JP2010100001A - Glossy paper for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glossy paper for inkjet recording which has glossy feeling equal to silver halide photograph while having satisfactory ink absorbing property and also has excellent emboss suppressive effect on a gloss developing layer. <P>SOLUTION: The glossy paper for inkjet recording has a one or more ink receiving layers provided on at least one surface of a paper substrate having air permeability and the gloss developing layer containing a pigment and a binder and provided on the ink receiving layer by a cast coat method, wherein the specific volume of the glossy paper for inkjet recording is 1.05-1.30 cm<SP>3</SP>/g, the thickness of the glossy paper for inkjet recording is 150-300 μm and the compressive hardness of the gloss paper for inkjet recording when continuously pressed by a metal made indenter having 10 mm tip diameter at 0.20 mm/sec velocity and 5-500 gf/cm<SP>2</SP>pressure from the upper side of the surface opposite to the surface on which the gloss developing layer is provided is ≥0.38. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to glossy paper for ink-jet recording, and in particular, has a gloss feeling similar to that of a silver salt photograph, has a printing quality close to a photographic image quality, and performs letterpress printing on the opposite side of the surface provided with a glossy expression layer. The present invention also relates to a glossy paper for ink jet recording that can suppress deformation of the glossy layer as much as possible.

The ink jet recording method is a method for recording by ejecting ink droplets and depositing them on a recording medium to form dots. In recent years, recording with high print quality has become possible due to technological advances in ink jet printers, inks, and recording media. As an element required for an inkjet recording medium,
(A) fast ink absorption and drying, (b) high printing density, (c) no dot spread, whiskers, or both. If ordinary plain paper has a certain size or more, it can be expected to have a certain level of print quality with less blur. 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 the medium dedicated for ink jet recording, a paper and / or film as a support, and a pigment coating layer mainly composed of a pigment and a binder or a resin coating layer not containing a pigment is provided on the surface. Used a lot.

Inkjet dedicated media are further classified into matte and glossy media from the surface state. The latter glossy medium is used when image quality closer to silver halide photography is required. The properties required for these glossy media include (d) high dot roundness and good image reproducibility in addition to the above properties (e) good water resistance and light fastness (f). For example, 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 absorbability and drying properties of (a). Are a method of forming an ink receiving layer by a cast coating method to give gloss to the surface, and a method of forming an ink receiving layer and a gloss developing layer by a multilayer coating method 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 portion, and quality. It is inferior to the latter. When the ink-receiving layer is formed on the surface of the photographic paper base, since the polyethylene film layer is formed on the paper base as generally called RC paper (resin-coated paper), the film surface Is smooth, the surface of the ink receiving layer is also smooth, and a glossy surface is easily formed.

  However, the overall cost needs to be increased in order to increase ink absorbency, and since the base material itself is more expensive than paper, it is higher than the former glossy media by the cast coating method. Become. In addition, when it is discarded, there is a problem that it cannot be recycled because it is a composite material.

  The glossy paper for ink jet recording by the cast coating 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 inkjet 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 glossiness increases while 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, it is said that the use of pearl necklace-shaped colloidal silica is effective in improving printing quality, particularly ink absorbability.

  Furthermore, recently, 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 glossiness similar to that of a silver salt photograph (for example, patents). (Ref. 4).

  An ink jet recording medium having glossiness very close to that of a silver salt photograph as in the above-mentioned document has been proposed as an alternative to a silver salt photograph, but is increasingly used as a postcard application. In the case of postcard use, a design image such as a postal frame is often offset printed on the surface opposite to the surface on which the glossy expression layer is provided. Also, for example, in the case of New Year's card postcards, letterpress printing is often performed when printing the number of New Year's cards, and this printed part is raised as a concave / convex pattern on the surface of the glossy expression layer, which is a drawback. There is a case. (Hereinafter, the phenomenon that the concavo-convex pattern appears on the surface of the glossy layer is abbreviated as “emboss”.)

  The embossing as described above tends to be more conspicuous in the glossy paper for ink-jet recording having a glossy expression layer aimed at replacing silver salt photography as compared with the so-called matte ink-jet recording medium. This is because the pigment used in the glossy layer often has a smaller particle size than the pigment used in the so-called matte ink jet recording paper, and therefore the surface inevitably becomes highly smooth and glossy. For this reason, even slight irregularities are visible to the human eye. Therefore, it can be said that this embossing problem is more serious in the ink jet recording paper having the glossy expression layer than in other ink jet recording papers.

  Therefore, as a prior art, a technique is disclosed in which embossing is suppressed by defining a compression rate in the thickness direction of the surface opposite to the surface on which the glossy expression layer of glossy paper for inkjet recording is provided (for example, Patent Document 5). See).

Japanese Patent Laid-Open No. 06-72017 JP-A-11-348416 JP 2000-108506 A Japanese Patent Laid-Open No. 06-055829 JP 2008-114602 A

  However, in the technique disclosed in Patent Document 5, since an attempt is made to solve the problem only by defining the compression ratio, the embossing problem cannot be solved completely.

  For glossy paper for inkjet recording with high gloss aimed at replacing silver salt photography, the embossing phenomenon tends to be remarkable when compared to inkjet recording paper with low gloss such as matte inkjet paper. However, it is very difficult to achieve both glossiness equivalent to silver halide photography and suppression of embossing, and it remains as a technical problem.

