JP4573229B2 - Cast coated paper for inkjet recording for postcard use with glossy side and back side for address printing - Google Patents

Description

  The present invention relates to glossy paper for ink-jet recording, and more particularly to a recording paper having glossiness similar to that of a silver salt photograph, excellent scratch resistance on a glossy surface, and high print quality close to photographic image quality.

The ink jet recording method is a method in which dots are formed by discharging ink droplets and adhering onto recording paper to perform recording. In recent years, recording with high print quality has become possible due to technological advances in inkjet printers, inks, and recording media. As an element required for an inkjet recording medium,
(A) fast ink absorption and drying;
(b) High print density,
(c) No dot spread or whiskers
Etc. If ordinary plain paper has a certain size or more, it can be expected to have a certain level of print quality with little blurring. On the other hand, when a higher print quality is required, a dedicated medium in which an ink receiving layer suitable for the ink of an ink jet printer is provided on various media on the medium is used. As a medium dedicated to ink jet recording, a paper or film is used as a support, and a pigment coating layer mainly composed of a pigment and a binder or a resin coating layer containing no pigment is provided on the surface. .

Inkjet recording media are further classified into matte media and glossy media based on the surface condition of the recording surface. The latter glossy media is used when image quality closer to silver halide photography is required. In addition to the properties described above, the properties required for these glossy media are as follows:
(d) High roundness of dots and good image reproducibility,
(e) good water resistance and light resistance;
(f) The glossiness of the image area and the blank area is high,
Etc.

  Various methods have been proposed for producing glossy media in order to maintain the properties (b) to (f) while maintaining the ink absorbency and drying properties of (a). A method of forming an ink receiving layer by a method and imparting gloss to the surface, and a method of forming an ink receiving layer on a photographic paper substrate.

  In general, the former is easier to control the ink absorptivity of (a) than the latter, but (d) dot roundness, image reproducibility, (f) image area, glossiness of blank paper, and quality are the latter. It is inferior. As the base material for photographic paper is generally called RC paper (resin coated paper), since the polyethylene film layer is formed on the paper base material, when the ink receiving layer is formed on the surface, the film surface is Since the surface is smooth, the surface of the ink receiving layer is also smooth, and a glossy surface is easily formed.

  However, it is necessary to increase the coating amount 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 glossy medium produced by the former casting method. In addition, there is also a problem that when it is discarded, it cannot be recycled because it is a composite material.

  The 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.

  For example, there is a proposal that an inkjet recording paper having high surface smoothness and excellent image quality can be obtained by defining the average roughness, glossiness and air permeability of the recording paper on the surface of the recording layer (for example, , See Patent Document 1).

  There is also a proposal that an ink jet recording paper having excellent gloss and ink receptivity can be obtained by defining the size and number of cracks on the surface of the recording layer (see, for example, Patent Document 2).

  However, in this case, if the number of cracks is too small, there is a problem that the glossiness increases while the ink absorbability decreases. Furthermore, there is also a proposal of an ink jet recording sheet containing a pearl necklace-shaped colloidal silica (see, for example, Patent Document 3). In this case, the use of pearl necklace-shaped colloidal silica has a certain effect in improving the printing quality, particularly the ink absorbability, but the surface strength and glossiness are not always satisfactory.

  In recent years, a paper coated with a mixture of alumina hydrate and a water-soluble binder has been proposed as a glossy paper for ink-jet recording having a high ink absorption rate and a glossiness similar to that of a silver salt photograph (for example, patent document). 4). These glossy papers for ink-jet recording have the characteristic that they are very excellent in glossiness, but they have the drawback that they are easily scratched because of their excellent glossiness. For example, when used for postcard applications, address printing is performed on the back side, but there is a drawback that scratches are easily caused by rubbing by the paper feed unit guide during printing and rubbing with the suction wheel of the paper discharge unit. In addition, there is also a problem in that scratches are likely to occur due to contact between the glossy surface and the paper feed roller during address printing with an inkjet printer.

