JP2010094850A - Glossy paper for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide glossy paper for inkjet recording which has: good ink absorbing property; glossiness as high as that of a silver salt film; excellent wear resistance on the glossy surface thereof; image quality and uniform glossiness comparable to those of a medium produced using a printing paper base material or a film base material; and recyclability. <P>SOLUTION: The glossy paper for inkjet recording is cast coat paper wherein one or more ink receiving layers are provided on at least one side of its base material, a glossiness-developing layer including a dye and an adhesive with mirror glossy finish conducted thereon is provided on the ink receiving layer. The glossiness-developing layer contains: only spherical colloidal silica whose average primary particle size is 10 to 80 nm, as a dye; and as an adhesive, 6 to 48 pts.mass of aqueous dispersion polymer emulsion whose glass transfer temperature is 60 to 100°C (A), and 1 to 20 pts.mass of aqueous dispersion polymer emulsion whose glass transfer temperature is 0 to 45°C (B), respectively, based on 100 pts.mass of the dye. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

The ink jet recording system is a system in which ink droplets are ejected and deposited on recording paper to form dots and recording is performed. 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 printing 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. Many of these ink-jet recording media have 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 provided on the surface. used.

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. As characteristics required for these glossy media. In addition to the above characteristics, (d) high dot roundness and good image reproducibility (e) good water resistance and light resistance (f) high glossiness of image areas and blank paper parts Etc.

  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). 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 is easier to control the ink absorptivity of (a) than the latter, but (d) the dot roundness, image reproducibility, (f) the image area, and the glossiness of the blank paper portion. Inferior to the latter. When the latter substrate for photographic paper is generally called RC paper (resin-coated paper), a polyethylene film layer is formed on the paper substrate, and therefore when an ink receiving layer is formed on the surface thereof, Since 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 of the method of forming an ink receiving layer on a photographic paper substrate requires a large amount of coating in order to increase ink absorbency, and the substrate itself is more expensive than paper. As a result, it is higher than the glossy medium produced by the former casting method. 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 casting method is advantageous in this respect, but there are problems in the quality aspects (d) and (f), 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).

  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 recent years, as a glossy paper for ink-jet recording having a high ink absorption speed and a glossiness similar to that of a silver salt photograph, a paper coated with a mixture of alumina hydrate and a water-soluble binder has been proposed (for example, a patent). (Ref. 4).

  In addition to the problems related to surface glossiness and ink absorption, various proposals have been made for scratch resistance of glossy surfaces. For example, there is a proposal to improve by specifying the average degree of polymerization or degree of saponification of polyvinyl alcohol used for the binder of the glossy layer (see, for example, Patent Document 5). In addition, there is a proposal to improve by specifying the smoothness and roughness of the surface of the glossy layer (see, for example, Patent Document 6).

  Furthermore, there is also a proposal for improving ink absorbability and surface scratch resistance by using two or more kinds of polymer fine particles having different minimum film forming temperatures and defining drying conditions (see, for example, Patent Document 7). ).

Japanese Patent Laid-Open No. 06-72017 JP-A-11-348416 JP 2000-108506 A Japanese Patent Laid-Open No. 06-055829 JP 2005-280012 A JP 2006-168046 A JP 2003-170658 A

  However, in the case of the technique described in Patent Document 2, if the number of cracks is too small, there is a problem in that the glossiness increases while the ink absorbability decreases.

  In the technique of Patent Document 3, the use of pearl necklace-shaped colloidal silica has a certain effect on improving the printing quality, particularly the ink absorbability, but the surface scratch resistance and glossiness are not always satisfactory. Not in.

  As described above, the glossy paper for ink-jet recording described in Patent Documents 1 to 4 has a feature that the glossiness is very excellent, but because it is excellent in glossiness, the glossy surface is easily damaged. Have. 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 section guide and rubbing with the suction wheel of the paper ejection section during printing. In addition, there is a problem in that scratches are easily caused by contact between the glossy surface and the paper feed roller during address printing with an ink jet printer.

  In recent years, as described above, the demand for scratch resistance on the glossy surface is gradually increasing due to the problem of workability in the printing process and post-processing process such as address printing on the non-glossy surface. . Therefore, it is easily guessed that the required level of scratch resistance required for glossy paper for ink-jet recording will gradually increase in the future.

  Then, although each proposal content of patent documents 5-7 was made | formed, in the technique of patent document 5, when a porous pigment like a vapor-phase method silica is used, for example, a coating layer May be easily plastically deformed and the scratch resistance may be unsatisfactory. Further, in the technique described in Patent Document 6, the scratch resistance may be unsatisfactory when the glossy layer is easily plastically deformed. Furthermore, in the technique described in Patent Document 7, when no pigment is added to the coating layer in addition to the polymer fine particles, the upper limit of the drying temperature depends greatly on the minimum film forming temperature of the polymer fine particles used, and the drying efficiency. May be significantly reduced, the coating speed may be slowed, and the operation efficiency may be reduced. In addition, since the coating layer is relatively easily plastically deformed, the scratch resistance may be inferior. Furthermore, even if a pigment is used in addition to the polymer fine particles, when a porous pigment such as gas phase method silica is used, the coating layer is easily plastically deformed and the scratch resistance becomes unsatisfactory. There is a case.

  Therefore, from the results of research on the scratch resistance of the glossy surface by the present inventors, it has been concluded that the above proposals cannot be completely satisfied with the increasing demand for scratch resistance. In view of the current situation, glossy paper for ink-jet recording produced by the casting method has an image quality and a uniform glossiness that exceed the media produced using a photographic paper substrate or film substrate, and is extremely At present, there is no recording medium having excellent gloss surface scratch resistance.

  Therefore, an object of the present invention is a glossy paper for ink-jet recording produced by a casting method, having a high gloss feeling comparable to silver salt photographs while having good ink absorbency, which is a problem of the prior art, Further, by providing a recording medium that is extremely excellent in scratch resistance on glossy surfaces, has an image quality comparable to that of a medium produced using a photographic paper substrate or a film substrate, and has a uniform gloss feeling and is recyclable. is there.

  In the cast coating method, the present inventors use only spherical colloidal silica having an average primary particle diameter of 10 to 80 nm as a pigment to be included in the gloss developing layer, and as a binder to be included in the gloss developing layer, (A The above-mentioned object is achieved by containing a water-dispersed polymer emulsion having a glass transition temperature of 60 to 100 ° C. and (B) a water-dispersed polymer emulsion having a glass transition temperature of 0 to 45 ° C. in a predetermined composition. The present invention has been completed by finding out what can be done. Specifically, the glossy paper for ink-jet recording according to the present invention is provided with at least one ink receiving layer on at least one side of a substrate, and contains a pigment and a binder on the ink receiving layer, and has a mirror surface. A cast coated paper provided with a glossy expression layer having a glossy finish, wherein the glossy expression layer contains only spherical colloidal silica having an average primary particle diameter of 10 to 80 nm as the pigment, and the binder. (A) an aqueous dispersion polymer emulsion having a glass transition temperature of 60 to 100 ° C. and (B) an aqueous dispersion polymer emulsion having a glass transition temperature of 0 to 45 ° C. with respect to 100 parts by mass of the pigment (A ) 6 to 48 parts by mass and (B) 1 to 20 parts by mass, respectively.

