JP2002166645A - Glossy paper for ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium which shows an improved image quality, especially an upgraded image density when printed, an improved dot roughness and the better uniformity of a feeling of gloss on the surface of an ink receiving layer, and also has an image quality and a feeling of uniform gloss equivalent to a medium manufactured of a photographic paper base material or a film base material, in a glossy paper for ink jet recording by a casting process. SOLUTION: This glossy paper for ink jet recording is a cast coated paper with a highly glossy coating layer formed on one or both faces of a base material. The coating layer contains a pigment and an adhesive, with a coagulating agent which coagulates with the adhesive, contained in the surface of the coating layer. The adhesive contains either of a polyvinyl alcohol or a polyvinyl acetal or both and the coagulating agent contains a boron compound, a colloidal silica and a resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glossy paper for ink-jet recording, and more particularly to a recording paper having a high print surface and a high print quality close to photographic quality.

[0002]

2. Description of the Related Art An ink jet recording system is a system in which dots are formed by discharging ink droplets and attaching them to recording paper. 2. Description of the Related Art In recent years, high-quality recording has become possible due to technological advances in ink jet printers, inks, and recording media.

[0003] Factors required for an ink jet recording medium include that ink is absorbed and dried quickly, that print density is high, that there is no spread of dots and that no whisker-like bleeding occurs. If ordinary plain paper has a certain size or more, bleeding can be reduced and some printing quality can be expected.

On the other hand, when higher print quality is required, a dedicated medium having an ink receiving layer suitable for ink of an ink jet printer on a medium is used on a medium. As such a medium dedicated to ink jet recording, a medium in which paper or a film is used as a support and a pigment coating layer mainly containing a pigment and a binder or a resin coating layer containing no pigment is provided on the surface is often used.

[0005] Ink-jet-only media are further classified into matte media and gloss media according to the surface condition. When an image quality closer to silver halide photography is required, the latter glossy medium is used. The characteristics required for these glossy media include, in addition to the above-mentioned characteristics, high dot roundness, good image reproducibility, good water resistance and light fastness, image area, and glossiness of white paper. The feeling is high.

Various methods have been proposed as a method for producing a glossy medium in order to maintain the characteristics (1) to (3) while maintaining the ink absorbency and drying property, but a general method is to cast the ink receiving layer by a casting method. A method of forming and giving a gloss to the surface and a method of forming an ink receiving layer on a photographic paper base material. In general, the former is easier to control the ink absorbency than the latter, but is inferior to the latter in terms of dot roundness, image reproducibility, image area, glossiness of blank portion, and quality. The base material for photographic paper is generally RC paper (resin-coated paper)
As it is said, when a polyethylene film layer is formed on a paper base and an ink receiving layer is formed on the surface thereof, the surface of the ink receiving layer is smooth and glossy because the film surface is smooth. A certain surface is easy to form. However, it is necessary to increase the amount of coating in order to increase the ink absorbency, and since the base material itself is more expensive than paper, the overall cost is higher than that of the former gloss method using the cast method. In addition, there is a problem that recycling is not possible due to the composite material when discarded.

[0007] Glossy paper for ink jet recording by the casting method is advantageous in this respect, but has the above-mentioned problems in quality, and various proposals have been made to solve these problems. JP-A-6-72017 discloses an ink jet recording paper having a high surface smoothness and an excellent quality of image quality by defining the average roughness, glossiness and air permeability of the recording layer surface. There is a proposal. Japanese Patent Application Laid-Open No. 11-348416 proposes that an ink jet recording paper having excellent glossiness and ink receptivity can be obtained by defining the size and number of cracks on the recording layer surface. If the number is too small, there is also a problem that the glossiness increases while the ink absorbency decreases. In any case, at present, there is no recording medium that has an image quality and uniform glossiness that exceed those of media manufactured using photographic paper base or film base in glossy paper for inkjet recording manufactured by the casting method. is there.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a glossy paper for ink-jet recording by a casting method, which is a problem of the above-mentioned prior art. Improves roundness and uniformity of glossiness on the surface of the ink receiving layer to provide recording media with image quality and uniform glossiness comparable to media manufactured using photographic paper or film substrates It is to be. The present inventors have set out to solve these problems.
Focusing on the important coagulation treatment when determining the surface condition of glossy paper for inkjet recording when manufacturing by casting method,
It has been found that there is a close relationship between the improvement of the coagulant and the image density, the improvement of dot roundness, and the uniformity of glossiness on the surface of the ink receiving layer.