In any case, glossy paper for ink-jet recording produced by the casting method has an image quality and uniform glossiness exceeding those of media produced using a photographic paper substrate or a film substrate, and has excellent resistance to light. At present, there is no recording medium having both scratching properties.
Japanese Patent Laid-Open No. 06-72017 JP-A-11-348416 JP-A-12-108506 Japanese Patent Laid-Open No. 06-055829

  In the glossy paper for ink-jet recording produced by the casting method, the present invention has a high gloss feeling similar to that of a silver salt photograph while having good ink absorbency, which is a problem of the above-described conventional technology, and further has a glossy surface. An object of the present invention is to provide a recyclable recording medium which has excellent scratch resistance, has an image quality comparable to that of a medium produced using a photographic paper substrate or a film substrate, and a uniform gloss.

The present inventors have for the above object, the cast coating method by a so-called solidification method, BET specific surface area is 55m ² / g~80m ² / g as pigments in glossy layer coating liquid θ- alumina or the θ- alumina and a BET specific surface area containing a mixture of γ- alumina is 55m ² / g~80m ² / g, and containing a polyvinyl alcohol and silanol-modified polyvinyl alcohol in the binder, the silanol-modified polyvinyl the alcohol content has reached the present invention that good results by 0.1 to 10 parts by der Rukoto respect pigment 100 parts by weight is obtained.
In the present invention, in consideration of printing quality, the content of the binder in the coating liquid is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the pigment. Moreover, since a higher glossiness can be obtained by containing a cationic acrylic resin in the binder in the coating liquid, it is preferable. Further, the cationic acrylic resin of the binder in the coating liquid is preferably a cationic acrylic silicone resin, so that glossiness is further improved, and a more uniform glossy surface by containing a boron compound as a coagulant. It is preferable because quality can be obtained.

  The glossy paper for ink-jet recording of the present invention is a glossy paper for ink-jet recording manufactured by a casting method, and it has good color development while balancing a very good surface glossiness, ink absorbability and scratch resistance at a high level. It is a thing with sex. In the present invention, since paper is used as a base material, the production cost is lower than that of a photographic paper base material having a film layer, and it is recyclable when discarded, which is preferable from the viewpoint of effective use of resources.

  Hereinafter, the present invention will be described in detail, but the present invention is not construed as being limited to these descriptions.

  In general, spherical colloidal silica is used as a coating liquid pigment for the glossy layer of ink jet glossy paper by a normal casting method. Spherical colloidal silica tends to have high surface strength and thus has high scratch resistance. However, since ink absorbency is relatively poor, it is very difficult to balance glossiness and ink absorbency at a high level. Further, pearl necklace-shaped colloidal silica is known as non-spherical colloidal silica, but there are problems that the ink absorbability is better than spherical colloidal silica but the gloss is inferior and the surface strength is weak.

On the other hand, by using alumina, it is possible to obtain a glossy paper for ink-jet recording that has excellent ink absorption performance and excellent glossiness, but as described above, it is easy to be scratched and the scratch resistance is compared with colloidal silica. Even so, it is inferior at a considerable level, and it is very difficult to maintain the printing performance, glossiness, and scratch resistance at a high level. Glossy layer coating liquid of the present invention is a BET specific surface area of 55m ² / g~80m is ² / g theta-alumina or the theta-alumina and a BET specific surface area of the pigment in 55m ² / g~80m ² / g It is characterized by containing a mixture with a certain γ-alumina and containing silanol-modified polyvinyl alcohol in the binder, which makes it possible to maintain printing performance, glossiness, and scratch resistance at a high level. It becomes.

Alumina fine particles used in the present invention, BET specific surface area of 55m ² / g~80m ² / g is θ- alumina or the θ- alumina and BET specific surface area is 55m ² / g~80m ² / g γ- alumina Even if these are mixed, the object of the present invention can be achieved. When the specific surface area of these aluminas is less than 50 m ² / g, the scratch resistance is increased, but the ink absorption performance is deteriorated, which is not preferable. On the other hand, when it is larger than 150 m ² / g, the ink absorption performance is increased, but the scratch resistance is inferior, which is not preferable.

