JP2006256157A - Gloss ink jet recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gloss ink jet recording sheet capable of realizing high surface gloss further realizing high color developing property relating to a pigment ink and scratch resistance of an image portion. <P>SOLUTION: In the gloss ink jet recording sheet in which a pigment layer, at least one layer of ink receiving layer are laminated in series on one face of a water absorbing support body, the average secondary particle size of a pigment included in the pigment layer is ≥1 μm and ≤5 μm, and 50 vol% or more of whole volume of the pigment has the average secondary particle size of ≥1.2 μm and ≤15 μm, and a first ink receiving layer directly coated on the pigment layer includes an inorganic superfine particle, a hydrophilic binder, and boric acid or a borate, and an ink receiving layer located in an uppermost side includes at least a polyolefin particle and an inorganic superfine particle. In addition, the mass ratio of the inorganic superfine particle and the polyolefin particle is 98/2 to 90/10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording sheet, and more particularly to a glossy ink jet recording sheet capable of realizing high color developability with respect to pigment ink and scratch resistance of an image portion.

  Inkjet recording is a method for recording images, characters, etc. by ejecting micro droplets of ink by various operating principles and attaching them to a recording medium such as paper. However, it has features such as easy recording patterns, high flexibility of recording patterns, no need for development and fixing, and is rapidly spreading as a recording apparatus for various figures and color images including Chinese characters in various applications. Further, an image formed by the multicolor ink jet method can obtain a recording that is inferior to that of multicolor printing by a plate making method or printing by a color photographic method. In applications where the number of copies to be produced is small, it is being applied widely to the field of full-color image recording because it is less expensive than that using photographic technology.

  The characteristics required for the recording sheet are printing density, color tone sharpness, ink absorbability for eliminating repellency and unevenness, and ink drying property for eliminating stains.

  As a recording sheet used in the ink jet recording method, a porous ink made of a pigment such as amorphous silica and a water-soluble binder such as polyvinyl alcohol on a support, which is called ordinary paper or an ink jet recording sheet A recording sheet provided with a receiving layer is known.

  In addition, with the recent increase in resolution and performance of inkjet printers, it has become possible to obtain so-called photographic-like high-quality recorded matter. With the progress of such inkjet printers, inkjet recording sheets have become available. Various types have also been developed. The characteristics required for this ink jet recording sheet are generally (1) fast drying (high ink absorbency), (2) no ink blur (high ink absorbency), ( 3) The roundness of the ink dots is high, (4) the color density is high, and (5) the water resistance, light resistance, and ozone resistance of the printed portion are good.

  In recent years, due to the widespread use of inkjet recording, inkjet printers are narrower, mainly for printing on A4 size paper, and are used for personal use desk printers mainly for sheet-fed printing, such as A1 size and A0 size. It has a wide range of products ranging from large printers to wide printers that can print even longer items, and is widely used from noun-size printed items to banner-level printed items.

  Wide printer applications include posters, graphics, signboards, banners, etc., but most of them are indoors or outdoors. Therefore, since it is necessary to catch the eye of a viewer, a glossy ink jet recording sheet is preferably used rather than a mat type ink jet recording sheet.

  In addition, in the case of postings, since the posting period is long, pigment inks having better storage stability than dye inks are used. In fact, most current wide printers are of the pigment ink type. Therefore, an inkjet recording sheet corresponding to pigment ink has also been proposed (Patent Document 1). However, in the case of pigment ink, although the ink itself is excellent in storage stability, it is weak to physical force because the ink is only deposited and deposited on the surface of the recording sheet, that is, easily by rubbing or scratching the surface of the printing portion. As a result, the ink is peeled off, and a large number of scratches are generated in the printing portion while the image is displayed for a long time, thereby degrading the quality of the image.

Various proposals have been made to contain an organic pigment in the ink-receiving layer or the protective layer, which is the outermost layer, but most of them are mainly aimed at improving the transportability of the recording sheet and improving the scratch resistance of the surface. Even the intended one had to undergo a process such as heat-treating the printed surface after printing to melt and densify the organic pigment (Patent Documents 2 to 5). An ink jet recording sheet in which organic resin fine particles are contained in the ink receiving layer has been proposed as a means for improving the scratch resistance of the image area by pigment ink, but it was not able to withstand scratches by nails or the like (Patent Document) 6).
JP 2005-1373 A JP 11-301108 A JP 2002-292997 A JP 2003-170658 A Japanese Patent Laid-Open No. 2003-226072 WO2002 / 034541 pamphlet

  An object of the present invention is to provide a glossy ink jet recording sheet capable of realizing high surface gloss and further realizing high color developability with respect to pigment ink and scratch resistance of an image area.

