JP4338580B2 - Glossy paper for inkjet recording - Google Patents

Description

  The present invention relates to glossy paper for ink-jet recording, and more particularly to a recording paper having excellent print surface gloss 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. 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 dedicated media are further classified into matte and glossy media from the surface state. The latter glossy media is used when image quality closer to silver halide photography is required. The properties required for these glossy media are other than those described above.
(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 white paper portion is high.

  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). There are a method of forming an ink receiving layer by a casting method and imparting gloss to the surface, and a method of forming an ink receiving layer on a photographic paper base.

  In general, the former (a) ink absorbency is easier to control than the latter, but (d) dot roundness, image reproducibility, (f) image area, glossiness of blank paper, and quality compared to the latter. 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 by defining the average roughness, glossiness and air permeability of the recording paper on the surface of the recording layer, an inkjet recording paper having high surface smoothness and excellent image quality can be obtained (patent) Reference 1).

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

  However, in this case, if the number of cracks is too small, the glossiness is increased, but the ink absorbability is also lowered. Furthermore, there is also a proposal of an ink jet recording sheet containing a pearl necklace-shaped colloidal silica (see 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 any case, there is currently no recording medium having glossy image quality and uniform glossiness in glossy paper for inkjet recording manufactured by the casting method, which exceeds that of a medium manufactured using a photographic paper substrate or a film substrate. is there.
JP-A-6-72017 No. 0008-0011 Japanese Laid-Open Patent Publication No. 11-348416 Japanese Patent Laid-Open No. 12-108506

  The present invention is a glossy paper for ink-jet recording produced by a casting method, which is a problem of the above-mentioned prior art, has a high gloss while having good ink absorbability, and also has a surface strength on the surface of the glossy expression layer. An object of the present invention is to provide a recyclable recording medium that is excellent, has an image quality comparable to that of a medium produced using a photographic paper substrate or a film substrate, and a uniform gloss.

That is, according to the present invention, at least one ink receiving layer is provided on at least one side of a substrate, and after applying a coating liquid containing a pigment and a binder as a gloss developing layer on the ink receiving layer, the coating is applied. A cast coated paper obtained by pressure-bonding the coated layer to a heated mirror-finished metal surface while the coated layer is in a wet state. Aggregation in which the working fluid contains only colloidal silica as a pigment , non-spherical colloidal silica as the colloidal silica, and a plurality of primary particles having a particle diameter of 5 to 100 nm are randomly bonded as the non-spherical colloidal silica. shape containing secondary particles having a particle size of 50~800nm with, and polyvinyl alcohol containing 3 to 15 parts by weight per 100 parts by weight of the pigment in the binder, the poly 5-100% by weight of alkenyl alcohol is polyvinyl alcohol of saponification degree 78 to 97 mol%, higher degree of saponification of the remaining polyvinyl alcohol than 97 mol%, and, at 20 ° glossiness pursuant to JIS Z 8741 is 20% or more The present invention relates to a glossy paper for ink-jet recording.
The following are advantageous embodiments of the invention:
(1) The content of the binder in the glossy layer coating liquid is 5 to 30 parts by weight with respect to 100 parts by weight of the pigment.
(2) A cationic acrylic resin is contained in the binder in the glossy layer coating liquid.
(3) The cationic acrylic resin is a cationic acrylic silicone resin.
(4) Contains a boron compound as a coagulant.

  By adopting such a configuration, the glossy paper for ink-jet recording of the present invention is a glossy paper for ink-jet recording manufactured by the casting method, but has a very good surface glossiness, ink absorbability and surface strength at a high level. It is a thing which has favorable color development property, making balance. 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.

The present invention is described in further detail below.
Colloidal silica is usually spherical or nearly spherical. Spherical colloidal silica has a high surface strength and is easily glossy, but has poor ink absorbability, making it 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. The pigment used in the glossy layer of the present invention always contains colloidal silica having an aggregate shape in which a plurality of particles are randomly bonded. By using colloidal silica having an aggregate shape, it is possible to balance ink absorbency and glossiness at a high level. The amount of this pigment necessarily contained is preferably 20% by weight or more in the pigment. Alternatively, other pigments present may be spherical colloidal silica or pearl necklace colloidal silica. If the amount of colloidal silica having an agglomerated shape is less than 20% by weight, ink absorbability may be insufficient.