A second object of the present invention is to provide a glossy paper for ink-jet recording having higher ink absorbability by using non-spherical colloidal silica as colloidal silica.

[0010] A third object of the present invention is to use borax as a boron compound to sufficiently coagulate and form a crack-free surface, to provide uniform glossiness, roundness of a pet, and image clarity. Is to provide a glossy paper for ink jet recording in which is further improved.

A fourth object of the present invention is to select one or more resins from starch, casein, cellulose derivatives, acryl, polyurethane, polyester, vinyl acetate, ethylene-vinyl acetate, and styrene-butadiene copolymer. It is an object of the present invention to provide a glossy paper for ink-jet recording, which is capable of preventing colloidal silica from falling off, having ink absorbency and glossiness.

A fifth object of the present invention is to reduce the number of cracks in the ink receiving layer by adding alumina as a pigment or silica having an average particle diameter of 1 μm or less as a pigment to thereby minimize the gloss. The object of the present invention is to provide a glossy paper for ink jet recording which ensures the ink absorption rate and has an appropriate ink absorption speed.

A sixth object of the present invention is to use paper as a base material, so that the production cost is lower than that of a photographic paper base material having a film layer. It is to do.

[0014]

[Means for Solving the Problems]

The glossy paper for ink jet recording of the present invention comprises:
A coating layer formed on one or both sides of a base material is a cast coated paper having a high gloss, the coating layer contains a pigment and an adhesive, and solidifies with the adhesive on the surface of the coating layer. The obtained coagulant is contained, the adhesive contains both or one of polyvinyl alcohol and polyvinyl acetal, and the coagulant contains a boron compound, colloidal silica and a resin.

In the glossy paper for ink jet recording of the present invention, the colloidal silica is preferably non-spherical colloidal silica.

Further, in the glossy paper for ink jet recording of the present invention, the boron compound is preferably borax.

In the glossy paper for ink jet recording of the present invention, the resin is selected from one or more of starch, casein, cellulose derivative, acrylic, polyurethane, polyester, vinyl acetate, ethylene-vinyl acetate, and styrene-butadiene copolymer. It is preferable that they are combined.

In the glossy paper for ink jet recording of the present invention, the pigment preferably contains alumina.

In the glossy paper for ink jet recording of the present invention, the pigment preferably contains silica having an average particle diameter of 1 μm or less.

Further, in the glossy paper for ink jet recording of the present invention, the substrate is preferably paper.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. In the present invention, for example, after applying a coating liquid having a pigment and a binder, the coated surface is subjected to a solidifying treatment using a coagulant, and the coated layer is heated to a mirror finish while the coated surface is in a wet state. To produce cast-coated paper. At this time, in the present invention, a boron compound, colloidal silica and a resin are essential components as a coagulant. In the present invention, the coagulation treatment has a large effect on the surface condition of the cast-coated paper. If the solidification is insufficient, cracks will be formed on the surface of the coating layer when moisture is evaporated by pressing against a heated mirror-finished metal surface. Due to the occurrence of the cracks, uniformity of glossiness and roundness of dots are impaired. As a result, the printed image becomes unclear and degrades the quality.

On the other hand, if the solidification is sufficient, cracks on the surface of the coating layer are extremely reduced, and a surface having no or almost no cracks can be formed. By forming such a surface, it is possible to obtain a clear printed image with good glossiness uniformity and good roundness of the pet.

In the coagulation treatment, it is important to select a material that effectively coagulates with the binder component of the coating layer.
Since the coating liquid contains polyvinyl alcohol and / or polyvinyl acetal as a binder, a boron compound is preferable as a substance that effectively coagulates with the binder. As the boron compound, which is one of the essential components of the coagulant, orthoboric acid, metaboric acid, borate and the like can be used. Specifically, H ₃ BO ₃ , NaBO ₂ .4H ₂ O, K
_{2 B 4 O 7 · 5H 2} O, KBO 2, NH 4 B 4 O 9 · 3H 2 0, NH 4 BO 2, Na 2 B 4 O 7 · 10
_{H 2 0, Ca 2 B 6} O 11 · 7H 2 0 and the like can be exemplified.