The above object of the present invention has been basically achieved by the following invention.
(1) In an inkjet recording sheet in which a pigment layer and at least one ink receiving layer are sequentially laminated on one surface of a water-absorbing support, the average secondary particle diameter of the pigment contained in the pigment layer is 1 μm or more and 5 μm. And 50% by volume or more of the total volume of the pigment has a secondary particle diameter of 1.2 μm or more and 15 μm or less, and the first ink receiving layer applied directly on the pigment layer is at least inorganic ultrafine particles, hydrophilic A glossy ink jet recording sheet comprising an adhesive binder, boric acid or borate, and an ink receiving layer located on the outermost surface containing at least polyolefin particles and inorganic ultrafine particles.
(2) The glossy ink jet recording sheet according to the above (1), wherein the mass ratio of the inorganic ultrafine particles and the polyolefin particles contained in the ink receiving layer located on the outermost surface is 98/2 to 90/10.
(3) The pH of the coating liquid of the pigment layer is 8 or more and 11 or less, and the pH of the coating liquid of the first ink receiving layer in contact with the pigment layer is 3 or more and 5 or less. ) Or (2).
(4) The inorganic ultrafine particles contained in the ink receiving layer located on the outermost layer are alumina hydrate and / or aluminum oxide, as described in any of (1) to (3) above Glossy inkjet recording sheet.
(5) The ink-receiving layer having two or more ink-receiving layers, wherein the inorganic ultrafine particles contained in the first ink-receiving layer that is in contact with the pigment layer are vapor-phase-process silica, and are located on the outermost layer The glossy inkjet recording sheet according to any one of (1) to (4) above, wherein the inorganic ultrafine particles contained in the layer are alumina hydrate and / or aluminum oxide.

  According to the present invention, a glossy inkjet recording sheet having high surface glossiness and high color developability with respect to pigment ink, and further, an image portion printed with pigment ink is hardly scratched, and even if scratched, the scratch is not noticeable. Can be obtained.

Hereinafter, the present invention will be described in detail.
In the glossy inkjet recording sheet of the present invention, a pigment layer and at least one ink receiving layer are sequentially laminated on one surface of a water-absorbent support, and an average secondary pigment contained in the pigment layer is further formed. A first ink-receiving layer having a particle diameter of 1 μm to 5 μm, 50% by volume or more of the total volume of the pigment having a secondary particle diameter of 1.2 μm to 15 μm, and applied directly on the pigment layer; A glossy ink jet recording sheet comprising at least inorganic ultrafine particles, a hydrophilic binder, boric acid or a borate, and an ink receiving layer located on the outermost surface containing at least polyolefin particles and inorganic ultrafine particles It is. The glossy ink jet recording sheet in the present invention is an ink jet recording sheet having a surface glossiness of more than 50% measured in accordance with “75-degree specular gloss test method for paper and paperboard” defined in JIS P 8142. Say.

Examples of the water-absorbing support in the present invention include fine paper, art paper, coated paper, cast coated paper, kraft paper, impregnated paper, etc., but are not particularly limited, and preferably a so-called base paper is used. Can do. For example, chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP and CGP, wood pulp such as waste paper pulp such as DIP, and non-wood pulp such as kenaf, bagasse and cotton, and A main component of a conventionally known pigment is mixed using one or more kinds of additives such as a binder, a sizing agent, a fixing agent, a yield improving agent, a cationizing agent, and a paper strength enhancing agent. This is a base paper manufactured by various devices such as a circular paper machine and a twin wire paper machine. The base paper may be used as it is as a water-absorbing support for the glossy ink jet recording sheet of the present invention, and a surface sizing agent, surface paper strength agent, fluorescent whitening agent, antistatic agent, dye, anchor agent, etc. may be applied on the surface. May be. In addition, such a base paper may be provided with the pigment layer according to the present invention as it is, and for the purpose of controlling the flattening, a flattening process is performed using a calendar device such as a machine calendar, a TG calendar, or a soft calendar. After that, a pigment layer may be provided. More preferably, the water absorption Cobb ₃₀ according to the Cobb method defined in JIS P 8140 on the surface of the base paper on which the pigment layer is provided is 10 to 18 g / m ² .

  In the glossy inkjet recording sheet of the present invention, a pigment layer and at least one ink receiving layer are sequentially laminated on one surface of a water-absorbing support. In the present invention, it is essential that the average secondary particle diameter of the pigment contained in the pigment layer is 1 μm or more and 5 μm or less, and 50% by volume or more of the total volume of the pigment is secondary particle diameter of 1.2 μm or more and 15 μm or less. It is. In the present invention, the secondary particles are particles that are formed in a dispersed state by agglomerating fine primary particles, and in the case of monodisperse particles, indicate the dispersed particle diameter.

  In the present invention, the volume% represents the ratio of the total volume of pigment particles having a particle diameter in a specified range to the total volume of pigment particles contained in the pigment layer. The average secondary particle diameter and volume% in the present invention are obtained from particle size distribution data measured by a particle size distribution meter using a laser diffraction / scattering method.

  The average secondary particle diameter of the pigment used in the pigment layer of the present invention is 1 μm or more and 5 μm or less. Preferably they are 1 micrometer or more and 4 micrometers or less. When the average secondary particle diameter of the pigment is smaller than 1 μm, the pigment in the pigment layer is greatly dropped on the paper support, and when the first ink-receiving layer coating liquid is applied, the pigment layer becomes the ink-receiving layer. The drop of the binder component or the like cannot be sufficiently suppressed, and as a result, the coating layer of the ink receiving layer is likely to crack. In addition, if the average secondary particle diameter of the pigment is larger than 5 μm, the smoothness of the pigment layer is lowered. Therefore, even if the ink receiving layer according to the present invention is provided on the pigment layer, a satisfactory surface gloss can be obtained. There may not be. Further, the gap between the pigment particles becomes too large, and the pigment layer cannot sufficiently suppress the drop of the binder component in the ink receiving layer, and as a result, the coating layer of the ink receiving layer is likely to crack. Sometimes.

