JP2003285545A - Ink jet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording medium which has a luster of a silver salt photograph and further, gives a high ink absorbability and a high scuffing resistance. <P>SOLUTION: A recording layer, which contains a pigment and a two component mixture comprising a polyvinyl alcohol (a) having a polymerization degree of 1,000 or lower and a saponification degree of from 98 to 99 mol% and a polyvinyl alcohol (b) having a polymerization degree of 1,500 or higher and a saponification degree of from 87 to 89 mol%, is laid on an air permeable base. A processing liquid which coagulates polyvinyl alcohol is coated on the recording layer and while the layer is still in wet state, it is pressed and dried on a heated mirror finished surface so as to provide a luster on the surface of the recording layer. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording medium suitable for recording using a dye ink and a pigment ink, and in particular, it has a glossy feeling comparable to that of a silver salt photograph and can have a high scratch resistance. The present invention relates to an inkjet recording medium.

[0002]

2. Description of the Related Art The ink jet recording system is one in which a small amount of ink is ejected by various mechanisms and is deposited on a recording paper to form dots for recording, which is different from the dot impact type recording system. There are advantages such as no noise, easy full-color printing, and high-speed printing. On the other hand, since the ink used for ink jet recording is usually a water-based ink using a direct dye, an acid dye, etc., it has a drawback of poor drying property.

The characteristics required for the ink jet recording paper used in such an ink jet recording system are that the ink drying speed is high, the printing density is high, the ink does not overflow or bleed, and the ink is The fact that the paper does not wavy due to the absorption of A method for producing a high-quality inkjet recording paper satisfying these characteristics by a cast coating method has already been proposed (Japanese Patent Laid-Open Nos. 62-95285 and 63-63).
264391, JP-A-2-274587, 5-5
No. 9694, etc.).

In any of these manufacturing methods, a recording layer comprising a pigment containing synthetic silica as a main component and a binder is pressure-bonded to a mirror-finished surface which is heated while it is still wet and wet. Although the mirror surface was copied and dried at the same time to obtain a high-gloss cast coated paper, the glossiness of the outermost layer was low, and it was far from the glossiness equivalent to that of silver salt photographs. 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 with a white pigment added on at least one surface of a base paper. There has been proposed a silver salt photographic ink jet recording sheet provided with a sheet (Japanese Patent Laid-Open No. 10-119423, Japanese Patent Laid-Open No. 11-20306, etc.). However, in the case of these inkjet recording papers, since resin-coated paper having no air permeability is used as a support, it takes a long time to dry after applying the recording layer, and there is a drawback that productivity is extremely low. .

As a result of various studies on the ink jet recording medium having a glossy feeling similar to that of a silver salt photograph, the present inventors provided a recording layer containing polyvinyl alcohol on the surface of the base paper and then solidified the recording layer with polyvinyl alcohol. An ink jet recording medium having a glossy feeling similar to that of a silver salt photograph by being treated with a treating liquid having a function of causing the recording layer to be dried and then brought into pressure contact with a heated mirror-finished surface while the recording layer is wet. You have already found that you can. However, in this case, when printing with an ink jet printer, paper and paper are rubbed with each other, and fine scratches are easily formed on the surface of the recording layer, which is a problem.

[0006]

Therefore, the present inventors
As a result of various studies to obtain an inkjet recording medium having a glossiness comparable to that of a silver salt photograph and having a sufficiently high scratch resistance in the recording layer, it was confirmed that the polyvinyl alcohol in the recording layer containing polyvinyl alcohol and a pigment was used. hand,
It has been found that good results can be obtained by including a mixture of two polyvinyl alcohols having a specific degree of polymerization and degree of saponification, and has reached the present invention. Therefore,
The object of the present invention is to have a glossy feeling comparable to that of a silver salt photograph,
An object of the present invention is to provide an inkjet recording medium which can obtain particularly high ink absorbency and scratch resistance of a recording layer.