  Therefore, the results of research on the embossing suppression technique by the present inventors have led to the conclusion that the above proposals cannot be completely satisfied with the requirement for solving the embossing problem of ink jet recording paper having a glossy expression layer. In view of such a current situation, there is no recording paper having excellent image quality and uniform glossiness, and having both excellent embossing resistance in glossy ink jet recording paper having a glossy expression layer. Is the current situation.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet recording glossy paper that has a high gloss feeling comparable to that of a silver salt photograph and further suppresses embossing, while having good ink absorption, which is a problem of the prior art. It is to provide glossy paper for recording.

The present inventors have found that the above problems can be solved by defining the specific volume, thickness and compression hardness of glossy paper for inkjet recording, and have completed the present invention. That is, the glossy paper for ink-jet recording according to the present invention has a glossy paper comprising at least one ink receiving layer on at least one side of a gas-permeable paper base, and containing a pigment and a binder on the ink receiving layer. A glossy paper for ink-jet recording provided with a cast layer method, wherein the glossy paper for ink-jet recording has a specific volume of 1.05 to 1.30 cm ³ / g, and the glossy paper for ink-jet recording And a metal indenter having a tip diameter of 10 mm from above the surface opposite to the surface on which the glossy layer is provided is 5 to 800 gf / mm in the thickness direction of the sample at a rate of 0.20 mm / sec. The compression hardness is 0.38 or more when continuously pressed at a pressure in the range of cm ² and pressed.

  In the glossy paper for ink jet recording according to the present invention, the Canadian standard freeness (CSF) of the pulp used for the paper substrate is preferably 450 to 600 ml. Since the specific volume of glossy paper tends to be high, embossing can be further suppressed.

  In the glossy paper for ink-jet recording according to the present invention, it is preferable that the paper substrate is made by multi-layer paper making of two or more layers. Embossing can be further suppressed.

  In the glossy paper for ink jet recording according to the present invention, the cast coating method is preferably a coagulation method. In particular, it is excellent in productivity and excellent in glossiness and image sharpness.

  In the glossy paper for ink-jet recording according to the present invention, the glossy expression layer preferably contains silica having an average secondary particle diameter of 500 nm or less, alumina having an average secondary particle diameter of 500 nm or less, or both. . In particular, it has excellent gloss and ink absorbability.

  The glossy paper for ink jet recording according to the present invention includes a case where it is processed into a postcard. The glossy paper for ink-jet recording in which the embossing phenomenon is greatly suppressed is particularly suitable for use as a postcard application.

  The glossy paper for ink-jet recording according to the present invention includes a case where the glossy paper for ink-jet recording is used in a postcard application in which letterpress printing is performed on the surface opposite to the surface on which the glossy expression layer is provided. The glossy paper for ink-jet recording in which the embossing phenomenon is greatly suppressed is particularly preferably used by letterpress printing on the opposite surface of the glossy expression layer.

  The glossy paper for ink-jet recording of the present invention can suppress embossing as much as possible while satisfying both surface glossiness and ink absorbability at a high level. In particular, glossy paper for inkjet recording with high glossiness is often used for postcard applications, and from the viewpoint of productivity during letterpress printing processing, the level of embossing suppression is likely to increase more and more easily. As estimated, the significance of the present invention is great.

  Next, the present invention will be described with reference to an embodiment. However, the embodiment is an example of the configuration of the present invention, and the present invention is not limited to this embodiment. In addition, the embodiment may be modified as long as the effects of the invention are achieved.

  Examples of the pigment contained in the glossy coating layer coating liquid for glossy glossy inkjet recording paper include, for example, spherical colloidal silica, aggregated colloidal silica in which a plurality of spherical colloidal silicas are combined, gas phase method silica, alumina, and the like. Is generally used. Since these pigments are used for the purpose of increasing gloss, the selected pigments are very often small particles having an average secondary particle diameter of less than 1 μm. On the other hand, since the pigment used for the ink receiving layer of a dull inkjet recording paper, so-called mat-like inkjet recording paper, does not need to have high gloss, the average secondary particle diameter is relatively large of about 1 μm to 30 μm. Particles are used. Therefore, the coating layer of the inkjet recording medium that necessarily has gloss has high smoothness as compared with matte paper, and even a slight unevenness tends to be visible to human eyes.

  Therefore, regarding glossy paper for ink-jet recording, it is extremely difficult to improve the embossing resistance, so that the establishment of an embossing suppression technique inevitably remains as a problem.

In the present invention, in order to achieve the above object, at least one ink receiving layer is provided on at least one side of a gas-permeable paper base material, and a gloss expression containing a pigment and a binder on the ink receiving layer is provided. The glossy paper for ink jet recording provided with a layer by a cast coating method, wherein the specific volume of the glossy paper for ink jet recording is 1.05 to 1.30 cm ³ / g, and the glossy paper for ink jet recording A metal indenter having a thickness of 150 to 300 μm and a tip diameter of 10 mm from above the surface opposite to the surface on which the glossy layer is provided is 5 to 800 gf / cm in the thickness direction of the sample at a speed of 0.20 mm / sec. It is essential that the compression hardness is 0.38 or more when continuously pressed with a pressure in the range of ² .

