JP2010234789A - Ink jet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording medium excellent in glossiness, high in print density in the case of conducting ink jet recording using dye ink, and excellent in water resistance and operatability. <P>SOLUTION: The ink jet recording medium is obtained by providing an application layer containing synthetic amorphous silica as a pigment, a polyvinyl alcohol as a binder, and a cationic resin on at least one surface of a gas permeable paper support, and an ink acceptance layer on the surface of the application layer by applying a coagulation solution containing not less than 3 but not more than 20 mass% of anionic colloidal silica by a coagulation cast coat method. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an inkjet recording medium having gloss suitable for an inkjet recording system.

  An ink jet recording medium has a structure in which an ink receiving layer containing a porous pigment such as silica or alumina and a binder is provided on the surface of a support such as paper, and an ink liquid is provided on the ink receiving layer. Drops are fixed. With the remarkable progress of ink jet printers in recent years and the remarkable spread of digital cameras, the quality required for ink jet recording media is increasing year by year. In particular, in an inkjet recording medium having a gloss comparable to that of a conventional silver salt photograph, quality requirements are strict and technological development is actively being carried out.

  The inkjet recording medium having gloss described above is generally produced by a cast coating method using a cast coater from the viewpoint of production cost. The cast coating method is a method in which a coating liquid mainly composed of a pigment and a binder is coated on a support to provide a coating layer, and the coating layer is gloss-finished using a cast drum. The gloss coating layer becomes the ink receiving layer. The cast coating method includes (1) a wet casting method (direct method) in which a coating layer is pressed onto a mirror-finished heating drum while the coating layer is wet, and (2) a wet coating layer is once dried. Or, semi-dried, swollen and plasticized with a re-wetting solution, pressed onto a mirror-finished heated drum and dried (re-wet cast method), (3) the wet coating layer is made into a gel state by coagulation treatment There are generally known three types: a solidification cast method (gelation cast method) in which a heated drum having a mirror finish is pressed and dried. The principle of each method is common in that the wet coating layer is pressed against the mirror-finished surface to give gloss to the coating layer surface.

  The quality characteristics required for such a glossy inkjet recording medium include high gloss on the surface of the recording medium, high print density, no ink overflow or bleeding, and uneven printing (light / dark unevenness). In order to improve these characteristics, it is necessary to improve the ink receiving layer. For example, a technique has been reported in which the ink receiving layer has a layer structure of one or more layers, and at least one layer contains colloidal particles having an average particle diameter of 300 nm or less and a cationic resin (for example, see Patent Document 1). Moreover, the technique containing the colloidal silica whose primary particle diameter is 30-100 nm in the cast coating layer is reported (for example, refer patent document 2).

  In addition, when an ink receiving layer is formed by a coagulation method by applying a coagulant that can coagulate with the adhesive of the coating layer, a technique in which the coagulant contains a boron compound, colloidal silica, and a resin has been reported (for example, (See Patent Document 3).

Japanese Patent Laid-Open No. 9-263039 JP-A-2005-35169 JP 2002-166645 A

  However, in the case of the techniques described in Patent Documents 1 and 2 above, there is room for improvement in terms of increasing the gloss of the recording medium, and further, the pigment contained in the ink receiving layer when ink jet recording is performed with a dye ink. Since the average particle size is large, there is a problem that the printing density is lowered.

In the case of the technique described in Patent Document 3, since the colloidal silica having a small average particle diameter exists on the surface of the ink receiving layer, the printing density of the dye ink is improved, but the cationic resin that fixes the ink on the surface of the ink receiving layer. There is a problem that the water resistance deteriorates because of the absence of.
Furthermore, in the technique described in Patent Document 3, when a cationic resin is blended in the coagulant, a shock is caused with anionic colloidal silica, so the cationic resin cannot be added, so the ink fixing property is deteriorated, and the ink absorption Inferior in water resistance and water resistance. Further, when the colloidal silica is cationic, it causes shock with the borate, so that the borate cannot be added to the coagulant, resulting in insufficient coagulation and a problem in operability.