[0007]

The above object of the present invention is to provide a recording layer containing a pigment and polyvinyl alcohol on a gas-permeable support, and to treat the polyvinyl alcohol on the recording layer. An ink jet recording medium comprising a recording layer having gloss applied to a recording layer surface by applying a liquid and then pressing the layer onto a heated mirror-finished surface while the recording layer is in a wet state and drying the layer. Polyvinyl alcohol having a degree of saponification of at least 1000 or less and a degree of saponification of 98 to 99 mol%,
A saponification degree of 1500 or more was achieved by an ink jet recording medium characterized by containing two components of 87 to 89 mol% polyvinyl alcohol. further,
The recording layer pigment is alumina (A) and the average particle size is 100 to
The weight ratio of silica (B) having a thickness of 500 nm is A: B = (9
When the mixture is a mixture of 5: 5) to (50:50), the scratch resistance of the recording layer is further improved. Further, the above-mentioned silica (B) is preferably silica having a cationic property, and the alumina (A) is preferably γ-alumina.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a support having air permeability can be appropriately selected and used, but paper (coated paper, uncoated paper, etc.) is particularly preferably used. The raw material pulp of this paper includes chemical pulp (bleached or unbleached kraft pulp of softwood, bleached or unbleached kraft pulp of hardwood), mechanical pulp (ground pulp, thermomechanical pulp, chemithermomechanical pulp, etc.), deinking Pulp and the like can be used alone or mixed at an arbitrary ratio. The pH of the paper may be acidic, neutral or alkaline. Further, it is preferable to improve the opacity of the paper by including a filler in the paper. The filler is hydrated silicic acid, white carbon, talc, kaolin, clay, calcium carbonate, titanium oxide,
It can be appropriately selected and used from known fillers such as synthetic resin fillers.

The recording layer in the present invention contains a pigment and polyvinyl alcohol, and the binder has a saponification degree of at least 1000 or less and a degree of saponification of 98 to 99 mol%.
Of polyvinyl alcohol and polyvinyl alcohol having a degree of polymerization of 1500 or more and a saponification degree of 87 to 89 mol% are specifically included in a weight ratio of 20:80 to 80:20, preferably 30:70 to 70:30. Mixed polyvinyl alcohol mixed in proportion is used. As a result, not only a gloss feeling close to that of a silver salt photograph can be obtained, but also the scratch resistance of the recording layer surface can be improved.

In the present invention, the binder for the recording layer has a saponification degree of 9 or less and a polymerization degree of 1000 or less as described above.
Polyvinyl alcohol (a) of 8 to 99 mol% and polyvinyl alcohol (b) having a degree of saponification of 87 or more and a polymerization degree of 1500 or more are 87:89 mol% in a weight ratio of 20:80 to 80: 2.
A mixture of 0, more preferably 30:70 to 70:30 is used. If the proportion of polyvinyl alcohol (b) is more than the above range, scratch resistance is deteriorated, and if the proportion of polyvinyl alcohol (a) is more than the above range, poor coagulation tends to occur during coating operation. Further, when the polymerization degree of polyvinyl alcohol (a) exceeds 1000, the viscosity stability of the coating liquid deteriorates, and when the polymerization degree of polyvinyl alcohol (b) is less than 1500, poor coagulation tends to occur during coating operation. is there. When the polymerization degree of polyvinyl alcohol (b) is 2000 or more, a better coagulated state can be maintained.

In the present invention, together with polyvinyl alcohol having the above-mentioned specific degree of polymerization and degree of saponification, completely saponified or partially saponified polyvinyl alcohol, carboxylic acid-modified polyvinyl alcohol, and silyl are used as long as the effects of the present invention are not impaired. Modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, polyvinyl acetal resin, starches such as oxidized starch and esterified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, polyvinylpyrrolidone, casein, gelatin, soybean protein, styrene-acrylic resin And its derivatives, styrene-butadiene latex, acrylic emulsion, vinyl acetate emulsion, vinyl chloride emulsion, urethane emulsion, urea emulsion, alkyl Emulsions and derivatives of these may be used in combination alone or plural.

The binder content is not particularly limited as long as the required recording layer strength can be obtained.
It is preferably 5 to 30 parts by weight, more preferably 20 parts by weight or less, relative to 0 parts by weight. If the blending amount of the binder is small, the strength of the recording layer tends to decrease, and if the blending amount is large, the ink absorbency tends to decrease. Further, when the blending amount of polyvinyl alcohol is small, white paper gloss tends to be difficult to appear. Therefore, the polyvinyl alcohol content in the binder component of the recording layer is preferably 30% by weight or more, and particularly preferably 50% by weight or more. preferable.