According to the research results of the present inventors, it has been found that the specific volume of glossy paper for ink jet recording affects the embossing. The specific volume here is obtained by the following calculation (Equation 1).
(Expression 1) Specific volume (cm ³ / g) = thickness (μm) ÷ basis weight (g / m ² )
When the specific volume of glossy paper for ink-jet recording is less than 1.05 cm ³ / g, the embossing deteriorates, and when it exceeds 1.30 cm ³ / g, the surface strength of the surface opposite to the glossy layer is lowered, and address side printing, etc. When performing offset printing, there are cases where defects such as those for paper occur. Here, the reason why the embossing deteriorates when the specific volume is low is not clear, but it is considered that the cushioning property of the base paper is lowered. Preferably, it is 1.10-1.27 cm < ³ > / g, More preferably, it is the range of 1.15-1.25 cm < ³ > / g. Since the specific volume is greatly influenced by the paper base material, it is necessary to adjust the specific volume to an appropriate specific volume at the time of paper base papermaking. In order to set the specific volume of glossy paper for ink-jet recording within the above range, the specific volume of the paper substrate is preferably 1.05 to 1.40 cm ³ / g. More preferably, the specific volume of the paper substrate is 1.10 to 1.30 cm ³ / g. In addition, the specific volume of the glossy paper for ink jet recording can be adjusted appropriately by a process such as a calendar process when the ink receiving layer is applied or when the glossy layer is applied.

  In the present invention, it is essential that the glossy paper for inkjet recording has a thickness of 150 to 300 μm. If it is less than 150 μm, the thickness is too thin and the embossing deteriorates. If it exceeds 300 μm, it is too thick and adversely affects the printer transportability. Preferably it is 170-280 micrometers. More preferably, it is 180-250 micrometers. Similar to the specific volume of glossy paper for ink jet recording, the thickness is greatly affected by the paper substrate, and therefore it is necessary to adjust the thickness to an appropriate thickness when the paper substrate is made. It is preferable that the thickness of the paper substrate is 130 to 290 μm. More preferably, the thickness of the paper substrate is 140 to 280 μm. In addition, the thickness can be appropriately adjusted by a treatment such as a calendar treatment when the ink receiving layer is applied, the glossy layer is applied, or both.

Further, in the present invention, a metal indenter having a tip diameter of 10 mm is continuously pressed from above the opposite surface of the glossy layer at a speed of 0.20 mm / second in the thickness direction of the sample at a pressure in the range of 5 to 800 gf / cm ^2. It is essential that the compression hardness when pushed in is 0.38 or more. The present inventors considered that the compression behavior in the thickness direction of glossy paper for ink jet recording was important, and as a result, the compression hardness specified in the present invention was set to 0.38 or more to achieve a glossy expression layer during letterpress printing. It was found that embossing can be suppressed. This compression hardness is suitable for capturing the characteristics of the process of being pressed by the pressurizer, and indicates how to deform with respect to the force compressed in the thickness direction. Those having a low compression hardness value are likely to be deformed by compression, and it is considered that embossing of the glossy layer tends to occur. In addition, it is considered that when the numerical value of the compression hardness is high, deformation during the compression process is suppressed and embossing on the glossy layer is less likely to occur. That is, in this invention, generation | occurrence | production of the embossing to a glossiness expression layer is suppressed by prescribing | compressing compression hardness to 0.38 or more. The compression hardness has no upper limit, but is 0.80, for example. The compression hardness is preferably 0.40 or more, and more preferably 0.43 or more.

Further, the compression hardness measurement method according to the present invention is a state in which the surface opposite to the surface provided with the glossy layer is fixed on the metal plate with a double-sided tape and is not affected by the curl of the paper. set. The sample is fixed on a sample table of a handy compression tester KES-G5 (manufactured by Kato Tech Co., Ltd.), and a pressurizer (with a metal ball having a diameter of 10 mm at the tip) is placed at a speed of 0.20 mm / second from above the sample Was pressed into the sample and pressurized. At this time, the pressure until the pressure of the pressurizer reached 5 to 800 gf / cm ² and the change in the depth of the pressure were measured, and the change was shown by the curve BA in FIG. 1 (B is A when the pressure is 5 gf / cm ^2. Indicates a pressure of 800 gf / cm ² ). A value obtained by dividing the area (a) surrounded by the curve BA, the straight line BC, and the straight line CA by the area of the triangle ABC having a right angle with the heel BCA shown in FIG. When expressed from FIG. 1, (a area / ΔABC area) = compression hardness. This “compression hardness” indicates that the value becomes closer to compression as the value approaches 1.00. This “compression hardness” is a dimensionless number.

  Furthermore, in the present invention, the Canadian Standard Freeness (CSF) of the pulp used for the paper substrate of the glossy paper for ink jet recording is preferably 450 to 600 ml. If the CSF is less than 450 ml, the air permeability resistance of the paper base material is high and cast coat productivity is poor, and if it exceeds 600 ml, the paper layer strength may be lowered. Preferably it is 470-580 ml, More preferably, it is 480-560 ml.

  Furthermore, in the present invention, it is preferable that the paper base of the glossy paper for ink-jet recording is made by multi-layer paper making of two or more layers. Compared with single-layer paper making (single-layer paper making), multilayer paper making can adjust the conditions such as filler type, filler ratio, paper strength, Canadian Standard Freeness (CSF), etc. for each layer. It is preferable that the thickness, specific volume and compression hardness of the material can be easily adjusted.