  In the present invention, the pigment particles contained in the pigment layer have a secondary particle diameter of 1.2 μm or more and 15 μm or less, with 50% by volume or more of the total volume of the pigment particles. 50% by volume or more of the total volume of the pigment particles contained in the pigment layer has a secondary particle diameter of 1.5 μm or more and 10 μm or less in order to improve the gloss and color developability of the ink receiving layer surface while maintaining the ink absorbability. More preferably. More preferably, the pigment particles having a secondary particle diameter of 1.5 μm or more and 10 μm or less are 65% by volume or more of the total volume of the pigment particles contained in the pigment layer. By setting the amount within this range, it is preferable that ink absorption can be more efficiently obtained without causing cracks on the surface of the ink receiving layer by preventing the ink receiving layer from dropping into the lower layer of the inorganic ultrafine particles.

  In the glossy inkjet recording sheet of the present invention, any conventionally known pigment can be used in the pigment layer as long as the above requirements are satisfied. For example, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic non White inorganic pigments such as crystalline silica, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, organic pigments such as styrene plastic pigment, acrylic plastic pigment, polyethylene, urea resin, melamine resin Etc. Of these, porous inorganic pigments are preferred from the balance of cracks in the coating layer and ink absorbability, and examples include porous synthetic amorphous silica, porous calcium carbonate, porous magnesium carbonate, and porous alumina. Porous synthetic amorphous silica is preferred.

  Two or more kinds of the same kind of pigment particles having different types of pigments or different properties such as average secondary particle diameter and oil absorption can be used in the pigment contained in the pigment layer.

  In the present invention, in addition to pigment particles, the pigment layer may contain a cationic compound in addition to the above when applied to an ink jet recording system in which a pigment ink and a dye ink are used in combination. it can. In addition, as additives, dye fixing agents, pigment dispersants, thickeners, fluidity improvers, surfactants, antifoaming agents, antifoaming agents, mold release agents, foaming agents, penetrating agents, colored dyes, Coloring pigments, fluorescent whitening agents, ultraviolet absorbers, antioxidants, preservatives, antibacterial agents, water resistance agents, wetting power enhancers, dry paper strength enhancing agents, and the like can be appropriately blended.

  The pigment layer of the present invention preferably further contains a binder. Examples of the binder include starch derivatives such as oxidized starch, etherified starch, and phosphate esterified starch; cellulose derivatives such as methylcellulose, carboxymethylcellulose, and hydroxyethylcellulose; polyvinyl alcohol derivatives such as polyvinyl alcohol and silanol-modified polyvinyl alcohol Casein, gelatin and modified products thereof, soy protein, pullulan, gum arabic, Karaya gum, albumin and other natural polymer resins or derivatives thereof, vinyl polymers such as polyacrylamide and polyvinylpyrrolidone, alginic acid, polyethyleneimine, polypropylene glycol, Hydrophilic binders such as polyethylene glycol, maleic anhydride or copolymers thereof, styrene-butadiene copolymer, methyl methacrylate-butadiene Conjugated diene copolymer latex such as styrene copolymer, acrylic copolymer latex such as acrylate ester and methacrylate ester polymer or copolymer, ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate Functional group-modified copolymer with functional group-containing monomers such as carboxy groups of vinyl-based copolymer latex such as copolymers, polyurethane resin latex, alkyd resin latex, unsaturated polyester resin latex, and these various copolymers Examples thereof include latex binders such as united latex, aqueous binders such as thermosetting synthetic resins such as melamine resins and urea resins, and polyvinyl butyral. One or more of these can be used. Of these, it is preferable to contain one or more hydrophilic binders and latex binders in terms of coating layer strength and cracks in the coating layer.

  As a compounding quantity of the binder used for the pigment layer of this invention, it is 5-70 mass parts with respect to 100 mass parts of sum total of a pigment particle, Preferably, it is 10-50 mass parts.

In the present invention, the range of the dry coating amount of the pigment layer is 3 to 30 g / m ² , more preferably 5 to 20 g / m ^2. By making the range of the dry coating amount of the pigment layer within this range, gloss is achieved. Ink absorbability can be obtained more efficiently without reducing the properties, which is preferable.

  The pigment layer coating method according to the present invention includes a slide hopper coating method, a curtain coating method, an extrusion coating method, an air knife coating method, a blade coating method, a roll coating method, a rod bar coating method, and a gravure coating method. A size press coating method, a spray coating method, etc. are mentioned. These coating methods can be performed on-machine or off-machine. Moreover, although it may finish using a calendar after coating, the conditions should be kept to such an extent that ink absorptivity is not inhibited. Examples of the calendar method include a machine calendar method, a TG calendar method, a super calendar method, a soft calendar method, and an embossed calendar method.