The recording layer in the present invention contains a pigment and polyvinyl alcohol, and as the pigment, alumina (A) and silica (B) having an average particle diameter of 100 to 500 nm are used in a weight ratio of A: B = ( 95: 5) to (50: 5)
The mixed pigment mixed in the ratio of 0) is used. This makes it possible to achieve rapid ink absorption and high print density for both dye ink and pigment ink. The alumina is an aluminum oxide 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, in terms of improving scratch resistance,
In particular, γ-alumina is preferably used. 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, and particularly an average of 1.5 to 3.3 μm. Those having a particle size are preferable.

In the present invention, silica having an average particle diameter of 100 to 500 nm is used as silica mixed with alumina. The preferable average particle diameter of silica is 120 to 45.
It is 0 nm, more preferably 200 to 400 nm. The average particle size of alumina and silica can be measured by a laser diffraction / scattering method.

From the viewpoint of stability of the coating liquid for the recording layer,
In the present invention, it is preferable to use silica having a cationic property. When silica is usually dispersed in water, it becomes an anionic slurry, but when silica having a cationic property is dispersed in water, the slurry becomes cationic. Such a cationic silica slurry can be obtained by adding a cationic substance to a silica dispersion and redispersing it.

When the average particle size of alumina and silica is small, the glossiness of white paper is high, but the ink absorbency tends to be low. Further, when the average particle size of these is large, the ink absorbency is improved, but the glossiness of the white paper tends to be lowered. In the present invention, as the pigment of the recording layer, a mixture in which alumina (A) and silica (B) are mixed at a weight ratio of A: B = (95: 5) to (50:50) as described above is used. . If the ratio of alumina is more than the above range, the ink absorbency is reduced, and if the ratio of silica is more than the above range, the ink absorbency is improved, but the glossiness of the white paper is decreased and the print density of the recorded image is also decreased. Become.
In the present invention, the preferable mixing ratio is alumina (A): silica (B) = (80:20) to (60:40).
It is also possible to mix pigments other than alumina and silica within the range that does not impair the effects of the present invention. Specific examples include aluminum hydroxide, kaolin, talc,
Calcium carbonate, titanium dioxide, clay, zinc oxide and the like can be mentioned, 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 coagulating liquid). Examples of the compound having a function of coagulating polyvinyl alcohol include boric acid and borate. When borate is used alone in the treatment liquid, the borate and polyvinyl alcohol in the recording layer have a strong coagulation action, so the wet recording layer is pressed onto the heated mirror drum via a press roll. When it is dried, the glossy surface of the drum surface cannot be sufficiently copied, and it is difficult to obtain a good glossy surface.

On the other hand, when boric acid is used alone in the treatment liquid, the coagulation action of polyvinyl alcohol and boric acid in the recording layer is not sufficient, so that the softening solidification recording layer adheres to the treatment liquid application roll. Therefore, it is difficult to obtain a recording layer in a good solidified state. Even if an attempt is made to increase the coagulation action of polyvinyl alcohol by increasing the concentration of boric acid in the treatment liquid, it is difficult to coagulate it to a desired hardness due to the low solubility of boric acid.

For the above reason, in the present invention, it is preferable to use a treatment liquid obtained by mixing borate and boric acid, rather than using a treatment liquid containing borate or boric acid alone. By doing so, the coagulated state of polyvinyl alcohol can be easily adjusted, and thus it becomes easy to obtain an inkjet recording medium having a good gloss feeling.

The mixing ratio of borate and boric acid in the treatment liquid is
In terms of weight ratio after conversion to anhydride, borate / boric acid = 1/4 to
It is preferably between 2/1. If the mixing ratio of borate and boric acid is less than 1/4, the proportion of boric acid becomes too large, so that the coagulation of polyvinyl alcohol in the recording layer becomes insufficient, and the soft-coagulated recording layer adheres to the treatment liquid application roll. However, it may not be possible to obtain a recording layer in a good wet state. On the other hand, when the compounding ratio of borate and boric acid exceeds 2/1, the polyvinyl alcohol in the recording layer is too hard and coagulates, and the heated recording layer is pressed against the heated mirror drum via the press roll. When dried by drying, the glossy surface of the drum surface cannot be sufficiently copied, 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.
The borate is not particularly limited to these, but it is preferable to use borax from the viewpoint of cost, availability and the like. The concentrations of borate and boric acid in the treatment liquid can be appropriately adjusted as necessary, but the total concentration of borate and boric acid in the treatment liquid is 1 to 8 in terms of anhydride.
It is preferably in the range of%. If the concentration of borate and boric acid, especially the concentration of borate is too high, the coagulation of polyvinyl alcohol becomes too strong, and the glossiness of white paper tends to decrease. Further, 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.