  In the glossy paper for ink-jet recording according to the present invention, after the ink receiving layer is provided and before the glossy expression layer is provided, JIS P 8117: 1998 “Paper and paperboard—Air permeability test method—Gurley tester method” is used. The air resistance (Gurley) is preferably 150 seconds or less. Excellent ink absorption and productivity.

  In the glossy paper for ink jet recording according to the present invention, the glossy layer preferably further contains 3 to 16 parts by mass of silanol-modified polyvinyl alcohol as the binder with respect to 100 parts by mass of the pigment. By including the silanol-modified polyvinyl alcohol in the glossy layer, it is possible to achieve both better ink absorbability and better scratch resistance.

  In the glossy paper for ink jet recording according to the present invention, the pigment of the glossy layer is preferably anionic spherical colloidal silica. In particular, the gloss development layer is excellent in scratch resistance.

  In the glossy paper for ink jet recording according to the present invention, it is preferable that the binder (A) of the glossy layer is an acrylic resin, an acrylic-styrene resin, or both. In particular, it has excellent gloss.

  In the glossy paper for ink jet recording according to the present invention, it is preferable that the binder (B) of the glossy layer is an acrylic resin, an acrylic-styrene resin, or both. In particular, it has excellent gloss.

  In the glossy paper for ink-jet recording according to the present invention, it is preferable that the glossy layer contains a cationic polymer. In particular, the water resistance of the printed part is excellent.

In addition, the glossy paper for ink jet recording according to the present invention is subjected to a scratch test on the surface of the glossy layer using a load fluctuation type frictional wear tester under the following scratch test conditions using a sapphire needle having a tip diameter of 75 μm. The critical load at which the surface layer film peels off and the cutting powder starts to appear is 100 gf or more. A paper having a glossy layer having a critical load of 100 gf or more at which the surface layer film is peeled off and the cutting powder begins to appear is excellent in scratch resistance.
(Scratch test conditions)
Scratching speed: 0.5 mm / sec Load increasing speed: 4 gf / sec

In addition, the glossy paper for ink jet recording according to the present invention includes a form in which the dynamic hardness under load of the glossy layer by the ultra-micro hardness meter is 1.0 or more under the following dynamic hardness test conditions. As a result of examining the relationship between the degree of plastic deformation of the surface of the glossy layer and the scratch resistance, the glossy layer having a smaller degree of plastic deformation is superior in scratch resistance.
(Dynamic hardness test conditions)
Indenter: Triangular pyramid diamond indenter (edge angle 115 degrees, indenter shape factor 3.8854)
Test force: 7mN
Load speed: 1.42 mN / sec

  The glossy paper for ink-jet recording according to the present invention has an optical comb width of 2 mm in accordance with JIS H 8686-2: 1999 “Method for testing the image clarity of anodized film of aluminum and aluminum alloy—Part 2: Instrument measurement method”. A mode in which the image clarity of the glossy layer under the condition of an incident / reflection angle of 60 ° is 50% or more is included. In particular, it has excellent gloss.

In the glossy paper for ink-jet recording according to the present invention, the coating amount of the ink receiving layer is preferably 5 to 12 g / m ² in terms of solid content. The balance between ink absorbability and scratch resistance is good.

The coating amount of the glossy layer is preferably 3 to ²⁰ g / m ² in terms of solid content. Excellent ink absorbability, and also excellent scratch resistance because binder migration does not occur during coating.

  In the glossy paper for ink-jet recording according to the present invention, the cast coating process is preferably a coagulation method, and preferably contains a boron compound as a coagulant. Furthermore, uniform glossy surface quality can be obtained.

  In the glossy paper for ink-jet recording according to the present invention, the glossy layer preferably has a surface pH of 6.4 or less. In particular, blank paper fading and discoloration are reduced.

  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 at the same time, achieves a very high level of surface glossiness, ink absorption and scratch resistance of the glossy layer surface. However, it has a good color developability. In particular, because of the problem of workability in post-processing, it can be easily assumed that the level of scratch resistance on the surface of the glossy layer is expected to increase further, so the significance of the present invention is considered to be great. Further, in the present invention, since paper is used as a base material, the manufacturing cost is low compared to a photographic paper base material having a film layer, and it can be recycled when discarded, which is also preferable from the viewpoint of effective use of resources. .

  Next, the present invention will be described in detail with reference to embodiments, but the present invention is not construed as being limited to these descriptions. In addition, the embodiment may be modified as long as the effects of the invention are achieved.

  The glossy paper for ink-jet recording according to this embodiment is provided with at least one ink receiving layer on at least one side of the substrate, and contains a pigment and a binder on the ink receiving layer, and has a mirror gloss finish. This is a cast-coated paper provided with a glossy layer. Here, the glossy layer contains only a spherical colloidal silica having an average primary particle diameter of 10 to 80 nm as a pigment, and (A) a water-dispersed polymer emulsion having a glass transition temperature of 60 to 100 ° C. as a binder. And (B) an aqueous dispersion polymer emulsion having a glass transition temperature of 0 to 45 ° C. within a range of (A) 6 to 48 parts by mass and (B) 1 to 20 parts by mass with respect to 100 parts by mass of the pigment. Contains. And after providing an ink receiving layer, before providing a gloss expression layer, the air permeation resistance (Gurley) according to JIS P 8117: 1998 “Paper and paperboard—Air permeability test method—Gurley tester method” is 150 seconds or less. It is.

  As a coating liquid pigment for glossy expression layer of inkjet glossy paper by casting method, it is common to use spherical colloidal silica, aggregated colloidal silica in which a plurality of spherical colloidal silicas are combined, gas phase method silica, alumina, etc. . Spherical colloidal silica has a high hardness as a material and may form a highly scratch-resistant surface, but has a relatively poor ink absorbability when a glossy expression layer is formed because there are no voids in the particles themselves. There is a tendency.

  Further, as an agglomerate colloidal silica in which a plurality of spherical colloidal silicas are combined, a pearl necklace-shaped colloidal silica is known. As a result of research on the scratch resistance of the glossy layer of the present inventors, Compared to its geometric shape, it is easy to form voids during film formation and has excellent ink absorbency, but because of its porous properties during film formation, it is prone to plastic deformation and cracking, and has excellent scratch resistance. There is an unsatisfactory point in achieving the goal of having sex.

  Gas phase method silica is a pigment generally used in glossy paper for ink-jet recording because of its excellent ink absorption resulting from its extremely high specific surface area. This is also the same reason as that of aggregate colloidal silica. It is extremely difficult to provide high scratch resistance.