  Accordingly, an object of the present invention is to provide an ink jet recording medium which is excellent in glossiness, has a high print density when ink jet recording is performed using a dye ink, and is excellent in water resistance and operability.

  As a result of various studies, the present inventors have formulated a cationic resin in the coating liquid for the ink receiving layer and an anionic colloidal silica in the coagulant solution when the ink receiving layer is provided by the coagulation cast coating method. As a result, coagulation is improved by anionic and cationic agglomeration reactions, and it is possible to coagulate without the cross-linking reaction between borate and / or boric acid and polyvinyl alcohol. It was. As a result, the inventors have found that the above problems can be solved, and have reached the present invention.

  That is, the inkjet recording medium of the present invention has a coating layer containing synthetic amorphous silica as a pigment, polyvinyl alcohol as a binder, and a cationic resin on at least one surface of a paper support containing air permeability. After coating, the surface of the coating layer is coated with a coagulant solution containing 3% by mass to 20% by mass of anionic colloidal silica, and an ink receiving layer is provided by a coagulation cast coating method. It is a recording medium.

  Further, the cationic resin in the ink receiving layer is preferably an ink fixing agent, and the coagulant solution may not contain borate and / or boric acid.

  According to the present invention, it is possible to obtain an ink jet recording medium which is excellent in glossiness, has a high printing density when ink jet recording is performed using a dye ink, and further has excellent water resistance and operability.

  Embodiments of the present invention will be described below. In the ink jet recording medium of the present invention, a coating layer containing a pigment and a binder is formed on at least one surface of a gas-permeable support, and then the binder is solidified on the surface of the coating layer. A coagulant solution is applied and an ink receiving layer is provided by a coagulation cast coating method.

(Paper support)
As the paper support used in the present invention, any material can be used as long as it has a gas permeability sufficient to transmit water vapor generated in the cast drum during cast coating. Paper such as paper is preferably used. Paper consists of pulp fibers and fillers. Raw material pulp includes chemical pulp (such as bleached or unbleached kraft pulp of softwood, bleached or unbleached kraft pulp of hardwood), mechanical pulp (grand pulp, thermomechanical pulp, chemi Thermo-mechanical pulp, etc.), deinked pulp, etc. can be used alone or mixed in any proportion. It is preferable that softwood pulp is contained as the raw material pulp. When softwood pulp is blended in the paper support, the strength of the base paper is improved and the glossiness of the ink receiving layer tends to be improved. However, since the surface property of the paper support tends to decrease as the content of softwood pulp increases, the content of softwood pulp is preferably 30% by mass or less in the total pulp. The pH of the paper support may be acidic, neutral or alkaline. The filler can be appropriately selected from known fillers such as hydrated silicic acid, white carbon, talc, kaolin, clay, calcium carbonate, titanium oxide, and synthetic resin fine particles.

  From the viewpoint of the production efficiency of the ink jet recording medium, the air permeability of the paper support is preferably 1000 seconds or less, and from the viewpoint of coating properties, the Steecht sizing degree of the base paper is 10 seconds or more. desirable.

  In addition, for the paper support, liquids containing various additives such as water-soluble polymer additives can be used on-machine or off using a tab size, size press, gate roll coater, or film transfer coater. It is possible to apply with a machine.

  Examples of the water-soluble polymer additive include starch derivatives such as starch, cationized starch, oxidized starch, etherified starch, and phosphate esterified starch; polyvinyl alcohol derivatives such as polyvinyl alcohol and carboxy-modified polyvinyl alcohol; carboxymethylcellulose Cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, cellulose sulfate; water-soluble natural polymers such as gelatin, casein, soybean protein; sodium polyacrylate, sodium styrene-maleic anhydride copolymer, sodium polystyrene sulfonate, etc. Water-soluble polymers such as maleic anhydride resins; aqueous polymer adhesives such as thermosetting synthetic resins such as melamine resins and urea resins are used. Other additives include petroleum resin emulsion, styrene-maleic anhydride copolymer alkyl ester ammonium salt, alkyl ketene dimer emulsion, styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, polyethylene as sizing agent. And dispersion such as polyvinylidene chloride. Examples of other additives include sodium chloride, calcium chloride, and bow glass that are inorganic electrolytes as antistatic agents, and glycerin, polyethylene glycol, and the like as hygroscopic substances. Examples of other additives include clay, kaolin, talc, barium sulfate, and titanium oxide as pigments. As other additives, hydrochloric acid, caustic soda, sodium carbonate, etc. are used as pH adjusters, and other additives such as dyes, fluorescent brighteners, antioxidants, ultraviolet absorbers, etc. can be used in combination. is there.

