JP2001010212A - Ink jet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording medium of which the absorbing property is favorable, which has a high coloring property, and also, wherein the light-resistance and the surface strength of recorded images and characters are excellent. SOLUTION: This recording medium is constituted by providing an ink receiving layer, and a protective layer on the top of the ink receiving layer, on a water-resistant opaque supporting body. In this case, the ink receiving layer is a layer which mainly contains an inorganic ultra-fine particle, and the protective layer comprises a layer mainly containing a transition metal oxide ultra-fine particle and a colloidal silica.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording medium, and more particularly, to a recording medium having good ink absorbency, high color saturation, and improved light fastness and surface strength of recorded images and characters. The present invention relates to an excellent ink jet recording medium.

[0002]

2. Description of the Related Art In recent years, a method has been adopted in an ink jet recording system in which fine droplets of ink are caused to fly according to various operating principles and adhere to a recording medium such as paper to record images, characters, and the like. . The ink jet recording method is rapidly spreading to various uses such as information equipment as an image recording device because of features such as high speed and low noise, easy colorization, and no need for development and fixing. Furthermore, it is also possible to obtain an image formed by the multi-color ink jet system, which is comparable to multi-color printing by the plate making system or printing by the color electrophotographic system. In particular, when the number of copies is small, the method is cheaper than ordinary multicolor printing and printing methods, and has been widely applied to the field of full-color image recording. Further, with the improvement of recording characteristics such as high-speed recording, high-definition, and full-color recording, recording devices and recording methods have been improved, and high characteristics have been required for recording media. Have been.

[0003] In order to improve recording characteristics corresponding to high speed, high definition, colorization, etc., various types of recording media have been conventionally proposed. For example, Japanese Patent Application Laid-Open No. 55-58
No. 30 discloses an ink jet recording paper provided with an ink absorbing coating layer on the surface of a support.
No. 5,158,583 discloses an example in which amorphous silica is used as a pigment in a coating layer.
Japanese Patent Application Laid-Open Publication No. H11-139,086 discloses an example using a water-soluble polymer coating layer. In recent years, for example, Japanese Patent Application Laid-Open Nos. 9-48173 and 9-272257 disclose γ-type alumina crystal fine particles, US Pat. Nos. 4,879,166 and 510473.
0, JP-A-2-276670, JP-A-4-3757
JP-A-6-32037 and JP-A-5-32037 disclose a recording medium having a coating layer using alumina hydrate having a pseudo-boehmite structure. However, the above prior art has the following problems.

1) US Pat. No. 5,104,730, JP-A-2-276670, JP-A-2-276671,
JP-A-3-275378 discloses that the average pore diameter is 1 nm.
There is disclosed a recording medium having a narrow pore size distribution at ~ 3 nm. In this pore size distribution, although the dye has good adsorptivity, beading occurs due to insufficient solvent absorbency. Here, beading means that when the next ink dot is applied adjacent to the previous ink dot before the previously applied ink dot is fixed on the recording medium, the ink dots become irregular in the horizontal direction. This is a phenomenon in which the image is moved, as a result, mixed and coagulated between adjacent dots, and the image density becomes uneven.

[0005] 2) In general, it has been clarified that the smaller the particle size of the pore-forming pigment, the higher the transparency and smoothness of the ink receiving layer. However, since the particles are densely packed, large pores are not formed, and the ink absorption speed is reduced. JP-A-5-3
No. 2413 discloses a recording medium using secondary particles in which small primary particles are aggregated. However, it has been difficult to simultaneously satisfy transparency and ink absorbency.
Further, the occurrence of coating film defects was remarkable, and it was difficult to form an ink receiving layer having a sufficient ink absorbing ability. In this regard, JP-A-58-65692 discloses that
It is described that since the cohesive bonding force between the primary particles is weak, the strength of the secondary particles is reduced and a coating film defect occurs in the ink receiving layer. Therefore, in the above-mentioned publication, a recording paper is disclosed, in which the primary particles are dispersed in advance in the presence of a water-soluble polymer, and then aggregated and dried, and the solid secondary particles containing the water-soluble polymer are used as pigments. I have. However, although this method is excellent in coating properties and ink absorption, the secondary particle diameter is too large, so that the transparency and image density of the ink receiving layer are reduced, and the entire image appears to be hazy. In addition, there is a problem that coating defects such as cracks and tears easily occur due to shrinkage of the coating film containing inorganic ultrafine particles during drying.

On the other hand, when the support is water-resistant such as resin-coated paper or polyester film instead of paper, the ink absorption by the support cannot be obtained like paper and the burden on the ink receiving layer is greater. .

[0007] An ink-receiving layer mainly composed of inorganic ultra-fine particles composed of ultra-fine particles such as alumina fine particles, alumina hydrate, colloidal silica and fumed silica as a void constituent pigment is disclosed in JP-A-5-24335. As described, since the ink absorption is not sufficient unless the coating amount is about 20 g / m ² or more, in order to obtain excellent ink absorption and quick drying, particularly on a film support, , Thick coating is required. However, when a thick film is applied, coating defects such as cracks and tears in the ink receiving layer are very likely to occur during drying, and it is necessary to suppress the occurrence of coating defects during drying. It is also effective to reduce the amount of the binder in order to improve the ink absorbency. However, in this case, there is a problem that the strength of the coating layer is reduced in combination with the thick film coating.

[0008] As a method for suppressing coating defects such as cracks and tears generated in the ink receiving layer formed of a coating film containing these inorganic ultrafine particles, polyvinyl alcohol as described in JP-A-7-76161 is disclosed. A method has been proposed in which is used as an adhesive to gel polyvinyl alcohol as an adhesive with boric acid or borate to improve the strength of a coating film. However, the gelation reaction between polyvinyl alcohol, boric acid and borate is extremely fast, and there is a problem that the viscosity of the coating solution cannot be changed with time, and the stability of the coating becomes poor. In addition, the gelation product causes a streak, and the surface quality is deteriorated. Japanese Patent Application Laid-Open No. Hei 6-218324 proposes a method in which a coating liquid comprising alumina hydrate is applied on a support, and ammonia gas is sprayed before removing the solvent to cause gelation. However, ammonia gas is not only highly corrosive but also explosive and dangerous. Also,
Excess ammonia gas must be recovered, which is undesirable in terms of simplicity of operation and equipment.

As a method for solving the above problems, Japanese Patent Laid-Open No. 7-89221 proposes an ink jet recording medium having an ink receiving layer composed of alumina hydrate and gelatin. This method utilizes the property that a gelatin solution dissolved in warm water gels at a low temperature. However, this method requires a special curtain coater that can be heated, and requires a cooling zone for gelling gelatin before the drying zone for removing the solvent. Undesirable in terms. In addition, if the drying temperature is increased, gelatinized gelatin is redissolved, and it is necessary to reduce the coating speed at a low temperature to dry, which is not desirable from the viewpoint of productivity.