  Furthermore, in the present invention, the cast coating method is preferably a coagulation method. When the cast coating method is a coagulation method, it is possible to achieve a high level of glossiness, ink absorptivity, and image sharpness.

  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, and in the present invention, the solidification method is preferable. The coagulation method is a method in which a coating liquid for glossy layer is applied and the coagulating liquid is applied and coagulated while it is in a wet state, and pressed against a cast drum. In the coagulation treatment, it is important to select one that effectively coagulates with the binder component of the coating layer, and boron compounds are preferred in the present invention. More preferably, sodium borate or boric acid or a combination of both. A high concentration of the coagulating liquid is preferable because the coagulation force is increased and the surface strength is further improved. Furthermore, a cationic polymer for fixing the ink to the coagulation liquid can be added. High glossiness is achieved 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 pressure bonding, and the line speed. A glossy layer can be formed. These various conditions need to be optimized by obtaining optimum conditions according to the equipment and paint used.

  The glossy layer preferably contains polyvinyl alcohol as a binder and a boron compound. By containing polyvinyl alcohol and a boron compound, it is easy to achieve both color developability and surface strength. The content of polyvinyl alcohol in the glossy expression layer is preferably 1 part by mass to 30 parts by mass with respect to 100 parts by mass of the pigment in the glossy expression layer. If it is less than 1 part by mass, the surface strength may be inferior, and if it exceeds 30 parts by mass, the ink absorbency may be inferior. More preferably, it is 3 mass parts-20 mass parts. The polyvinyl alcohol that can be used in the present invention includes modified polyvinyl alcohols such as carboxyl-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, and cation-modified polyvinyl alcohol. Further, the content of the boron compound is preferably 5% by mass or more with respect to polyvinyl alcohol. If it is less than 5% by mass, the surface strength may be lowered. More preferably, it is 10 mass% or more. Although the kind of boron compound is not specifically limited, Sodium borate or boric acid or both are preferable.

  Examples of binders that can be used in combination with the polyvinyl alcohol that can be used in combination with the polyvinyl alcohol include polyvinyl acetal, oxidized starch, etherified starch, carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, soy protein, and polyethyleneimide. Resin, polyvinyl pyrohydrin resin, polyacrylic acid or copolymer thereof, 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 ester, methacrylic acid ester Acrylic polymer latex such as tellurium polymer or copolymer; vinyl polymer latex such as ethylene-vinyl acetate copolymer; copolymer resin of colloidal silica and acrylic; colloidal silica and styrene-acrylic. Examples of the resin such as a copolymer resin are not particularly limited as long as the effects of the present invention are not impaired.

  The gloss developing layer can further contain a cationic polymer. By containing a cationic polymer, it is possible to improve the water resistance of the printed portion. Examples of such cationic polymers include polyethyleneimine, epichlorohydrin-modified polyalkylamine, polyamine, 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, Rialylamine, 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, etc. are used It is done. The content of the cationic polymer is preferably 1 part by mass to 50 parts by mass with respect to 100 parts by mass of the pigment of the glossy layer. If the amount is less than 1 part by mass, the water resistance of the printed part may be reduced, and if it exceeds 50 parts by mass, the ink absorbability may be reduced.

  The glossy layer preferably contains silica having an average secondary particle diameter of 500 nm or less, alumina having an average secondary particle diameter of 500 nm or less, or both. By containing silica having an average secondary particle diameter of 500 nm or less, alumina having an average secondary particle diameter of 500 nm or less, or both, it is possible to achieve both glossiness and ink absorbability at a higher level. In order to further improve the glossiness, it is more preferable to contain silica having an average secondary particle diameter of 450 nm or less, alumina having an average secondary particle diameter of 450 nm or less, or both. When both silica and alumina are used, for example, the mass ratio is silica: alumina = 95: 5 to 5:95, preferably silica: alumina = 90: 10 to 10:90. In the present invention, the average secondary particle diameter is a value measured by a dynamic light scattering method (for example, DLS-6500, manufactured by Otsuka Electronics Co., Ltd.). In addition, since spherical colloidal silica (excluding aggregate colloidal silica) exists as primary particles without forming secondary particles, in the present invention, when spherical colloidal silica is used as silica, average secondary particles are used. The concept of silica having a diameter of 500 nm or less is treated as including spherical colloidal silica having an average primary particle diameter of 500 nm or less.

  Furthermore, the glossy layer includes a release agent, a dispersant, a thickener, an antiseptic, an antifoaming agent, a coloring dye, a coloring pigment, a fluorescent whitening agent, a water-resistant agent, a leveling agent, an antioxidant, Additives such as ultraviolet absorbers can be appropriately selected and added.

As coating methods of the coating liquid for forming the glossy layer, known coating machines such as an air knife coater, roll coater, reverse roll coater, bar coater, comma coater, blade coater, curtain coater, simultaneous multilayer coater, etc. Is used and there is no particular limitation. Amount of coating is, 3 to 20 g / ^{m 2} in terms of solid content, preferably in the range of 5 to 15 g / ^{m 2.} When the coating amount exceeds 20 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.

  Further, in the present invention, the glossy paper for ink jet recording according to the present invention is preferably used for postcard use. This is because the glossy paper that suppresses embossing as much as possible is preferably used for postcard use.