  Alumina is also a pigment that is very frequently used because of its excellent ink absorbability and glossiness. However, as with the colloidal colloidal silica and the vapor-phase method silica, it is extremely high in scratch resistance due to the origin of the material. The result was difficult.

  According to the above research results, in view of the properties of the pigment, when trying to obtain a glossy paper for ink-jet recording that is truly excellent in scratch resistance, the pigment can be used only for spherical colloidal silica. As described above, since the ink absorbability is difficult, there remains a technical problem in trying to balance the ink absorbability and the scratch resistance at a high level.

  Further, in order to suppress the plastic deformation of the gloss developing layer to a minimum and improve the scratch resistance, it is necessary to increase the binder component of the gloss developing layer, that is, the resin component as much as possible. As a result of intensive studies by the present inventors, it has been found that an aqueous dispersion polymer emulsion having a lower glass transition temperature is an effective resin in order to suppress plastic deformation of the coating layer to a small extent. May be too strong, that is, there may be no gap for absorbing ink, and ink absorbability may be reduced. On the other hand, when a water-dispersed polymer emulsion having a higher glass transition temperature is used, the coating layer is easily cracked (cracked) and becomes brittle, while the scratch resistance is reduced, but the ink absorbability is improved. It was observed. From these phenomena, it has been found that the selection and combination of the glass transition temperature of the water-dispersed polymer emulsion used as the binder is a very important factor for achieving both scratch resistance and ink absorbability.

  On the other hand, the present inventors have also intensively studied the mechanism of scratches generated in the glossy layer. For example, in the case of postcard use, it is passed through an offset printing machine to print the address frame on the non-glossy surface, but it comes into contact with a material that is clearly harder than the glossy expression layer, such as a paper feed guide. Scratches occur as the surface wears. In general, the mechanism of wear is extremely complicated, but is roughly divided into two types: adhesive wear and abrasive wear. Adhesive wear refers to wear resulting from shearing or breaking of the adhesive part that constitutes the real contact area of the friction surface. Abrasive wear is wear due to a cutting action that occurs when one of the friction surfaces is hard or when a hard foreign object is interposed between the friction surfaces. The wear amount of any wear is often inversely proportional to the hardness. As a result of observing scratches that actually occurred in the printing process with an electron microscope, the majority of the scratches were broken as if the coating film was cracked. Since the (wedge) is formed, most of the factors are assumed to be abrasive wear. Therefore, in order to increase the scratch resistance of the glossy layer, it is necessary to form a coating film that is extremely difficult to break due to surface cracks, and at the same time, make the coating film hard and difficult to plastically deform. There is. However, since the conventional glossy paper for ink-jet recording has the ink absorption ability, naturally, the coated film must be porous, and its porous property, plastic deformation resistance and resistance Cracking has a trade-off, and it has been a technical problem because it seems extremely difficult to achieve both. In addition, the Taber abrasion tester, the Gakushin type fastness friction tester, etc. can be cited as general abrasion testers. However, since the scratches after the abrasion are observed, the shape of the scratches by the offset printing machine is quite different. In addition, the actual glossy layer surface cannot be consistent with the superiority or inferiority of the scratch resistance.

  Therefore, it is considered essential to improve the scratch resistance on the surface of the glossy layer and to establish a methodology for constructing the glossy layer and to precisely evaluate the surface scratch resistance.

  In the present invention, in order to achieve the above object, it is necessary to use only spherical colloidal silica as the pigment of the coating liquid for forming the glossy layer. The average primary particle diameter of the spherical colloidal silica needs to be in the range of 10 to 80 nm, more preferably 15 to 50 nm. The spherical colloidal silica used in the present invention is monodispersed fine particles, and the particle diameter is almost uniform and is not aggregated. When the average primary particle diameter of the spherical colloidal silica is less than 10 nm, the coating film surface becomes brittle and the scratch resistance is poor. On the other hand, when the average primary particle diameter exceeds 80 nm, the film formability of the coating film is too good to cause appropriate cracking, and the ink absorbability is poor. Further, the spherical colloidal silica used in the present invention can be mixed in a plurality of types having different particle diameters as long as the average primary particle diameter is within the above range. Further, the spherical colloidal silica used in the present invention may be used in any production method as long as it is within the range of the average primary particle diameter. The average primary particle diameter of the spherical colloidal silica can be determined mainly by a dynamic light scattering method (for example, DLS-6500, manufactured by Otsuka Electronics Co., Ltd.), and a field emission type electron microscope capable of high-magnification observation. It can also be obtained by direct observation.

  In the present invention, the binder contained in the glossy layer includes (A) an aqueous dispersion polymer emulsion having a glass transition temperature of 60 to 100 ° C. and (B) water having a glass transition temperature of 0 to 45 ° C. It is a dispersion polymer emulsion. And (A) is contained in 6-48 mass parts with respect to 100 mass parts of pigments, and (B) is contained in the range of 1-20 mass parts, respectively. As described above, in order to improve the scratch resistance, the pigment is limited to spherical colloidal silica, but the ink absorbability is difficult. In addition, since spherical colloidal silica has almost no pores, it is necessary to generate cracks suitable for ink absorption in the glossy layer in order to improve ink absorbability. As described above, the higher the glass transition temperature of the binder, the film formability is insufficient, so that cracks are likely to occur and the glossiness is lowered. In addition, when the glass transition temperature of the binder is low, the film formability is improved, so that cracks are less likely to occur, and the scratch resistance is improved while the glossiness is improved. In the present invention, by containing binders having different glass transition temperatures in the gloss ratio in the above ratio, it is possible to cause appropriate cracks in ink absorption even when only spherical colloidal silica is used as a pigment. For this reason, the present inventors have succeeded in producing a glossy paper for ink-jet recording having excellent ink absorbability, scratch resistance, and glossiness.

  In the present invention, when the content of the binder (A) contained in the glossy layer is more than 48 parts by mass with respect to 100 parts by mass of the pigment, the glossiness is inferior, and the binder (A) When the content is less than 6 parts by mass with respect to 100 parts by mass of the pigment, the ink absorbability is inferior. Further, when the content of the binder (B) contained in the glossy layer is more than 20 parts by mass relative to 100 parts by mass of the pigment, the ink absorbability is inferior, and the content of the binder (B) is low. When the amount is less than 1 part by mass relative to 100 parts by mass of the pigment, the glossiness is inferior. The content of the binder contained in the glossy layer is more preferably 10 for (A) with respect to 100 parts by mass of the pigment, considering the balance between ink absorbency, scratch resistance of the glossy layer surface and glossiness. -40 mass parts and (B) are in the range of 2-18 mass parts. Further, when the glass transition temperature of the binder (A) exceeds 100 ° C., many cracks may occur and the glossiness may be lowered. Absorbability may be reduced. Further, when the glass transition temperature of the binder (B) is less than 0 ° C., the ink absorbability may be lowered, and when it exceeds 45 ° C., the glossiness may be lowered. In the present invention, as long as the glass transition temperature range and the blending ratio are satisfied, two or more types of water-dispersed polymer emulsions are mixed for the binders (A) and (B). It can also be used.