In the coagulation treatment, it is preferable that the concentration of the coagulant is as high as possible from the viewpoint of effective coagulation treatment. Among them, sodium tetraborate (borax) is capable of obtaining an aqueous solution having a high concentration. This is the most preferred boron compound because the coagulation treatment can be performed effectively. Although not particularly limited, it is particularly preferable that the concentration of the aqueous solution is 2% or more in the coagulation treatment.

Further, it contains colloidal silica as an essential component as a coagulant. Colloidal silica is classified into an alkaline type and an acidic type, and both types can be used. However, it is necessary to use different types depending on the pH of an aqueous solution of a boron compound.

When borax is used as the boron compound,
Since the pH of the borax aqueous solution is 9 to 9.5, it is preferable to use alkaline type colloidal silica. As the particle shape of the colloidal silica, spherical colloidal silica and non-spherical colloidal silica can be used. The non-spherical colloidal silica is a colloidal silica in which spherical colloidal silica is connected in a specific number, in series, or partially branched. As the spherical colloidal silica has a smaller particle size, the glossiness is more likely to be obtained, but the ink absorbency may decrease. Therefore, the average particle size is preferably 1 nm to 100 nm in terms of the glossiness and the ink absorbability. Further, as the non-spherical colloidal silica, the smaller the particle size, the smaller the voids, the lower the ink absorbency because the voids become smaller, and if the particle size is too large, the voids become too large and may cause a decrease in image density. Is 30n
m to 200 nm is preferred. Non-spherical colloidal silica is more likely to form a void structure and thus has better ink absorbency, and is more preferably spherical in terms of glossiness. Therefore, it is important to appropriately select them according to the purpose, and it is also possible to use a mixture of both.

The resin contained in the coagulant is used for the purpose of improving the surface strength and preventing the colloidal silica from falling off. Therefore, any material that meets this purpose may be used, but at the same time, it is necessary to be stable to the boron compound.
Such materials include oxidized starch, etherified starch,
Cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, soy protein, polyethyleneimide resin, polyacrylic acid or its copolymer, maleic anhydride copolymer, acrylamide resin, acrylate resin, polyamide resin Resin, polyurethane resin, polyester resin,
Acrylics such as alkyd resins, epoxy resins, epichlorohydrin resins, urea resins, melamine resins, styrene-butadiene copolymers, methyl methacrylate-butadiene copolymers, acrylic acid esters, methacrylic acid ester polymers or copolymers Examples include resins of vinyl polymer latexes, vinyl acetate, and vinyl polymer latexes such as ethylene-vinyl acetate copolymer, which may be used alone or in combination. Among these, surface strength,
One selected from starch, casein, cellulose derivatives, acryl, polyurethane, polyester, vinyl acetate, ethylene-vinyl acetate, styrene-butadiene copolymer as a material that has good colloidal silica prevention, ink absorption, and gloss. It is preferable that it is above.

The amount of the resin to be added is 1 to 100 parts by weight, more preferably 3 to 50 parts by weight, based on 100 parts by weight of the colloidal silica. If the amount is less than 1 part by weight, the effect of preventing colloidal silica from falling off is insufficient.
When the amount is more than 0 parts by weight, the ink absorbency is reduced.

The coagulant of the present invention not only has the original purpose of coagulating the coating layer but also improves the glossiness and ink jet printability by distributing colloidal silica used as an essential component on the outermost surface. It is to let. Therefore, a certain amount of the coagulant is required to be applied to the coating layer. If the amount of the coagulant is small, the object of the present invention cannot be achieved. For this reason, as a coagulant amount, the boron compound which is a component for coagulating the coating layer is 0.1 g / m ² or more in terms of solid weight,
Further, it is preferable to apply the colloidal silica so as to have an adhesion amount of 0.05 g / m ² or more in terms of solid weight. Even if the coagulant adhesion amount is large, it does not inhibit the effect of the present invention,
There is no particular upper limit on the amount of adhesion, but since the coagulation liquid is a low-concentration aqueous solution, if the amount of adhesion is large, there is a risk of causing a drying load and a decrease in operability, so the total solid content of the boron compound and colloidal silica is reduced. The weight is preferably 10 g / m ² or less. If the amount of the coagulant adhered is within an appropriate range, it is possible to obtain a necessary and sufficient coagulation effect and an effect of improving printability.

