JP4301339B2 - Inkjet recording medium - Google Patents

Description

  The present invention relates to an ink jet recording medium suitable for recording using a dye ink and a pigment ink, and more particularly to an ink jet recording medium having glossiness similar to that of a silver salt photograph and having high scratch resistance.

  The ink jet recording method is a method in which dots are formed by ejecting ink droplets by various mechanisms and adhering to the recording paper, but there is no noise compared to the dot impact type recording method, In addition, there are advantages such as easy full color and high-speed printing. On the other hand, inks used for ink jet recording are usually water-based inks using direct dyes, acid dyes, etc., and thus have a drawback of poor drying properties.

  The characteristics required for the ink jet recording paper used in such an ink jet recording method are that the ink drying speed is high, the print density is high, there is no ink overflow or bleeding, and the ink is absorbed. As a result, the paper does not wavy. A method of manufacturing a high-quality inkjet recording paper satisfying these characteristics by a cast coating method has already been proposed (Patent Documents 1 to 4 and the like).

  In any of these production methods, a recording layer composed of a pigment mainly composed of synthetic silica and a binder is pressure-bonded to a heated mirror-finished surface while it is in an undried wet state to copy the mirror surface. At the same time, it was dried to obtain a high-gloss cast-coated paper, but the glossiness of the outermost layer was low, and it was far from the glossiness of a silver salt photograph. On the other hand, a recording layer containing a hydrophilic binder such as polyvinyl alcohol and gelatin and inorganic fine particles on a resin-coated paper (so-called resin-coated paper) having a polyolefin coating layer to which a white pigment or the like is added on at least one side of the base paper A silver salt photographic-type ink jet recording paper provided with the above has been proposed (Patent Documents 5, 6, etc.). However, in the case of these ink jet recording papers, since a resin-coated paper having no air permeability is used as a support, it takes time to dry after the recording layer is applied, and there is a disadvantage that productivity is extremely low. .

  As a result of various studies on an ink jet recording medium having glossiness similar to that of a silver salt photograph, the present inventors have provided a recording layer containing polyvinyl alcohol on the surface of the base paper, and then a function of solidifying the polyvinyl alcohol on the recording layer. Then, the recording layer is processed with the processing liquid, and then dried while being pressed against the heated mirror-finished surface while the recording layer is in a wet state, thereby obtaining an inkjet recording medium having glossiness equivalent to that of a silver salt photograph. Has already found that it can. However, in this case, when printing is performed with an ink jet printer, the papers are rubbed with each other and fine scratches are likely to occur on the surface of the recording layer.

JP-A-62-95285 JP-A-63-264391 Japanese Patent Laid-Open No. 2-27487 JP-A-5-59694 JP 10-119423 A Japanese Patent Laid-Open No. 11-20306

  Accordingly, the present inventors have made various studies in order to obtain an ink jet recording medium having a glossiness similar to that of a silver salt photograph and having a sufficiently high scratch resistance, and as a result, a recording layer containing polyvinyl alcohol and a pigment. It has been found that good results can be obtained by adding a mixture of two kinds of polyvinyl alcohols having a specific polymerization degree and a saponification degree as the polyvinyl alcohol therein. Accordingly, an object of the present invention is to provide an ink jet recording medium which has glossiness similar to that of a silver salt photograph and can obtain particularly high ink absorbability and scratch resistance of a recording layer.

The object of the present invention is to provide a recording layer containing a pigment and polyvinyl alcohol on a gas-permeable support, and after applying a treatment liquid having a function of coagulating polyvinyl alcohol on the recording layer, An ink jet recording medium in which a gloss is imparted to the surface of a recording layer by press-bonding the layer to a heated mirror-finished surface and drying while the recording layer is in a wet state, wherein the pigment of the recording layer is γ -Alumina or a mixture of γ-alumina and silica having an average particle diameter of 100 to 500 nm mixed in a weight ratio of alumina: silica = 95: 5 to 50:50, and the polyvinyl of the recording layer Polyvinyl alcohol (a) having a saponification degree of 98 to 99 mol% with an alcohol polymerization degree of 1000 or less, and a saponification degree of 87 to 89 mol with a polymerization degree of 1500 or more. % Polyvinyl alcohol (b), and the treatment liquid is achieved by an ink jet recording medium containing borate and boric acid.

