intermediate layer liquid) is used together with the ink receiving layer coating liquid (coating liquid (A)) and the mordant solution (coating liquid (B)). It is preferable to apply three layers simultaneously, interposing between the liquids.

  About the said barrier layer liquid, it can select without a restriction | limiting in particular. For example, an aqueous solution containing a trace amount of water-soluble resin, water, or 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, since the calendering process may cause a decrease in porosity (that is, a decrease in ink absorbency), it is important to set the conditions under which the decrease in 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 an ink jet recording medium, the 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 0.050 μm, more preferably 0.01 to 0.035 μm in terms of median diameter. The porosity and pore median diameter can be measured using a mercury porosimeter (trade name “Boresizer 9320-PC2” manufactured by Shimadzu Corporation).

  In addition, the ink receiving layer is preferably excellent in transparency, as a guide, the haze value when the ink receiving layer is formed on a transparent film support is preferably 30% or less, More preferably, it is 20% or less. This haze value can be measured using a haze meter (for example, “HGM-2DP” manufactured by Suga Test Instruments Co., Ltd.).

  A dispersion of polymer fine particles may be added to a layer (for example, an ink receiving layer or a back layer) constituting the ink jet recording medium of the present invention. This polymer fine particle dispersion is used for the purpose of improving film physical 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.

  Ink jet recording media of the present invention are disclosed in JP-A-10-81064, JP-A-10-119423, JP-A-10-157277, JP-A-10-217601, JP-A-11-348409, JP-A-2001-138621, 2000. No. 43401, No. 2000-21235, No. 2000-309157, No. 2001-96897, No. 2001-138627, JP-A-11-91242, No. 8-2087, No. 8-2090, No. 8- It can also be produced by the methods described in Japanese Patent Nos. 2091 and 8-2093.

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

(Production of support)
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 0 in terms of absolute dry mass. The base paper was impregnated to a density of 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 / ml.

After the corona discharge treatment was performed on the wire surface (back surface) side of the obtained base paper, high-density polyethylene was coated to a thickness of 19 μm using a melt extruder to form a resin layer composed of a mat surface. (Hereinafter, the resin layer surface is referred to as “back surface”). The back side resin layer is further subjected to a 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 Industries, Ltd. Snowtex O ") and a 1: a dispersion 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 applied to the felt surface (surface) side where the resin layer is not provided, anatase-type titanium dioxide 10%, a trace amount of ultramarine blue, and a fluorescent whitening agent 0.01% (vs. polyethylene) A low-density polyethylene containing MFR (melt flow rate) 3.8 is extruded using a melt extruder to a thickness of 29 μm, and a high gloss thermoplastic resin layer is formed on the surface side of the base paper. (Hereinafter, this high-gloss surface is referred to as a “front side”), which was used as a support.

[Example 1]
(Preparation of coating liquid A for ink receiving layer)
(1) Gas phase method silica fine particles, (2) ion-exchanged water, and (3) “Charol DC-902P” in the following composition are mixed, and a disperser “KD-P” manufactured by Shinmaru Enterprises Co., Ltd. (4) A sulfoxide compound according to the present invention described below, (5) polyaluminum chloride as a water-soluble polyvalent metal salt, (6) zirconyl acetate, and a disperser “KD-P”. Used to disperse. Next, a solution containing (7) polyvinyl alcohol, (8) boric acid, (9) surfactant “Olfin PD-101”, and (10) ion-exchanged water is added to prepare a coating solution (A) for an ink receiving layer. did.
Here, the mass ratio between the silica fine particles and the water-soluble resin (PB ratio = (1) / (7)) is 4.5 / 1, and the pH of the coating liquid for ink-receiving layer (A) is 3.3. Showed acidity.

(Composition of coating liquid (A) for ink receiving layer)
(1) Gas phase method silica fine particles (inorganic fine particles) 10 parts (“Leosil QS-30” manufactured by Tokuyama Corporation, average primary particle diameter 7 nm)
(2) Ion-exchanged water 51.5 parts (3) Dispersant 1 part (Charol DC-902P, 51% aqueous solution, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
(4) Sulphoxide compound according to the present invention (Exemplary Compound A-2) 0.3 part (5) Polyaluminum chloride 0.6 part (40% aqueous solution, basic structure: Al ₂ (OH) ₅ Cl, basicity 83%, mordant)
(6) Zirconyl acetate (25% aqueous solution, mordant) 0.3 part (7) Polyvinyl alcohol (8% aqueous solution, water-soluble resin) 27.8 parts ("PVA235" manufactured by Kuraray Co., Ltd., saponification degree 88 mol%) , Degree of polymerization 3500)
(8) Boric acid water (5% aqueous solution, crosslinking agent) 8 parts (9) Surfactant (Olfin PD-101, manufactured by Nissin Chemical Industry Co., Ltd.) 0.1 part (10) Ion-exchanged water 25.4 Part