The paint for forming the ink receiving layer of the present invention contains a pigment, a binder and, if necessary, an ink fixing agent and a release agent. The pigments used in the present invention are inorganic pigments such as light calcium carbonate, magnesium carbonate, kaolin, barium sulfate, aluminum silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, wet and dry silica sol, alumina, colloidal alumina, zeolite, and diatomaceous earth. And white pigments such as magnesium hydroxide. In the present invention, since the cracks in the ink receiving layer are extremely small, it is preferable to use alumina when the ink absorption rate decreases. Specific examples of alumina include γ-alumina, δ-alumina, η-alumina, θ-alumina, and hydrated alumina. The particle size of the inorganic pigment is at most 1 μm or less, preferably 0.01 to 0.5 μm. If it exceeds 1 μm, the ink absorbency is too good and the ink penetrates deep into the receiving layer, so that the color density is remarkably reduced. If it is 0.01 μm or less, the surface of the ink receiving layer is easily cracked and the ink absorbing property is deteriorated. Furthermore, the pigment of the present invention has the same effect as the addition of alumina by containing silica having an average particle diameter of 1 μm or less in addition to alumina.

Incidentally, it is also possible to add an organic pigment in combination with the inorganic pigment.

The binder of the ink receiving layer used in the present invention is polyvinyl alcohol, polyvinyl acetal,
Oxidized starch, etherified starch, carboxymethyl cellulose, hydroxyethyl cellulose, casein, gelatin, soy protein, polyethylene imide resin, polyvinyl pyrohydrin resin, polyacrylic acid or its copolymer, maleic anhydride copolymer, acrylamide Resin, acrylate resin, polyamide resin, polyurethane resin, polyester resin, polyvinyl butyral resin, alkyd resin, epoxy resin, epichlorohydrin resin, urea resin, melamine resin, styrene-butadiene copolymer, methyl Methacrylate-
Examples include resins of acrylic polymer latexes such as butadiene copolymer, acrylic acid ester and methacrylic acid ester polymer or copolymer, and vinyl polymer latexes such as ethylene-vinyl acetate copolymer. , Alone or in combination. Particularly preferred binders are polyvinyl alcohol and polyvinyl acetal,
These are used alone or in combination with the above resins. The amount of the binder used is determined in consideration of the printability of the recording medium, the strength of the ink receiving layer, and the properties of the coating liquid. Usually, it is added in the range of about 1 to 200% by weight, preferably about 5 to 100% by weight based on the weight of the pigment.

In the present invention, it is preferable to add a cationic polymer in addition to the above-mentioned pigments and binders. The effect of the cationic polymer is to react with an anionic component in the dye used in the ink to form a water-insoluble salt, thereby fixing the ink and improving the water resistance. Examples of such a cationic polymer include polyethyleneimine, epichlorohydrin-modified polyalkylamine, polyamine polyamide epichlorohydrin, dimethylamine ammonia epichlorohydrin, polyvinylbenzyltrimethylammonium halide, polydiacryldimethylammonium halide, polydimethylaminoethyl methacrylate hydrochloride, and polyvinylpyridium halide. , Cationic polyacrylamide, cationic polystyrene copolymer, diallyldimethylammonium chloride polymer, diallyldimethylammonium chloride sulfur dioxide copolymer, diallyldimethylammonium chloride amide copolymer, dicyandiamide formalin polycondensate, dicyandiamidediethylenetriamine polycondensate , Polyallylua , Polyallylamine hydrochloride, polyacrylamide resin, polyamide epoxy resin, melamine resin acid colloid, urea resin, cation-modified PVA, amino acid type amphoteric surfactant, betaine type compound, other quaternary ammonium salts and polyamine Used. The addition amount is 1 to 50 with respect to the total binder weight.
Used in the range of weight percent. A particularly preferred addition range is 5 to 30% by weight.

As other additives, antifoaming agents, lubricants, dispersants, wetting agents and the like can be used as required.