  In addition, JIS Z 8741 stipulates that the glossy index is measured at an incident / reflection angle of 75 °, but when observing a recording paper on which a normal image is formed, it is observed in a state close to perpendicular to the paper. In many cases, the glossiness at 75 ° does not necessarily reflect the actual glossiness. Therefore, in the present invention, the glossiness at 20 °, which is closer to actuality, is defined. If the glossiness is 20 ° or more at 20 ° glossiness, it can be said that the glossiness is also good.

  The aggregate-shaped colloidal silica used in the present invention refers to an amorphous aggregate in which a plurality of primary particles having a spherical shape or a nearly spherical shape are randomly bonded. The size of the aggregate is not particularly limited, but 5 to 100 nm is suitable for the primary particles, and about 50 to 800 nm is suitable for the aggregate. If the primary particles are too fine, the stability as an aggregate may be deteriorated. If the primary particles are too large, the particle diameter as an aggregate will be too large. Therefore, the primary particle is preferably about 5 to 100 nm. If the aggregate is too small, the ink absorbability is deteriorated, and if it is too large, problems such as a decrease in image density occur. Therefore, about 50 to 800 nm is appropriate.

  The aggregate-shaped colloidal silica used in the present invention can be obtained by various methods. In the present invention, the colloidal silica can be obtained by any method as long as the colloidal silica has an aggregate shape. Can be used for invention.

  In the glossy layer of the present invention, one or more known pigments can be appropriately selected and used in addition to the aggregated colloidal silica as long as the effects of the present invention are not impaired. Examples of such pigments include synthetic silica, alumina, alumina-doped silica, and spherical colloidal silica, but are not particularly limited.

In the present invention, the binder used for the glossy layer contains polyvinyl alcohol having a saponification degree of 97 mol% or less. By containing polyvinyl alcohol having a saponification degree of 97 mol% or less, preferably 70 to 96 mol%, more preferably 78 to 95 mol%, the surface has a high coagulation force while balancing ink absorbency and glossiness at a high level. The strength can be increased. Although details are not clear, in the case of only polyvinyl alcohol having a saponification degree higher than 97 mol%, the coagulation force is weak, and thus the surface strength of the glossy layer may be deteriorated. Therefore, in such a case, the object of the present invention can be achieved by mixing polyvinyl alcohol having a smaller saponification degree. When two or more kinds of polyvinyl alcohols having different saponification degrees are contained, the polyvinyl alcohol having a saponification degree of 97 mol % or less is preferably in the range of 5 to 100% by weight based on the total polyvinyl alcohol. The total amount of polyvinyl alcohol used is preferably 1 to 30 parts by weight, particularly preferably 2 to 20 parts by weight, especially 3 to 15 parts by weight, based on 100 parts by weight of the pigment.

  Furthermore, as a binder that can be used in a small amount in combination with these polyvinyl alcohols, preferably 0 to 20 parts by weight with respect to 100 parts by weight of the pigment, polyvinyl acetal, oxidized starch, etherified starch, carboxymethyl cellulose, hydroxyethyl cellulose, Casein, gelatin, soybean protein, polyethylene imide resin, polyvinyl pyrohydrin resin, polyacrylic acid or copolymers thereof, maleic anhydride copolymer, acrylamide resin, acrylate resin, polyamide resin, polyurethane Resins, polyester resins, polyvinyl butyral resins, alkyd resins, epoxy resins, epichlorohydrin resins, urea resins, melamine resins, styrene-butadiene copolymers, methyl methacrylate-butadiene copolymers, polymers Resin of acrylic polymer latexes such as polymers or copolymers of lauric acid ester, methacrylic acid ester, vinyl polymer latexes such as acrylic silicone resin, styrene-acrylic resin, ethylene-vinyl acetate copolymer Although there is no particular limitation, the class can be exemplified.

  The amount of the binder used is determined in consideration of the printability of the recording medium, the strength of the glossy layer, and the paint liquid property. 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.

  Furthermore, it is preferable to contain a cationic acrylic resin in the binder. Since the acrylic resin has high transparency, it is difficult to impair the transparency of the coating layer, and it is possible to obtain an image with good image clarity. Moreover, since it is excellent in light resistance, the storage performance as a recording sheet can be improved. Furthermore, among the acrylic resins, it is preferable to use a cationic acrylic silicone resin having a silyl group because the transparency of the coating layer is increased and the image clarity is further improved.