  The ink jet recording medium of the present invention has a glossiness similar to that of a silver salt photograph, has excellent scratch resistance on the surface of the recording layer, and can obtain a printed matter with excellent ink absorbability and high print density. High-quality ink jet recording can be realized.

  In the present invention, a support having air permeability can be appropriately selected and used, but it is particularly preferable to use paper (coated paper, uncoated paper, etc.). The raw material pulp of this paper includes chemical pulp (coniferous bleached or unbleached kraft pulp, hardwood bleached or unbleached kraft pulp, etc.), mechanical pulp (ground pulp, thermomechanical pulp, chemisermomechanical pulp, etc.), deinking Pulp or the like can be used alone or mixed at an arbitrary ratio. The pH of the paper may be acidic, neutral or alkaline. Moreover, it is preferable to improve the opacity of paper by containing a filler in the paper. 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 filler.

  The recording layer in the present invention contains a pigment and polyvinyl alcohol. As a binder, polyvinyl alcohol having a saponification degree of at most 1000 or less and a saponification degree of 98 to 99 mol%, and a saponification degree of 1500 or more and 87 to 87%. Specifically, mixed polyvinyl alcohol in which two components of 89 mol% polyvinyl alcohol are mixed at a weight ratio of 20:80 to 80:20, preferably 30:70 to 70:30 is used. As a result, not only a glossy feeling similar to a silver salt photograph can be obtained, but also the scratch resistance of the recording layer surface can be improved.

In the present invention, as described above, as a binder for the recording layer, polyvinyl alcohol (a) having a saponification degree of 1000 or less and a saponification degree of 98 to 99 mol%, and a saponification degree having a polymerization degree of 1500 or more and 87 to 89 mol% polyvinyl alcohol. A mixture in which (b) is mixed at a weight ratio of 20:80 to 80:20, more preferably 30:70 to 70:30 is used. When the ratio of the polyvinyl alcohol (b) is more than the above range, the scratching property is deteriorated, and when the ratio of the polyvinyl alcohol (a) is more than the above range, poor coagulation tends to occur during the coating operation.
Furthermore, when the degree of polymerization of the polyvinyl alcohol (a) exceeds 1000, the viscosity stability of the coating liquid deteriorates, and when the degree of polymerization of the polyvinyl alcohol (b) is less than 1500, there is a tendency to cause a coagulation failure during the coating operation. is there. If the degree of polymerization of the polyvinyl alcohol (b) is 2000 or more, a better solidified state can be maintained.

  In the present invention, together with the polyvinyl alcohol having the above specific polymerization degree and saponification degree, the saponified or partially saponified polyvinyl alcohol, carboxylic acid-modified polyvinyl alcohol, and silyl-modified polyvinyl alcohol are within the range not impairing the effects of the present invention. , Acetoacetyl group-modified polyvinyl alcohol, polyvinyl acetal resin, starches such as oxidized starch and esterified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, polyvinylpyrrolidone, casein, gelatin, soybean protein, styrene-acrylic resin and derivatives thereof , Styrene-butadiene latex, acrylic emulsion, vinyl acetate emulsion, vinyl chloride emulsion, urethane emulsion, urea emulsion, alkyd emulsion And it may be used in combination singly or a plurality of these derivatives.

  The blending amount of the binder is not particularly limited as long as the required recording layer strength is obtained, but it is preferably 5 to 30 parts by weight, and 20 parts by weight or less with respect to 100 parts by weight of the pigment. Is more preferable. When the blending amount of the binder is small, the strength of the recording layer is likely to be lowered, and when it is large, the ink absorbability is easily lowered. Further, since the gloss of white paper tends to be difficult to be produced when the blending amount of polyvinyl alcohol is small, the polyvinyl alcohol in the binder component of the recording layer is preferably 30% by weight or more, particularly 50% by weight or more. preferable.

The recording layer in the present invention contains a pigment and polyvinyl alcohol. As the pigment, γ-alumina or γ-alumina and silica having an average particle diameter of 100 to 500 nm are used in a weight ratio of alumina: silica = 95: 5. It is preferable to use a mixed pigment mixed in a ratio of ˜50: 50. This makes it possible to achieve quick ink absorbency and high print density for both dye ink and pigment ink.
Alumina is an oxide of aluminum obtained by firing aluminum hydroxide or the like. Many crystal forms of alumina are known, and examples thereof include α-alumina, β-alumina, and γ-alumina. In the present invention, γ-alumina is particularly preferably used from the viewpoint of improving scratch resistance.
The particle diameter and BET specific surface area of alumina can be appropriately selected as necessary, but it is preferable to use alumina having an average particle diameter of 1.0 to 4.0 μm, particularly 1.5 to 3.3 μm. What has a particle diameter is preferable.