(Preparation of inkjet recording sheet)
After the corona discharge treatment is applied to the front surface of the support, the ink receiving layer coating solution (A) obtained above is applied to the front surface of the support at 200 ml / m ² using an extrusion die coater. It was applied in an amount (application step), and dried with a hot air dryer at 80 ° C. (wind speed 3 to 8 m / sec) until the solid content concentration of the application layer reached 20%. This coating layer exhibited a constant rate of drying during this period. Immediately after that, it was immersed in a mordant coating solution (B) (pH: 9.2) 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 at 80 ° C. It was dried under 10 minutes (drying process). Thus, an ink jet recording sheet (ink jet recording medium) of Example 1 provided with an ink receiving layer having a dry film thickness of 32 μm was produced.

(Composition of mordant coating liquid (B))
(1) Boric acid (crosslinking agent) 0.65 part (2) Ammonium zirconium carbonate 6.5 part ("Zircozol AC-7" 28% aqueous solution manufactured by Daiichi Elemental Chemical Co., Ltd.)
(3) Ammonium carbonate 6.0 parts (4) Ion-exchanged water 83.8 parts (5) Surfactant 0.2 parts (Mecha-Flick F-1405, manufactured by Dainippon Ink & Chemicals, Inc.)

[Example 2]
Except that the sulfoxide compound (Exemplary Compound A-2) in the composition of the Ink Receptive Layer Coating Liquid A in Example 1 (Preparation of Ink Receptive Layer Coating Liquid A) was changed to Exemplified Compound A-4. In the same manner as in Example 1, an inkjet recording sheet of Example 2 was produced.

[Example 3]
In Example 1 (Preparation of coating liquid A for ink-receiving layer), except that the sulfoxide compound (Exemplary Compound A-2) in the composition of Coating Liquid A for Ink-Receptive Layer was changed to Exemplified Compound A-12. In the same manner as in Example 1, an ink jet recording sheet of Example 3 was produced.

[Example 4]
In Example 1 (Preparation of coating liquid A for ink-receiving layer), except that the sulfoxide compound (Exemplary Compound A-2) in the composition of Coating Liquid A for Ink-Receptive Layer was changed to Exemplified Compound A-16. In the same manner as in Example 1, an inkjet recording sheet of Example 4 was produced.

[Example 5]
Except that in Example 1 (Preparation of coating liquid A for ink-receiving layer), the sulfoxide compound (Exemplary Compound A-2) in the composition of Coating Liquid A for Ink-Receptive Layer was changed to Exemplified Compound A-21. In the same manner as in Example 1, an inkjet recording sheet of Example 5 was produced.

[Example 6]
Except that the sulfoxide compound (Exemplary Compound A-2) in the composition of the Ink Receptive Layer Coating Liquid A in Example 1 (Preparation of Ink Receptive Layer Coating Liquid A) was changed to Exemplified Compound A-39. In the same manner as in Example 1, an inkjet recording sheet of Example 6 was produced.

[Example 7]
In Example 1 (Preparation of coating liquid A for ink receiving layer), except that the sulfoxide compound (Exemplary Compound A-2) in the composition of Coating Liquid A for Ink Receptive Layer was changed to Exemplified Compound A-40. In the same manner as in Example 1, an ink jet recording sheet of Example 7 was produced.

[Example 8]
In Example 1 (Preparation of coating liquid A for ink-receiving layer), 25 parts of sulfoxide compound (Exemplary Compound A-2) in the composition of coating liquid A for ink-receiving layer was added to the mordant coating liquid (B). An ink jet recording sheet of Example 8 was produced in the same manner as Example 1 except that.

[Example 9]
Except that the sulfoxide compound (Exemplary Compound A-2) in the composition of the Ink Receptive Layer Coating Liquid A in Example 1 (Preparation of Ink Receptive Layer Coating Liquid A) was changed to Exemplified Compound A-41. In the same manner as in Example 1, an inkjet recording sheet of Example 9 was produced.

[Comparative Example 1]
In the same manner as in Example 1 except that the sulfoxide compound (Exemplified Compound A-2) in the composition of the coating liquid A for ink-receiving layer was removed in (Preparation of coating liquid A for ink-receiving layer) in Example 1. Thus, an inkjet recording sheet of Comparative Example 1 was produced.