Alumina used in the present invention is obtained by various methods, in the present invention, even those obtained by any method, BET specific surface area is 55m ² / g~80m ² / g θ- alumina or the θ- alumina and BET specific surface area can be used in the present invention if a mixture of γ- alumina is 55m ² / g~80m ² / g. Further, θ and γ of θ-alumina or γ-alumina mean the crystal form of alumina and can be determined by X-ray diffraction. The amount of θ-alumina or a mixture of θ-alumina and γ-alumina used in the present invention is 5 to 100 parts by weight, preferably 20 to 100 parts by weight, per 100 parts by weight of the pigment. When the amount is less than 5 parts by weight, the scratch resistance becomes insufficient.

Moreover, the glossy layer of the present invention, is as long as it does not impair the effects BET specific surface area of 55m ² / g~80m is ² / g theta-alumina or the theta-alumina and the BET specific surface area of the present invention 55m ² / g~80m ² / well of a mixture of certain γ- alumina g to appropriately select one or more known pigments can be used. As such pigments, synthetic silica, gas phase method silica, α-alumina, β-alumina, σ-alumina, alumina-doped silica, spherical colloidal silica, pearl necklace-shaped colloidal silica, a plurality of particles aggregated randomly. Examples thereof include colloidal silica having a shape, but are not particularly limited.

  In the present invention, it is indispensable to contain silanol-modified polyvinyl alcohol as a binder used for the glossy layer. Since silanol-modified polyvinyl alcohol has extremely high adhesion to inorganic substances, it can have high surface strength due to strong coagulation force while balancing ink absorbency and glossiness at a high level. The degree of modification and the degree of polymerization of the silanol-modified polyvinyl alcohol can be appropriately selected.

  The amount of the binder used for the glossy layer is determined in consideration of the printability of the recording medium, the strength of the glossy layer, and the liquidity of the coating liquid. Usually, it is preferably added in the range of 5 to 30 parts by weight with respect to 100 parts by weight of the pigment. More preferably, it is 10-25 weight part. If it is less than 5 parts by weight, the strength of the coating layer is inferior, and if it exceeds 30 parts by weight, the ink absorbency is adversely affected. The content of silanol-modified polyvinyl alcohol in the binder used for the glossy layer is 0.1 to 10 parts by weight, preferably 0.1 to 7 parts by weight per 100 parts by weight of the pigment. When the amount is less than 0.1 part by weight, the strength of the coating layer is weak, and when the amount is more than 10 parts by weight, the viscosity of the glossy layer coating liquid becomes too high.

  Moreover, in this invention, it is preferable to contain a cationic acrylic resin in the binder in a gloss expression layer coating liquid. This cationic acrylic resin has the effect of improving glossiness by enhancing the adhesion between the cast drum and the coating layer. In addition, since the acrylic resin has high transparency, it is difficult to impair the transparency of the coating layer, it is possible to obtain a good image sharpness, and the light resistance is excellent, so that the storage stability as a recording sheet is deteriorated. The effect of being difficult is also obtained.

  Furthermore, in the present invention, the cationic acrylic resin in the binder of the glossy layer coating liquid is preferably a cationic acrylic silicone resin. Since the cationic acrylic silicone resin is further excellent in drum adhesion, it becomes possible to further improve the scratch resistance while having a high gloss feeling.