As a method of applying the paint for forming the ink receiving layer of the present invention, a known coating machine such as an air knife, a roll coater, a bar coater, a comma coater, a blade coater and the like is used. The coating amount is 5 to 40 g / solid equivalent.
m ² , preferably in the range of 7 to 30 g / m ² .
If the coating amount exceeds 40 g / m ² , cracks are likely to be formed on the surface of the ink receiving layer, and if the coating amount is less than 5 g / m ² , it is difficult to form a sufficiently glossy surface.

In the present invention, the glossy surface is formed by applying a coating material with the above coater, applying a coagulating liquid to the coating surface, solidifying the coating material, and pressing the surface to a cast drum. This step is an important step in forming the ink receiving layer of the present invention having a small surface crack and high ink absorption performance. The coagulant to be used is as described above, but the time until the coagulant is added and reaches the cast drum, the cast drum temperature, the pressure at the time of pressing,
By adjusting the line speed, an ink receiving layer surface with less surface cracks can be formed. These conditions need to be optimized by finding the optimal conditions according to the equipment and paint used.

As the base material used in the present invention, paper base materials such as ordinary high quality paper, medium quality paper, and white paperboard are used. Considering the case of recycling as fuel, it is desirable to use ECF pulp or TCE pulp with low chlorine content as raw pulp. In order to suppress excessive penetration of the paint at the time of cast coating, it is preferable to use base paper coated with a water-soluble polymer such as starch or polyvinyl alcohol by a size press.

It is also possible to provide an undercoat layer composed of a pigment and an adhesive on a base material, and then provide the cast coat layer of the present invention thereon.

[0040]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. In the examples, “parts” and “%” indicate solid parts by weight and solid weight% unless otherwise specified.

Example 1 A primary particle size of 13 nm was used as a pigment.
(Aluminum Oxide C: trade name, manufactured by Nippon Aerosil Co., Ltd.)
Parts by weight) of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) as a binder and 20 parts by weight of a cationic polymer (Papiogen P-10) as an ink fixing agent.
5: manufactured by Senka Co., Ltd.) and a coating having a solid content of 14% by weight was prepared. As a coagulant, borax / non-spherical colloidal silica (Snowtex PS-M: manufactured by Nissan Chemical Co., Ltd.) / Casein was dissolved in water at a solid weight ratio of 3/1 / 0.15 to give a solid content of 5%. The coagulation liquid was prepared. The above coating material was applied to a high-quality paper having a basis weight of 160 g / m ² surface-treated with oxidized starch to a coating amount of 15 g / m ² using a roll coater, and then a coagulant was added at a solid weight of 1.5 g / m ^2.
m ² and then subjected to a coagulation treatment. After the surface of the obtained coating layer is in a wet state, the surface temperature becomes 100.
C. to a cast drum at a temperature of .degree. C. to produce glossy paper for inkjet recording.

Example 2 A coagulating solution was prepared as in Example 1 except that casein as a coagulant was used as a phosphate esterified starch (MS4600: manufactured by Nippon Shokuhin Co., Ltd.). A glossy paper for inkjet recording was prepared under the following conditions.

Example 3 In Example 1, the coagulant casein was replaced with methylcellulose (Metroze 90SH-10).
0: manufactured by Shin-Etsu Chemical Co., Ltd.), and a glossy paper for ink jet recording was prepared under the same conditions as described in Example 1 except that the coagulation liquid was prepared and applied.

(Example 4) In Example 1, casein as a coagulant was replaced with polyurethane (Adekabon titer HUX23).
2: Asahi Denka Co., Ltd.), a glossy paper for ink jet recording was prepared under the same conditions as described in Example 1 except that the coagulation liquid was prepared and applied.

Example 5 The same conditions as described in Example 1 were used except that the coagulating solution was prepared and coated using vinyl acetate (Movinyl 206: manufactured by Clariant Polymer Co., Ltd.) as the coagulant casein in Example 4. Produced glossy paper for ink jet recording.

Example 6 A coagulant was prepared as described in Example 1 except that casein, a coagulant, was used as a modified polyester resin (CW-11: manufactured by Mikuni Pigment Co., Ltd.) to prepare and coagulate a coagulant. A glossy paper for inkjet recording was prepared under the following conditions.

Example 7 In Example 1, casein as a coagulant was replaced with ethylene-vinyl acetate (Polysol EVA A).
D-6: manufactured by Showa High Polymer Co., Ltd.)
Glossy paper for ink jet recording was prepared under the same conditions as described in Example 1 except that the coating was performed.