  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 paint for forming the glossy layer of the present invention, a known coating machine such as an air knife, roll coater, reverse roll coater, bar coater, comma coater, blade coater or the like is used. Coating amount 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. These various conditions need to be optimized by obtaining optimum conditions according to the equipment and paint used.

  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 raised.

  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, soybean protein, polyethylene imide resin, polyvinyl pyrohydrin resin , Polyacrylic acid or its copolymer, maleic anhydride copolymer, acrylamide resin, acrylate ester 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 coating liquid property. Usually, it is added in the range of about 1 to 200 parts by weight, preferably about 5 to 100 parts by weight with respect to 100 parts by weight of the pigment.

  In the present invention, it is preferable to add a cationic polymer in addition to the above pigments and binders. 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 PVA, amino acid type amphoteric surfactant, betaine type compound, other quaternary ammonium salts, polyamine, etc. 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 when 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 fuel, it is desirable to use ECF pulp or TCE pulp with 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.

A high-quality paper having a basis weight of 160 g / m ² surface-treated with oxidized starch, 100 parts by weight of synthetic silica (Mizukasil P-78A, manufactured by Mizusawa Chemical Co., Ltd.), a polyvinyl alcohol having a saponification degree of 98 mol% and a polymerization degree of 1700 10 parts by weight of alcohol (PVA117: manufactured by Kuraray Co., Ltd.), 40 parts by weight of ethylene-vinyl acetate (Polysol EVA AD-6: manufactured by Showa Kogyo Co., Ltd.), 30 parts by weight of cationic polymer (Smileys resin 1001: manufactured by Sumitomo Chemical Co., Ltd.) The coating solution with a solid content of 16% was coated and dried with an air knife coater so that the dry coating amount was 10 g / m ^2, and the ink receiving layer was coated. Next, 100 parts by weight of colloidal silica (HS-M-20, primary particle diameter 25 nm, aggregate particle diameter 280 nm: manufactured by Nissan Chemical Industries, Ltd.) having an aggregate shape as a pigment of the glossy layer coating material, and a saponification degree of 78 mol% Thus, a coating solution having a solid content of 20% was obtained using 10 parts by weight of polyvinyl alcohol having a polymerization degree of 2000 (PVA420: manufactured by Kuraray Co., Ltd.) and 1 part by weight of a polyethylene emulsion (SN coat 287: manufactured by San Nopco) as a release agent. . This coating solution was coated so that the Ze'inuinuriko weight 10 g / m ² by air knife coater, followed after performing the coating to coagulated sodium 3% aqueous boric acid, obtained coating layer While the surface was wet, it was pressure-bonded to a cast drum having a surface temperature of 100 ° C. to prepare glossy paper for ink jet recording.

  The same conditions as described in Example 1 were used except that 10 parts by weight of polyvinyl alcohol (PVA235: manufactured by Kuraray Co., Ltd.) having a saponification degree of 87 mol% and a polymerization degree of 3500 was used as a binder for the glossy layer paint in Example 1. A glossy paper for ink jet recording was prepared.

The same conditions as described in Example 1 were used except that 10 parts by weight of polyvinyl alcohol (PVA617: manufactured by Kuraray Co., Ltd.) having a saponification degree of 95 mol% and a polymerization degree of 1700 was used as a binder for the glossy layer coating material in Example 1. A glossy paper for ink jet recording was prepared.

In Example 1, 5 parts by weight of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) having a saponification degree of 98 mol% and a polymerization degree of 1700 as a binder of the glossy layer coating material, and a polyvinyl alcohol having a saponification degree of 87 mol% and a polymerization degree of 3500 ( Glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1 except that PVA235 (manufactured by Kuraray Co., Ltd.) was changed to 5 parts by weight.

  A glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1 except that the polyvinyl alcohol in the glossy layer coating material was changed to 5 parts by weight in Example 1.

  Example 1 except that colloidal silica having an aggregate shape (HS-L, primary particle diameter 47 nm, aggregate particle diameter 285 nm: manufactured by Nissan Chemical Industries, Ltd.) was used as the pigment of the glossy layer coating material in Example 1. A glossy paper for ink-jet recording was prepared under the conditions described in 1.