Examples of the cationic acrylic silicone resin include a block polymer or a graft polymer prepared by reacting an acrylic acid polymer with an organopolysiloxane. The organosiloxane includes a linear polymer having an —OH functional group, and can include a compound of the following formula:
_{HO-Si (CH 3) 2} -O- (Si (CH 3) 2 -O) n -Si (CH 3) 2 -OH
(Where n is a number between 10 and 5000)
The acrylic acid polymer is a polymer or copolymer obtained by polymerizing monomers such as α, β-unsaturated acid or its ester including (meth) acrylic acid alone or with each other or with a comonomer. It is. Examples of the α, β-unsaturated acid or ester thereof include acrylic acid, methacrylic acid, and methyl ester, ethyl ester, butyl ester, stearyl ester, 2-ethylhexyl ester, 2-hydroxyethylhexyl ester, and 3-hydroxypropyl. An ester etc. can be illustrated. Further, the comonomer that can be polymerized with the α, β-unsaturated acid or its ester is maleic acid, itaconic acid, fumaric acid, styrene, α-methylstyrene, vinyl acetate, vinyl propionate, or the like.

  In addition, binders that can be used in combination with silanol-modified polyvinyl alcohol as a binder include polyvinyl alcohol, polyvinyl acetal, oxidized starch, etherified starch, carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, soy protein, and polyethyleneimide resin. , Polyvinylpyrohydrin resins, polyacrylic acid or copolymers thereof, maleic anhydride copolymers, acrylamide resins, acrylate resins, polyamide resins, polyurethane resins, polyester resins, polyvinyl butyral resins , Alkyd resin, epoxy resin, epichlorohydrin resin, urea resin, melamine resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic ester, meta Examples include acrylic polymer latexes such as a polymer or copolymer of a crylate ester, and resins of vinyl polymer latexes such as a styrene-acrylic resin and an ethylene-vinyl acetate copolymer. If it is a range which does not impair the effect of this invention, it will not specifically limit.

  Further, the glossy layer has a cationic polymer for fixing the ink for ink jet recording, a release agent, a dispersant, a thickener, an antiseptic, an antifoaming agent, a coloring dye, a coloring pigment, a fluorescent whitening agent, water resistance. Additives such as an agent, a leveling agent, an antioxidant, and an ultraviolet absorber can be appropriately selected and added.

As a coating method of the coating liquid for forming the glossy layer of the present invention, known coating machines such as an air knife, a roll coater, a reverse roll coater, a bar coater, a comma coater, and a blade coater are used. The coating amount of the glossy layer is 3~40g / ^{m 2} in terms of solid content, preferably in the range of 5 to 30 g / ^{m 2.} When the coating amount exceeds 40 g / m ² , the productivity is inferior, and when the coating amount is less than 3 g / m ² , it is difficult to form a sufficiently glossy surface.

  The gloss developing layer is formed by a known cast coating method. As the cast coating method, a wet method, a solidification method, and a rewetting method are known. In the present invention, the solidification method is preferable. The coagulation method is a method in which a gloss-expressing layer is applied and coated with a coagulating liquid while it is in a wet state, subjected to coagulation treatment and pressed against a cast drum. In the coagulation treatment, it is important to select a material that effectively coagulates with the binder component of the coating layer. In the present invention, a boron compound is preferable. More preferred is sodium borate. It is also possible to add a cationic polymer for fixing the ink to the coagulant. By adjusting the time from application to application of the coagulant, the time from application of the coagulant to reaching the cast drum, the temperature of the cast drum, the pressure during crimping, and the line speed A high glossy layer can be formed. About these conditions, it is necessary to optimize by calculating | requiring optimal conditions according to the installation to be used and the coating liquid which forms a gloss expression layer.

  In addition, calendar processing such as machine calendar, soft calendar, super calendar, etc. may be performed after casting, and for curl adjustment, water or curl adjuster is applied on the back surface or humidified to adjust the curl. You can also.

  In the glossy paper for ink jet recording of the present invention, one or more ink receiving layers are provided under the glossy expression layer. The ink receiving layer is composed of a white pigment and a binder component.