  In the present invention, silica having an average particle diameter of 100 to 500 nm is used as silica mixed with γ-alumina. The average particle diameter of silica is preferably 120 to 450 nm, more preferably 200 to 400 nm. The average particle diameter of alumina and silica can be measured by a laser diffraction / scattering method.

  From the viewpoint of the stability of the recording layer coating liquid, it is preferable to use silica to which cationicity is imparted in the present invention. Usually, when silica is dispersed in water, an anionic slurry is formed. However, when silica having a cationic property is dispersed in water, the slurry becomes cationic. Such a slurry of cationic silica can be obtained by adding and redispersing a cationic substance in a silica dispersion.

When the average particle diameters of γ-alumina and silica are reduced, the glossiness of white paper is increased, while the ink absorbability tends to be reduced. Further, when these average particle sizes are increased, the ink absorbability is improved, but the glossiness of blank paper tends to be lowered.
In the present invention, as the pigment of the recording layer, as described above, a mixture in which γ-alumina and silica are mixed at a weight ratio of γ-alumina: silica = 95: 5 to 50:50 is used. If the ratio of γ-alumina is more than the above range, the ink absorbability is lowered. If the ratio of silica is more than the above range, the ink absorbability is improved, but the glossiness of blank paper is lowered and the print density of the recorded image is also lowered. It becomes a trend. A preferable mixing ratio in the present invention is γ-alumina: silica = 80: 20 to 60:40.
In addition, it is also possible to mix pigments other than γ-alumina and silica as long as the effects of the present invention are not impaired. Specific examples include aluminum hydroxide, kaolin, talc, calcium carbonate, titanium dioxide, clay, zinc oxide and the like, and these may be used alone or in combination.

  The recording layer in the present invention is treated with a treatment liquid having a function of coagulating polyvinyl alcohol (hereinafter also referred to as a coagulation liquid). Examples of the compound having a function of coagulating polyvinyl alcohol include boric acid and borates. When borate is used alone in the processing solution, the coagulation action of borate and polyvinyl alcohol in the recording layer is strong, so the wet recording layer is pressed against the heated mirror drum via a press roll. When it is dried, the glossy surface of the drum surface cannot be copied sufficiently, and it is difficult to obtain a good glossy surface.

  On the other hand, when boric acid is used alone in the processing liquid, the solidified recording layer may adhere to the processing liquid application roll because the coagulation action of polyvinyl alcohol and boric acid in the recording layer is not sufficient, It is difficult to obtain a recording layer in a good solidified state. Even if an attempt is made to strengthen the coagulation action of polyvinyl alcohol by increasing the concentration of boric acid in the treatment liquid, it is difficult to coagulate to a desired hardness due to the low solubility of boric acid.

  For the above reasons, in the present invention, a treatment liquid in which borate and boric acid are mixed is used rather than a treatment liquid containing borate or boric acid alone. By doing so, it becomes easy to adjust the solidified state of polyvinyl alcohol, and it becomes easy to obtain an ink jet recording medium having a good gloss.

  The mixing ratio of borate and boric acid in the treatment solution is preferably a borate / boric acid = 1/4 to 2/1 weight ratio after conversion to anhydride. If the blending ratio of borate and boric acid is less than 1/4, the proportion of boric acid is too high, so that the polyvinyl alcohol in the recording layer is not sufficiently solidified, and the softly solidified recording layer adheres to the treatment liquid application roll. In some cases, a recording layer in a good wet state cannot be obtained. On the other hand, when the mixing ratio of borate and boric acid exceeds 2/1, the polyvinyl alcohol in the recording layer is too hard and solidified, and the wet recording layer is pressed against the heated mirror drum via a press roll. When dried, the glossy surface on the drum surface cannot be copied sufficiently, and it may be difficult to obtain a good glossy surface.

  Examples of the borate used in the present invention include borax, orthoborate, diborate, metaborate, pentaborate, and octaborate. In addition, although borate is not specifically limited to these, From a viewpoint of cost, availability, etc., it is preferable to use borax. The concentration of borate and boric acid in the treatment liquid can be adjusted as needed, but the total concentration of borate and boric acid in the treatment liquid is in the range of 1 to 8% in terms of anhydride. Is preferred. If the concentration of borate and boric acid, especially the concentration of borate is too high, the solidification of polyvinyl alcohol becomes too strong, and the glossiness of blank paper tends to decrease. On the other hand, when the concentration is high, boric acid is likely to be precipitated in the treatment liquid, so that the stability of the treatment liquid is deteriorated.