  In Example 1, 10 parts by weight of polyvinyl alcohol (PVA420: manufactured by Kuraray Co., Ltd.) having a saponification degree of 78 mol% and a polymerization degree of 2000 as a binder for the glossy layer coating material, a cationic acrylic silicone resin (Aquabrid 922: Daicel Chemical Industries) A glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1 except that the amount was 20 parts by weight.

  In Example 1, 10 parts by weight of polyvinyl alcohol (PVA420: manufactured by Kuraray Co., Ltd.) having a saponification degree of 78 mol% and a polymerization degree of 2000 as a binder for the glossy layer coating composition, cationic styrene-acrylic resin (Pascol JK718: Meisei Chemical Industry) A glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1 except that the amount was 20 parts by weight.

Colloidal silica having an aggregate shape as a pigment of the glossy layer coating material in Example 1 (HS-M-20, primary particle diameter 25 nm, aggregate particle diameter 280 nm: manufactured by Nissan Chemical Industries, Ltd.), spherical colloidal silica (Ludox TMA: manufactured by Grace Devison) 20 parts by weight, and as a binder, 5 parts by weight of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) with a saponification degree of 98 mol% and a polyvinyl alcohol with a saponification degree of 87 mol% and a polymerization degree of 3500 5 parts by weight of alcohol (PVA235: manufactured by Kuraray Co., Ltd.), 1 part by weight of a polyethylene emulsion (SN coat 287: manufactured by San Nopco) as a release agent, and 5 parts of a cationic polymer (Papiogen P-105: manufactured by Senka) are used. A coating solution having a solid content of 20% was obtained. The coating solution was coated with an air knife coater so that the dry coating amount was 10 g / m ^2, and then solidified by applying a 3% aqueous solution of sodium borate, and then the obtained coating layer While the surface was wet, it was pressure-bonded to a cast drum having a surface temperature of 100 ° C. to prepare glossy paper for ink jet recording.

  In Example 9, colloidal silica (HS-M-20, primary particle size 25 nm, aggregate particle size 280 nm: manufactured by Nissan Chemical Industries, Ltd.) having an aggregate shape as a pigment of the glossy layer coating material, pearl necklace shape A glossy paper for ink-jet recording was prepared under the same conditions as described in Example 9 except that 20 parts by weight of colloidal silica (Snowtex PS-SO: manufactured by Nissan Chemical Industries, Ltd.) was used.

In Example 9, as a binder for the glossy layer coating material, polyvinyl alcohol (PVA235: Kuraray Co., Ltd.) having a saponification degree of 98 mol% and a polymerization degree of 1700 polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) and a saponification degree of 87 mol% and a polymerization degree of 3500. 5 parts by weight Ltd.), cationic acrylic silicone resin (Aquabrid 922 except that manufactured by Daicel Chemical Industries, Ltd.) was used as a 10 parts by weight was prepared for ink jet recording glossy paper in conditions as described in example 9.

Comparative Example 1:
A glossy paper for inkjet recording was prepared under the same conditions as described in Example 1, except that the ink receiving layer was not applied in Example 1.

Comparative Example 2:
A glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1 except that 100 parts by weight of spherical colloidal silica (Ludox HS-40: manufactured by Grace Devison) was used as a pigment for the glossy layer coating material in Example 1. .

Comparative Example 3:
Inkjet printing was performed under the same conditions as described in Example 1, except that 10 parts by weight of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) having a saponification degree of 98 mol% and a polymerization degree of 1700 was used as a binder for the glossy layer coating material in Example 1. Glossy paper for recording was made.

Comparative Example 4:
In Example 1, except that 10 parts by weight of polyvinyl alcohol (PVA120: manufactured by Kuraray Co., Ltd.) having a saponification degree of 98 mol% and a polymerization degree of 2000 was used as a binder for the glossy layer coating composition, ink jet printing was performed under the same conditions as described in Example 1. Glossy paper for recording was made.

Comparative Example 5:
Inkjet recording was carried out under the same conditions as described in Example 1, except that 10 parts by weight of polyvinyl alcohol (PVA105: manufactured by Kuraray Co., Ltd.) having a saponification degree of 98 mol% and a polymerization degree of 500 was used as a binder for the glossy layer coating material in Example 1. Glossy paper was made.