The ink receiving layer according to the present invention will be described.
In the present invention, the ink receiving layer coated on the pigment layer is not particularly limited as long as it is at least one layer. When one ink-receiving layer is coated on the pigment layer, it is essential that the ink-receiving layer contains at least inorganic ultrafine particles, a hydrophilic binder, boric acid or borate, and polyolefin particles. It becomes. Further, when two or more ink receiving layers are coated on the pigment layer, the first ink receiving layer applied directly on the pigment layer is at least inorganic ultrafine particles, a hydrophilic binder, It is essential that the ink receiving layer that contains boric acid or borate and is located on the outermost layer contains at least polyolefin particles and inorganic ultrafine particles.

  Polyolefin refers to an aliphatic hydrocarbon polymer containing one or more carbon-carbon double bonds. Industrially, polyethylene, polypropylene, and polybutene are in practical use. Specifically, Mitsumi Chemical Co., Ltd. has promoted the Chemipearl series as a fine particle dispersion of polyolefin, and Sumitomo Seika Co., Ltd. has introduced the powdered Fluxen series and Flow beads series. The polyolefin particles in the present invention are not particularly limited as long as the raw material is polyolefin, but polyethylene particles and polypropylene particles can be preferably used because of their availability. The particle size is preferably 3 μm to 22 μm without impairing the gloss and high color developability of the glossy inkjet recording sheet of the present invention.

  The inorganic ultrafine particles used in the ink receiving layer of the present invention are inorganic ultrafine particles having an average secondary particle diameter of 500 nm or less when primary particles are aggregated to form secondary particles. For example, JP-A-1-97678, 2-275510, 3-281383, 3-285814, 3-285815, 4-92183, 4-267180 Pseudo boehmite sol which is an alumina hydrate disclosed in Japanese Patent Laid-Open Nos. 4-27517, etc., JP-A-60-219083, 61-19389, 61-188183, 63- Colloidal silica as described in JP 178074 A, JP 5-51470 A, etc., silica / alumina hybrid sol as described in JP 4-19037 A, JP 62-286787 A, etc. , Gas phase process silica as described in JP-A-10-119423 and JP-A-10-217601. A silica sol dispersed with a high-speed homogenizer, mechanically pulverized as described in JP-A-10-181191, JP-A-10-272833, JP-A-2001-199158 and JP-A-2002-331747 Typical examples include wet silica, smectite clays such as hectite and montmorillonite (JP-A-7-81210), zirconia sol, chromia sol, yttria sol, ceria sol, iron oxide sol, zircon sol, and antimony oxide sol. Can be mentioned. Furthermore, colloidal particles such as colloidal silica, gas phase method silica, alumina, and alumina hydrate are preferable.

  The average primary particle diameter of the inorganic ultrafine particles referred to in the present invention is the average of the diameters of the circles equal to the projected area of each of the 100 primary particles existing within a certain area by electron microscopic observation of the fine particles. The average secondary particle size of the inorganic ultrafine particles is obtained by measuring the diluted dispersion with a particle size distribution meter using a laser diffraction / scattering method.

In general, silica fine particles are fine particles composed of SiO ₂ 93% or more, Al ₂ O ₃ about 5% or less, Na ₂ O about 5% or less on a dry basis, such as white carbon, silica gel, fine powder silica, etc. There is amorphous silica. As methods for producing amorphous silica fine particles, there are a liquid phase method, a pulverized solid phase method, a crystallization solid phase method, and a gas phase method. Among them, the vapor phase method is a method for producing fine particles by thermal decomposition of vapors of volatile metal compounds, heating and evaporation of raw materials, cooling of generated vapor phase species, and condensation. Amorphous silica is referred to as vapor phase silica.

  Vapor phase silica is generally made by flame hydrolysis. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or tetrachlorosilane instead of silicon tetrachloride. It can be used in a mixed state with silicon. Vapor phase method silica is commercially available as, for example, Aerosil from Nippon Aerosil Co., Ltd. and can be obtained.

  Colloidal silica is a synthetic silica having a primary particle size of about several nanometers to 100 nm synthesized by a wet method, and its shape is generally spherical or nearly spherical. The colloidal silica according to the present invention is more preferably an elongated shape in which small silica particles are connected in a chain or a non-spherical shape having a three-dimensional network structure. Elongated particles are particles that do not extend in the three-dimensional direction but extend in the same plane. The elongated particles include those that are almost straight, bent, those that have branches, and those that have a ring. In contrast, particles having a three-dimensional network structure refer to those having a network structure in which these elongated particles are literally three-dimensionally entangled.

Alumina hydrate can be represented by the following general formula.
Al ₂ O ₃ · nH ₂ O
Alumina hydrates are classified into dipsite, vialite, norstrandite, boehmite, boehmite gel (pseudoboehmite), diaspore, amorphous amorphous, etc., depending on the composition and crystal form. In particular, in the above formula, when the value of n is 1, it represents an alumina hydrate having a boehmite structure, and when n is more than 1 and less than 3, it represents an alumina hydrate having a pseudo boehmite structure, where n is 3 or more represents an amorphous alumina hydrate. In particular, the preferred alumina hydrate for the present invention is an alumina hydrate having a pseudo boehmite structure in which at least n is more than 1 and less than 3.