[Comparative Example 2]
In Example 1 (Preparation of coating liquid A for ink-receiving layer), polyaluminum chloride and zirconyl acetate, which are mordants in the composition of coating liquid A for ink-receiving layer, and carbonic acid in the composition of mordant coating liquid (B) An inkjet recording sheet of Comparative Example 2 was produced in the same manner as Example 1 except that zirconium ammonium was omitted.

[Comparative Example 3]
In Example 1 (Preparation of coating liquid A for ink receiving layer), the mordant polyaluminum chloride and zirconyl acetate in the composition of coating liquid A for ink receiving layer were removed, and the mordant coating liquid (B) The inkjet recording sheet of Comparative Example 3 was prepared in the same manner as in Example 1 except that the ammonium zirconium carbonate in the composition was changed to 25 parts of polyallylamine (“PAA-10C” 10% aqueous solution, manufactured by Nittobo Co., Ltd.). Produced.

[Comparative Example 4]
Example 1 except that the sulfoxide compound (Exemplary Compound A-2) in the composition of the ink-receiving layer coating liquid A in Example 1 (Preparation of ink-receiving layer coating liquid A) was changed to the following compound. In the same manner, an inkjet recording sheet of Comparative Example 4 was produced.

(Evaluation test)
The ink jet recording sheet obtained above was subjected to the following evaluation test, and the results are shown in Table 1 below.
(1) Image blurring test Each ink jet recording sheet is loaded into the paper feeding unit of an ink jet printer “PM-950C” manufactured by Seiko Epson Corporation, and the black ink for “PM-950C” is used. A 3 cm × 3 cm square pattern is formed by arranging a 1 mm white background gap to form a “field”, and a print pattern is created. This image sample is placed in an environment of temperature 25 ° C. and humidity 90% RH 72. After storage for a while, the black ink blur in the white background gap is visually observed, and the increase in the black density of the white background immediately after printing is 0.01 or less in the status A Bk filter (A), 0.01 The case of -0.05 was evaluated as (B), and the case of 0.05 or more was evaluated as (C).

(2) Light resistance test Each ink jet recording sheet was loaded into the paper feeding unit of an ink jet printer “PM-950C” manufactured by Seiko Epson Corporation, and an ink set for “PM-950C” was used. After printing a solid image of magenta, Xenon Weather-ometer “Ci65A” (manufactured by ATLAS) was passed through a filter that cuts out ultraviolet rays in a wavelength region of 365 nm or less under an environmental condition of a temperature of 25 ° C. and a humidity of 32% RH. A cycle of standing for 1 hour under an environmental condition of a temperature of 20 ° C. and a relative humidity of 91% with the lamp turned on for 3.8 hours and then turned off was performed for 168 hours. The density of the magenta image before and after this test was measured with a reflection densitometer “Xrite 938” manufactured by Xrite, the residual ratio of magenta was calculated, and evaluated according to the following evaluation criteria. Furthermore, the presence or absence of discoloration of the magenta image before and after the test was visually confirmed.
[Standard]
A: The density residual ratio of the magenta image exceeded 90%.
B: The density residual ratio of the magenta image was 80 to 90%.
C: The density residual ratio of the magenta image was 70 to 80%.
D: The residual density ratio of the magenta image was less than 70%.

(3) Evaluation of glossiness Each ink jet recording sheet is loaded into the paper feeding unit of an ink jet printer “PM-950C” manufactured by Seiko Epson Corporation, and the black ink for “PM-950C” is used. A 3 cm × 3 cm square solid print was performed. The glossiness of the black print portion was visually observed and evaluated according to the following evaluation criteria.
[Evaluation criteria]
○: High gloss and good quality.
Δ: The gloss was slightly inferior to the above.
X: The gloss was low and poor.

(4) Coloring after storage The printed inkjet recording sheet is put in a file and stored in a constant temperature and humidity chamber at a temperature of 40 ° C. and a relative humidity of 90% for 4 days, and then at room temperature and humidity (23 ° C., 65% RH). ) For 3 days. The whiteness of the paper surface subjected to the above treatment was visually observed and evaluated according to the following evaluation criteria.
[Evaluation criteria]
○: The ink receiving layer was not colored.
Δ: Slight coloration of the ink receiving layer was observed.
X: The ink receiving layer was markedly colored.