JP-A-9-309264 discloses that a first coating liquid containing alumina hydrate is applied and dried, and then a second coating liquid having a pH of 8 or more is laminated and dried. A method for manufacturing an ink jet recording medium by repeating this process a plurality of times is disclosed. In this method, the ink receiving layer can be laminated by repetition, and although high ink absorption and quick drying are excellent, the manufacturing process becomes complicated,
The production cost is high.

In order to avoid such drawbacks using inorganic ultrafine particles, the present inventors have made Japanese Patent Application No. 10-319428.
And Japanese Patent Application No. 11-116744 have proposed a method for specifying the shape of the surface of a support on which an ink receiving layer is provided. However, other drawbacks of inorganic ultrafine particles, such as pseudo-boehmite sol, are that film strength, water resistance, and image storability are inferior in addition to the above. .

Here, in an ink jet recording medium containing inorganic ultrafine particles, generally, fading of the dye due to ozone, light or the like is apt to proceed. Means for improving the fading of the dye due to ozone, light, etc. are described in, for example,
Japanese Patent Application Laid-Open No. 57-87988 includes specific metal oxides such as phosphotungstic acid and phosphomolybdic acid and specific metal chlorides such as chromic chloride as proposed in JP-A-7-87987. It has been proposed to include an ultraviolet absorber having a specific structure such as phenylsalicylic acid as proposed in a gazette or the like. In addition, Japanese Patent Application Laid-Open Nos.
JP-A-88066 and JP-A-11-78218 propose a method for improving light resistance using a transition metal oxide such as zinc oxide or cerium oxide in combination with a pigment for an ink receiving layer.

However, in these methods, when the support is water-resistant and non-absorbable, it is necessary to thickly coat the inorganic ultrafine particle-containing layer of the ink-receiving layer as described above. However, the effect of improving light resistance was still insufficient.

On the other hand, as means for preventing the adhesion of water or the bleeding of the dye during long-term storage under high humidity conditions, for example, JP-A-4-320877 and JP-A-4-320877
No. 23075, etc., although a cationic fixing agent is contained or a crosslinking agent is proposed, even when such a cationic fixing agent is used, a cationic fixing agent is used. In some cases, the dye itself is inferior in stability to ozone and light, which may promote the fading of the dye.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet recording medium having good absorbency, high color and excellent light fastness and surface strength of recorded images and characters. It is in.

[0016]

Means for Solving the Problems The present inventors have made intensive studies on the above problems in the ink jet recording medium, and as a result, provided an ink receiving layer and a protective layer thereon on a water-resistant opaque support. In the ink jet recording medium, the ink receiving layer is a layer mainly containing inorganic ultrafine particles, and the protective layer is an ink jet recording medium mainly composed of a layer containing transition metal oxide ultrafine particles and colloidal silica. It has been found that the purpose can be achieved.

The ultrafine transition metal oxide particles of the protective layer are preferably at least one selected from the group consisting of cerium oxide, zinc oxide, titanium oxide and yttrium oxide.

Further, the inorganic ultrafine particles may be composed of alumina hydrate, γ
1 selected from the group of aluminum oxide and fumed silica
More preferably, it is a seed.

Further, the transition metal oxide ultrafine particles are ultrafine particles having an average particle size of 1 nm to 80 nm, and the coating amount is 1 g / g.
The range of m ^{2 to} 15 g / m ² is more preferable because the image color is excellent and the light fastness is improved. In addition, colloidal silica is preferably spherical or chain colloidal silica because it has the effect of improving strength.

The water-resistant opaque support preferably comprises a paper and a coating layer of a thermoplastic resin containing or not containing a white pigment, provided on the surface on the side on which the ink receiving layer is provided.

The water-resistant opaque support is a polyolefin-coated paper, and the coating layer of the polyolefin is formed by bringing a molten polyolefin into close contact with a finely rough cooling roll when coating the paper with the extrusion coating method. Are preferred.

It is more preferable that the surface of the polyolefin resin layer on the side on which the ink receiving layer is provided has a 75-degree specular gloss of 70% or less according to JIS-P8142.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The inorganic ultrafine particles in the ink jet recording medium of the present invention are inorganic fine particles having a primary particle diameter of 100 nm or less, and when they are aggregated or connected to form secondary particles, the average secondary particle diameter thereof. Is 0.5 μm or less. For example, JP-A-1-97678,
JP-A-2-275510, JP-A-3-281383, JP-A-3-285814, JP-A-3-285815, JP-A-4-92183, JP-A-4-267180, JP-A-4-275917 and the like. Proposed pseudo-boehmite sol, JP-A-60-219083,
JP-A-61-19389, JP-A-61-188183, JP-A-63-178074, and JP-A-5-5147.
No. 0, etc., colloidal silica, Japanese Patent Publication No. 4-19037, and Japanese Patent Application Laid-Open No. 62-286.
No. 787, silica / alumina hybrid sol, JP-A-10-119423,
Silica sol as described in JP-A-10-217601 in which ultrafine silica is dispersed by a high-speed homogenizer, smectite clay such as hectite and montmorinite (JP-A-7-81210), zirconia sol , Chromia sol, yttria sol, ceria sol, iron oxide sol, zircon sol, antimony oxide sol, and the like.

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

Among these inorganic ultrafine particles, alumina hydrate, γ-type aluminum oxide fine particles, and fumed silica fine particles can be preferably used.

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

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

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

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

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

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

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

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

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

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

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

In order to obtain γ-type alumina crystal fine particles, usually, γ-type alumina crystals, which are secondary particles of several thousands to tens of thousands of nm, are averaged by a pulverizing means such as a bead mill, an ultrasonic homogenizer, and a high-pressure homogenizer. Grinding is performed until ultrafine particles having a secondary particle diameter of 200 nm or less, preferably 100 nm or less. If the average secondary particle size exceeds 200 nm, the ink absorbency increases, but the coating is brittle and the transparency is reduced. As a grinding means, a method using an ultrasonic homogenizer or a high-pressure homogenizer is preferable,
In other pulverization methods such as a bead mill, since the γ-type alumina crystal is a hard crystal, foreign matter is easily mixed in from the pulverization container, which causes a decrease in transparency and the generation of defects. γ-type alumina crystal fine particles are excellent in ink absorption, dryness, printing quality such as ink fixability, etc.
An ink jet recording medium having excellent transparency can be obtained even when contained in the ink receiving layer at a high ratio.

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

The silica fine particles are amorphous silica, and more than 93% of SiO _2, about 5% or less of Al ₂ O ₃ ,
Fine particles composed of about 5% or less of a2O, such as so-called white carbon, silica gel, and finely divided silica. Methods for producing silica fine particles include a liquid phase method, a pulverized solid phase method, a crystallization solid phase method, and a gas phase method. What is the liquid phase method?
This is a method for producing fine particles in which a silicate compound or the like existing in a liquid is precipitated in a solid state by a chemical change or a physical change. The pulverized solid phase method is a method for mechanically pulverizing silica solids, and the crystallization solid phase method is a method for producing fine particles utilizing melting, phase transition of a solid, or the like. The gas phase method is a method for producing fine particles by thermal decomposition of vapor of a volatile metal compound, heating and evaporation of raw materials, cooling and condensation of generated gas phase species.