  Further, in the present invention, it is preferable that the glossy paper for ink jet recording according to the present invention is used for a postcard application in which letterpress printing is performed on the surface opposite to the surface provided with the glossy expression layer. This is because the glossy paper for ink-jet recording in which the embossing phenomenon is greatly suppressed is particularly suitable for use in relief printing on the opposite surface of the glossy expression layer.

  Further, according to JIS H 8686-2: 1999 “Analysis of anodic oxide film of aluminum and aluminum alloy” of gloss developing layer, the image clarity under conditions with an optical comb width of 2 mm and an incident reflection angle of 60 ° is 50% or more. It is preferable from the viewpoint of glossiness. More preferably, the image clarity is 55% or more. If the image clarity is 60% or more, it can be said that the glossiness is further improved. Here, the reason for changing the incident / reflective angle from 45 ° described in JIS to 60 ° is to facilitate evaluation of the difference in glossiness.

  In addition, calender treatment such as machine calendar, soft calender, super calender, etc. may be performed after the glossy expression layer is formed, and for curl adjustment, water, curl adjuster, etc. are applied to the back surface and humidified to curl. Adjustments can also be made.

  In the ink jet recording medium of the present invention, one or more ink receiving layers are provided below the glossy layer. The ink receiving layer is mainly composed of a white pigment and a binder component. The ink receiving layer may be a single layer or two or more layers in order to obtain a thickness. Even if two or more ink receiving layers are provided, there is no difference in performance from the single layer except for the influence on the thickness. In addition, an ink receiving layer and a glossy expression layer may be provided on both sides in order to support double-sided printing.

  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, and carbonate. White inorganic pigments such as zinc, calcium silicate, aluminum silicate, magnesium silicate, diatomaceous earth, aluminum hydroxide, magnesium hydroxide, satin white, synthetic silica, colloidal silica, and alumina, or organic such as acrylic-styrene, ethylene, vinyl chloride, nylon Pigment.

  The binder used in the ink receiving layer is polyvinyl alcohol, polyvinyl acetal, oxidized starch, etherified starch, carboxymethyl cellulose, hydroxyethyl cellulose, casein, gelatin, soy protein, polyethyleneimide resin, polyvinyl pyrohydrin resin, poly Acrylic 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 - resins of the vinyl polymer latexes such as vinyl acetate copolymer and the like, 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 1 to 200 parts by mass with respect to the pigment mass. Preferably, it is added in the range of about 5 to 100 parts by mass. If it is less than 1 part by mass, the coating layer strength may decrease. If it exceeds 200 parts by mass, the ink absorbability may decrease.

  In the present invention, it is preferable to add the cationic polymer exemplified above to the ink receiving layer in addition to the pigment and the binder. As an action of the cationic polymer, it reacts with an anionic component in the dye used in the ink to form a water-insoluble salt, so that the ink is more firmly fixed on the ink receiving layer, Water resistance is improved. Although content in an ink receiving layer is not specifically limited, It is used in 1-50 mass parts with respect to 100 mass parts of pigments. Preferably, it is added in the range of about 5 to 40 parts by mass. If the amount is less than 1 part by mass, the water resistance of the printed part may decrease. If it exceeds 50 parts by mass, the ink absorbability may be inferior.

  Other additives to be included in the ink receiving layer include antifoaming agents, lubricants, dispersants, wetting agents, fluorescent whitening agents, colored dyes, colored pigments, thickeners, preservatives, and water resistance as necessary. Agents, ultraviolet absorbers, antioxidants and the like can be used.

As a coating method of the coating liquid for forming the ink receiving layer, a known coating machine such as an air knife, a roll coater, a bar coater, a comma coater, a blade coater or a simultaneous multilayer coater is used. The coating amount is not particularly limited, but if the coating amount is too small, the ink absorbability is inferior, and therefore it is preferably 5 g / m ² or more in terms of solid content. Moreover, when there is too much coating amount, binder migration generate | occur | produces at the time of glossiness expression layer coating, and since there exists a possibility that the surface strength of a glossiness expression layer may fall, 25 g / m < ² > or less is preferable. More preferably 6~20g / ^{m 2.}

  Further, in order to obtain a certain smoothness after coating, the ink receiving layer can be processed by a known calendar device such as a super calendar, a machine calendar, or a soft calendar.

  As the paper substrate having air permeability used in the present invention, paper substrates such as high-quality paper, medium-quality paper, and white paperboard can be used. Acidic paper and neutral paper can also be used. In the present invention, it is desirable to use ECF (Elemental Chlorine Free) pulp or TCF (Totally Chlorine Free) pulp having a low chlorine content as a raw material pulp in consideration of the case of being recycled as fuel. As fillers to be used, known are heavy calcium carbonate, light calcium carbonate, magnesium carbonate, titanium oxide, synthetic silica, alumina, talc, calcined kaolin clay, kaolin clay, bentonite, zeolite, aluminum hydroxide, zinc oxide, etc. It is possible to use other pigments.

  In addition to the pulp and filler, known paper strength agents, sulfuric acid bands, yield improvers, sizing agents, dyes, fluorescent dyes, and other various papermaking chemicals are appropriately used in the paper stock. The preparation method, blending, and addition method of each papermaking chemical for each paper stock are not particularly limited as long as the effects of the present invention are not impaired. Moreover, it is possible to carry out paper making by applying a known paper machine such as a circular net paper machine, a long net paper machine, and a twin wire paper machine using the above-mentioned stock.