Comparative Example 6:
In Example 1, glossy paper for ink-jet recording was prepared under the same conditions as described in Example 1, except that the coagulant was not used and the cast drum was pressure-bonded at the time of applying the glossy layer.

Comparative Example 7:
The conditions as described in Example 1 except that after the glossy layer was applied in Example 1, the glossy layer was dried and then rewetted with a 3% aqueous solution of sodium borate as a rewetting liquid and pressure-bonded to the cast drum. Thus, glossy paper for ink-jet recording was prepared.

The following tests were performed on the glossy paper for ink jet recording, and the 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, the color is sunk, and there is a problem in practical use.
X: The recorded image is unclear, the color is sunk, and cannot be used practically.

(2) Ink absorbability:
CMYK and RGB solids (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) Glossiness:
The specular glossiness of the surface of the glossy layer was measured. The glossiness was measured with a glossiness meter (gross meter GM26D: manufactured by Murakami Color Research Laboratory Co., Ltd.) according to JIS Z 8741 at an incident / reflection angle of 20 °. As the evaluation, when the gloss value is 20% or more, the glossiness is excellent, and when it is less than 20%, the glossiness is poor and inferior.

(4) Surface strength:
Using a Gakushin type fastness tester (manufactured by Tester Sangyo Co., Ltd.), the surface was rubbed 20 times under the condition of a load of 300 g, and the degree of surface strength (scratched, powder falling) of the glossy layer was visually determined.
A: Good with no scratches or powder falling.
○: Scratches and powder fall are not noticeable and good.
(Triangle | delta): A crack and powder fall are conspicuous and have a problem practically.
X: Scratches and powder fall off are conspicuous and impractical.

  As is apparent from Table 1, the glossy layer provided on one or more ink-receiving layers contains colloidal silica having a shape in which a plurality of particles are randomly aggregated as a pigment, and the binder contains It can be seen that Examples 1 to 11 containing polyvinyl alcohol having a saponification degree of 97 mol% or less are superior in printing performance, gloss and surface strength compared to Comparative Examples 1 to 7. In Examples 7, 8 and 11 in which a cationic acrylic resin was used in combination in the binder, it was found that the image sharpness and the surface strength of the glossy surface were particularly excellent. In particular, in Examples 7 and 11 using an acrylic silicone resin, the glossiness is as high as 28, which proves that the use of the acrylic silicone resin achieves a high glossiness. In the case of Comparative Example 6, which is the same as Example 1 except that it does not contain a boron compound as a coagulant, not only the glossiness is low, but also the image clarity and gloss surface strength are poor, and boron as the coagulant. It reveals the effect achieved by using the compound.

Claims (5)

One or more ink-receiving layers are provided on at least one surface of the substrate, and after applying a coating liquid containing a pigment and a binder as a gloss developing layer on the ink-receiving layer, the coating layer is in a wet state. A cast-coated paper in which the coating layer is pressure-bonded to a heated mirror-finished metal surface, and the cast-coating process is performed by a coagulation method, and the gloss-developing layer coating solution is colloidal as a pigment. contain only silica, contain non-spherical colloidal silica as the colloidal silica, and 50 with aggregated form a plurality of primary particles with a particle size of 5~100nm as non spherical colloidal silica is bonded randomly contains secondary particles of particle diameter of 800 nm, and the polyvinyl alcohol in the binder contained 3 to 15 parts by weight per 100 parts by weight of pigment, 5 of the polyvinyl alcohol Is 100% by weight a degree of saponification of 78 to 97 mol% of polyvinyl alcohol, and wherein the degree of saponification of the remaining polyvinyl alcohol is higher than 97 mol%, and, 20 ° gloss equivalent to JIS Z 8741 is 20% or more Glossy paper for inkjet recording. The glossy paper for ink-jet recording according to claim 1, wherein the content of the binder in the glossy layer coating liquid is 5 to 30 parts by weight with respect to 100 parts by weight of the pigment. The glossy paper for ink jet recording according to claim 1 or 2, wherein the binder in the glossy layer coating liquid contains a cationic acrylic resin. The glossy paper for ink jet recording according to claim 3, wherein the cationic acrylic resin is a cationic acrylic silicone resin. The glossy paper for ink-jet recording according to any one of claims 1 to 4, wherein the coagulant contains a boron compound.