The silica fine particles used in the present invention are amorphous silica fine particles synthesized by the above gas phase method. Among them, ultrafine silica having an average primary particle diameter of 3 nm to 100 nm is preferable. Particularly preferred primary particle size is 4 nm or more.
It is of 50 nm. In addition, the secondary particles in which these are connected are preferably 20 nm to 200 nm, more preferably 30 nm to 200 nm.
nm to 100 nm. Aerosil (Texa) corresponds to a commercially available product as amorphous silica fine particles synthesized by the gas phase method.

The fumed silica fine particles used in the present invention are:
Silica fine particles having the above-mentioned primary particle diameter are added to water and dispersed with a high-speed homogenizer or the like to give an average secondary particle diameter of 200.
nm or less, preferably 100 nm or less.

The ink jet recording medium of the present invention is a coating type ink jet recording medium, in which an ink receiving layer and a protective layer are provided on a water-resistant opaque support. The ink receiving layer referred to in the present invention refers to a layer mainly composed of inorganic ultrafine particles, which constitutes a void for allowing a solvent in the ink to penetrate and retain or absorb the solvent. This ink receiving layer may be a single layer or a laminated structure. In the case of a laminated structure, all layers may be layers having the same composition, or may be a laminated structure with a layer composed of other components.

The coating amount of the ink receiving layer containing the inorganic ultrafine particles of the present invention is required to be 20 g or more per unit square meter in terms of solid content. 25 g or more and 60 g or less.

The protective layer referred to in the present invention is a layer provided on the ink receiving layer and mainly has a role of protecting the coloring material of the ink jet recorded image held in the ink receiving layer from decomposition by ultraviolet rays. In addition, it also has a function of improving the strength of the ink receiving layer to protect the ink receiving layer from being scratched, and a function of imparting gloss. The protective layer of the present invention mainly contains ultrafine transition metal oxide particles and colloidal silica.

Cerium oxide contained in the protective layer is as follows:
Specific examples of transition metal oxide fine particles such as titanium oxide, zinc oxide and yttrium oxide will be shown below, but the present invention is not limited to these.

The cerium oxide in the present invention is a fine particle of a white or pale yellow metal oxide having crystals of an equiaxed crystal system and a fluorite structure, for example, oxalate,
It is obtained by heating carbonate, nitrate, ammonium, cerium nitrate and the like to a high temperature and then washing with dilute nitric acid to remove impurities (such as other dilute salt oxides) or heating cerium metal in air. Such cerium oxide is useful as a catalyst because it can store a large amount of oxygen in the fine particles of the metal oxide. As such a sol of cerium oxide, a commercially available sol can be used. For example, ultrafine cerium oxide, Niedral W-15, Niedral U-15, Niedral W-100, Nedral U-100 (Taki Kagaku ( Co., Ltd., average particle size 0.08 μm, true specific gravity 1.21)
And the like.

Titanium oxide in the present invention is classified into rutile type and anatase type according to the crystal system. Anatase type titanium oxide has high reflectance to short-wavelength light, and therefore has whiteness, coloring power, and shielding property. Although it is excellent in power, its crystal structure is unstable and it is photochemically active, so that it has poor light resistance. On the other hand, rutile-type titanium oxide is inferior in whiteness, coloring power and shielding power as compared with anatase-type titanium oxide, but is excellent in light resistance because of its stable crystal structure. The fine particles of titanium oxide are produced by, for example, hydrolyzing titanium tetrachloride vapor in an oxyhydrogen flame to obtain a titanium oxide sol having an average particle diameter of 5 to 10 nm and a specific gravity of about 1.04. As such a titanium oxide sol, a commercially available one can be used. For example, ultrafine titanium oxide AUF-0015S (manufactured by Osaka Titanium Manufacturing Co., Ltd., average particle diameter 10 to 20 nm, true specific gravity 3.8, bulk specific gravity) 0.0
7-0.1), ultrafine titanium oxide MT-150W, 5
00B, 600B (manufactured by Teikoku Processing Co., Ltd., average particle size 5 to 5)
50 nm), ultrafine titanium oxide TTO-55 (N)
(Ishihara Sangyo Co., Ltd., average particle diameter 30-40 nm, true specific gravity 4.2, bulk specific gravity 0.5-0.7).

The zinc oxide used in the present invention is naturally produced as rhombic acid. In general, a dry method obtained by oxidizing zinc vapor in the air and an acid salt of zinc such as zinc chloride and zinc sulfate are used. Is neutralized by alkali neutralization in an aqueous solution. In the case of the wet method, zinc oxide fine particles of various shapes can be produced by controlling the kind of alkali to be mixed and neutralization conditions, and the particle diameter can be adjusted to 100 nm or less. Such zinc oxide has a hexagonal urnolite-type crystal structure. As the sol of zinc oxide, a commercially available sol can be used. For example, zinc oxide ultrafine particles ZnO-100 (manufactured by Sumitomo Cement Co., Ltd.)
Average particle diameter 9 nm, true specific gravity 5.78, bulk specific gravity 0.4),
Ultrafine zinc oxide particles ZnO-200 (Sumitomo Cement Co., Ltd.)
And an average particle diameter of 1.6 nm, a true specific gravity of 5.78, and a bulk specific gravity of 0.31).

The yttrium oxide in the present invention is produced using uranium ore or xenotime as a main raw material, and is used for applications such as phosphors and ceramic additives (added as stabilizers for zirconia fine particles). . Such yttrium oxide has an average particle size of 1.5.
２．５2.5 μm, and the crystals are cubic.
The yttrium oxide fine particles used in the present invention are sols having an average particle diameter of about 5 nm to 10 nm.

Next, colloidal silica which is one of the components contained in the protective layer of the present invention will be described. The shape of the colloidal silica is generally spherical or nearly spherical. The colloidal silica according to the present invention is preferably a chain-like one having an elongated shape in which the spherical or small silica particles are connected in a chain-like manner. Elongated particles mean particles that have no extension in the three-dimensional direction but extend in the same plane. Elongated particles include those that are substantially straight, bent, branched, ringed, and the like. On the other hand, what is called amorphous silica or silica gel is secondary aggregated silica particles bonded in a three-dimensional direction, and the amorphous silica or silica gel is mechanically dispersed to reduce the secondary particle diameter. 10
Even if dispersed in particles in the 300 nm colloid region, it is a dispersion of three-dimensionally bonded particles and cannot be dispersed into spherical primary particles or elongated chain-like particles. In this regard, the colloidal silica and the colloidally dispersed particles of amorphous silica of the present invention are completely different.