  In the present invention, the air permeation resistance (Gurley) according to JIS P 8117: 1998 “Paper and paperboard—Air permeability test method—Gurley tester method” after the ink receiving layer is provided and before the glossy expression layer is provided. ) Is preferably 150 seconds or shorter. When the air permeation resistance before providing the glossy layer after the ink receiving layer is more than 150 seconds, the drying efficiency of the glossy layer is lowered and the drying time for reaching the predetermined moisture is increased. For this reason, since the film formation of the binder contained in the glossy layer progresses further, the cracks are reduced and the ink absorbability is lowered. Moreover, since air permeability deteriorates, drying efficiency falls and coating speed becomes low, it is inferior also from a productivity viewpoint. It is more preferable from the viewpoint of ink absorbency that the air resistance after the ink receiving layer is provided is 130 seconds or less. More preferably, it is more preferably 100 seconds or less from the viewpoint of ink absorbability. The lower limit value of the air permeability resistance is not particularly limited, but is 20 seconds, preferably 30 seconds.

  Furthermore, in this invention, it is preferable that a gloss expression layer contains 3-16 mass parts of silanol modified polyvinyl alcohol as a binder with respect to 100 mass parts of pigments. By containing silanol-modified polyvinyl alcohol as a binder, good ink absorbability can be maintained even when spherical colloidal silica is used as a pigment. Since silanol-modified polyvinyl alcohol has extremely high adhesion to inorganic substances, drying shrinkage is large, and it is estimated that ink absorbency is improved by generating appropriate cracks in the coating film. In addition, when the silanol-modified polyvinyl alcohol is contained in the glossy layer, the degree of plastic deformation of the glossy layer is reduced, and scratch resistance is improved. The degree of modification and the degree of polymerization of the silanol-modified polyvinyl alcohol used in the present invention can be appropriately selected. If the number of added parts is less than 3 parts, the scratch resistance of the glossy layer may be inferior. On the other hand, when the amount added exceeds 16 parts, the ink absorption may be inferior because the coating film is less cracked. The number of added silanol-modified polyvinyl alcohol is more preferably 4 to 14 parts by mass in consideration of the balance between the ink absorbability and the scratch resistance of the surface of the glossy layer. Furthermore, it is preferably 5 to 12 parts by mass.

  Furthermore, in the present invention, it is preferable that the ionicity of the spherical colloidal silica that is a pigment used for the glossy layer is anionic. This is because anionic spherical colloidal silica tends to have a higher scratch resistance of the glossy layer, and it is assumed that the reason is that the cohesion between particles is stronger.

  Further, in the present invention, as the water-dispersed polymer emulsion having a glass transition temperature of 60 to 100 ° C. of the binder (A) of the glossy layer, acrylic resin or acrylic-styrene resin can be used alone or in combination. Preferably there is. High glossiness can be obtained by using an acrylic resin or an acrylic-styrene resin alone or using them in combination.

  Further, in the present invention, as the water-dispersed polymer emulsion having a glass transition temperature of 0 to 45 ° C. of the binder (B) of the glossy layer, acrylic resin or acrylic-styrene resin can be used alone or in combination. It is also preferable that there is. High glossiness can be obtained by using an acrylic resin or an acrylic-styrene resin alone or using them in combination.

  Furthermore, as the binder that can be used in combination with the binder (A) and binder (B) of the glossy layer, in addition to the silanol-modified polyvinyl alcohol, 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 copolymer thereof, maleic anhydride copolymer, acrylamide resin, Acrylic ester resins, polyamide resins, polyurethane resins, polyester resins, polyvinyl butyral resins, alkyd resins, epoxy resins, epichlorohydrin resins, urea resins, melamine resins, styrene-butadiene copolymers, methyl methacrylate Acrylic polymer latexes such as acrylate-butadiene copolymer, acrylic acid ester, methacrylic acid ester polymer or copolymer, vinyl polymer latexes such as ethylene-vinyl acetate copolymer, colloidal silica and the like Examples of the resin include acrylic copolymer resin and colloidal silica and styrene-acrylic copolymer resin, but are not particularly limited as long as the effects of the present invention are not impaired.

  Furthermore, in the present invention, it is preferable that the glossy layer contains a cationic polymer from the viewpoint of the water resistance of the printed portion.

  Further, in the present invention, the surface of the glossy layer is scratched by a load-fluctuating frictional wear tester using a sapphire needle having a tip diameter of 75 μm and a scratching speed of 0.5 mm / second and a load increasing speed of 4 gf / second. It is preferable that the critical load at which the surface layer film is peeled off and the cutting powder starts to appear is 100 gf or more. If the critical load is less than 100 gf, there is concern about the scratch resistance of the glossy layer. If the critical load is 120 gf or more, the scratch resistance is still stronger and more preferable. The upper limit value of the critical load is not particularly limited, but is 200 gf, for example. In the critical load measurement, a needle with a fixed material and tip diameter is applied to the sample surface and swept while applying a continuous load. The load when the sample surface is damaged and cutting powder begins to be taken out is taken as the critical load. . Usually, at the critical load point, the relationship between the load load and the vertical load received by the needle is a discontinuous point, and can be easily obtained from the graph chart. Further, it is possible to obtain a more accurate critical load by measuring while visually observing the tip of the needle with a CCD camera or the like. The load change type frictional wear tester (Tribogear HHS2000, manufactured by Shinto Kagaku Co., Ltd.) was used for the measurement of the critical load, but any measurement is possible as long as it is a load change type frictional wear tester having the same principle as this measuring instrument. The machine can also be used. The material and tip diameter of the scratching needle could be selected as appropriate, but as a result of intensive studies by the present inventors, for example, in order to reproduce the shape of a scratch that becomes a defect in the printing process of a non-glossy surface. It has proven reasonable to use a sapphire needle having a tip diameter of 75 μm.