If desired, a release agent can be added to the coating liquid for the recording layer and the treatment liquid. The melting point of the releasing agent to be added is preferably 90 to 150 ° C., and particularly 95
It is preferably ˜120 ° C. In the above range, the melting point of the release agent is almost the same as the metal surface temperature of the mirror-finished surface, so that the ability of the release agent is maximized. The release agent is not particularly limited as long as it has the above characteristics.

If necessary, the coating liquid and the treating liquid for the recording layer used in the present invention include a pigment dispersant, a water retention agent, a thickener, an antifoaming agent, an antiseptic agent, a colorant, a water resistant agent, and a wetting agent. Agent, fluorescent dye,
An ultraviolet absorber, a cationic polymer electrolyte, etc. can be added as appropriate.

In the present invention, the recording layer in a wet state after being coated with the treatment liquid is pressed onto a heated mirror-finished surface and dried to impart gloss to the surface of the recording layer. The recording layer when applying the treatment liquid may be in a wet state or a dry state, but in the former case (the treatment liquid is applied while the recording layer is in a wet state), a mirror finish is applied. It is easy to copy the surface and it is possible to reduce the minute irregularities on the surface, so it is easy to obtain the glossy feeling equivalent to silver salt photography.

The method for providing the recording layer on the support is as follows:
A blade coater, an air knife coater, a roll coater, a brush coater, a kiss coater, a squeeze coater, a curtain coater, a die coater, a bar coater, a gravure coater, a comma coater, etc. may be appropriately selected from among methods using a known coating machine. . The method of applying the treatment liquid is not particularly limited as long as it can be applied to the recording layer, and can be appropriately selected and used from known methods (for example, roll method, spray method, curtain method, etc.).

The coating amount of the recording layer can be arbitrarily adjusted within a range that covers the surface of the base paper and obtains sufficient ink absorbency, but from the viewpoint of achieving both print density and ink absorbency, one side Per 5 to 30 g / m in terms of solid content
² is preferable, and 10 to 2 when productivity is taken into consideration.
It is particularly preferably 5 g / m ² . When it exceeds 30 g / m ² , the releasability from the specular drum is deteriorated, which causes a problem that the coated recording layer adheres to the specular drum. If a large coating amount is required, an undercoat layer may be provided between the support and the recording layer.

[0027]

INDUSTRIAL APPLICABILITY The ink jet recording medium of the present invention has a glossy feeling comparable to that of a silver salt photograph, has excellent scratch resistance on the surface of the recording layer, and gives a printed matter having excellent ink absorption and high printing density. It is possible to realize high quality ink jet recording.

[0028]

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Unless otherwise specified, "parts" and "%" described below represent "parts by weight" and "% by weight", respectively.

Example 1. 10 parts of talc, 1.0 part of aluminum sulfate, 0.1 part of synthetic sizing agent, and 0.02 part of retention aid were added to a pulp consisting of 100 parts of hardwood bleached kraft pulp (L-BKP) with a beating degree of 285 ml. The pulp slurry was used to make a paper using a paper machine to obtain a support. Both sides of this support were coated with starch by a gate roll device so that the dry coating amount per one side would be 1.5 g / m ² , and at the same time, one side was coated with the coating solution A described below by a blade system. As an undercoat layer to a dry coating amount of 7 g / m ² and a basis weight of 190 g / m 2.
^A base paper for inkjet recording medium No. 2 was obtained.

Coating liquid A: Synthetic silica (Fineseal X
-37: 5 parts of SB latex (LX438C: product name of Sumitomo Chemical Co., Ltd.), 100 parts of Tokuyama Co., Ltd. product name, 20 parts of polyvinyl alcohol (PVA117: Kuraray Co., Ltd. product name), and sizing agent (Polymaron) 360: Arakawa Chemical Co., Ltd. product name) was mixed to prepare a coating liquid 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 in a dry coating amount of 20.
The surface of the mirror-finished drum was coated with a roll coater so that the recording layer became g / m ^2, and while the recording layer was in a wet state, solidified with the following solidification liquid C, and then heated to 105 ° C. through a press roll. Press for 20 seconds and copy the mirror surface, 2
An inkjet recording medium of 10 g / m ² was obtained.