The chain silica particles preferably used in the present invention can be obtained by various methods, and in the present invention, even if they are obtained by any method,
If the silica particles have a chain shape, they can be preferably used in the present invention. As a method of forming chain silica particles,
For example, it can be obtained by removing alkali from general water glass to obtain activated silicic acid, and growing the particles by adding a cation having a valence of 2 or more so as to form a chain.

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

To the aqueous colloidal solution of activated silicic acid, a cation having a valence of 2 or more is added so as to be linked in a chain form to grow particles. As the divalent or higher cation, a calcium ion and a magnesium ion are preferable, and a calcium salt,
It is preferably added as an aqueous solution in the form of a magnesium salt or a mixture thereof. This calcium salt,
The total amount of the magnesium salt or the mixture thereof is 15 in the weight ratio [(CaO + MgO) / SiO ₂ ] calculated as the oxide with respect to the active silicic acid.
00 to 25000 ppm, especially 15 in the case of elongated particles.
The amount which becomes 00-8500 ppm is preferable.

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

If a polyvalent metal component other than calcium and magnesium is contained in the above-mentioned colloidal solution of activated silicic acid together with the calcium salt and magnesium salt, a silica sol can be produced more preferably. Examples of polyvalent metals other than calcium and magnesium include:
Sr, Ba, Zn, Sn, Pb, Cu, Fe, Ni, C
o, Mn, Al, Cr, Y, Ti, Zn and other divalent,
Trivalent or tetravalent metals are mentioned. As the amount of these polyvalent metal components, when the amounts of the calcium salt and the magnesium salt were converted into the amounts of CaO and MgO, respectively,
About 80% by weight is preferable.

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

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

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

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

The mixture obtained by the above steps is
30 minutes to 40 hours at 300 ° C., preferably 90 to 150 hours
SiO ₂ concentration 1 by heating 2 to 12 hours at ℃
A silica sol having a chain shape of 6% by weight is obtained.
By concentrating this sol if desired, a higher concentration sol can be obtained. The chain-like silica particles obtained by the above method have a secondary particle diameter of 40 to 300 nm as measured by a dynamic light scattering method, and have a thickness of 5 to 40 nm according to electron microscope observation. It has a shape grown in a plane or three-dimensionally.

The chain-like silica particles according to the present invention need only be present in a chain-like form at least in the coating liquid for forming the ink-receiving layer in the ink-jet recording medium of the present invention. Prior to the preparation of the coating liquid for use, the chain-like silica particles according to the present invention including the above-described method are prepared, and the ink-receiving layer-forming coating liquid may be prepared using the silica particles. At the time of preparing the coating liquid for forming, the coating liquid may be prepared while preparing the chain-like silica particles according to the present invention including the above method in the coating liquid. If the chain-like silica particles according to the present invention are prepared before preparing the coating liquid, commercially available silica particles can be used. Examples of commercially available chain-like silica particles include Snowtex UP and Snowtex OUP manufactured by Nissan Chemical Industries.

A water-soluble or water-insoluble polymer compound may be added as an adhesive to the ink receiving layer or the protective layer used in the present invention. The polymer compound used in the present invention is a compound having an affinity for ink as a component of the ink receiving layer. For example, as the water-soluble polymer compound, polyvinyl alcohol, acrylic resin, styrene-acrylic copolymer, maleic anhydride polymer, styrene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer, starch, polyvinyl butyral, gelatin,
Casein, ionomer, gum arabic, carboxymethyl cellulose, alginic acid, sodium alginate,
Pullulan, polyvinylpyrrolidone, polyacrylamide, polyethylene glycol, polypropylene glycol and the like. Preferably, it is polyvinyl alcohol.

Examples of the water-insoluble polymer compound include alcohols such as ethanol and 2-propanol, and water-insoluble adhesives that are soluble in a mixed solvent of these alcohols and water. It is particularly preferred because it is stabilized. Such water-insoluble adhesives include vinylpyrrolidone / vinyl acetate copolymer, polyvinyl butyral,
Acetal resins such as polyvinyl formal can be mentioned, and particularly, the degree of acetalization is 5 mol% or more and 20 mol%.
Acetal resins in the following ranges are particularly preferred because they can contain some water and can facilitate dispersion of inorganic ultrafine particles, particularly alumina fine particles or alumina hydrate.

These polymer compounds may be used alone or in combination of two or more, and may be 2 to 30% by weight based on the solid weight of the inorganic ultrafine particles of the ink receiving layer or the transition metal oxide and the colloidal silica of the protective layer. Is added. Preferably, 5-1
5% by weight. If the amount is less than the above range, the strength of the coating film becomes weak, and if it is too large, the ink absorbency decreases.

Further, other additives include inorganic pigments, cationic dye fixing agents, pigment dispersants, thickeners, flow improvers, viscosity stabilizers, pH adjusters, hardeners, surfactants, Foaming agents, foam inhibitors, release agents, foaming agents, penetrants, coloring dyes, coloring pigments, optical brighteners, ultraviolet absorbers, antioxidants, pigment dispersants, defoamers, leveling agents, preservatives In addition, an anti-binder, a water-proofing agent, a wet paper strength enhancer, a dry paper strength enhancer, and the like can be appropriately added as long as the object of the present invention is not impaired.

In the ink jet recording medium of the present invention, an inorganic pigment is added to the ink receiving layer or the protective layer within a range that does not affect the storage properties such as absorption, image color, transparency, water resistance, ozone resistance and light resistance. It can be used in combination with the layers as appropriate.

As the pigments other than those described above to be incorporated in the ink receiving layer according to the present invention, one or more known white pigments can be used. For example, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, talc,
Calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, alumina, aluminum hydroxide, lithopone, zeolite, water Examples include white inorganic pigments such as halloysite and magnesium hydroxide, and organic pigments such as styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsules, urea resin, and melamine resin.

Among the above-mentioned inorganic pigments, it is particularly preferable to use synthetic amorphous silica for the ink receiving layer, and an ink jet recording medium having excellent print density, ink absorbency, and sharpness of a printed image can be obtained. . Such synthetic amorphous silica is described in, for example, Japanese Patent Application Laid-Open No. 57-1577.
No. 86, No. 61-141584, No. 61-2
JP-A-30979, JP-A-62-292476, and the like are microporous, irregular fine particles having a three-dimensional structure of SiO ₂ formed by gelation of silicic acid, and Hunter whiteness It has a pore size of about 90 or more and a pore diameter of about 10 to 2000 angstroms.