Furthermore, in the present invention, it is preferable that the dynamic hardness at the time of loading of the glossy layer by the ultra-micro hardness meter is 1.0 or more. Moreover, it is more preferable that the dynamic hardness under load is 1.2 or more because the surface of the glossy layer is more difficult to be plastically deformed. Dynamic hardness is not a method of applying a force such as Vickers hardness or Knoop hardness, which is widely used for measuring the hardness of metallic materials, to create a dent, and determining the hardness from the diagonal length of the dent, but to determine the hardness. Adopts a method to determine the hardness according to how much has penetrated into the sample. When the sample force P (mN) and the penetration depth (push-in depth) A (μm) of the indenter into the sample are defined, the dynamic hardness D is obtained by the following equation (Equation 1).
(Expression 1) D = α × P ÷ A ² (α: indenter shape factor)
This dynamic hardness D is the hardness obtained from the sample force P and the indentation depth A in the process of indenting the indenter, and can be said to be a strength characteristic in a state including not only plastic deformation of the sample but also elastic deformation. . In addition, the dynamic hardness by the ultra micro hardness tester can be obtained by performing the load test and the load unloading test at the same time. In the present invention, the dynamic hardness by the load test is adopted. The measurement of dynamic hardness is performed using an ultra-micro hardness meter (DUH-201, manufactured by Shimadzu Corporation), and the indenter is a triangular pyramid diamond indenter (corner angle 115 °, indenter shape factor: 3.8484). The test force was measured under the condition of 7 mN, and the load speed was measured under the condition of 1.42 mN / sec.

  Further, the glossy layer includes a release agent, a dispersant, a thickener, an antiseptic, an antifoaming agent, a coloring dye, a coloring pigment, a fluorescent brightening agent, a water-resistant agent, a leveling agent, an antioxidant, an ultraviolet ray. An additive such as an absorbent can be appropriately selected and added.

As a coating method of the coating liquid for forming the glossy layer of the present invention, a known coating machine such as an air knife, a roll coater, a reverse roll coater, a bar coater, a comma coater, or a blade coater is used. 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. Further, when the coating amount is less than 3 g / m ² it is difficult to form a sufficient glossy surface.

  Furthermore, in accordance with JIS H 8686-2: 1999 “Image clarity test method of anodized film of aluminum and aluminum alloy—Part 2: Instrument measurement method”, a glossy expression layer with an optical comb width of 2 mm and an incident reflection angle of 60 ° The image clarity is preferably 50% or more 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.

  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 gloss developing layer is applied and a coagulating liquid is applied to the cast drum while being in a wet state and subjected to coagulation treatment. 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 both are used. A high concentration of the coagulating liquid is preferable because the coagulation force is increased and the scratch resistance is further improved. Further, it is possible to add a cationic polymer for fixing the ink to the coagulant. 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.

  Depending on one or both of the components of the coagulant and / or the pH of the coagulant, the surface pH of the glossy layer after drying may be affected. It is preferable to adjust the surface pH of the glossy layer to 6.4 or less because discoloration and discoloration of blank paper are reduced. More preferably, the surface pH is 6.0 or less. The lower limit of the surface pH is practically 5.0.

  In addition, calendar processing such as machine calendar, soft calendar, super calendar, etc. may be performed after casting processing, and for curling adjustment, water, curling agent etc. are applied on the back side and humidification is adjusted by humidification. It can also be done.

  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 mainly 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, 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 Pigments.

  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, polyethyleneimide resin, polyvinyl pyrohydrin Resins, polyacrylic acid or copolymers thereof, maleic anhydride copolymers, acrylamide resins, acrylate resins, polyamide resins, polyurethane resins, polyester resins, polyvinyl butyral resins, alkyd resins, epoxy resins Resin, epichlorohydrin resin, urea resin, melamine resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic ester, methacrylic ester polymer or copolymer Acrylic polymer latexes of polymer such as 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 mass of the pigment in the ink receiving layer. Preferably, it is added in the range of about 5 to 100 parts by mass. If the amount 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.

  It is preferable to add a cationic polymer to the ink receiving layer in addition to the pigment and the binder. The action of the cationic polymer is to react with an anionic component in the dye used in the ink to form a salt that is insoluble in water. Improves. Such cationic polymers include polyethyleneimine, epichlorohydrin modified polyalkylamine, polyamine, polyamine polyamide epichlorohydrin, dimethylamine ammonia epichlorohydrin, polyvinylbenzyltrimethylammonium halide, polydiacryldimethylammonium halide, polydimethylaminoethyl methacrylate hydrochloride, polyvinyl Pyridium halide, cationic polyacrylamide, cationic polystyrene copolymer, diallyldimethylammonium chloride polymer, diallyldimethylammonium chloride sulfur dioxide copolymer, diallyldimethylammonium chloride amide copolymer, dicyandiamide formalin polycondensate, dicyandiamide diethylenetriamine Polycondensate Polyallylamine, polyallylamine hydrochloride, polyacrylamide resin, polyamide epoxy resin, melamine resin acid colloid, urea resin, cation-modified PVA, amino acid type amphoteric surfactant, betaine type compound, and other quaternary ammonium salts are used. It is done. Although the addition amount is not particularly limited, it is used in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the total pigment in the ink receiving layer. 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 include antifoaming agents, lubricants, dispersants, wetting agents, fluorescent whitening agents, coloring dyes, coloring pigments, thickeners, preservatives, water-proofing agents, UV absorbers, as necessary. Antioxidants 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 or a blade 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 glossy expression layer coating, and since there exists a possibility that the scratch resistance of the glossy expression layer surface may fall, 12 g / m < ² > or less is preferable. More preferably 6-10 g / ^{m 2.} The ink receiving layer coating liquid may be applied twice or more to form two or more ink receiving layers.

  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.

  In the glossy paper for ink-jet recording according to this embodiment, the ink receiving layer and the gloss developing layer are provided on one side of the substrate. However, in the case of duplex printing, the ink receiving layer and the gloss developing layer are provided on both sides of the substrate. May be.

  As the base material used in the present invention, a paper base material such as normal high quality paper, medium quality paper, white paperboard or the like is used. Considering the case of recycling as a fuel, it is desirable to use ECF (Elemental Chlorine Free) pulp or TCF (Totally Chlorine Free) pulp having a low chlorine content as raw material pulp. The Canadian standard freeness (CSF) of the pulp used for the substrate is preferably 400 to 580 ml, more preferably 450 to 550 ml. After providing the ink receiving layer, the air permeation resistance in the state before providing the glossy developing layer can be lowered, and it is easy to adjust to 150 seconds or less.

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

  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 indicate solid mass parts and solid mass% unless otherwise specified.