  In order to suppress excessive penetration of the glossy layer coating liquid, it is preferable to apply a known water-soluble polymer such as starch, polyvinyl alcohol, or polyacrylamide with a size press or the like. Moreover, it becomes possible to adjust to a desired specific volume and thickness by appropriately performing treatment with facilities such as a wet press and a soft calendar of a paper machine.

  EXAMPLES Next, although an Example is given and this invention is further explained in full detail, this invention is not limited to these examples. Further, “parts” and “%” shown in the examples represent solid mass parts and solid mass% unless otherwise specified.

Example 1:
As a paper base material, 100 parts of L-BKP (hardwood bleached kraft pulp) beaten to 480 ml of Canadian Standard Freeness (CSF), 5 parts of talc (trade name: T Light 83, manufactured by Taihei Talc Co., Ltd.) as an internal filler 3% sulfuric acid band, acidic rosin sizing agent (trade name: AL-120, manufactured by Seiko PMC) 0.25 part, cationized starch (trade name: Mermaid C-50, manufactured by Shikishima Starch) 1 0.0 part was added to prepare the stock, and paper was made by three-layer papermaking with a long paper machine, and then oxidized starch (MS # 3600, manufactured by Nippon Shokuhin Kako Co., Ltd.) was surface-treated with a size press. A high-quality paper having an amount of 180 g / m ² , a thickness of 216 μm, and a specific volume of 1.20 cm ³ / g was produced. Subsequently, 100 parts by mass of synthetic silica (Mizukasil P-78A, manufactured by Mizusawa Chemical Co., Ltd.), 10 parts by mass of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) as a binder, ethylene-vinyl acetate (Polysol EVA AD-10: Showa High) (Molecular Co., Ltd.) 40 parts by mass and cationic polymer (Papiogen P-105: Senka Co., Ltd.) 30 parts by mass were used to prepare a coating solution having a solid content of 22%, and this coating solution was completely removed with an air knife coater. The ink receiving layer was coated by applying and drying the fine paper so that the dry coating amount was 10 g / m ² . Next, 100 parts by mass of spherical colloidal silica (Adelite AT-20Q, average primary particle size 10 nm: manufactured by ADEKA) as a pigment to be included in the coating liquid for glossy layer coating, acrylic resin emulsion (Likabond ES-63 as a binder) : Chuo Rika Kogyo Co., Ltd.) 10 parts by mass, Silanol-modified polyvinyl alcohol (PVA-R1130: Kuraray Co., Ltd.) 3 parts by mass, and a polyethylene emulsion (SN coat 287: San Nopco) 1 part by mass as a release agent A coating solution of 18% was obtained. This coating solution was applied to the surface of the ink receiving layer with an air knife coater so that the dry coating amount was 9.6 g / m ^2, and then sodium borate 1.0%, cationic polymer (Smiles Resin 1001: manufactured by Sumitomo Chemical Co., Ltd.) After applying a mixed aqueous solution of 1.0% to a dry coating amount of 0.4 g / m ² and coagulating, the surface of the obtained coating layer was wet While being in the state, it was pressure-bonded to a cast drum having a surface temperature of 105 ° C., and after drying, the thickness was adjusted by a calendar process to prepare glossy paper for inkjet recording. The produced glossy paper for ink-jet recording had a basis weight of 200 g / m ² , a thickness of 240 μm, and a specific volume of 1.20 cm ³ / g.

Example 2:
In Example 1, as the glossy layer coating, the pigment was 50 parts by mass of alumina (PG-003, average secondary particle size 150 nm, crystal form -γ, θ mixture: manufactured by CABOT), gas phase method silica (Leolosil QS- 102, average secondary particle diameter 160 nm: manufactured by Tokuyama Corporation) Glossy paper for ink jet recording was produced under the same conditions as described in Example 1 except that the amount was 50 parts by mass.

Example 3:
In Example 1, colloidal silica (Snowtex HS-M-20, average secondary particle diameter 278 nm: Nissan Chemical Co., Ltd.) having an aggregate shape in which a plurality of primary particles are randomly combined as a pigment as a paint layer for gloss development. (Product made) Glossy paper for inkjet recording was produced on the conditions as described in Example 1 except having set it as 100 mass parts.

Example 4:
In the same manner as in Example 1, a paper substrate (quality paper) having a basis weight of 130 g / m ² , a thickness of 143 μm, and a specific volume of 1.10 cm ³ / g was produced. After coating the ink receiving layer and the glossy expression layer in the same manner as in Example 1, the thickness was adjusted by a calendar process to prepare a glossy paper for inkjet recording. The produced glossy paper for ink-jet recording had a basis weight of 150 g / m ² , a thickness of 165 μm, and a specific volume of 1.10 cm ³ / g.

Example 5:
A paper substrate (quality paper) having a basis weight of 200 g / m ² , a thickness of 250 μm, and a specific volume of 1.25 cm ³ / g was produced in the same manner as in Example 1. After coating the ink receiving layer and the glossy expression layer in the same manner as in Example 1, the thickness was adjusted by a calendar process to prepare a glossy paper for inkjet recording. The produced glossy paper for ink-jet recording had a basis weight of 220 g / m ² , a thickness of 275 μm, and a specific volume of 1.25 cm ³ / g.