(Example 8) In Example 1, borane / spherical colloidal silica composite acrylic resin (Movinyl 8050: manufactured by Clariant Polymer Co., Ltd.) was used as a coagulant.
Glossy paper for ink jet recording was prepared under the same conditions as in Example 1 except that the paper was set to 2.

Example 9 In Example 1, borax / non-spherical colloidal silica (Snowtex PS) was used as a coagulant.
-M: Nissan Chemical Co., Ltd.) / Spherical colloidal silica composite acrylic resin (Movinyl 8050: Clariant Polymer Co., Ltd.) was changed to 3 / 0.9 / 0.2 as described in Example 1. Under the conditions, glossy paper for inkjet recording was prepared.

Example 10 The coagulant casein of Example 1 was replaced with a styrene-butadiene copolymer (L-197).
0: manufactured by Asahi Kasei Co., Ltd.), and a glossy paper for ink jet recording was prepared under the same conditions as described in Example 1 except that the coagulation liquid was prepared and applied.

(Example 11) In Example 1, the binder was polyvinyl acetal (Eslek KX-1: manufactured by Sekisui Chemical Co., Ltd.), and the same coagulant as in Example 1 was prepared.
Glossy paper for ink jet recording was prepared under the same conditions as described in Example 1 except that the coating was performed.

(Example 12) As described in Example 1, except that the binder was 10 parts by weight of polyvinyl alcohol and 10 parts by weight of polyvinyl acetal in Example 1, and the same coagulant as in Example 1 was prepared and applied. A glossy paper for inkjet recording was prepared under the following conditions.

(Example 13) Synthetic silica having an average particle diameter of 0.3 µm (Sirojet 703C: Grace Japan Co., Ltd.) instead of alumina in Example 1
Glossy paper for ink jet recording was prepared under the same conditions as described in Example 1 except for using.

Comparative Example 1 A glossy paper for ink jet recording was prepared under the same conditions as in Example 1 except that the coating was carried out without using a coagulant.

(Comparative Example 2) Glossy paper for ink jet recording was prepared under the same conditions as in Example 1 except that only the borax was used as the coagulant in Example 1.

Comparative Example 3 A glossy paper for ink jet recording was prepared under the same conditions as in Example 1 except that borax as a coagulant was not used.

(Comparative Example 4) Glossy paper for ink jet recording was prepared under the same conditions as in Example 1 except that casein as a coagulant was not used.

Comparative Example 5 Glossy paper for ink jet recording was prepared under the same conditions as in Example 3 except that colloidal silica as a coagulant was not used in Example 3.

The glossy paper for ink jet recording was evaluated as follows, and the results are shown in Table 1.

[Table 1] The criteria for the evaluation results in Table 1 were as follows.

Image clarity An ISO standard image (ISO / JIS-SCID high-definition color digital standard image data, image name: portrait, image identification number: N1) was used as an ink jet printer “PM-770C” manufactured by Seiko Epson Corporation. And printed. The printed image was visually evaluated. A: The recorded image is very clear and the contrast is clear. ：: The recorded image is clear and the contrast is clear. Δ: The recorded image is clear but the contrast is not clear and the color is sinking. X: The recorded image is unclear and the color is sinking.

Bleeding CMYK and RGB solids (100% density) and characters were printed using an inkjet printer “PM-770C” manufactured by Seiko Epson Corporation. The boundaries between solid colors and the degree of bleeding of characters were visually evaluated. ：: The boundaries are clear, there is no blur, and the characters are clear. ：: Border bleed is not conspicuous and characters are clear. Δ: Boundary blur is conspicuous, characters are unclear, and there is a practical problem. ×: Border bleeding was severe, characters could not be distinguished, and practically impossible.

Dot shape Halftone (10% density) using an inkjet printer "PM-770C" manufactured by Seiko Epson Corporation
Was printed. Next, the printed portion was magnified 200 times with an optical microscope and observed, and the state of cracks on the surface of the coating layer and the roundness of the dot shape were evaluated. A: There is no crack on the surface, and the roundness of the dot shape is very high. ：: Cracks on the surface are not conspicuous, and the dot shape has high roundness. Δ: Cracks on the surface are conspicuous, and the dot shape has low roundness. ×: Cracks on the surface were very noticeable, and the shape of the totes was indefinite.