Coating liquid B: High purity alumina (U
A5605: Showa Denko KK product name, average particle size 2.8 μm, 50 parts and high-purity alumina (AKP-G01)
5: Product name of Sumitomo Chemical Co., Ltd., average particle size 2.2μ
m) 50 parts, completely 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: Kuraray Co., Ltd.) Product name, degree of polymerization 2400, degree of saponification 88.0) 8.5
Part, and 0.2 parts of antifoaming agent, and solid concentration 28%
A coating solution of was prepared. Coagulating liquid C: Borax (anhydrous equivalent) 1.5% and boric acid 3
%, And 0.2% of a stripping agent (FL-48C: product name of Toho Chemical Industry Co., Ltd.) were mixed to prepare a coagulation liquid having a solid content concentration of 4.7%.

Example 2. The blending amount of the completely saponified polyvinyl alcohol used in the coating liquid B was calculated as (PVA105: product name of Kuraray Co., Ltd., polymerization degree 500, saponification degree 98.
5) 8.5 parts, partially saponified polyvinyl alcohol (PV
A224: Product name of Kuraray Co., Ltd., degree of polymerization 2400,
An inkjet recording medium was obtained in the same manner as in Example 1 except that the saponification degree was 88.0) and was 4.5 parts.

Example 3. Instead of the completely saponified polyvinyl alcohol (PVA105: product name of Kuraray Co., Ltd., polymerization degree 500, saponification degree 98.5) used in the coating liquid B, a completely saponified polyvinyl alcohol (PVA110:
Product name of Kuraray Co., Ltd., polymerization degree 1000, saponification degree 9
An inkjet recording medium was obtained in exactly the same manner as in Example 1 except that 8.5 parts of 8.5) were blended.

Example 4. Instead of the 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 (PVA2
17: An inkjet recording medium was obtained in exactly the same manner as in Example 1 except that 8.5 parts of Kuraray Co., Ltd. product name, polymerization degree 1700, saponification degree 88.0) were blended. Example 5. As the pigment used in the coating liquid B, 50 parts of high-purity alumina (UA5605), high-purity alumina (AKP-
G015) Instead of 50 parts, high-purity alumina (UA5
605) 75 parts, silica (Silojet 703C: product name of Grace Japan Co., Ltd., average particle size 330 n)
m) An inkjet recording medium was obtained in exactly the same manner as in Example 1 except that 25 parts were used.

Comparative Example 1. The compounding amount of the partially saponified polyvinyl alcohol (PVA-224) used in the coating liquid B is 1
An ink jet recording medium was obtained in exactly the same manner as in Example 1 except that the amount was 3 parts and the completely saponified polyvinyl alcohol was not added.

Comparative Example 2. The compounding amount of the partially saponified polyvinyl alcohol (PVA-224) used in the coating liquid B is 2
An ink jet recording medium was obtained in exactly the same manner as in Example 1 except that the amount was 0 part and the completely saponified polyvinyl alcohol was not added.

Comparative Example 3. Instead of the completely saponified polyvinyl alcohol (PVA-105) used in the coating liquid B,
Acrylic / styrene resin emulsion (RAX-15
4: An ink jet recording medium was obtained in exactly the same manner as in Example 1 except that 4.5 parts of Aika Kogyo Co., Ltd.) was added. Comparative Example 4. Except that 4.5 parts of a 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 the coating liquid B. An inkjet 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) An inkjet recording medium was obtained in exactly the same manner as in Example 1 except that 4.5 parts were blended. Comparative Example 6. Instead of the partially saponified polyvinyl alcohol (PVA-224) used in the coating liquid B, the partially saponified polyvinyl alcohol (PVA210: product name of Kuraray Co., Ltd., polymerization degree 1000, saponification degree 88.0) 8.5 An inkjet recording medium was obtained in exactly the same manner as in Example 1 except that parts were mixed.

With respect to the ink jet recording media obtained in Examples 1 to 5 and Comparative Examples 1 to 6, the ink jet recording test, the white paper glossiness, and the recording layer strength were evaluated by the following methods. The results are summarized in Table 1. When the evaluation symbols in the table are ⊚ to ∘, it can be used without any particular problem.