Example 6:
In Example 1, glossy paper for ink-jet recording was produced under the same conditions as described in Example 1 except that the Canadian Standard Freeness (CSF) of the pulp used for the paper substrate was changed to 580 ml.

Example 7:
In Example 1, glossy paper for ink-jet recording was produced under the same conditions as described in Example 1 except that the paper base was produced by four-layer papermaking using a circular paper machine.

Comparative Example 1:
In the same manner as in Example 1, a paper substrate (quality paper) having a basis weight of 180 g / m ² , a thickness of 180 μm, and a specific volume of 1.00 cm ³ / g was produced. After coating the ink receiving layer and the glossy expression layer in the same manner as in Example 1, the thickness was adjusted by a calendar process to prepare a glossy paper for inkjet recording. The produced glossy paper for ink-jet recording had a basis weight of 200 g / m ² , a thickness of 200 μm, and a specific volume of 1.00 cm ³ / g.

Comparative Example 2:
In the same manner as in Example 1, a paper substrate (quality paper) having a basis weight of 180 g / m ² , a thickness of 243 μm, and a specific volume of 1.35 cm ³ / g was produced. After coating the ink receiving layer and the glossy expression layer in the same manner as in Example 1, the thickness was adjusted by a calendar process to prepare a glossy paper for inkjet recording. The glossy paper for ink-jet recording produced had a basis weight of 200 g / m ² , a thickness of 270 μm, and a specific volume of 1.35 cm ³ / g.

Comparative Example 3:
In Example 1, glossy paper for ink-jet recording was produced under the same conditions as described in Example 1 except that the ink receiving layer was not provided.

Comparative Example 4:
In the same manner as in Example 2, a paper substrate (quality paper) having a basis weight of 180 g / m ² , a thickness of 180 μm, and a specific volume of 1.00 cm ³ / g was produced. After coating the ink receiving layer and the gloss developing layer in the same manner as in Example 2, the thickness was adjusted by a calendar process to prepare glossy paper for ink jet recording. The produced glossy paper for ink-jet recording had a basis weight of 200 g / m ² , a thickness of 200 μm, and a specific volume of 1.00 cm ³ / g.

Comparative Example 5:
In the same manner as in Example 3, a paper base material (quality paper) having a basis weight of 180 g / m ² , a thickness of 180 μm, and a specific volume of 1.00 cm ³ / g was produced. After coating the ink receiving layer and the gloss developing layer in the same manner as in Example 3, the thickness was adjusted by a calendar process to prepare a glossy paper for ink jet recording. The produced glossy paper for ink-jet recording had a basis weight of 200 g / m ² , a thickness of 200 μm, and a specific volume of 1.00 cm ³ / g.

Comparative Example 6:
In the same manner as in Example 1, a paper substrate (quality paper) having a basis weight of 110 g / m ² , a thickness of 121 μm, and a specific volume of 1.10 cm ³ / g was produced. After coating the ink receiving layer and the glossy expression layer in the same manner as in Example 1, the thickness was adjusted by a calendar process to prepare a glossy paper for inkjet recording. The produced glossy paper for ink-jet recording had a basis weight of 130 g / m ² , a thickness of 143 μm, and a specific volume of 1.10 cm ³ / g.

Comparative Example 7:
In the same manner as in Example 1, a paper substrate (quality paper) having a basis weight of 280 g / m ² , a thickness of 336 μm, and a specific volume of 1.20 cm ³ / g was produced. After coating the ink receiving layer and the glossy expression layer in the same manner as in Example 1, the thickness was adjusted by a calendar process to prepare a glossy paper for inkjet recording. The produced glossy paper for ink-jet recording had a basis weight of 300 g / m ² , a thickness of 360 μm, and a specific volume of 1.20 cm ³ / g.

(1) Measurement of compression hardness:
It is fixed on a metal plate with double-sided tape with the surface opposite to the surface on which the glossy layer is provided facing upward, and is set without being affected by paper curl. The sample is fixed on a sample table of a handy compression tester KES-G5 (manufactured by Kato Tech Co., Ltd.), and a pressurizer (with a metal ball having a diameter of 10 mm at the tip) is placed at a speed of 0.20 mm / second from above the sample Was pressed into the sample and pressurized. At this time, the pressure until the pressure of the pressurizer reached 5 to 800 gf / cm ² and the change in the depth of the pressure were measured and indicated by a curve BA in FIG. 1 (B is a pressure of 5 gf / cm ² , A is (Indicating a pressure of 800 gf / cm ² ). A value obtained by dividing the area (a) surrounded by the curve BA, the straight line BC, and the straight line AC by the area of the triangle ABC having the right angle BCA shown in FIG. When expressed from FIG. 1, the area of a / the area of ΔABC = compression hardness. This “compression hardness” indicates that the value becomes closer to compression as the value approaches 1.00. This “compression hardness” is a dimensionless number.

(2) Measurement of the surface strength of the surface opposite to the glossy layer:
The measuring method is Japan Tappi No. 1 (2000 version; method A). The practical level is 14A or more.