Example 1:
As a base material, 100 parts of L-BKP (hardwood bleached kraft pulp) beaten to 530 ml of Canadian Standard Freeness (CSF), and 5 parts of talc (trade name: T Light 83, manufactured by Taihei Talc Co., Ltd.) as an internal filler Further, 3% sulfuric acid band, 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 Co.) 1.0 After adding and preparing parts, the paper was surface-treated with oxidized starch to produce a high-quality paper having a basis weight of 180 g / m ² . On one surface of this fine paper, 100 parts by mass of synthetic silica (Mizukasil P-78A, manufactured by Mizusawa Chemical Co., Ltd.) as a pigment, 10 parts by mass of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) as a binder, ethylene-vinyl acetate (Polysol) EVA AD-10: 40 parts by mass of Showa High Polymer Co., Ltd.) and 30 parts by mass of cationic polymer (Papiogen P-105: Senka Co., Ltd.) were applied to the coating solution with a solid content concentration of 22% with an air knife coater. The ink receiving layer was applied by applying and drying so that the work amount was 12 g / m ² . At this time, the air resistance according to JIS P 8117: 1998 after coating of the ink receiving layer was 100 seconds. Subsequently, 100 parts by mass of spherical colloidal silica (SYLOJET 4000C, cationic, average primary particle size 30 to 40 nm: manufactured by Grace Devison Co., Ltd.) as a pigment of the coating liquid for the gloss developing layer, and an acrylic resin emulsion (Likabond ES-63 as a binder) , Glass transition temperature 90 ° C .: Chuo Rika Kogyo Co., Ltd.) 10 parts by mass, styrene-acrylic resin emulsion (Movinyl 880, glass transition temperature 3 ° C .: manufactured by Nichigo Mobile Vinyl), 4 parts by mass, silanol-modified polyvinyl alcohol (PVA-R1130) : Kuraray Co., Ltd.) 3 parts by mass, cationic polymer (Sumirez resin 1001: Sumitomo Chemical Co., Ltd.) 10 parts by mass, polyethylene emulsion (SN coat 287: San Nopco Co., Ltd.) 1 part by mass as a release agent A coating solution having a concentration of 20% was obtained. This coating solution was applied onto the ink receiving layer with an air knife coater so that the dry coating amount was 10 g / m ^2, and then a 1% aqueous solution of sodium borate was applied and solidified. While the surface of the obtained coating layer was wet, it was pressure-bonded to a cast drum having a surface temperature of 105 ° C. to produce glossy paper for ink jet recording.

Example 2:
A substrate was prepared in the same manner as in Example 1 except that L-BKP beaten in 450 ml of Canadian Standard Freeness (CSF) was used, and an ink receiving layer was coated in the same manner as in Example 1. At this time, the air resistance after coating of the ink receiving layer was 150 seconds. Further, a glossy expression layer was provided in the same manner as in Example 1 to prepare a glossy paper for ink jet recording.

Example 3:
A substrate was prepared in the same manner as in Example 1, and an ink receiving layer was applied in the same manner as in Example 1. Subsequently, 100 parts by mass of spherical colloidal silica (Adelite AT-20Q, anionic, average primary particle size 10 nm: manufactured by ADEKA) as a pigment of the glossy layer coating material, and an acrylic resin emulsion (Likabond ES-63, glass transition as a binder) Temperature 90 ° C .: Chuo Rika Kogyo Co., Ltd.) 10 parts by mass, styrene-acrylic resin emulsion (Movinyl 880, glass transition temperature 3 ° C .: manufactured by Nichigo Movinyl) 4 parts by mass, silanol-modified polyvinyl alcohol (PVA-R1130: Kuraray Co., Ltd.) 3 parts by mass) and 1 part by mass of a polyethylene emulsion (SN coat 287: manufactured by San Nopco) as a release agent were used to obtain a coating solution having a solid content concentration of 19%. The coating liquid was coated to a Ze'inuinuriko weight 10 g / m ² by an air knife coater on the ink-receiving layer, then 1% sodium borate, cationic polymer (SumirezResin 1001: Sumitomo Chemical (Co., Ltd.) After applying a 2% mixed aqueous solution and coagulating, the resulting coating layer surface was wet and pressed against a cast drum having a surface temperature of 105 ° C., and glossy paper for ink jet recording Was made.

Example 4:
In Example 3, the binder of the glossy layer coating was 10 parts by mass of a styrene-acrylic resin emulsion (Pascoal JK-730, glass transition temperature 70 ° C .: manufactured by Meisei Chemical Co., Ltd.), acrylic resin emulsion (mobile 747, glass transition). Glossy paper for ink jet recording under the same conditions as described in Example 3 except that the temperature was 42 ° C .: 4 parts by mass, manufactured by Nichigomo Vinyl Co., Ltd., and 3 parts by mass of silanol-modified polyvinyl alcohol (PVA-R1130: manufactured by Kuraray Co., Ltd.). Was made.

Example 5:
In Example 3, the binder of the gloss developing layer paint was 48 parts by mass of a styrene-acrylic resin emulsion (Pascor JK-730, glass transition temperature 70 ° C .: manufactured by Meisei Chemical Co., Ltd.), acrylic resin emulsion (mobile 747, glass transition). Glossy paper for ink-jet recording under the same conditions as described in Example 3 except that the temperature was 42 ° C .: 20 parts by mass (made by Nichigomo Vinyl) and 3 parts by mass of silanol-modified polyvinyl alcohol (PVA-R1130: made by Kuraray). Was made.

Example 6:
In Example 3, the binder of the glossy layer coating material was 6 parts by mass of a styrene-acrylic resin emulsion (Pascor JK-730, glass transition temperature 70 ° C .: manufactured by Meisei Chemical Industry Co., Ltd.), an acrylic resin emulsion (mobile 747, glass transition). Glossy paper for ink jet recording under the same conditions as described in Example 3 except that the temperature was 42 ° C .: 1 part by mass of Nichigomo Vinyl Co., Ltd. and 3 parts by mass of silanol-modified polyvinyl alcohol (PVA-R1130: Kuraray Co., Ltd.). Was made.

Example 7:
Example 3 was described in Example 3 except that the pigment of the glossy layer coating material in Example 3 was 100 parts by mass of spherical colloidal silica (cataloid SI-80P, anionic, average primary particle size 78 nm: manufactured by Catalyst Kasei Kogyo Co., Ltd.). A glossy paper for ink-jet recording was produced under the same conditions.

Example 8:
In Example 3, except that the coagulation liquid was a mixed aqueous solution of 3% sodium borate and 2% cationic polymer (Smilease Resin 1001: manufactured by Sumitomo Chemical Co., Ltd.), ink jetting was performed under the same conditions as described in Example 3. A glossy recording paper was prepared.

Example 9:
In Example 3, the coagulating liquid was described in Example 3 except that the coagulation liquid was a mixed aqueous solution of 1% boric acid, 3% sodium borate, and 2% cationic polymer (Smileze Resin 1001: manufactured by Sumitomo Chemical Co., Ltd.). A glossy paper for ink-jet recording was produced under the same conditions.

Example 10:
In Example 3, the absolute dry coating amount of the ink receiving layer was 7 g / m ^2, and the air resistance after coating of the ink receiving layer was 90 seconds, as described in Example 3. Glossy paper for inkjet recording was produced under the conditions.

Comparative Example 1:
Example 1 except that 100 parts by mass of gas phase method silica (Aerosil 200, average primary particle size 12 nm: manufactured by Nippon Aerosil Co., Ltd.) having a BET specific surface area of 200 m ² / g was used as the pigment of the glossy layer coating material in Example 1. Glossy paper for ink-jet recording was prepared under the same conditions as described above.