(1) Inkjet recording test Using the following two types of inkjet printers, predetermined solid and image patterns were recorded 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 solid patterns of black, cyan, magenta, and yellow can be measured with a Macbeth densitometer (RD915, Macbet).
(manufactured by company h), and the total of the measured values was used as the print density. b. Ink absorbency (bleeding) A pattern in which solid images of red (a mixture of magenta and yellow) and green (a mixture of cyan and yellow) are adjacent to each other is printed, and bleeding at the boundary is visually observed according to the following criteria. It was evaluated by. Bleed at the boundary between red and green becomes black, which allows more rigorous evaluation. ⊚: No bleeding is observed at the boundary ◯: Almost no bleeding is observed at the boundary Δ: Some bleeding is observed at the boundary ×: Significant bleeding is observed at the boundary

(2) White paper glossiness The 20-degree specular glossiness of the white paper portion measured according to the method of JIS K7105 was defined as the white paper glossiness. When the glossiness of the white paper is 15% or more, it has a glossiness comparable to that of silver salt photographs.

(3) When 10 sheets of inkjet recording paper are set on a scratch-type inkjet printer (MC-2000, trade name of Seiko Epson Co., Ltd.) and printing is performed, scratches are formed on the edges of the second and subsequent sheets. Was visually evaluated. ⊚: No scratches are observed ○: Scratches are slightly observed Δ: Scratches are recognized ×: Scratches are significantly recognized

(4) Coating operability a. Coagulation property: When coating with a cast coater, the contamination of the coagulation liquid application roll was visually evaluated. ⊚: No stain on the coagulation liquid application roll ○: Slight transfer of the coating layer to the coagulation liquid application roll due to insufficient coagulation ×: Many coating layers on the coagulation liquid application roll due to insufficient coagulation Transferred b. Viscosity stability ○: Can be applied without problems even if the coating solution is left for 30 minutes or longer. ×: Gelation occurs if the coating solution is left for 30 minutes or more, and coating becomes impossible.

[0045]

[Table 1]

As is clear from Table 1, in the ink jet recording media of the present invention of Examples 1 to 5, ink absorbency,
It was proved that the print density, the glossiness of the white paper, and the coating operability were well balanced and the scratchability was also good. On the other hand, in Comparative Example 1 in which the completely saponified PVA is not contained in the recording layer, the scratch resistance is reduced. In addition, partially saponified PVA
In the case of blending only, in Comparative Example 2 in which the blending amount of the binder is increased, the rubbing property is improved, but the ink absorbency is deteriorated. Further, in Comparative Examples 3 and 4 in which the resin emulsion was blended instead of the completely saponified PVA, the scratching property was significantly reduced, and in any case, it was not possible to obtain a printed matter of satisfactory quality. In addition, completely saponified PVA
In Comparative Example 5 in which the degree of polymerization is high, the viscosity stability of the coating liquid deteriorates, and in Comparative Example 6 in which the degree of polymerization of partially saponified PVA is low,
Poor solidification occurs during coating operation.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoichi Endo             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Industries             Product Research Institute Co., Ltd. (72) Inventor Jiro Yoshimura             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Industries             Product Research Institute Co., Ltd. F-term (reference) 2C056 EA04 EA13 FC06                 2H086 BA01 BA15 BA17 BA21 BA33                       BA35 BA37 BA41 BA45

Claims (4)

[Claims] 1. A recording layer containing a pigment and polyvinyl alcohol is provided on a support having air permeability, and the recording layer is coated with a treatment liquid having a function of coagulating polyvinyl alcohol. An inkjet recording medium in which the recording layer surface is glossy by applying pressure to the heated mirror-finished surface while being in a wet state and drying the layer, wherein the polyvinyl alcohol has a polymerization degree of at least 1000 or less. An inkjet recording medium containing two components, a polyvinyl alcohol (a) having a saponification degree of 98 to 99 mol% and a polyvinyl alcohol (b) having a polymerization degree of 1500 or more and a saponification degree of 87 to 89 mol%. 2. The pigment of the recording layer comprises alumina (A) and silica (B) having an average particle diameter of 100 to 500 nm in a weight ratio of A: B = (95: 5) to (50:50). The inkjet recording medium according to claim 1, which is a mixed mixture. 3. The ink jet recording medium according to claim 1 or 2, wherein the silica (B) is a silica having a cationic property. 4. The ink jet recording medium according to claim 1, wherein the alumina (A) is γ-alumina.