As such synthetic amorphous silica, commercially available ones can be suitably used. For example, Mizukasil P-
526, Mizukacil P-801, Mizukasil NP-8,
Mizukacil P-802, Mizukasil P-802Y, Mizukasil C-212, Mizukacil P-73, Mizukacil P
-78A, Mizukacil P-78F, Mizukacil P-8
7, Mizukacil P-705, Mizukasil P-707, Mizukasil P-707D, Mizukasil P-709, Mizukasil C-402, Mizukasil C-484 (all manufactured by Mizusawa Chemical), Toksil U, Toksil UR, Toksil G
U, Toksil AL-1, Toksil GU-N, Toksil N, Toksil NR, Toksil PR, Solex, Fine Seal E-50, Fine Seal T-3
2, Fine Seal X-37, Fine Seal X-7
0, Fine Seal RX-70 Fine Seal A, Fine Seal B (all manufactured by Tokuyama), Carplex F
PS-101, carplex CS-7, carplex 80, carplex XR, carplex 67 (all manufactured by Shionogi & Co., Ltd.), thyroid 63, thyroid 6
5, thyroid 66, thyroid 77, thyroid 7
4, thyroid 79, thyroid 404, thyroid 6
20, thyroid 800, thyroid 150, thyroid 244, and thyroid 266 (all manufactured by Fuji Silysia Chemical Ltd.).

The method for providing the ink receiving layer on the support in the present invention is as follows. Each of the coating compositions is prepared using a hydrophilic organic solvent such as water or alcohol, or a mixed solvent thereof, and the ink receiving layer is formed on the support. The protective layer may be coated simultaneously and in layers, or the ink receiving layer may be coated and dried, and then the protective layer may be coated and dried. In addition, there is no problem in providing the protective layer by a casting method in which the protective layer is pressed against a heated mirror roll while the protective layer is in a wet state, dried and finished. The coating method is not particularly limited, and a known coating method can be used. For example, conventionally known air knife coaters, curtain coaters, slide lip coaters,
Die coater, blade coater, gate roll coater, bar coater, rod coater, roll coater,
The coating can be performed on the support by various devices such as a bill blade coater, a short dwell blade coater, and a size press. In the present invention, a slide lip system, a curtain system, and the like are preferable because two layers can be simultaneously coated.

The ink receiving layer can be applied by applying a certain amount of coating in several times. As a method of applying the ink receiving layer by dividing it into several times, there may be mentioned a method of applying the ink by drying each layer, and a method of applying a plurality of layers simultaneously on a wet-on-wet basis. After the application of the ink receiving layer, a smoothing treatment can be performed using a calendar device such as a machine calender, a TG calender, a super calender, and a soft calender.

The coating amount of the protective layer of the present invention is not particularly limited, but is preferably 0.5 to 20 g / m ² . More preferably, it is 1 to 15 g / m ² . When the coating amount is less than 0.5 g / m ² , sufficient strength and light resistance improvement effects cannot be obtained, which is not preferable. When the coating amount is more than 20 g / m ² , the absorption and the image color deteriorate. In some cases, this is not preferable.

On the other side of the ink receiving layer with the support interposed therebetween, a back coat layer can be applied to impart curl aptitude. When the back coat layer is applied, the pigment is preferably a tabular pigment or hydrohaloysite.

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

The base paper constituting the resin-coated paper preferably used in the present invention is not particularly limited, and generally used paper can be used. More preferably, for example, a base paper used for a photographic support is used. It is a smooth base paper.
As the pulp constituting the base paper, natural pulp, recycled pulp, synthetic pulp or the like may be used alone or in combination of two or more. The base paper is blended with additives generally used in papermaking, such as a sizing agent, a paper strength enhancer, a filler, an antistatic agent, a fluorescent whitening agent, and a dye.

Further, a surface sizing agent, a surface paper strength agent, a fluorescent whitening agent, an antistatic agent, a dye, an anchoring agent and the like may be coated on the surface.

The thickness of the base paper is not particularly limited, but preferably has good surface smoothness, such as compressing the paper by applying a pressure with a calender or the like during or after papermaking. ~250g / m ² is preferred.

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

In the resin of the resin-coated paper, white pigments such as titanium oxide, zinc oxide, talc and calcium carbonate; fatty acid amides such as stearic acid amide and arachidic acid amide; zinc stearate; calcium stearate; Aluminum, fatty acid metal salts such as magnesium stearate, antioxidants such as Irganox 1010 and Irganox 1076, blue pigments and dyes such as cobalt blue, ultramarine blue, cecilian blue, and phthalocyanine blue, cobalt violet, fast violet, and manganese purple It is preferable to add various additives such as magenta pigments and dyes, fluorescent brighteners and ultraviolet absorbers in an appropriate combination.

The resin-coated paper, which is preferably used in the present invention, is a so-called extrusion coating method in which, in the case of a thermoplastic resin such as a polyolefin resin or a polyester resin, a heated and molten resin is cast on a running base paper. And the side or both sides on which the ink receiving layer is provided is covered with a resin. In the case of a resin that is cured by an electron beam, the resin is applied by a commonly used coater such as a gravure coater or a blade coater, and then irradiated with an electron beam to cure and coat the resin. Further, before coating the resin on the base paper, the base paper is preferably subjected to an activation treatment such as a corona discharge treatment or a flame treatment.
The surface (surface) of the support on which the ink receiving layer is applied may be a glossy surface or a matte surface depending on the application. In the present invention, the 75-degree specular glossiness according to JIS-P8142 is 70% or less. It is preferable to use a finely roughened surface. Even if such a roughening treatment is applied to the support, the recording surface provided with the ink receiving layer has a high gloss, and a sufficient practical gloss can be obtained.

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

In the production of a resin-coated paper used in the present invention and having a finely roughened surface having a 75 ° specular gloss of 70% or less according to JIS-P8142, a polyolefin resin or the like is heated and melted by an extruder. Then, it is extruded into a film shape between a sheet-like substrate such as paper and a cooling roll, pressed and cooled, and manufactured. The cooling roll is used to form the surface shape of the resin coating layer, and the surface of the resin-coated paper is formed to be high gloss, matte, or patterned, for example, silk or mat depending on the shape of the cooling roll surface. You can do it. In the present invention, it is necessary to use a cooling roll whose surface is finely roughened, and make the 75-degree specular glossiness according to JIS-P8142 of the surface of the resin coating layer on which the ink receiving layer is provided to be 70% or less. More preferably, the gloss is 50% or less.

The surface shape of the cooling roll used in the present invention is not particularly limited.
As disclosed in Japanese Patent No. 3379, the shape of the surface provided on the roll surface which is basically extremely smooth finished has a shape constituted by a continuous and uniform foam-like curved surface, and the shape of the foam-like curved surface There is a cooling roll having a surface having a height of 0.3 to 1.0 μm and a diameter of 5 to 30 μm. That is, for example, a 50-70 μm chrome plating is applied to a smooth polished base metal on a cooling roll surface, and then a 10-20 μm polished surface is processed to a smooth surface, and a 50-70 μm chrome plating is performed again. , And after polishing again for 10 to 20 μm,
It is obtained by subjecting the chrome-plated surface to a micro-roughening process using mesh sand. The height of the unevenness on the processed surface is usually about 0.1 to 10 μm, and the glossiness of the processed surface decreases as the roughness increases.