  The shape of the alumina hydrate used in the present invention may be any of a flat plate shape, a fiber shape, a needle shape, a spherical shape, a rod shape, and the like, and a preferable shape is a flat shape from the viewpoint of ink absorbability. The plate-like alumina hydrate has an average aspect ratio of 3 to 8, and preferably an average aspect ratio of 3 to 6. The aspect ratio is expressed as the ratio of the “diameter” to the “thickness” of the particles. Here, the diameter of the particle represents the diameter of a circle equal to the projected area of the particle when the alumina hydrate is observed with an electron microscope. When the aspect ratio is smaller than the above range, the pore size distribution of the glossy expression layer becomes narrow, and the ink absorbability may be lowered. On the other hand, when the aspect ratio exceeds the above range, it may be difficult to produce alumina hydrate by aligning the particles.

  The alumina hydrate used in the present invention can be produced by a known method such as hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali, hydrolysis of aluminate. The physical properties of alumina hydrate, such as particle size, pore size, pore volume, and specific surface area, should be controlled by conditions such as precipitation temperature, aging temperature, aging time, solution pH, solution concentration, and coexisting compounds. Can do.

  Commercially available alumina hydrate can also be suitably used for the glossy ink jet recording sheet of the present invention. One example is given below, but the present invention is not limited thereto. For example, as alumina hydrate, cataloid AS-1, cataloid AS-2, cataloid AS-3 (above, Catalytic Chemical Industry Co., Ltd.) alumina sol 100, alumina sol 200, alumina sol 520 (above, Nissan Chemical Industries, Ltd.) ), M-200 (above, Mizusawa Chemical Co., Ltd.), aluminum sol 10, aluminum sol 20, aluminum sol 132, aluminum sol 132S, aluminum sol SH5, aluminum sol CSA55, aluminum sol SV102, aluminum sol SB52 (above, Kawaken Fine Chemical Co., Ltd.) Can be mentioned.

  The aluminum oxide ultrafine particles used in the present invention are preferably γ-type aluminum oxide fine particles which are γ-type crystals. If γ-type crystals are classified crystallographically, they can be further divided into γ group and δ group. Fine particles having a δ group crystal form are preferred.

  The aluminum oxide of γ-type crystal fine particles can reduce the average particle diameter of primary particles to about 10 nm, but in general, the primary particles form a secondary aggregated form (hereinafter referred to as secondary particles). Thus, the particle diameter increases from several thousand to several tens of thousands of nm. When such γ-type alumina crystal fine particles having a large particle diameter are used, the ink-receiving layer has good printability and absorbability, but lacks transparency and tends to cause coating film defects.

  In order to obtain a γ-type aluminum oxide fine particle sol, the average particle size of the γ-type aluminum oxide crystals, which are usually secondary particles of several thousand to several tens of thousands nm, is obtained by pulverizing means such as a bead mill, an ultrasonic homogenizer, or a high-pressure homogenizer. It grind | pulverizes until it becomes the ultrafine particle whose diameter is 200 nm or less, Preferably it is 100 nm or less. When the average particle diameter exceeds 200 nm, the ink absorbability increases, but the coating becomes brittle and the transparency is lowered. As the pulverization means, a method using an ultrasonic homogenizer or a high-pressure homogenizer is preferable. In other pulverization methods such as a bead mill, the γ-type aluminum oxide crystal is a hard crystal, so that foreign substances are likely to be mixed from the pulverization container and transparent. Cause deterioration of the property and occurrence of defects. γ-type aluminum oxide crystal fine particles have excellent ink absorbability, good print quality such as drying and ink fixability, and excellent transparency even when included in the glossy layer at a high ratio by making ultrafine particles. An ink jet recording sheet can be obtained.

  The γ-type aluminum oxide crystal fine particles are commercially available as aluminum oxide C belonging to δ group (Nippon Aerosil Co., Ltd.), AKP-G015 (Sumitomo Chemical Co., Ltd.) belonging to γ group, and the like.

As boric acid used in the first ink receiving layer in the present invention, not only orthoboric acid but also metaboric acid, hypoboric acid and the like can be used. The borate is preferably a soluble salt such as Na ₂ B ₄ O ₇ · 10H ₂ O, NaBO ₂ · 4H ₂ O, K ₂ B ₄ O ₇ · 5H ₂ O, NH ₄ HB ₄ O. _{7 · 3H 2 O, NH 4} BO 2 , and the like, but the present invention is not limited thereto. When the ink receiving layer has two or more layers, it is preferable that at least one ink receiving layer excluding the first ink receiving layer contains boric acid or borate.

The addition amount of boric acid or borate in H ₃ BO ₃ in terms of 1 to 15 wt% with respect to the hydrophilic binder contained in the ink-receiving layer of adding boric acid or a borate, preferably 3 -10 mass%.

  In the present invention, the mass ratio of the inorganic ultrafine particles and the polyolefin particles contained in the ink receiving layer located at the outermost layer is preferably 98/2 to 90/10. By being in this range, the glossy inkjet recording sheet of the present invention can further improve the color developability.

  Furthermore, the inorganic ultrafine particles contained in the ink receiving layer located at the outermost layer in the present invention are preferably alumina hydrate and / or aluminum oxide. By using alumina hydrate and / or aluminum oxide, glossiness of the glossy ink jet recording sheet of the present invention is further improved.

  Further, in the glossy ink jet recording sheet of the present invention, the inorganic ultrafine particles contained in the first ink receiving layer in contact with the pigment layer are vapor phase silica, and the inorganic superfine particles contained in the ink receiving layer located on the outermost layer. The fine particles are preferably alumina hydrate and / or aluminum oxide. By adopting such a configuration, the glossy ink jet recording sheet of the present invention with improved glossiness and color developability can be obtained.