(Pigment of ink receiving layer)
Ink-receiving layer (In the present invention, the coating layer is given a gloss by bringing the surface of the coating layer into contact with the heated mirror-finished surface by a solidified cast coating method to form an ink-receiving layer. As the pigments used without distinguishing between the ink layer and the ink receiving layer, known inorganic fine particles and organic fine particles can be used. Examples of the pigment include synthetic amorphous silica, colloidal silica, aluminum hydroxide, alumina hydrate (alumina sol, colloidal alumina, pseudoboehmite, etc.), alumina (α type crystal alumina, θ type crystal alumina, γ type) Crystal alumina, etc.), kaolin, talc, calcium carbonate, titanium dioxide, clay, zinc oxide and the like can be used. These can be used alone or in combination of two or more, but it is essential that the pigment contains synthetic amorphous silica from the viewpoint of color development and ink absorbability.

(Binder for ink receiving layer)
As a binder for the ink receiving layer, polyvinyl alcohol, which is a water-based binder resin, is essential from the viewpoint of the strength of the coating layer. Other water-based binder resins are also blended as necessary to ensure the coating layer strength. The term “aqueous” means that the resin is dissolved or dispersed and stabilized (water-soluble and / or water-dispersible resin emulsion) in water or a medium composed of water and a small amount of an organic solvent. The aqueous binder resin means a water-soluble resin and a water-dispersible resin. The aqueous binder resin is dissolved or dispersed in the coating liquid to be coated on the support, but after coating and drying, it becomes a binder for the pigment and forms an ink receiving layer.

  Examples of other aqueous binder resins include polyvinyl pyrrolidone; urethane resins derived from urethane resin emulsions; starches such as oxidized starch and esterified starch; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; casein; gelatin; soy protein; -Acrylic resin and derivatives thereof; styrene-butadiene resin latex; acrylic resin emulsion, vinyl acetate resin emulsion, vinyl chloride resin emulsion, urea resin emulsion, alkyd resin emulsion, and derivatives thereof. These aqueous binder resins can be used by mixing with polyvinyl alcohol.

(Polyvinyl alcohol)
In the present invention, the polyvinyl alcohol is preferably partially saponified polyvinyl alcohol. The addition amount of polyvinyl alcohol is preferably 5 to 30 parts by mass with respect to 100 parts by mass of the total pigment in the ink receiving layer. However, the type of the binder is not particularly limited as long as the required coating layer strength is obtained.

(Synthetic amorphous silica)
The synthetic amorphous silica can be roughly classified into wet method silica and gas phase method silica depending on the production method. Synthetic amorphous silica produced by a wet process is inferior to gas phase process silica in pigment transparency, but is excellent in paint stability when used in combination with polyvinyl alcohol. Furthermore, wet process silica has better dispersibility than gas phase process silica without internal voids, and can increase the coating concentration. Therefore, the ratio of the pigment (to the binder) in the ink receiving layer can be increased, and the absorbability of the ink receiving layer can be increased, so that the ink absorbability can be improved and the color developability of the dye ink can be improved. It is preferred that the secondary particle size of the wet silica in terms of obtaining high glossiness is 1 to 4 [mu] m, BET specific surface area is preferably 100 to 300 m ² / g. Moreover, it is preferable that the primary particle diameter of the said vapor phase method silica is 4 nm-30 nm, and it is preferable that a BET specific surface area is 100-400 m < ² > / g from the point of obtaining a coating layer with high transparency.