  The pigment used in the ink receiving layer contains at least one known white pigment, such as kaolin, talc, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, titanium dioxide, zinc oxide, zinc sulfate, zinc carbonate. White inorganic pigments such as calcium silicate, aluminum silicate, magnesium silicate, diatomaceous earth, aluminum hydroxide, magnesium hydroxide, satin white, synthetic silica, colloidal silica and alumina, and organic pigments such as acrylic, styrene, ethylene, vinyl chloride and nylon Is mentioned.

  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-butadiene copolymer, acrylic acid ester, methacrylic acid ester polymer or copolymer, etc. Acrylic polymer latexes, ethylene - the resins of the vinyl polymer latexes such as vinyl acetate copolymer exemplified, used alone or in combination. 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 liquid property of the paint. Usually, it is added in an amount of about 1 to 200% by weight, preferably about 5 to 100% by weight, based on the pigment weight.

  In the paint of the present invention, it is preferable to add a cationic polymer in addition to the pigment and the binder. The action of the cationic polymer reacts with an anionic component in the dye used in the ink to form a salt that is insoluble in water, thereby fixing the ink and improving the water resistance. Such cationic polymers include polyethyleneimine, epichlorohydrin-modified polyalkylamine, polyamine polyamide epichlorohydrin, dimethylamine ammonia epichlorohydrin, polyvinylbenzyltrimethylammonium halide, polydiacryldimethylammonium halide, polydimethylaminoethyl methacrylate hydrochloride, polyvinylpyridium halide. , Cationic polyacrylamide, cationic polystyrene copolymer, diallyldimethylammonium chloride polymer, diallyldimethylammonium chloride sulfur dioxide copolymer, diallyldimethylammonium chloride amide copolymer, dicyandiamide formalin polycondensate, dicyandiamide diethylenetriamine polycondensate , Polyallylua , Polyallylamine hydrochloride, polyacrylamide resin, polyamide epoxy resin, melamine resin acid colloid, urea resin, cation-modified polyvinyl alcohol, amino acid type amphoteric surfactant, betaine type compound, other quaternary ammonium salts and polyamines, etc. Is used. Although the addition amount is not particularly limited, it is used in the range of about 1 to 50 parts by weight with respect to 100 parts by weight of the pigment.

  Other additives include antifoaming agents, lubricants, dispersants, wetting agents, fluorescent whitening agents, coloring dyes, coloring pigments, thickeners, preservatives, water-proofing agents, UV absorbers, as necessary. An antioxidant etc. can be used.

As a coating method of the coating material for forming the ink receiving layer of the present invention, known coating machines such as an air knife, a roll coater, a bar coater, a comma coater, and a blade coater are used. The coating amount is not particularly limited, but if the coating amount is too small, the ink absorbability is inferior, so that it is preferably 3 g / m ² or more in terms of solid content.

  It is also possible to use a known calendar device such as a super calendar, a machine calendar, or a soft calendar in order to give a certain smoothness after coating the ink receiving layer.

  As the base material used in the present invention, a normal paper base material such as high-quality paper, medium-quality paper, and white paperboard is used. Considering the case of recycling as a fuel, it is desirable to use ECF (chlorine-free gas bleached) pulp or TCE (chlorine-free bleached) pulp having a low chlorine content as raw material pulp.

  In order to suppress excessive penetration of the paint during cast coating, it is preferable to use a base paper coated with a water-soluble polymer such as starch or polyvinyl alcohol by a size press.

Example:
EXAMPLES Hereinafter, although an Example is given and this invention is further explained in full detail, this invention is not limited to these examples. In the examples, “parts” and “%” indicate solid parts by weight and solids% by weight unless otherwise specified.