  As the binder contained in the ink receiving layer in the present invention, the same binder as that contained in the pigment layer can be appropriately used. The amount of the binder contained in the ink receiving layer according to the present invention is not particularly limited as long as it does not impair the ink absorbability of the ink receiving layer. Preferably, it is 2-100 mass parts with respect to 100 mass parts of pigments. More preferably, it is 2-50 mass parts.

  In the present invention, it is preferable that the ink receiving layer other than the first ink receiving layer also contains boric acid or borate. Furthermore, for the ink receiving layer, coloring dyes, coloring pigments, UV absorbers, antioxidants, pigment dispersants, antifoaming agents, leveling agents, preservatives, fluorescent brighteners, viscosity stabilizers, surfactants, etc. These various known additives can also be added.

The dry coating amount of the ink receiving layer of the present invention is preferably ³ to 25 g / m ² , more preferably 5 to 20 g / m ² .

  As an ink receiving layer coating method on the pigment layer according to the present invention, slide hopper coating method, curtain coating method, extrusion coating method, air knife coating method, blade coating method, roll coating method, rod bar coating method And gravure coating method, size press coating method, spray coating method and the like. These coating methods can be performed on-machine or off-machine. Moreover, although it may finish using a calendar after coating, the conditions should be kept to such an extent that ink absorptivity is not inhibited. Examples of the calendar method include a machine calendar method, a TG calendar method, a super calendar method, a soft calendar method, and an embossed calendar method.

  In the present invention, the pH of the coating liquid for the pigment layer is preferably 8 or more and 11 or less, and the pH of the coating liquid for the first ink receiving layer is preferably 3 or more and 5 or less. More preferably, the pH of the coating liquid for the pigment layer is 8.5 or more and 11 or less, and the pH of the coating liquid for the first ink receiving layer is 3 or more and 4.5 or less. By setting it in this range, the binder and inorganic ultrafine particles in the ink receiving layer in the pigment layer are less dropped and the surface gloss is improved, which is preferable.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the examples and comparative examples, “parts” and “%” indicate parts by mass and mass% unless otherwise specified.

<Pigment layer coating liquid 1>
100 parts of synthetic amorphous silica (average secondary particle diameter: 1.2 μm, secondary particle diameter: 1.2 to 15 μm, proportion of inorganic particles: 50% by volume) is dispersed in 400 parts of pure water using a homogenizer. A pigment layer coating solution 1 having a solid content concentration of 16.7% and pH 6.4 was prepared by mixing 250 parts of a 10% polyvinyl alcohol (completely saponified, degree of polymerization 1700) aqueous solution.

<Synthesis of alumina hydrate>
The synthesis example of the alumina hydrate used for an ink receiving layer is shown below. All the raw materials used were commercial products and were used as they were without any purification.

  1200 g of pure water and 900 g of isopropyl alcohol were charged into a 3 L reactor and heated to 75 ° C. 408 g of aluminum isopropoxide was added, and hydrolysis was performed at 75 ° C. for 24 hours and at 95 ° C. for 4 hours. Thereafter, 24 g of acetic acid was added and stirred at 95 ° C. for 40 hours, and then dispersed using a sawtooth blade type disperser and concentrated to a solid content concentration of 16% to form white ultrafine particles. A dispersion of alumina hydrate was obtained. The average secondary particle diameter of the alumina hydrate fine particles measured by a laser diffraction / scattering method was 180 nm.

  When this sol was dried at room temperature and measured for X-ray diffraction, it showed a pseudo-boehmite structure. Further, when the average primary particle diameter was measured with a transmission electron microscope, it was about 20 nm and was an alumina hydrate having a flat pseudoboehmite structure with an aspect ratio of 6.

<Ink-receiving layer coating liquid 1>
Using the above dispersion of 16% ultrafine alumina hydrate, 594 parts of the alumina hydrate dispersion, 60 parts of an aqueous solution of 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400), 4 parts 12.5 parts of a 1% aqueous boric acid solution and 12.5 parts of a polyolefin particle dispersion (Mitsui Chemicals, Inc. Chemipearl W310, particle size 9.5 μm, solid content concentration 40%) were added, and the required amount of pure water was added. Ink-receiving layer coating solution 1 having a solid content concentration of 15.4% and pH 4.0 was prepared. In addition, the ratio of the alumina hydrate which is inorganic ultrafine particles to the polyolefin particles is 95/5.

Prepare high-quality paper with a basis weight of 102 g / m ² as a water-absorbing support, and apply the pigment layer coating solution 1 prepared above on one side with a wire bar so that the dry coating amount is 12 g / m ^2. , Dried. Next, the ink receiving layer coating liquid 1 prepared above is applied onto the pigment layer with a wire bar so that the dry coating amount is 9 g / m ² , dried, and then subjected to a soft calendering treatment. A glossy ink jet recording sheet was obtained.