  When two or more kinds of pigments having different average particle diameters are used as the pigment of the ink receiving layer, the “average pigment particle diameter” is a value obtained by weighted averaging the average particle diameter of each pigment by the content ratio of each pigment. To do. The average particle size of the pigment in the ink receiving layer is preferably 1 to 4 μm. If it is smaller than 1 μm, the ink absorbency is inferior, and if it exceeds 4 μm, the glossiness tends to decrease.

(Cationic resin)
When a cationic resin is included in the ink receiving layer, the cationic resin adheres to (is present on) the surface of the ink receiving layer due to cast coating. The cationic resin fixes the ink and improves the water resistance. In the present invention, both an electrically positive cationic resin and colloidal silica coexist in the ink receiving layer, and both do not aggregate.

  Examples of the cationic resin include polyamine sulfone, polyalkylene polyamine, polyamine condensate, polyallylamine, polydiallylamine, polyvinylamine, polyethyleneimine, dicyandiamide condensate, cationic acrylic resin, and cationic urethane resin. Species or multiple species can be selected and used.

  The ink receiving layer contains the above-described pigment and binder, but other components such as a thickener, an antifoaming agent, an antifoaming agent, a pigment dispersant, a release agent, a foaming agent, a pH adjusting agent, and a surface. Sizing agent, coloring dye, coloring pigment, fluorescent dye, ultraviolet absorber, antioxidant, light stabilizer, preservative, water resistance agent, dye fixing agent, surfactant, wet paper strength enhancer, water retention agent, cation In the range which does not impair the effect of this invention, a conductive polymer electrolyte etc. can be suitably added to the coating layer used as the precursor of an ink receiving layer.

  As a method of applying a coating liquid to be an ink receiving layer on a paper support, blade coater, air knife coater, roll coater, brush coater, kiss coater, squeeze coater, curtain coater, die coater, bar coater, gravure coater, gate A known coating machine such as a roll coater or a short dwell coater can be appropriately selected from the coating methods used on-machine or off-machine.

The coating amount of the ink receiving layer can be arbitrarily adjusted within the range that covers the surface of the support and sufficient ink absorbability is obtained. From the viewpoint of achieving both recording density and ink absorbency, is preferably 3 to 25 g / ^{m 2} in terms of solid content, in particular, when considering also the productivity is preferably 5 to 20 g / ^{m 2.} If it exceeds 25 g / m ² , the peelability from the cast drum mirror-finished surface may be reduced, and problems such as adhesion of the coating layer to the mirror-finished surface may occur.

  In the present invention, when a large coating amount of the ink receiving layer is required, the ink receiving layer can be multi-layered. Further, an undercoat layer having various functions such as ink absorptivity, adhesiveness and the like may be provided between the support and the ink receiving layer. Further, a back coat layer having various functions such as ink absorbability, writing property, printer printability and the like may be further provided on the side opposite to the surface on which the ink receiving layer is provided.

(Formation of ink receiving layer)
In the present invention, gloss is imparted by forming the outermost ink receiving layer by a solidified cast coating method. The coagulation cast coating method is performed as follows, for example. First, a coating liquid to be an ink receiving layer is applied to a support. Next, a coagulant solution having the action of coagulating the binder (particularly the aqueous binder) in the coating solution is applied to an undried coating layer and gelled, and then heated to a mirror-finished surface. Crimp and dry. The coagulation cast coating method can provide the ink receiving layer with a surface feel and gloss comparable to silver salt photography.

  If the coating layer is in a dry state when applying the coagulant solution, it is difficult to copy the mirror drum surface, and the resulting ink-receiving layer surface has many minute irregularities, making it difficult to obtain glossiness similar to that of a silver salt photograph. . After applying the coagulant solution while the coating layer is in a wet state, the surface of the coating layer is brought into contact with a heated mirror-finished surface to give gloss.

(Coagulation method)
In the present invention, the coagulation method is such that a cationic resin is blended in the coating liquid for the ink receiving layer and an anionic colloidal silica is blended in the coagulant solution to coagulate by anionic and cationic aggregation reactions. A new coagulation method is used.

  The method for applying the coagulant solution is not particularly limited as long as it can be applied to the coating layer, and can be appropriately selected from known methods (for example, roll method, spray method, curtain method, etc.).