  A release agent can be added to the recording layer coating liquid and the treatment liquid as necessary. The melting point of the release agent to be added is preferably 90 to 150 ° C, and particularly preferably 95 to 120 ° C. In the above range, since the melting point of the release agent is substantially equal to the metal surface temperature of the mirror finish, the ability as a release agent is maximized. The release agent is not particularly limited as long as it has the above characteristics.

  For the recording layer coating solution and processing solution used in the present invention, a pigment dispersant, a water retention agent, a thickening agent, an antifoaming agent, a preservative, a colorant, a water resistant agent, a wetting agent, a fluorescent agent are used as necessary. A dye, an ultraviolet absorber, a cationic polymer electrolyte, and the like can be appropriately added.

  In the present invention, the wet recording layer after applying the treatment liquid is pressed against a heated mirror-finished surface and dried to give gloss to the recording layer surface. The recording layer when applying the treatment liquid may be in a wet state or in a dry state, but in the former case (particularly in the case where the treatment liquid is applied while the recording layer is in a wet state), a mirror finish is applied. The surface can be easily copied, and the surface can be reduced in minute irregularities, so that it is easy to obtain glossiness equivalent to that of a silver salt photograph.

  As a method for providing a recording layer on a support, known coating machines such as blade coaters, air knife coaters, roll coaters, brush coaters, kiss coaters, squeeze coaters, curtain coaters, die coaters, bar coaters, gravure coaters, comma coaters, etc. What is necessary is just to select suitably from the methods using this. The method for applying the treatment liquid is not particularly limited as long as it can be applied to the recording layer, and can be appropriately selected from known methods (for example, a roll method, a spray method, a curtain method, etc.).

The coating amount of the recording layer can be arbitrarily adjusted within the range that covers the surface of the base paper and sufficient ink absorbency is obtained, but from the viewpoint of achieving both print density and ink absorbency, It is preferably 5 to 30 g / m ² in terms of minutes, and particularly preferably 10 to 25 g / m ² in consideration of productivity. If it exceeds 30 g / m ² , the peelability from the mirror drum is lowered, and there arises a problem that the coated recording layer adheres to the mirror drum. When a large coating amount is required, an undercoat layer may be provided between the support and the recording layer.

  EXAMPLES Hereinafter, although an Example and a comparative example further explain in detail this invention, this invention is not limited by these. Unless otherwise specified, “parts” and “%” described below represent “parts by weight” and “% by weight”, respectively.

Example 1.
Add 10 parts of talc, 1.0 part of aluminum sulfate, 0.1 part of synthetic sizing agent, and 0.02 part of yield improver to 100 parts of hardwood bleached kraft pulp (L-BKP) with a beating degree of 285 ml. A paper support was obtained by making paper from the pulp slurry thus obtained using a paper machine. On both sides of this support, starch is applied by a gate roll device so that the dry coating amount per side is 1.5 g / m ² , and at the same time, the following coating solution A is applied on one side by a blade method. as undercoat layer, dry coating amount by coating so that 7 g / m ^2, to obtain a base paper for ink jet recording medium having a basis weight of 190 g / m ^2.

  Coating liquid A: Synthetic silica (fine seal X-37: product name of Tokuyama Co., Ltd.) 100 parts SB latex (LX438C: product name of Sumitomo Chemical Co., Ltd.) 5 parts, polyvinyl alcohol (PVA117: Kuraray Co., Ltd.) 20 parts of a product name and 5 parts of a sizing agent (Polymalon 360: product name of Arakawa Chemical Industries, Ltd.) were blended to prepare a coating solution having a solid content concentration of 20%.

On the undercoat layer of the base paper obtained as described above, the following coating liquid B was applied with a roll coater so that the dry coating amount was 20 g / m ^2, and the recording layer was in a wet state. In the meantime, it is solidified using the following coagulation liquid C, and then pressed onto a mirror drum surface heated to 105 ° C. via a press roll for 20 seconds to copy the mirror surface to obtain a 210 g / m ² ink jet recording medium. It was.