Comparative Example 2:
In Example 1, the pigment of the glossy layer coating material was 100 parts by mass of alumina having a BET specific surface area of 220 m ² / g (TM-300, crystal form-γ type, average primary particle size 7 nm: manufactured by Daimei Chemical Co., Ltd.). Produced a glossy paper for ink jet recording under the conditions as described in Example 1.

Comparative Example 3:
In Example 1, as a pigment of the glossy layer coating material, a pearl necklace-shaped colloidal silica (Snowtex PS-MO, cationic, average primary particle diameter of 18 to 25 nm, average secondary particle diameter of 80 to 80), which is a kind of aggregate colloidal silica. Glossy paper for ink-jet recording was produced under the same conditions as described in Example 1 except that it was 100 parts by mass (150 nm: manufactured by Nissan Chemical Industries, Ltd.).

Comparative Example 4:
In Example 1, as a pigment of the glossy layer coating material, a pearl necklace-shaped colloidal silica (Snowtex PS-MO, cationic, average primary particle diameter of 18 to 25 nm, average secondary particle diameter of 80 to 80), which is a kind of aggregate colloidal silica. 150 nm: manufactured by Nissan Chemical Industries, Ltd.) 20 parts by mass, spherical colloidal silica (SYLOJET 4000C, cationic, average primary particle size 30-40 nm: manufactured by Grace Devison Co., Ltd.) 80 parts by mass, as described in Example 1. Glossy paper for inkjet recording was produced under the conditions.

Comparative Example 5:
As described in Example 1, except that the pigment of the glossy layer coating material in Example 1 was 100 parts by mass of spherical colloidal silica (Snowtex AK-YL, cationic, average primary particle size 114 nm: manufactured by Nissan Chemical Industries, Ltd.). Glossy paper for inkjet recording was prepared under the same conditions.

Comparative Example 6:
As described in Example 3, except that in Example 3, 100 parts by mass of spherical colloidal silica (Snowtex XS, anionic, average primary particle size 4 to 6 nm: manufactured by Nissan Chemical Industries, Ltd.) was used as the pigment of the glossy layer coating. Glossy paper for inkjet recording was prepared under the same conditions.

Comparative Example 7:
In Example 3, as a binder for the glossy layer coating, 10 parts by mass of a styrene-acrylic resin emulsion (New Coat H5200, glass transition temperature 105 ° C .: Shin-Nakamura Chemical Co., Ltd.), styrene-acrylic resin emulsion (Mobile 880, glass) Gloss for inkjet recording under the same conditions as described in Example 3 except that the transition temperature was 3 ° C .: 4 parts by mass (made by Nichigo Movinyl) and 3 parts by mass of silanol-modified polyvinyl alcohol (PVA-R1130: made by Kuraray). Paper was made.

Comparative Example 8:
In Example 3, as a binder of the glossy layer coating, 10 parts by mass of an acrylic resin emulsion (Likabond ES-63, glass transition temperature 90 ° C .: Chuo Rika Kogyo Co., Ltd.) as a binder, polyurethane resin emulsion (Superflex 500) , Glass transition temperature -39 ° C .: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 4 parts by mass, silanol-modified polyvinyl alcohol (PVA-R1130: manufactured by Kuraray Co., Ltd.) 3 parts by mass, under the same conditions as described in Example 3. A glossy paper for ink jet recording was prepared.

Comparative Example 9:
In Example 3, 50 parts by mass of an acrylic resin emulsion (Rikabond ES-63, glass transition temperature 90 ° C .: manufactured by Chuo Rika Kogyo Co., Ltd.) as a binder, a styrene-acrylic resin emulsion (mobile 880, glass transition temperature 3 ° C .: Nichigo) A glossy paper for ink-jet recording was produced under the same conditions as described in Example 3 except that 22 parts by mass of Movinyl Co., Ltd. and 3 parts by mass of silanol-modified polyvinyl alcohol (PVA-R1130: manufactured by Kuraray Co., Ltd.) were used.

Comparative Example 10:
In Example 3, 5 parts by mass of an acrylic resin emulsion (Rikabond ES-63, glass transition temperature 90 ° C .: manufactured by Chuo Rika Kogyo Co., Ltd.) as a binder, 3 parts by mass of silanol-modified polyvinyl alcohol (PVA-R1130: manufactured by Kuraray Co., Ltd.) A glossy paper for inkjet recording was produced under the same conditions as described in Example 3 except that.

Comparative Example 11:
A substrate was prepared in the same manner as in Example 1 except that L-BKP beaten in 400 ml of Canadian Standard Freeness (CSF) was used, and an ink receiving layer was applied in the same manner as in Example 1. At this time, the air resistance after coating of the ink receiving layer was 180 seconds. Further, a glossy expression layer was provided in the same manner as in Example 1 to prepare a glossy paper for ink jet recording.

  The obtained glossy paper for ink jet recording was subjected to the following test, and the results are shown in Table 1.

(1) Critical load in the scratch test on the surface of the glossy layer:
The critical load was measured by a scratch test on the surface of the glossy layer of the obtained ink jet recording paper. The scratch test was carried out using a load-fluctuating friction and wear tester (Tribogear HHS2000, manufactured by Shinto Kagaku Co.) under the following conditions. The critical load is preferably 100 gf or more from the viewpoint of scratch resistance. If the critical load is less than 100 gf, there is a practical problem from the viewpoint of scratch resistance.
Scratch needle: Sapphire, tip diameter 75μm
Scratching speed: 0.5 mm / sec Load increasing speed: 4 gf / sec

(2) Dynamic hardness of the glossy layer surface:
The dynamic hardness of the glossy layer surface of the obtained ink jet recording paper was measured. The dynamic hardness was measured under the following conditions using an ultra-micro hardness meter (DUH-201, manufactured by Shimadzu Corporation). The dynamic hardness was obtained from the indentation depth when the test force was loaded by the following calculation formula. It is preferable from the viewpoint of scratch resistance that the dynamic hardness under load is 1.0 or more. If the dynamic hardness under load is less than 1.0, there is a practical problem from the viewpoint of scratch resistance.
Working indenter: Triangular pyramid diamond indenter (angle between ridges 115 degrees, indenter shape factor: 3.8484)
Test force: 7mN
Loading speed: 1.42 mN / second Calculation of dynamic hardness: D = α × P ÷ A ² (D: Dynamic hardness, P: Test force (mN), A: Depth of indenter into sample surface (μm), α: Indenter shape factor)

(3) Image clarity on the surface of the glossy layer:
In order to evaluate the specularity of the glossy layer surface of the obtained ink jet recording paper, image clarity was measured. The image clarity is in accordance with JIS H 8686-2 "Image quality test method for anodized films of aluminum and aluminum alloys-Part 2: Instrument measurement method" with an optical comb width of 2 mm and an incident / reflection angle of 60 °. Measured with a sexometer (ICM-1T: manufactured by 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 (practically problematic).