^On high-quality paper having a basis weight of 160 g / m ² surface-treated with oxidized starch, 100 parts of synthetic silica (Mizukasil P-78A, manufactured by Mizusawa Chemical Co., Ltd.), 10 parts of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) as a binder, Using 40 parts of ethylene-vinyl acetate (Polysol EVA AD-6: manufactured by Showa Polymer Co., Ltd.) and 30 parts of cationic polymer (Papiogen P-105: manufactured by Senka Co., Ltd.), the paint having a solid content of 16% was completely dried with an air knife coater. The ink receiving layer was applied and dried so that the coating amount was 10 g / m ² . Subsequently, 100 parts of alumina having a BET specific surface area of 55 m ² / g (PG-003, crystal form-γ, θ mixture: manufactured by CABOT) as a pigment of the glossy layer coating liquid, and silanol-modified polyvinyl alcohol (as a binder) R-1130: manufactured by Kuraray Co., Ltd.) 5 parts, polyvinyl alcohol (PVA420: manufactured by Kuraray Co., Ltd.) 10 parts, cationic polymer as an ink fixing agent (Smiles Resin 1001: manufactured by Sumitomo Chemical Co., Ltd.), polyethylene as a release agent A coating solution having a solid content of 20% was obtained by using 1 part of an emulsion (SN coat 287: manufactured by San Nopco). This coating solution was applied with an air knife coater so as to have an absolutely dry coating amount of 10 g / m ² per side, and then solidified by applying a 3% aqueous solution of sodium borate to obtain a coating solution. While the coating layer surface was in a wet state, it was pressure-bonded to a cast drum having a surface temperature of 100 ° C. to prepare glossy paper for ink jet recording.
[ Example (reference example) 2]

As described in Example 1, except that 100 parts of alumina (AKP-G015, crystal form-γ type: manufactured by Sumitomo Chemical Co., Ltd.) having a BET specific surface area of 150 m ² / g was used as the pigment of the glossy layer coating liquid in Example 1. A glossy paper for inkjet recording was prepared under the same conditions.

As described in Example 1, except that 100 parts of alumina having a BET specific surface area of 80 m ² / g (AKP-G008, crystal form-θ type: manufactured by Sumitomo Chemical Co., Ltd.) was used as the pigment of the glossy layer coating liquid in Example 1. A glossy paper for inkjet recording was prepared under the same conditions.

  Example 1 except that the binder for the glossy layer coating liquid in Example 1 was 5 parts of silanol-modified polyvinyl alcohol (R-1130: manufactured by Kuraray Co., Ltd.) and 25 parts of polyvinyl alcohol (PVA420: manufactured by Kuraray Co., Ltd.). A glossy paper for ink-jet recording was prepared under the conditions described in 1.

  In Example 1, as a binder for the glossy layer coating liquid, 5 parts of silanol-modified polyvinyl alcohol (R-1130: manufactured by Kuraray Co., Ltd.), 10 parts of polyvinyl alcohol (PVA420: manufactured by Kuraray Co., Ltd.), cationic acrylic resin ( A glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1 except that 10 parts (Viniblanc 2580: manufactured by Nissin Chemical Industry Co., Ltd.) were used.

  In Example 1, as a binder for the glossy layer coating liquid, 5 parts of silanol-modified polyvinyl alcohol (R-1130: manufactured by Kuraray Co., Ltd.), 10 parts of polyvinyl alcohol (PVA420: manufactured by Kuraray Co., Ltd.), cationic acrylic resin ( A glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1 except that 10 parts (Viniblanc 2687: manufactured by Nissin Chemical Industry Co., Ltd.) were used.

  In Example 1, as a binder of the glossy layer coating liquid, 5 parts of silanol-modified polyvinyl alcohol (R-1130: manufactured by Kuraray Co., Ltd.), 10 parts of polyvinyl alcohol (PVA420: manufactured by Kuraray Co., Ltd.), cationic styrene-acrylic resin Glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1 except that 10 parts (Passcoal JK718: manufactured by Meisei Chemical Co., Ltd.) were used.

  In Example 1, as a binder for the glossy layer coating liquid, 5 parts of silanol-modified polyvinyl alcohol (R-1130: manufactured by Kuraray Co., Ltd.), 10 parts of polyvinyl alcohol (PVA420: manufactured by Kuraray Co., Ltd.), cationic acrylic silicone resin ( A glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1 except that 10 parts (Aquabrid 922: manufactured by Daicel Chemical Industries, Ltd.) were used.