Coating liquid B: 50 parts of high-purity alumina (UA5605: product name of Showa Denko KK, average particle size 2.8 μm) as pigment and high-purity alumina (AKP-G015: product name of Sumitomo Chemical Co., Ltd., average particle size) 2.2 parts) 50 parts, fully saponified polyvinyl alcohol (PVA105: product name of Kuraray Co., Ltd., polymerization degree 500, saponification degree 98.5) 4.5 parts, partially saponified polyvinyl alcohol (PVA224: Corporation) Kuraray product name, polymerization degree 2400, saponification degree 88.0) 8.5 parts, and 0.2 part of antifoaming agent were blended to prepare a coating solution having a solid content concentration of 28%.
Coagulation liquid C: Borax (anhydride equivalent) 1.5%, boric acid 3%, release agent (FL-48C: product name of Toho Chemical Industry Co., Ltd.) 0.2%, solid content concentration 4 A 7% coagulation solution was prepared.

Example 2
The compounding amount of the completely saponified polyvinyl alcohol used in the coating liquid B (PVA105: Kuraray Co., Ltd., product name: polymerization degree 500, saponification degree 98.5) 8.5 parts, partially saponified polyvinyl alcohol (PVA224: An ink jet recording medium was obtained in the same manner as in Example 1 except that the product name of Kuraray Co., Ltd., polymerization degree 2400, saponification degree 88.0) was 4.5 parts.

Example 3 FIG.
Instead of completely saponified polyvinyl alcohol (PVA105: product name of Kuraray Co., Ltd., polymerization degree 500, saponification degree 98.5) used in coating liquid B, completely saponified polyvinyl alcohol (PVA110: product of Kuraray Co., Ltd.) The ink jet recording medium was obtained in exactly the same manner as in Example 1 except that 8.5 parts of name, polymerization degree 1000, saponification degree 98.5) were blended.

Example 4
Instead of partially saponified polyvinyl alcohol (PVA224: product name of Kuraray Co., Ltd., polymerization degree 2400, average saponification degree 88.0) used in coating liquid B, partially saponified polyvinyl alcohol (PVA217: Kuraray Co., Ltd.) An ink jet recording medium was obtained in exactly the same manner as in Example 1 except that 8.5 parts of the product name, polymerization degree 1700, saponification degree 88.0) were blended.
Embodiment 5 FIG.
Instead of 50 parts of high-purity alumina (UA5605) and 50 parts of high-purity alumina (AKP-G015) as pigments used in coating liquid B, 75 parts of high-purity alumina (UA5605), silica (Silojet 703C: Grace Japan Co., Ltd.) An ink jet recording medium was obtained in exactly the same manner as in Example 1 except that 25 parts of the company's product name, average particle diameter 330 nm) were used.

Comparative Example 1
Inkjet recording medium exactly the same as Example 1 except that the amount of partially saponified polyvinyl alcohol (PVA-224) used in coating solution B was 13 parts and no completely saponified polyvinyl alcohol was blended. Got.

Comparative Example 2
Inkjet recording medium exactly as in Example 1, except that the amount of partially saponified polyvinyl alcohol (PVA-224) used in coating liquid B was 20 parts and no completely saponified polyvinyl alcohol was blended. Got.

Comparative Example 3
Instead of completely saponified polyvinyl alcohol (PVA-105) used in coating liquid B, except that 4.5 parts of acrylic / styrene resin emulsion (RAX-154: product name of Aika Industry Co., Ltd.) was blended, An ink jet recording medium was obtained in exactly the same manner as in Example 1.
Comparative Example 4
Implemented except that 4.5 parts of urethane resin emulsion (Superflex E-2000: Daiichi Kogyo Seiyaku Co., Ltd.) was blended in place of the completely saponified polyvinyl alcohol (PVA-105) used in coating liquid B An ink jet recording medium was obtained in exactly the same manner as in Example 1.

Comparative Example 5
Instead of the completely saponified polyvinyl alcohol (PVA-105) used in the coating liquid B, completely saponified polyvinyl alcohol (PVA117: product name of Kuraray Co., Ltd., polymerization degree 1700, saponification degree 98.5) 4.5 An ink jet recording medium was obtained in the same manner as in Example 1, except that the parts were blended.
Comparative Example 6
Instead of partially saponified polyvinyl alcohol (PVA-224) used in coating solution B, partially saponified polyvinyl alcohol (PVA210: product name of Kuraray Co., Ltd., polymerization degree 1000, saponification degree 88.0) 8.5 An ink jet recording medium was obtained in the same manner as in Example 1, except that the parts were blended.