When the height of the foamed curved surface of the cooling roll surface is less than 0.3 μm, the smoothness is basically excessively high, and the surface on which the hot melt resin is extrusion-coated has a high glossiness. On the other hand, if it exceeds 1.0 μm, the smoothness is basically reduced, and as a result, a surface with low gloss is obtained.

The ink referred to in the present invention is a recording liquid comprising the following dyes, solvents and other additives.
CIDirect Yellow 12, CIDirect Yellow 24, CIDire
ct Yellow 26, CIDirect Yellow 44, CIDirect Yello
w 86, CIDirect Yellow 98, CIDirect Yellow 100, C.
I.Direct Yellow 142, CIDirect red 1, CIDirect re
d 4, CIDirect red 17, CIDirect red 28, CIDirect
red 83, CIDirect Orenge 34, CIDirect Orenge 39,
CIDirect Orenge 44, CIDirect Orenge 46, CIDire
ct Orenge 60, CIDirect Violet 47, CIDirect Viole
t48, CIDirect Blue 6, CIDirect Blue 22, CIDire
ct Blue 25, CIDirect Blue 71, CIDirect Blue 86,
CIDirect Blue 90, CIDirect Blue 106, CIDirect
Blue 199, CIDirect Black 17, CIDirect Black 19,
CIDirect Black 32, CIDirect Black 51, CIDirect
Black 62, CIDirect Black 71, CIDirect Black 10
8, direct dyes such as CIDirect Black 146, CIDirect Black 154, CIAcid Yellow 11, CIAcid Yellow 17, C.I.
I.Acid Yellow 23, CIAcid Yellow 25, CIAcid Yello
w 29, CIAcid Yellow 42, CIAcid Yellow 49, CIAci
d Yellow 61, CIAcid Yellow 71, CIAcid red1, CIA
cid red 6, CIAcid red 8, CIAcid red 32, CIAcid
red 37, CIAcidred 51, CIAcid red 52, CIAcid red
80, CIAcid red 85, CIAcid red 87, CIAcid red 9
2, CIAcid red 94, CIAcid red 115, CIAcid red 18
0, CIAcid red 256, CIAcid red 317, CIAcid red 3
15, CIAcid Orenge 7, CIAcidOrenge 19, CIAcid Vi
olet 49, CIAcid Blue 9, CIAcid Blue 22, CIAcid
Blue 40, CIAcid Blue 59, CIAcid Blue 93, CIAcid
Blue 102, CIAcid Blue104, CIAcid Blue 113, CIA
cid Blue 117, CIAcid Blue 120, CIAcid Blue167, C.
I.Acid Blue 229, CIAcid Blue 234, CIAcid Blue 25
4, CIAcid Black 2, CIAcid Black 7, CIAcid Black
24, CIAcid Black 26, CIAcid Black31, CIAcid Bl
ack 52, CIAcid Black 63, CIAcid Black 112, CIAc
acid dyes such as id Black118, other basic dyes,
Water-soluble dyes such as reactive dyes or food dyes, or
Pigments such as carbon black can be used.

Examples of the solvent for the ink include water and various water-soluble organic solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol. Alkyl alcohols having 1 to 4 carbon atoms such as alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol and polypropylene glycol Polyalkylene glycols; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1, 2, 6
Alkylene glycols having 2 to 6 alkylene groups, such as hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; and many such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl ether. And lower alkyl ethers of polyhydric alcohols.

Among the above water-soluble organic solvents, polyhydric alcohols such as diethylene glycol, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are particularly preferable.

In addition to the above-mentioned water-soluble organic solvents, water-insoluble insulating solvents having excellent safety such as flammability and toxicity represented by high-boiling aliphatic hydrocarbons may be used. Organic pigments and the like are often used as pigments.

Other additives to be added to the ink include, for example, a pH regulator, a metal sequestering agent, an antioxidant,
Examples include a fungicide, a viscosity modifier, a surface tension modifier, a wetting agent, a surfactant, and a rust inhibitor.

[0091]

EXAMPLES The present invention will be described below with reference to examples of the present invention, but the present invention is not limited to these examples. Further, “parts” and “%” shown in the examples are parts by weight and% by weight unless otherwise specified.

<Preparation of Water-Resistant Opaque Support> A 1: 1 mixture of bleached hardwood kraft pulp (LBKP) and softwood bleached sulphite pulp (NBSP) was beaten to 300 ml with Canadian Standard Freeness to prepare a pulp slurry. . As a sizing agent, alkyl ketene dimer to pulp is 0.5% by weight, polyacrylamide is 1.0% by weight to pulp, cationized starch is 2.0% by weight to pulp, and polyamide epichlorohydrin resin is a sizing agent. 0.5% by weight of pulp was added and diluted with water to obtain a 1% slurry. The slurry was paper-made to have a basis weight of 170 g / m ² by a Fourdrinier paper machine, and used as a base paper for polyolefin resin-coated paper. A polyethylene resin composition obtained by uniformly dispersing 10% by weight of anatase type titanium with respect to a resin of 100% by weight of low-density polyethylene having a density of 0.918 g / cm ³ at 320 ° C. was melted at 320 ° C. Extrusion coating was performed so as to obtain a thickness of 30 μm per minute, and extrusion coating was performed using a roughening-treated cooling roll, and this surface was used as a surface on which an ink receiving layer was provided. The glossiness of the surface was 50%. On the other side, a high-density polyethylene resin having a density of 0.962 g / cm ³ was similarly melted at 320 ° C. and extrusion-coated to a thickness of 30 μm.

<Synthesis of Alumina Hydrate> Ion-exchanged water 1
200 g and isopropyl alcohol 900 g were charged into a 3 L reactor and heated to 75 ° C. 408 g of aluminum isopropoxide were added, and 75 g for 24 hours, followed by 9 g
Hydrolysis was performed at 5 ° C. for 10 hours. After hydrolysis, acetic acid 2
4 g was added and the mixture was stirred at 95 ° C. for 48 hours. Next, the mixture was concentrated so that the solid content concentration became 15% by weight to obtain a white alumina hydrate dispersion.

The sol was dried at room temperature and measured by X-ray diffraction, which showed a pseudo-boehmite structure. When the average particle size was measured with a transmission electron microscope, it was 30 nm, and it was a plate-like alumina hydrate having an aspect ratio of 6.0. Also, when the average pore radius, pore volume and BET specific surface area were measured by a nitrogen adsorption / desorption method,
7.1 nm, 0.65 ml / g and 200 m respectively
² / g.

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

<Ink-receiving layer coating liquid B> As alumina fine particles, 600 g of aerosil aluminum oxide C (manufactured by Nippon Aerosil Co., Ltd.) having a primary particle diameter of 13 nm, which is a γ-type alumina crystal powder of the δ group, was placed in 2400 g of ion-exchanged water. The mixture was dispersed by a stirrer to prepare a 20% by weight slurry-like viscous liquid. Using this 20 wt% γ-type alumina dispersion, 10 wt% was added to 100 parts of the alumina dispersion.
30 parts of an aqueous solution of polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.) was mixed. After mixing, 10,000 r into a homomixer
The dispersion was uniformly dispersed over 10 minutes at pm to obtain a coating liquid B.
The average secondary particle diameter of the γ-type alumina crystal powder in the dispersion is 1
20 nm.