In Example 1, 80 parts of alumina (PG-003, crystal form-γ, θ mixture: manufactured by CABOT) having a BET specific surface area of 55 m ² / g was used as a pigment of the glossy layer coating liquid, gas phase method silica (Aerosil 200). : Nippon Aerosil Co., Ltd.) Glossy paper for ink jet recording was prepared under the same conditions as described in Example 1 except that 20 parts were used.

Comparative Example 1

As described in Example 1, except that 100 parts of alumina having a BET specific surface area of 220 m ² / g (TM-300, crystal form-γ type: manufactured by Daimei Chemical Co., Ltd.) was used as the pigment of the glossy layer coating liquid in Example 1. A glossy paper for inkjet recording was prepared under the same conditions.

Comparative Example 2

As described in Example 1, except that 100 parts of alumina (AKP-30, crystal form-α type: manufactured by Sumitomo Chemical Co., Ltd.) having a BET specific surface area of 10 m ² / g was used as the pigment of the glossy layer coating liquid in Example 1. A glossy paper for inkjet recording was prepared under the same conditions.

Comparative Example 3

In Example 1, except that 100 parts of alumina having a BET specific surface area of 275 m ² / g (cataloid AP-1, crystal form-pseudo boehmite type: manufactured by Catalyst Kasei Co., Ltd.) was used as the pigment of the glossy layer coating liquid in Example 1. A glossy paper for ink jet recording was prepared under the conditions as described.

Comparative Example 4

  A glossy paper for inkjet recording was prepared under the same conditions as described in Example 1 except that no silanol-modified polyvinyl alcohol was added in Example 1.

Comparative Example 5

  A glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1 except that the ink receiving layer was not provided in Example 1.

  The glossy paper for ink jet recording obtained in the above examples and comparative examples was subjected to the following tests, and the evaluation results are shown in Table 1.

(1) Image clarity:
An ISO standard image (ISO / JIS-SCID high-definition color digital standard image data, image name: portrait, image identification number: N1) was printed using an ink jet printer “PM-900C” manufactured by Seiko Epson Corporation. 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 sunk and inferior.
X: The recorded image is unclear and the color is sunk and inferior.

(2) Ink absorbability:
CMYK and RGB solid (100% density) and characters were printed using an ink jet printer “PM-900C” manufactured by Seiko Epson Corporation. The boundary of each color of the solid portion and the degree of blurring of the characters were visually evaluated.
A: The border is clear, there is no blur, and the characters are clear.
○: The blurring of the boundary is not conspicuous and the characters are clear.
(Triangle | delta): The blur of a boundary is conspicuous, a character is unclear, and there exists a problem practically.
X: The blurring of the boundary is severe, and the character cannot be identified, so that it is not practical.

(3) Image clarity (incidence / reflection angle 60 °):
The image clarity was measured to evaluate the specularity of the glossy surface. The image clarity is in accordance with JIS H8866-2: 1999 “Image clarity test method for anodized films of aluminum and aluminum alloys—Part 2: Instrument measurement method”, with an optical comb width of 2 mm, and here an incident reflection angle of 60 °. Then, it measured with the image clarity measuring device (ICM-1T: manufactured by Suga Test Instruments Co., Ltd.). As an evaluation, when the image clarity is 55% or more, the reflected image is clearly visible, and the glossiness is excellent. If it is less than 55%, the reflected image appears unclear and the glossiness is inferior.

(4) Scratch resistance of glossy surface:
Visual evaluation of the degree of abrasion on the glossy surface that occurred when 20 sheets of inkjet recording paper were set on an offset printing machine (LITHRON 40, manufactured by KOMORI) and printing on the back side was performed at a printing speed of 8000 sheets / hour. did.
(Double-circle): There is no scratch and it is favorable.
○: Scratches are slightly observed.
Δ: Scratches are clearly recognized and inferior.
X: Scratch is remarkably recognized and inferior.