  For the ink jet recording media obtained in Examples 1 to 5 and Comparative Examples 1 to 6, the ink jet recording test, blank paper glossiness, and recording layer strength were evaluated by the following methods. The results are summarized in Table 1. In addition, when the evaluation symbol in a table | surface is (double-circle), it can be used without a problem in particular.

(1) Inkjet recording test Predetermined solids and image patterns were recorded using the following two types of inkjet printers, and evaluated according to the following criteria.
Inkjet printer PM-800C: Seiko Epson Corporation product name (using dye ink)
a, Print Density The density of a solid pattern of black, cyan, magenta, and yellow was measured with a Macbeth densitometer (RD915, manufactured by Macbeth), and the total of the measured values was taken as the print density.
b. Ink absorbability (bleeding)
A pattern in which a solid image of red (mixed color of magenta and yellow) and green (mixed color of cyan and yellow) were adjacent was printed, and bleeding (bleed) at the boundary portion was visually evaluated according to the following criteria. The bleeding (bleed) at the boundary between red and green is black, and a stricter evaluation is possible.
◎: No bleeding at the boundary part ○: Little bleeding at the boundary part △: Slight bleeding at the boundary part X: Bleeding is noticeable at the boundary part

(2) Blank paper glossiness The 20-degree specular glossiness of the blank paper portion measured according to the method of JIS K7105 was defined as the blank paper glossiness. When the glossiness of the blank paper is 15% or more, the glossiness is equivalent to that of a silver salt photograph.

(3) Friction When 10 sheets of ink jet recording paper are set in an ink jet printer (MC-2000, product name of Seiko Epson Corporation) and printing is performed, the degree of scratches that can be formed on the second and subsequent edges is determined. Visually evaluated.
◎: No scratches are observed ○: Scratches are slightly observed Δ: Scratches are observed ×: Scratches are remarkably recognized

(4) Coating operability a. Coagulation property: The dirt of the coagulation liquid application roll when coated with a cast coater was visually evaluated.
◎: No contamination of the coagulation liquid application roll ○: Coagulation liquid transfer roll slightly transferred due to insufficient coagulation ×: Coagulation liquid application roll has many coating layers due to insufficient coagulation B. Viscosity stability ○: Even if the coating liquid is allowed to stand for 30 minutes or longer, it can be applied without any problem. X: If the coating liquid is left for 30 minutes or longer, gelation occurs and coating becomes impossible.

  As is clear from Table 1, the ink jet recording media of Examples 1 to 5 of the present invention have a good balance in terms of ink absorbability, print density, white paper glossiness, and coating operability, and have good scratching properties. It was proved that. On the other hand, in Comparative Example 1 in which completely saponified PVA is not contained in the recording layer, the scratching property is lowered. Further, in the case where only partially saponified PVA is blended, in Comparative Example 2 in which the blending amount of the binder is increased, the scratch resistance is improved, but the ink absorbability is deteriorated. Further, in Comparative Examples 3 and 4 in which a resin emulsion is blended in place of the completely saponified PVA, the scratching property is greatly reduced, and in any case, a printed matter with satisfactory quality cannot be obtained. Further, in Comparative Example 5 in which the degree of polymerization of fully saponified PVA is high, the viscosity stability of the coating liquid is deteriorated, and in Comparative Example 6 in which the degree of polymerization of partially saponified PVA is low, poor solidification occurs during the coating operation.

Claims (1)

A recording layer containing a pigment and polyvinyl alcohol is provided on a gas-permeable support, and after applying a treatment liquid having a function of coagulating polyvinyl alcohol on the recording layer, the recording layer is in a wet state. The inkjet recording medium is formed by applying pressure to a heated mirror-finished surface and drying to give gloss to the surface of the recording layer, wherein the pigment of the recording layer is γ-alumina or γ-alumina. It is any mixture in which silica having an average particle diameter of 100 to 500 nm is mixed in a weight ratio of alumina: silica = 95: 5 to 50:50, and the polyvinyl alcohol of the recording layer has a polymerization degree of 1000 or less. Polyvinyl alcohol (a) having a saponification degree of 98 to 99 mol% and polyvinyl alcohol having a saponification degree of 87 to 89 mol% having a polymerization degree of 1500 or more. An ink jet recording medium comprising the two components (b), wherein the treatment liquid contains borate and boric acid.