(Components of coagulant solution)
The coagulant solution used in the present invention essentially contains anionic colloidal silica.
(Anionic colloidal silica)
The anionic colloidal silica is preferably 3% by mass or more and 20% by mass or less. If it is less than 3 masses, the operability and the glossiness are lowered. On the other hand, when the content exceeds 20% by mass, aggregates (precipitates) are generated, resulting in operational trouble, poor ink fixability, and poor water resistance.

The concentration of the coagulant solution is preferably 3% by mass or more and less than 25% by mass. If it is less than 3% by mass, the amount of the coagulant solution deposited (solid content is less than 0.5 g / m ² ) is insufficient, and the coagulation action becomes insufficient. On the other hand, if it is 25% by mass or more, it cannot be dissolved in an aqueous solution, and aggregates (precipitates) are generated, resulting in operational trouble, poor ink fixability, and poor water resistance.

The adhesion amount (solid content) of the coagulant solution is preferably 0.3 g / m ² or more and 5 g / m ² or less. If it is less than 0.3 g / m ² , the coagulation property is inferior, and the operability and glossiness are deteriorated. On the other hand, if it exceeds 5 g / m ² , the ink fixing property is inferior and the water resistance deteriorates.

  When anionic colloidal silica is contained in the coagulant, the anionic colloidal silica adheres to (is present on) the surface of the ink receiving layer due to the cast coat. If the colloidal silica has a small average particle diameter, the printing density of the dye ink is improved. Further, since colloidal silica having a small average particle diameter is present on the outermost surface of the ink receiving layer, the surface of the ink receiving layer becomes smooth and the glossiness is improved.

  Anionic colloidal silica is colloidal silica whose particle surface is highly negatively charged. Anionic colloidal silica is, for example, colloidal silica obtained by heating and aging a silica sol obtained through metathesis with an acid of sodium silicate or the like through an ion exchange resin layer, and has no positive charge. Examples of commercially available anionic colloidal silica include Snowtex series manufactured by Nissan Chemical Industries, Ltd. In the present invention, two or more kinds of anionic colloidal silica may be mixed and used.

  From the viewpoint of improving glossiness and transparency of the ink receiving layer, the average particle diameter of the anionic colloidal silica is preferably in the range of 10 nm to 70 nm. When the average particle diameter of the anionic colloidal silica is smaller than 10 nm, the glossiness of the coating layer is excellent, but the absorbability of the dye ink may be inferior. On the other hand, when the average particle diameter of the anionic colloidal silica is larger than 70 nm, the transparency of the coating layer may be lowered, and the printing density of the dye ink may be lowered. Further, for the purpose of supplementing ink absorbency, those having a large average particle diameter or different shapes may be used in combination.

  Further, from the viewpoint of smoothing the outermost surface of the ink receiving layer and improving the glossiness, the average primary particle diameter of the anionic colloidal silica is smaller than the average particle diameter (weighted average particle diameter) of the pigment used in the ink receiving layer. It is preferable. In this way, the finest anionic colloidal silica covers the outermost surface of the ink receiving layer, so that the glossiness is improved.

  When two or more types of anionic colloidal silica having different average particle diameters are used, the “primary particle diameter of anionic colloidal silica” means the average particle diameter of each anionic colloidal silica and the content ratio of each anionic colloidal silica. The weighted average value. Similarly, when two or more kinds of pigments having different average particle diameters are used as the pigment of the ink receiving layer, the “primary particle diameter of the pigment” is a value obtained by weighted averaging the average particle diameter of each pigment by the content ratio of each pigment And The primary particle diameter of colloidal silica can be measured by, for example, a light intensity distribution analysis type particle diameter distribution measuring apparatus.

  However, since anionic colloidal silica causes aggregation with boric acid and borate, it is difficult to control coagulation.

  Therefore, in the present invention, a cationic resin is blended in the ink receiving layer coating liquid, the aqueous solution for coagulation is made anionic, and the coagulation reaction is utilized without containing boric acid and borate in the aqueous solution for coagulation. Stable operation is possible.