As it is evident from Table 1, BET specific surface area as glossy layer is a pigment provided on one or more ink receiving layers and the θ- alumina or the θ- alumina is 55m ² / g~80m ² / g implementation BET specific surface area is silanol modified polyvinyl alcohol in 55m ² / g~80m contained a mixture of some γ- alumina ² / g, and a binder examples 1 and 3-9, Comparative It turns out that it is excellent in printing performance, glossiness, and abrasion resistance compared with Examples 1-5.

Table 1 shows the following. Gloss of a mixture of a BET specific surface area as pigment and 55m ² / g~80m is ² / g theta-alumina or the theta-alumina and the BET specific surface area is 55m ² / g~80m ² / g γ- alumina In the case of Examples 1 and 3 to 9 of the present invention which are contained in the layer coating solution and contain silanol-modified polyvinyl alcohol in the binder, the glossy surface has no or little scratches, and the image is clear. Property, ink absorbability and image clarity are also good. On the other hand, in the case of Comparative Example 1 having a BET specific surface area of 220 m ² that departs from the scope of the present invention, scratches are clearly observed on the glossy surface and the scratch resistance is insufficient. In the case of Comparative Example 2 in which α-alumina having a BET specific surface area of 10 m ² / g was used as a pigment, the ink absorptivity was very poor, and accordingly, the image was unclear and the image sharpness was poor. In the case of Comparative Example 3 in which pseudo-boehmite type alumina having a BET specific surface area of 275 m ² / g is used as a pigment, the abrasion resistance of the glossy surface is poor and scratches are remarkable. In the case of Comparative Example 4 in which a glossy layer containing no silanol-modified polyvinyl alcohol is provided in the binder, the image clarity is poor and the gloss resistance of the glossy surface is insufficient. Further, in the case of Comparative Example 5 in which the glossy expression layer of the present invention is provided without providing the ink receiving layer, the ink absorbability is very poor and characters cannot be distinguished, and the image clarity is insufficient.

  Further, from Table 1, in Examples 5 to 8 where a cationic acrylic resin was used in the binder, the image sharpness and the abrasion resistance of the glossy surface were particularly excellent compared to other examples. I know that.

Claims (5)

One or more ink-receiving layers are provided on at least one side of a paper substrate, and after applying a coating liquid containing a pigment and a binder as a glossy layer on the ink-receiving layer, the coating layer is in a wet state A coated paper for inkjet recording for postcard use having a glossy surface and a back surface for address printing, wherein the coated layer is pressure-bonded to a heated mirror-finished metal surface. there are made at the solidification method, the glossy layer coating liquid BET specific surface area of 55m ² / g~80m is θ- alumina or the θ- alumina and BET specific surface area is ² / g as the pigment 55m ² / g containing a mixture of certain γ- alumina ~80m 2 ^/ g, and containing a polyvinyl alcohol and silanol-modified polyvinyl alcohol in the binder, contained in the silanol-modified polyvinyl alcohol Inkjet recording cast-coated paper for postcard applications having a rear surface, wherein 0.1 to 10 parts by weight der Rukoto to the glossy surface and address printing on but pigment 100 parts by weight. ” The postcard having a glossy surface and a back surface for address printing according to claim 1, wherein the content of the binder in the coating liquid is 5 to 30 parts by weight with respect to 100 parts by weight of the pigment. ink-jet recording cast-coated paper applications. 3. A cast for postcard use for postcards having a glossy surface and a back surface for address printing according to claim 1, wherein the binder in the coating liquid contains a cationic acrylic resin. Coated paper. The glossy surface according to any one of claims 1 to 3, wherein the cationic acrylic resin of the binder in the coating liquid is a cationic acrylic silicone resin ; Cast coated paper for inkjet recording for postcard use . 5. A cast-coated paper for ink-jet recording for postcard use, having a glossy surface and a back surface on which address printing is carried out, containing a boron compound as a coagulant.