<Pigment layer coating liquid 2>
100 parts of synthetic amorphous silica (average secondary particle diameter of 1.5 μm, secondary particle diameter of 1.2 to 15 μm: proportion of inorganic particles: 50% by volume) is dispersed in 400 parts of pure water using a homogenizer. A pigment layer coating solution 2 having a solid content concentration of 16.7% and a pH of 6.1 was prepared by mixing 250 parts of an aqueous solution of 10% polyvinyl alcohol (completely saponified, degree of polymerization 1700).

  A glossy inkjet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the pigment layer coating solution 1 was changed to the pigment layer coating solution 2.

<Ink-receiving layer coating liquid 2>
Using the above dispersion of 16% ultrafine alumina hydrate, 594 parts of the alumina hydrate dispersion, 60 parts of an aqueous solution of 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400), 4 parts 12.5 parts of an aqueous boric acid solution and 12.5 parts of a polyolefin particle dispersion (Mitsui Chemicals, Inc. Chemipearl M200, particle size 6.0 μm, solid content concentration 40%) were added, and the required amount of pure water was added. Ink-receiving layer coating liquid 2 having a solid content concentration of 15.4% and pH 4.0 was prepared. In addition, the ratio of the alumina hydrate which is inorganic ultrafine particles to the polyolefin particles is 95/5.

  A glossy ink jet recording sheet of the present invention was obtained in the same manner as in Example 2 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 2.

<Ink-receiving layer coating liquid 3>
Using the above dispersion of 16% ultrafine alumina hydrate, 594 parts of the alumina hydrate dispersion, 60 parts of an aqueous solution of 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400), 4 parts 12.5 parts of an aqueous boric acid solution and 5 parts of polyolefin particles (Sumitomo Seika Co., Ltd., Flocene UF20, particle size 22.0 μm) are mixed, and the required amount of pure water is added to obtain a solid content concentration of 15.4%, pH 4 0.0 ink-receiving layer coating solution 3 was prepared. In addition, the ratio of the alumina hydrate which is inorganic ultrafine particles to the polyolefin particles is 95/5.

  A glossy ink jet recording sheet of the present invention was obtained in the same manner as in Example 2 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 3.

<Pigment layer coating solution 3>
100 parts of synthetic amorphous silica (average ratio of inorganic particles having a secondary particle diameter of 1.5 μm, secondary particle diameter of 1.2 to 15 μm: 80% by volume) is dispersed in 400 parts of pure water using a homogenizer. A pigment layer coating solution 3 having a solid content concentration of 16.7% and a pH of 6.1 was prepared by mixing 250 parts of a 10% polyvinyl alcohol (completely saponified, degree of polymerization 1700) aqueous solution.

  A glossy inkjet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the pigment layer coating solution 1 was changed to the pigment layer coating solution 3.

<Pigment layer coating solution 4>
100 parts of synthetic amorphous silica (average secondary particle size 1.5 μm, secondary particle size 1.2 to 15 μm inorganic particle ratio: 100% by volume) is dispersed in 400 parts pure water using a homogenizer. A pigment layer coating solution 4 having a solid content concentration of 16.7% and a pH of 6.1 was prepared by mixing 250 parts of a 10% polyvinyl alcohol (completely saponified, degree of polymerization 1700) aqueous solution.

  A glossy inkjet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the pigment layer coating solution 1 was changed to the pigment layer coating solution 4.

<Pigment layer coating solution 5>
100 parts of synthetic amorphous silica (average ratio of inorganic particles having a secondary particle diameter of 4 μm and secondary particle diameter of 1.2 to 15 μm: 100% by volume) is dispersed in 400 parts of pure water using a homogenizer. A pigment layer coating solution 5 having a solid content concentration of 16.7% and a pH of 6.2 was prepared by mixing 250 parts of a% polyvinyl alcohol (completely saponified, degree of polymerization 1700) aqueous solution.

  A glossy inkjet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the pigment layer coating solution 1 was changed to the pigment layer coating solution 5.

<Pigment layer coating liquid 6>
Using a homogenizer, 0.5 parts of sodium hydroxide and 100 parts of synthetic amorphous silica (ratio of inorganic particles having an average secondary particle size of 1.5 μm and a secondary particle size of 1.2 to 15 μm: 80% by volume) were purified using a homogenizer. Dispersed in 400 parts of water, 250 parts of a 10% polyvinyl alcohol (completely saponified, degree of polymerization 1700) aqueous solution was mixed with this to prepare a pigment layer coating solution 6 having a solid concentration of 16.7% and a pH of 8.1.

  A glossy inkjet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the pigment layer coating solution 1 was changed to the pigment layer coating solution 6.

<Pigment layer coating liquid 7>
400 parts of pure water using a homogenizer and 1 part of sodium hydroxide and 100 parts of synthetic amorphous silica (ratio of inorganic particles having an average secondary particle size of 1.5 μm and a secondary particle size of 1.2 to 15 μm: 80% by volume) A pigment layer coating solution 7 having a solid content concentration of 16.7% and a pH of 9.6 was prepared by mixing 250 parts of a 10% polyvinyl alcohol (completely saponified, degree of polymerization 1700) aqueous solution.

  A glossy inkjet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the pigment layer coating solution 1 was changed to the pigment layer coating solution 7.