  Moreover, a release agent can be added to the coating layer and / or the coagulant as necessary. The melting point of the release agent is preferably 90 to 150 ° C, and particularly preferably 95 to 120 ° C. In the above temperature range, since the melting point of the release agent is substantially equal to the temperature of the mirror finish surface, the ability as a release agent is maximized. The release agent is not particularly limited as long as it has the above characteristics, but it is preferable to use a polyethylene wax emulsion.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. “Part” and “%” represent “part by mass” and “% by mass”, respectively, unless otherwise specified.

[Example 1]
Light calcium carbonate (Albuquer 5970: manufactured by SMI Co., Ltd.) is used as a filler for pulp slurry with a beating degree of 300 ml comprising 95 parts of hardwood bleached kraft pulp (L-BKP) and 5 parts of softwood bleached kraft pulp (N-BKP). It was added to 20%, and 1.0 part of aluminum sulfate, 0.20 part of AKD, and 0.05 part of a yield improver were added. The slurry was paper in a paper machine using a coating that time 5% of starch and 0.2% of a surface sizing agent and (AKD) such that 1.5 g / ^{m 2} by solid content, 180 g / An m ² paper support was obtained.
The following coating solution A was applied to this support with an air knife coater at 8 g / m ^2, and while the coating layer was in a wet state, the following coagulation solution B was applied at 2.0 g / m ² to be solidified, Next, the mirror surface was pressed through a press roll onto a mirror-finished surface, and the mirror surface was copied to obtain an inkjet recording medium having a weight of 190 g / m ² .
Coating liquid A: Gas phase method synthetic amorphous silica (Aerosil 300: manufactured by Nippon Aerosil Co., Ltd.) 20 parts and wet method synthetic amorphous silica (Fine Seal X-37: manufactured by Tokuyama Co., Ltd.) 80 as pigments Part, 20 parts of polyvinyl alcohol (PVA217: manufactured by Kuraray Co., Ltd.) as a binder, 3% of a cationic resin (Saftmer ST3300, manufactured by Mitsubishi Chemical Corporation), 0.1 part of an antifoaming agent (SN deformer 480: manufactured by San Nopco) A coating solution having a concentration of 18% was prepared by blending.
Coagulant solution B: anionic colloidal silica (Snowtex O: manufactured by Nissan Chemical Industries, Ltd.) 10%, mold release agent (Maycatex HP65: manufactured by Meisei Chemical Co., Ltd.) 1%, antifoaming agent (SN deformer 480: A coagulant solution B containing 0.1% of San Nopco) was prepared.

[Example 2]
An ink jet recording medium was obtained in the same manner as in Example 1 except that the amount of the anionic colloidal silica (Snowtex O: manufactured by Nissan Chemical Industries, Ltd.) in the coagulant solution B was changed to 20%.

[Example 3]
An ink jet recording medium was obtained in the same manner as in Example 1 except that the blending amount of the anionic colloidal silica (Snowtex O: manufactured by Nissan Chemical Industries, Ltd.) of the coagulant solution B was changed to 3%.

[Comparative Example 1]
An ink jet recording medium was obtained in the same manner as in Example 1 except that the anionic colloidal silica was not blended in the coagulant solution B.

[Comparative Example 2]
An ink jet recording medium was obtained in the same manner as in Example 1 except that the blending amount of the anionic colloidal silica (Snowtex O: manufactured by Nissan Chemical Industries, Ltd.) in the coagulant solution B was changed to 2%.

[Comparative Example 3]
An ink jet recording medium was obtained in the same manner as in Example 1 except that the amount of the anionic colloidal silica (Snowtex O: manufactured by Nissan Chemical Industries, Ltd.) in the coagulant solution B was changed to 22%.

[Comparative Example 4]
Inkjet recording was conducted in the same manner as in Example 1 except that cationic colloidal silica (manufactured by LUDOX CL Grace) was used instead of anionic colloidal silica (Snowtex O: manufactured by Nissan Chemical Industries, Ltd.) of the coagulant solution B. A recording medium was obtained.

  The following items were evaluated for the inkjet recording papers obtained in Examples 1 to 3 and Comparative Examples 1 to 4. The obtained results are shown in Table 1.