<Ink Receiving Layer Coating Liquid C> The coating composition for the ink receiving layer is 100 ppm silica (AEROSIL300, manufactured by Nippon Aerosil Co.) having a primary particle diameter of 7 nm.
g in 500 g of ion-exchanged water with a stirrer,
10% by weight of polyvinyl alcohol (Kuraray PVA)
235) 80 g of aqueous solution was mixed. After mixing, the mixture was homogenized in a homomixer at 10,000 rpm for 10 minutes to obtain a coating liquid C. The average secondary particle diameter of the fumed silica in the dispersion was 115 nm.

<Ink Receiving Layer Coating Liquid D> The coating composition for the ink receiving layer is 100 ppm silica (AEROSIL 300: manufactured by Nippon Aerosil Co.) having a primary particle diameter of 7 nm.
g in 500 g of ion-exchanged water with a stirrer,
10% by weight of polyvinyl alcohol (Kuraray PVA)
235) 80 g of aqueous solution was mixed. After mixing, the mixture was uniformly dispersed in a homomixer at 10,000 rpm for 30 minutes to obtain a coating liquid D. The average secondary particle diameter of the fumed silica in the dispersion was 70 nm.

<Ink receiving layer coating liquid E> The coating composition of the ink receiving layer is a synthetic amorphous silica (fine seal X) having a primary particle diameter of about 20 nm and a BET specific surface area of 270 m ² / g.
100 parts of -37B: manufactured by Tokuyama Corporation, 30 parts of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.), and 20 parts of a cationic dye fixing agent (Smileds Resin 1001: manufactured by Sumitomo Chemical Co., Ltd.) were mixed to prepare a coating liquid E. . The average secondary particle size of the synthetic amorphous silica in the dispersion was 3.7 μm.

<Ink-receiving layer coating liquid F> The coating composition for the ink-receiving layer is a vapor-phase fine-particle silica having a primary particle diameter of 7 nm (AEROSIL300: manufactured by Nippon Aerosil Co., Ltd.).
g in 500 g of ion-exchanged water with a stirrer,
10% by weight of polyvinyl alcohol (Kuraray PVA)
235) 80 g of aqueous solution was mixed. Further, cerium oxide having a particle diameter of 8 nm (Neidral U-15; manufactured by Taki Chemical Co., Ltd.)
Solid content 2g, colloidal silica (Snowtex-O;
(Nissan Chemical Industries, particle size 10-20 nm, concentration 20%) 6
After mixing 0 g, the mixture was uniformly dispersed in a homomixer at 10,000 rpm for 10 minutes to obtain a coating liquid F.

<Ink Receiving Layer Coating Liquid G> The coating composition for the ink receiving layer was prepared by adding 80 g of ultrafine zinc oxide particles (ZnO-100; manufactured by Sumitomo Cement Co., Ltd.) having an average particle diameter of 9 nm to 30 g.
0 g of ion-exchanged water was dispersed with a stirrer, and polyvinyl alcohol (polymerization degree: 1700, saponification degree: 88.0 mol)
%) Was mixed with 200 g of a 10% by weight aqueous solution of a resin obtained by acetalizing 5 mol% with n-butyraldehyde, and uniformly dispersed to obtain a coating liquid G.

<Protective Layer Coating Solution A> The protective layer coating composition was composed of cerium oxide (Neidral U-1) having a particle diameter of 8 nm.
5; Taki Chemical Co., Ltd.) 40 parts solids, spherical colloidal silica (Snowtex-O; Nissan Chemical Co., Ltd., particle size 10-)
300 parts of 20 nm, 20% concentration), 80 parts of polyvinyl alcohol (PVA117: Kuraray Co., Ltd., 10% solution),
20 parts of a cationic dye fixing agent (Smileds Resin 1001: manufactured by Sumitomo Chemical Co., Ltd., concentration: 30%) was mixed to obtain a coating solution A for a protective layer.

<Protective Layer Coating Solution B> The protective layer coating composition is composed of ultrafine titanium oxide (AUF-0015S; Osaka Titanium Manufacturing Co., Ltd.) 40 having an average particle diameter of 10 to 20 nm.
Part, spherical colloidal silica (Snowtex-O; manufactured by Nissan Chemical Industries, particle size 10-20 nm, concentration 20%) 300
Parts, polyvinyl alcohol (PVA117: 10% solution, manufactured by Kuraray Co., Ltd.), 80 parts, cationic dye fixing agent (Smileds Resin 1001: manufactured by Sumitomo Chemical Co., concentration: 30%) 2
0 parts were mixed to prepare a protective layer coating liquid B.

<Protective Layer Coating Solution C> The coating composition for the protective layer was made of zinc oxide ultrafine particles (ZnO-1) having an average particle diameter of 9 nm.
00; manufactured by Sumitomo Cement Co., Ltd.), 40 parts of spherical colloidal silica (Snowtex-O; manufactured by Nissan Chemical Co., Ltd., particle size: 10-)
300 parts of 20 nm, 20% concentration), 80 parts of polyvinyl alcohol (PVA117: Kuraray Co., Ltd., 10% solution),
20 parts of a cationic dye fixing agent (Smired's Resin 1001: manufactured by Sumitomo Chemical Co., Ltd., concentration: 30%) was mixed to prepare a protective layer coating liquid C.

<Protective Layer Coating Liquids DI> The coating composition for the protective layer was made of zinc oxide ultrafine particles (Zn) having an average particle diameter of 1.6 nm.
O-200; manufactured by Sumitomo Cement Co., Ltd.) X part, chain colloidal silica (Snowtex-UP; manufactured by Nissan Chemical Industries, particle thickness 5 to 20 nm, length 40 to 300 nm, concentration 20%)
Solid part Y part, polyvinyl alcohol (PVA117: 10% solution, manufactured by Kuraray Co., Ltd.) 80 parts, cationic dye fixing agent (Smileds Resin 1001: manufactured by Sumitomo Chemical Co., Ltd., concentration: 30)
%), And X / Y was adjusted to 0/100, 2
0/80, 40/60, 60/40, 80/20, 10
0/0 and protective layer coating solutions D, E, F, G, H,
I.

<Protective Layer Coating Liquid J> The coating composition for the protective layer was changed from synthetic amorphous silica (Nipsi silica) having an average secondary particle diameter of 1.5 μm in place of the colloidal silica of the protective layer coating liquid C.
l-E1011, primary particle diameter 24 nm) was pulverized and dispersed by a sand grinder, and further pulverized and dispersed by a pressure homogenizer, and a pulverization and dispersion operation was repeated until the average secondary particle diameter became 120 nm. Protective layer coating liquid J was prepared in exactly the same manner as protective layer coating liquid C.