(3) Image clarity on the surface of the glossy layer:
The image clarity was measured in order to evaluate the specularity of the surface of the glossy layer of the obtained inkjet recording paper. The image clarity is in accordance with JIS H 8686-2: 1999 “Image quality test method for anodized films of aluminum and aluminum alloys” with an optical comb width of 2 mm and an incident / reflection angle of 60 °. 1T: Suga Test Instruments Co., Ltd.). As an evaluation, when the image clarity is 50% or more, the reflected image is clearly visible and the glossiness is excellent. If it is less than 50%, the reflected image is unclear and inferior in gloss. Here, the reason for changing the incident / reflective angle from 45 ° described in JIS to 60 ° is to facilitate evaluation of the difference in glossiness.

(4) Image clarity:
Inkjet obtained by using ISO standard image (ISO / JIS-SCID high-definition color digital standard image data, image name: portrait, image identification number: N1) using a Seiko Epson inkjet printer “PM-G820” Printed on recording paper. The printed image was visually evaluated.
(Double-circle): The recorded image is very clear and contrast is clear, and it can be used practically.
○: The recorded image is clear and the contrast is clear, and can be used practically.
(Triangle | delta): The recorded image is clear, but contrast is not clear, the color is sinking, and there exists a problem in practical use.
X: The recorded image is unclear and the color is sinking, impractical.

(5) Ink absorbability:
Using the ink-jet printer “PM-G820” manufactured by Seiko Epson Corporation, solid (100% density) and characters are printed on the obtained ink-jet recording paper for each of the primary colors of CMYK ink and RGB (Red-Green-Blue). Printed. The boundary of each color of the solid part and the degree of blurring of the characters were evaluated visually.
(Double-circle): A boundary is clear, there is no blur, a character is clear, and it can be used practically.
○: The blur of the boundary is not conspicuous, the characters are clear, and can be used practically.
(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 characters cannot be distinguished, so that it is not practical.

(6) Evaluation of the embossing of the glossy layer:
Numbering was performed by letterpress printing on a printing machine “JM” manufactured by Hashimoto Iron Works Sales Co., Ltd., and the embossing on the surface of the glossy layer was visually evaluated.
A: Embossing is not very noticeable and there is no problem.
○: Embossing is visible, but there is no practical problem.
(Triangle | delta): The level which emboss is conspicuous and becomes a problem in practical use.
X: Embossing is conspicuous and impractical.

(7) Transportability evaluation with inkjet printer:
Ten sheets of postcard-sized glossy paper for ink-jet recording were set in an inkjet printer “Photosmart 2710” manufactured by Hewlett-Packard Co., and transportability was evaluated.
○: A paper jam does not occur even once, and there is no problem at all.
Δ: A level where a paper jam occurs once and becomes a practical problem.
X: Paper jam occurs twice or more, impractical.

  As is clear from Table 1, Examples 1 to 7 are superior to Comparative Examples 1 to 7 in printing performance and glossiness, are excellent in the embossing suppression effect of the gloss developing layer, and are opposite to the gloss developing layer. Excellent surface strength and excellent transportability.

In Comparative Examples 1, 4, and 5, the specific volume was less than 1.05 cm ³ / g, and the compression hardness was less than 0.38, so the embossing suppression effect was inferior. In Comparative Example 2, since the specific volume exceeded 1.30 cm ³ / g, the surface strength on the surface opposite to the glossy layer was inferior. Comparative Example 3 was inferior in image clarity and printing performance on the surface of the glossy layer because no ink receiving layer was provided. Since the comparative example 6 was less than 150 micrometers in thickness, it was inferior to the emboss suppression effect. Comparative Example 7 was inferior in printer transportability because the thickness exceeded 300 μm.

It is a graph for demonstrating the measuring method of compression hardness.

Claims (7)

For ink-jet recording, wherein at least one ink receiving layer is provided on at least one surface of a gas-permeable paper base, and a glossy expression layer containing a pigment and a binder is provided on the ink receiving layer by a cast coating method. Glossy paper,
The specific volume of the glossy paper for ink jet recording is 1.05 to 1.30 cm ³ / g, the thickness of the glossy paper for ink jet recording is 150 to 300 μm, and the surface on which the glossy expression layer is provided The compressive hardness when a metal indenter with a tip diameter of 10 mm is continuously pressed from above the opposite surface in the thickness direction of the sample at a speed of 0.20 mm / sec with a pressure in the range of 5 to 800 gf / cm ^2. Glossy paper for ink-jet recording, characterized by being 0.38 or more.   The glossy paper for ink-jet recording according to claim 1, wherein the Canadian standard freeness (CSF) of the pulp used for the paper substrate is 450 to 600 ml.   The glossy paper for ink-jet recording according to claim 1 or 2, wherein the paper substrate is made by multi-layer paper making of two or more layers.   The glossy paper for ink jet recording according to claim 1, wherein the cast coating method is a coagulation method.   The said glossy expression layer contains the silica whose average secondary particle diameter is 500 nm or less, the alumina whose average secondary particle diameter is 500 nm or less, or both, The said 1, 2, 3, or 4 characterized by the above-mentioned. 2. Glossy paper for ink-jet recording as described in 1.   The glossy paper for ink-jet recording according to claim 1, wherein the glossy paper is processed into a postcard. The glossy paper for ink-jet recording is used in a postcard application in which letterpress printing is performed on the surface opposite to the surface on which the glossy expression layer is provided. Glossy paper for inkjet recording.

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