<Evaluation>
1. Dye ink printing density A predetermined pattern is recorded on the obtained ink jet recording medium using a dye ink jet printer (PM-970C: manufactured by Epson Corporation), and the vividness of the recorded image portion is visually evaluated according to the following criteria. did. If the evaluation is Δ or more, there is no practical problem.
◎: Very vivid ○: Vivid △: Slightly inferior x: Invisible

2. Image clarity (image clarity)
The obtained inkjet recording medium (the ink receiving layer surface thereof) was measured using a image clarity measuring device (model number: ICM-1DP, manufactured by Suga Test Instruments Co., Ltd.) according to JIS-K 7105. The MD direction of the paper was measured under the conditions of a measurement angle of 60 degrees and a comb width of 2 mm. If the image clarity is 60% or more, the reflected image is clearly visible and the glossiness is excellent. When the image clarity is less than 60%, the reflected image is unclear and inferior in gloss.

3. 20 ° Glossiness The 20 ° glossiness of the unprinted portion of the ink receiving layer surface of the obtained inkjet recording medium was measured in accordance with JIS-Z 8741. It measured using the glossiness meter (Murakami Color Research Laboratory make, True GLOSS GM-26PRO). If the 20 degree glossiness is 20% or more, there is no practical problem.
4). Water resistance A predetermined pattern was recorded on the obtained ink jet recording medium using a dye ink jet printer (PM-970C: manufactured by Epson Corporation). After dropping water droplets on this pattern, the ink jet printer was allowed to stand for 3 hours. The bleeding was visually evaluated according to the following criteria. If the evaluation is Δ or more, there is no practical problem.
○: Bleeding is hardly observed.
Δ: Slight bleeding is observed.
X: Significant bleeding is observed.

5). Coating property The fogging state of the cast drum after continuous coating of 20,000 m at a coating speed of 50 m / min was visually observed and evaluated according to the following criteria. If the evaluation is Δ or more, there is no practical problem.

◎: No fogging on the drum surface at all ○: Slight fogging on the drum surface can be confirmed, but there is almost no problem with suitability for long run △: Cloudiness on the drum surface can be confirmed, and there is a problem level ×: Entire surface of the drum surface A lot of cloudiness was confirmed in

表１に示されるように、実施例は、染料インク記録時の印字濃度が高く、写像性、光沢感に優れ、さらに耐水性にも優れていた。さらに、操業性にも優れていた。凝固剤中のアニオン性コロイダルシリカの配合量が３％未満である比較例２は光沢度、写像性ともに劣っていた。凝固剤中のアニオン性コロイダルシリカの配合量が２０％を超えた比較例３は耐水性が劣っていた。凝固剤中にアニオン性コロイダルシリカを配合しなかった比較例１、カチオン性コロイダルシリカを配合した比較例４の場合、凝固剤が凝集して塗工できず、インクジェット記録媒体が得られなかった。

As shown in Table 1, the examples had high printing density during dye ink recording, excellent image clarity and gloss, and excellent water resistance. Furthermore, the operability was excellent. Comparative Example 2 in which the blending amount of the anionic colloidal silica in the coagulant was less than 3% was inferior in both glossiness and image clarity. Comparative Example 3 in which the blending amount of the anionic colloidal silica in the coagulant exceeded 20% was inferior in water resistance. In Comparative Example 1 in which the anionic colloidal silica was not blended in the coagulant and in Comparative Example 4 in which the cationic colloidal silica was blended, the coagulant aggregated and could not be applied, and an ink jet recording medium was not obtained.

Claims (3)

  After providing a coating layer containing synthetic amorphous silica as a pigment, polyvinyl alcohol as a binder, and a cationic resin on at least one surface of a paper support containing air permeability, An ink jet recording medium comprising a surface on which a coagulant solution containing 3% by mass to 20% by mass of anionic colloidal silica is applied and an ink receiving layer is provided by a coagulation cast coating method.   The inkjet recording medium according to claim 1, wherein the cationic resin in the ink receiving layer is an ink fixing agent.   2. The inkjet recording medium according to claim 1, wherein the coagulant solution does not contain boric acid and / or borate.