The coating was carried out by applying a coating amount of the ink-receiving layer coating liquid shown in Table 1 on the support by using a wire bar.
It was applied so as to be 5 g / m ² and dried. Next, the coating liquids for the protective layer shown in Table 1 were applied to the respective coating amounts shown in Table 1 and dried to obtain recording paper. However, in Comparative Example 5, the ink-receiving layer coating liquid F was dried at a coating amount of 30 g / m.
² and no protective layer was provided thereon.
In Comparative Example 6, the ink receiving layer coating liquid G was applied in a dry coating amount of 1
0 g / m ² (about 10 μm thickness) was applied, and no protective layer was provided thereon.

<Evaluation of Coating Film Strength> Evaluation of “coating film strength” was carried out by using a friction tester (manufactured by Suga Test Instruments Co., Ltd.) and pressing cotton gauze against the coated surface of the sheet with a load of 300 g.
A friction test was carried out 00 times.
And In addition, some scratches were generated in the 100-time friction test, but no scratch was generated in the 20-time friction test, and “x” was obtained in the 20-time friction test.

<Evaluation of light fastness>
To the inkjet printer (Made by EPSON, M
J-700V2C) solid ink of Y, M, C, Bk ink
Character. These inkjet recording sheets,
Xenon arc fade meter, Atlas Ci-3
5f, black panel temperature 63 ° C, relative humidity 65
Magenta before and after 30 hours of light irradiation in a% RH environment
The color difference of the ink colors was measured. Color difference ΔE ^*Is L^*, A^*,
b^*Sample before and after light irradiation according to (CIE1976)
Based on the result of measuring the color of
it can. The larger the color difference, the more color degradation
If the color difference is less than 3.0, the difference in color is visually large.
There is no difference.

[0110]

１E ^* = ｛(△ L ^* ) ² + (△ a ^* ) ² + (△ b ^* ) ² ｝ ^1/2 where こ こ E ^* is the color difference, △ L ^* and △ a ^* Δb ^* is L ^* before and after light irradiation and the difference between a ^* and b ^* , respectively. The results ΔE ^* is less than 3.0 ○, ΔE ^* is less than 3.0~7.0 △, ΔE ^* was evaluated as × 7.0 or higher.

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

<Evaluation of Image Color> Canon BJC-42
Solid printing of magenta and cyan was performed using 0J. The color was visually evaluated as follows. A: Good color and no dullness. B: Good color, slightly dull, but practically no problem. C: Looks somewhat dull. D: The color is rough and dull.

[0113]

[Table 1]

Table 1 shows that in Examples (1 to 16) in which inorganic ultrafine particles were used for the ink receiving layer and transition metal oxide fine particles and colloidal silica were contained in the protective layer, the coating film strength, ink absorbency, Excellent color balance and light fastness are obtained in a good balance, but the ink receiving layer is silica with a large secondary particle size that is commonly used in inkjet paper (Comparative Example 1). When the protective layer does not contain a transition metal oxide (Comparative Example 2), light resistance is low, and when the protective layer does not contain colloidal silica (Comparative Examples 3, 4), the coating film strength decreases. , Poor overall inkjet suitability. In addition, when the inorganic ultrafine particles, the transition metal oxide, and the colloidal silica are mixed and contained in one layer (Comparative Example 5) instead of having a two-layer structure as in the present invention, sufficient film strength and light resistance are obtained. I can't get it. When a single layer is composed of only a transition metal oxide and a binder resin (acetal resin) (Comparative Example 6) instead of having a two-layer configuration, transparency and light resistance can be obtained, but absorption and color properties are low. Insufficient.

[0115]

As described above, according to the present invention,
It is possible to provide a well-balanced inkjet recording medium having excellent ink absorbency, image color properties, and image light fastness and having sufficient coating film strength.

Claims (18)

[Claims] 1. An ink jet recording medium comprising an ink-receiving layer and a protective layer provided on a water-resistant opaque support, wherein the ink-receiving layer is a layer mainly containing inorganic ultrafine particles, and An ink jet recording medium, wherein the layer is a layer mainly containing transition metal oxide ultrafine particles and colloidal silica. 2. The transition metal oxide ultrafine particles of the protective layer,
2. The ink jet recording medium according to claim 1, wherein the medium is at least one selected from the group consisting of cerium oxide, zinc oxide, titanium oxide, and yttrium oxide. 3. The ink jet recording medium according to claim 1, wherein the inorganic ultrafine particles of the ink receiving layer mainly consist of alumina hydrate. 4. The ink jet recording medium according to claim 3, wherein said alumina hydrate has a pseudo-boehmite structure. 5. The ink jet recording medium according to claim 1, wherein the inorganic ultrafine particles of the ink receiving layer mainly consist of γ-type aluminum oxide. 6. The ink jet recording medium according to claim 5, wherein the average primary particle diameter of the γ-type aluminum oxide is 80 nm or less. 7. The ink jet recording medium according to claim 1, wherein the inorganic ultrafine particles of the ink receiving layer mainly consist of fumed silica. 8. The fumed silica has an average primary particle size of 8
The inkjet recording medium according to claim 7, wherein the thickness is 0 nm or less. 9. The ink jet recording medium according to claim 1, wherein the transition metal oxide of the protective layer is zinc oxide ultrafine particles having an average particle size of 1 nm to 80 nm. 10. The ink jet recording medium according to claim 1, wherein the transition metal oxide of the protective layer is cerium oxide ultrafine particles having an average particle size of 1 nm to 80 nm. 11. The colloidal silica of the protective layer is a spherical or chain colloidal silica.
Item 7. The ink jet recording medium according to any one of the above items. 12. The coating amount of the protective layer is from 1 g / m ² to 1 g / m ^2.
Claim, characterized in that in the range of 5 g / m ² 1 to 1
2. The ink jet recording medium according to claim 1. 13. The ink jet recording medium according to claim 1, wherein the water-resistant opaque support is a resin-coated paper having a thermoplastic resin coating layer provided on paper. 14. The ink jet recording medium according to claim 13, wherein said thermoplastic resin is a polyolefin resin. 15. The ink jet recording medium according to claim 14, wherein the polyolefin resin is a polyethylene resin or a polypropylene resin. 16. The ink jet recording medium according to claim 13, wherein the coating layer of the thermoplastic resin contains a pigment. 17. The water-resistant opaque support is a thermoplastic resin-coated paper, and a coating layer of the thermoplastic resin is formed by closely adhering to a fine-rolled cooling roll during melt extrusion coating of the thermoplastic resin. Claims 1, 13-1
7. The ink jet recording medium according to any one of 6. 18. The water-resistant opaque support having a surface on the side on which an ink-receiving layer is provided, having a specular glossiness at 75 degrees according to JIS-P8142 of 70% or less.
18. The ink jet recording medium according to any one of items 17 to 17.