Uniformity of glossiness The glossiness of the glossy paper surface was judged by observing the surface condition with the naked eye from the lateral direction. ：: The glossiness of the white paper is high and the uniformity is good. Δ: The glossiness of the white paper is slightly low. X: The glossiness of the white paper is low and the uniformity is poor.

(5) Surface Strength Using a Gakushin-type fastness tester (manufactured by Tester Sangyo Co., Ltd.), the surface was rubbed five times without weight, and the degree of surface strength (scratch, powder drop) was visually observed. It was determined by ：: good without any scratches or powder dropping. ：: good, with no noticeable scratches and powder drop. Δ: Scratches and powder dropout are conspicuous, causing practical problems. ×: Scratches and powder fall are conspicuous and practically impossible.

[0065]

According to the invention described in claim 1, the glossy paper for ink jet recording is a glossy paper for ink jet recording manufactured by a casting method, but is applied to a medium manufactured using a photographic paper base or a film base. Comparable image quality, very good uniformity of surface glossiness of the ink receiving layer surface, and dot roundness when printing were obtained. Further, it was possible to improve the image quality, and in particular, to improve the color development by increasing the density of the image when printing.

According to the second aspect of the present invention, it is possible to provide a glossy paper for ink-jet recording having higher ink absorbability by using non-spherical colloidal silica as colloidal silica.

According to the third aspect of the present invention, by using borax as the boron compound, the solidification treatment is sufficiently performed to form a crack-free surface, and the glossiness uniformity, the roundness of the pet, and the sharpness of the image are improved. Further, an improved glossy paper for inkjet recording could be provided.

According to the invention of claim 4, as the resin,
Prevent colloidal silica from falling off and absorb ink by using a combination of one or more selected from starch, casein, cellulose derivatives, acrylic, polyurethane, polyester, vinyl acetate, ethylene-vinyl acetate, and styrene-butadiene copolymer. Thus, a glossy paper for ink jet recording having properties and glossiness can be provided.

According to the fifth or sixth aspect of the present invention, alumina is contained as a pigment, or silica having an average particle diameter of 1 μm or less is contained as a pigment, so that cracks in the ink receiving layer are extremely reduced and gloss is secured. Thus, a glossy paper for ink jet recording having an appropriate ink absorption speed can be provided.

According to the seventh aspect of the present invention, by using paper as a base material, the production cost is lower than that of a photographic paper base material having a film layer. Could be done.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihisa Meguro 3-5-1 Nishizao, Nagaoka, Niigata Pref. Hokuetsu Paper Mills Co., Ltd. (72) Inventor Kenji Kawada 9 Kirihara-cho, Fujisawa-shi, Kanagawa Taiho Kogyo Co., Ltd. F-term (reference) 2C056 FC06 2H086 BA15 BA21 BA24 BA31 BA33 BA35 BA36 BA41 BA45

Claims (7)

[Claims] 1. A cast coated paper having a high gloss coating layer formed on one or both surfaces of a base material, wherein the coating layer contains a pigment and an adhesive, and An ink-jet printer, comprising: an adhesive and a coagulant capable of coagulating; the adhesive contains both or one of polyvinyl alcohol and polyvinyl acetal; and the coagulant contains a boron compound, colloidal silica and a resin. Glossy paper for recording. 2. The glossy paper for ink jet recording according to claim 1, wherein said colloidal silica is non-spherical colloidal silica. 3. The glossy paper for ink jet recording according to claim 1, wherein said boron compound is borax. 4. The resin comprises starch, casein, a cellulose derivative, acryl, polyurethane, polyester,
4. The glossy paper for inkjet recording according to claim 1, wherein the glossy paper is a combination of at least one selected from vinyl acetate, ethylene-vinyl acetate, and styrene-butadiene copolymer. 5. The glossy paper for ink-jet recording according to claim 1, wherein the pigment contains alumina. 6. The glossy paper for ink jet recording according to claim 1, wherein the pigment contains silica having an average particle diameter of 1 μm or less. 7. The glossy paper for ink-jet recording according to claim 1, wherein said base material is paper.