(5) Ozone fading test Each ink jet recording sheet is loaded into the paper feeding unit of an ink jet printer “PM-950C” manufactured by Seiko Epson Corporation, and an ink set for “PM-950C” is used. After printing a solid cyan image, printing human and landscape images, leaving them in an ozone atmosphere with a concentration of 3 ppm for 12 hours, and then visually observing the degree of coloration and color fading in each image, and evaluating the following Evaluation was made according to criteria.
[Evaluation criteria]
A: Almost no fading was observed.
○: Slight fading was observed.
Δ: A considerable fading was observed.
X: The degree of scarlet was remarkable.

  From the results shown in Table 1, the ink jet recording sheets of Examples 1 to 9 containing a sulfoxide compound and a water-soluble polyvalent metal salt have little aging and coloration, and the formed image has high light resistance and ozone resistance. Showed sex. On the other hand, Comparative Example 1 excluding the sulfoxide-based compound was poor in light resistance and ozone resistance, although there was little aging blur and coloring. Further, Comparative Example 2 excluding the water-soluble polyvalent metal salt was inferior in aging blur, glossiness, light resistance, and ozone resistance. In Comparative Example 3 in which polyallylamine was used as a mordant instead of the water-soluble polyvalent metal salt, the light fastness and ozone resistance were good, but the aging and coloration after storage deteriorated. The compounds used in Example 9 and Comparative Example 4 had the same amino acid site and differed in whether they were sulfoxide or sulfone, so that it was confirmed that sulfone had little effect compared to sulfoxide.

Claims (12)

In an inkjet recording medium having an ink receiving layer on a support,
An ink jet recording medium, wherein the ink receiving layer contains at least one sulfoxide-based compound and at least one water-soluble polyvalent metal salt.   The inkjet recording medium according to claim 1, wherein the water-soluble polyvalent metal salt is a water-soluble aluminum compound and / or a water-soluble zirconium compound. The inkjet recording medium according to claim 1, wherein the sulfoxide-based compound has at least one structure represented by the following general formula (1) in a molecule.

  The inkjet recording medium according to any one of claims 1 to 3, wherein the sulfoxide-based compound has a hydrophilic group. The inkjet recording medium according to any one of claims 1 to 4, wherein the sulfoxide-based compound is a compound represented by the following general formula (2).

[In General Formula (2), each of R ¹ and R ³ independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, or a polymer residue comprising them. Represents a group, and R ¹ and R ³ may be the same or different, and may combine to form a ring. R ² represents a substituted or unsubstituted divalent to hexavalent linking group, and may be bonded to R ¹ and R ² , R ² and R ³ to form a ring. m represents 0 or an integer of 1 or more, and n represents 0 or 1. At least one of R ¹ , R ² , and R ³ is a substituted or unsubstituted amino group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted sulfamoyl group, a substituted or unsubstituted ammonium, or a hydroxyl group Sulfonic acid, carboxylic acid, phosphoric acid, ethyleneoxy group, alkyl group substituted with a hydrophilic group represented by a substituted or unsubstituted nitrogen-containing heterocycle, aryl group, heterocyclic group, and polymer residue To express. ]   The ink jet recording medium according to claim 1, wherein the ink receiving layer contains a water-soluble resin.   The water-soluble resin is at least one selected from the group consisting of polyvinyl alcohol resins, cellulose resins, resins having an ether bond, resins having a carbamoyl group, resins having a carboxy group, and gelatins. The ink jet recording medium according to claim 6.   The inkjet recording medium according to claim 6 or 7, wherein the ink receiving layer contains a crosslinking agent capable of crosslinking the water-soluble resin.   The ink jet recording medium according to claim 1, wherein the ink receiving layer further contains fine particles.   The inkjet recording medium according to claim 9, wherein the fine particles are at least one selected from the group consisting of silica fine particles, colloidal silica, alumina fine particles, and pseudoboehmite.   11. The fine particles according to claim 10, wherein the fine particles are vapor-phase method silica fine particles, and are used in an ink receiving layer as an aqueous dispersion of vapor-phase method silica containing the vapor-phase method silica fine particles and a dispersant. Inkjet recording medium.   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 includes (1) coating the coating layer by applying the coating solution. Simultaneously with the formation, (2) a basic solution having a pH of 7.1 or higher at any time during the drying of the coating layer formed by applying the coating solution and before the coating layer exhibits reduced-rate drying The ink jet recording medium according to any one of claims 1 to 11, wherein the ink is applied to the coating layer and a crosslinking agent is added to the coating solution and / or the basic solution. .