(4) Image clarity:
Ink jet 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-900C” 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 an ink jet printer “PM-900C” manufactured by Seiko Epson, each ink of CMYK and solid (100% density) of RGB (Red-Green-Blue) and characters were printed on the obtained ink jet recording paper. 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) Scratch resistance of the glossy layer surface:
Gloss generated when 20 sheets of inkjet recording paper obtained on an offset printing machine (LITHRON 40, manufactured by KOMORI) were set and printing on the back side was performed at a high printing speed (8500 sheets / hour) at which scratches easily occur. The degree of scratches on the surface of the expression layer was visually evaluated.
(Double-circle): There is no scratch and it is favorable and can be used practically.
○: Scratches are slightly recognized but are not noticeable and can be used practically.
Δ: Scratches are clearly recognized, and there is a problem in practical use.
X: Scratches are remarkably recognized and impractical.

(7) Surface pH of gloss developing layer surface:
Using the pH meter for paper quality inspection manufactured by Kyoritsu Riken, the surface pH of the glossy layer surface of the obtained ink jet recording paper was measured.

  As is clear from Table 1, the gloss developing layer provided on one or more ink receiving layers contains only spherical colloidal silica having an average primary particle diameter of 10 to 80 nm and is included in the gloss developing layer. The binder comprises (A) an aqueous dispersion polymer emulsion having a glass transition temperature of 60 to 100 ° C. and (B) an aqueous dispersion polymer emulsion having a glass transition temperature of 0 to 45 ° C. with respect to 100 parts by mass of the pigment. (A) 6 to 48 parts by mass and (B) 1 to 20 parts by mass, respectively, and the air resistance after the ink receiving layer is provided is 150 seconds or less. No. 10 was superior to Comparative Examples 1 to 11 in printing performance and glossiness, and was found to be excellent in scratch resistance of the glossy layer.

  In Comparative Example 1, gas phase method silica was used as the pigment used in the glossy layer, so that the scratch resistance of the glossy surface was poor. Since Comparative Example 2 used alumina as a pigment used in the glossy layer, it was similarly inferior in the scratch resistance of the glossy surface. In Comparative Example 3, since pearl necklace-shaped colloidal silica was used as a pigment used in the glossy layer, it was similarly inferior in the scratch resistance of the glossy surface. In Comparative Example 4, although spherical colloidal silica was added as a pigment to be used in the glossy layer, pearl necklace-like colloidal silica was also added, so that the glossy surface was similarly poor in scratch resistance. In Comparative Example 5, since spherical colloidal silica having an average primary particle size that is too large was added, the image clarity and ink absorbability were poor. In Comparative Example 6, since spherical colloidal silica having an average primary particle size that was too small was added, the image sharpness and ink absorbency were excellent, but the scratch resistance of the glossy surface was poor. In Comparative Example 7, since the glass transition temperature of the binder having the higher glass transition temperature was too high, the glossiness was inferior. In Comparative Example 8, since the glass transition temperature of the binder having the lower glass transition temperature was too low, the ink absorbability was inferior. Comparative Example 9 was inferior in ink absorptivity because the added amount of the binder having the higher and lower glass transition temperatures was too large. Comparative Example 10 was inferior in scratch resistance because the addition amount of the binder having the higher and lower glass transition temperatures was too small. Comparative Example 11 was inferior in ink absorbability because the air permeation resistance by the Gurley tester method after coating the ink receiving layer was too high.

Claims (14)

A cast-coated paper in which at least one ink receiving layer is provided on at least one side of a base material, and on the ink receiving layer, a gloss expression layer containing a pigment and a binder and having a specular gloss finish is provided. There,
The gloss developing layer contains only spherical colloidal silica having an average primary particle diameter of 10 to 80 nm as the pigment, and (A) a water-dispersed polymer emulsion having a glass transition temperature of 60 to 100 ° C. as the binder. And (B) an aqueous dispersion polymer emulsion having a glass transition temperature of 0 to 45 ° C. within the range of (A) 6 to 48 parts by mass and (B) 1 to 20 parts by mass with respect to 100 parts by mass of the pigment. Glossy paper for ink-jet recording characterized by containing each of them.   After providing the ink receiving layer, the air resistance (Gurley) according to JIS P 8117: 1998 “Paper and paperboard—Air permeability test method—Gurley tester method” before providing the glossy expression layer is 150 seconds or less. The glossy paper for ink-jet recording according to claim 1, wherein   The glossy paper for ink-jet recording according to claim 1 or 2, wherein the glossy layer further contains 3 to 16 parts by mass of silanol-modified polyvinyl alcohol as the binder with respect to 100 parts by mass of the pigment. .   The glossy paper for ink jet recording according to claim 1, 2 or 3, wherein the pigment of the glossy layer is anionic spherical colloidal silica.   The glossy paper for ink-jet recording according to claim 1, wherein the binder (A) for the glossy layer is an acrylic resin, an acrylic-styrene resin, or both.   The glossy paper for ink-jet recording according to claim 1, wherein the binder (B) of the glossy layer is an acrylic resin, an acrylic-styrene resin, or both.   The glossy paper for ink-jet recording according to claim 1, wherein the glossy layer contains a cationic polymer. Using a sapphire needle with a tip diameter of 75 μm under the following scratch test conditions, the surface layer film was peeled off and cutting powder was produced when the surface of the glossy layer was scratched by a load-fluctuating frictional wear tester. 8. The glossy paper for ink jet recording according to claim 1, wherein a starting critical load is 100 gf or more.
(Scratch test conditions)
Scratching speed: 0.5 mm / sec Load increasing speed: 4 gf / sec The dynamic hardness test condition shown below is characterized in that the dynamic hardness under load of the glossy layer by an ultra-micro hardness tester is 1.0 or more. The glossy paper for ink jet recording according to 7 or 8.
(Dynamic hardness test conditions)
Indenter: Triangular pyramid diamond indenter (edge angle 115 degrees, indenter shape factor 3.8854)
Test force: 7mN
Load speed: 1.42 mN / sec   According to JIS H 8686-2: 1999 "Image clarity test method of anodized film of aluminum and aluminum alloy-Part 2: Instrument measurement method" 10. The glossy paper for ink-jet recording according to claim 1, wherein the image clarity is 50% or more. The inkjet according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein the coating amount of the ink receiving layer is 5 to 12 g / m ² in terms of solid content. Glossy paper for recording. The coating amount of the gloss developing layer is 3 to ²⁰ g / m ² in terms of solid content, 12, ² , 3, 4, 5, 6, 8, 9, 10, or 11. Glossy paper for inkjet recording.   The inkjet according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, wherein the cast coating is a coagulation method and a boron compound is contained as a coagulant. Glossy paper for recording.   14. The inkjet recording according to claim 1, wherein the glossy layer has a surface pH of 6.4 or less. 13. Glossy paper.