<Pigment layer coating solution 8>
1.5 parts of sodium hydroxide and 100 parts of synthetic amorphous silica (ratio of inorganic particles having an average secondary particle size of 1.5 μm and a secondary particle size of 1.2 to 15 μm: 80% by volume) were purified using a homogenizer. Dispersed in 400 parts of water, 250 parts of a 10% polyvinyl alcohol (completely saponified, degree of polymerization 1700) aqueous solution was mixed with this to prepare a pigment layer coating solution 8 having a solid concentration of 16.7% and a pH of 10.3.

  A glossy inkjet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the pigment layer coating solution 1 was changed to the pigment layer coating solution 8.

<Pigment layer coating solution 9>
Purify 100 parts of sodium hydroxide and 100 parts of synthetic amorphous silica (average secondary particle size of 1.5 μm, secondary particle size of 1.2 to 15 μm of inorganic particles: 80% by volume) using a homogenizer. Dispersed in 400 parts of water, 250 parts of a 10% polyvinyl alcohol (completely saponified, degree of polymerization 1700) aqueous solution was mixed with this to prepare a pigment layer coating solution 9 having a solid content of 16.7% and a pH of 11.6.

  A glossy inkjet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the pigment layer coating solution 1 was changed to the pigment layer coating solution 9.

<Ink-receiving layer coating solution 4>
Using the above dispersion of 16% ultrafine alumina hydrate, 619 parts of the alumina hydrate dispersion, 60 parts of an aqueous solution of 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400), 4 parts 12.5 parts of an aqueous boric acid solution and 2.5 parts of a polyolefin particle dispersion (Mitsui Chemicals, Inc. Chemipearl W310, particle size 9.5 μm, solid content concentration 40%) were mixed, and the required amount of pure water was added. Ink-receiving layer coating solution 4 having a solid content concentration of 15.4% and pH 4.0 was prepared. In addition, the ratio of the alumina hydrate which is an inorganic ultrafine particle and polyolefin particle | grains is 99/1.

  A glossy ink jet recording sheet of the present invention was obtained in the same manner as in Example 5 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 4.

<Ink-receiving layer coating solution 5>
Using the above dispersion of 16% ultrafine alumina hydrate, 613 parts of the alumina hydrate dispersion, 60 parts of an aqueous solution of 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400), 4 parts 12.5 parts of an aqueous boric acid solution and 5 parts of a polyolefin particle dispersion (Mitsui Chemicals, Inc. Chemipearl W310, particle size 9.5 μm, solid content concentration 40%) are mixed, and the required amount of pure water is added to obtain a solid content. Ink-receiving layer coating solution 5 having a concentration of 15.4% and pH 4.0 was prepared. In addition, the ratio of the alumina hydrate which is an inorganic ultrafine particle and polyolefin particle | grains is 98/2.

  A glossy ink jet recording sheet of the present invention was obtained in the same manner as in Example 5 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 5.

<Ink-receiving layer coating liquid 6>
Using the above dispersion of 16% ultrafine alumina hydrate, 563 parts of the alumina hydrate dispersion, 60 parts of an aqueous solution of 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400), 4 parts 12.5 parts of an aqueous boric acid solution and 25 parts of a polyolefin particle dispersion (Mitsui Chemicals, Inc. Chemipearl W310, particle size 9.5 μm, solid content concentration 40%) are mixed, and the required amount of pure water is added to obtain a solid content. Ink-receiving layer coating liquid 6 having a concentration of 15.4% and pH 4.0 was prepared. In addition, the ratio of the alumina hydrate which is inorganic ultrafine particles to the polyolefin particles is 90/10.

  A glossy ink jet recording sheet of the present invention was obtained in the same manner as in Example 5 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 6.

<Ink-receiving layer coating liquid 7>
Using the above dispersion of 16% ultrafine alumina hydrate, 550 parts of this alumina hydrate dispersion, 60 parts of 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400) aqueous solution 4 parts, 12.5 parts of an aqueous boric acid solution and 30 parts of a polyolefin particle dispersion (Mitsui Chemicals, Inc., Chemipearl W310, particle size 9.5 μm, solid content concentration 40%) were mixed, and the required amount of pure water was added to obtain a solid content. Ink-receiving layer coating liquid 7 having a concentration of 15.4% and pH 4.0 was prepared. In addition, the ratio of the alumina hydrate which is an inorganic ultrafine particle and polyolefin particle | grains is 88/12.

  A glossy ink jet recording sheet of the present invention was obtained in the same manner as in Example 5 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 7.

  Except that the prepared ink-receiving layer coating solution 1 was stirred and 10% nitric acid aqueous solution was appropriately added until the pH of the ink-receiving layer coating solution 1 became 2.5, the same as in Example 9. A glossy ink jet recording sheet of the present invention was obtained.

  The present invention was carried out in the same manner as in Example 9 except that the prepared ink-receiving layer coating solution 1 was stirred and used after appropriately adding a 10% nitric acid aqueous solution until the pH of the ink-receiving layer coating solution 1 reached 3. A glossy inkjet recording sheet was obtained.

  The same procedure as in Example 9 was followed, except that the prepared ink-receiving layer coating solution 1 was stirred and used after appropriately adding a 5% aqueous sodium hydroxide solution until the pH of the ink-receiving layer coating solution 1 reached 5. A glossy ink jet recording sheet of the present invention was obtained.

  The same procedure as in Example 9 was followed, except that the prepared ink-receiving layer coating solution 1 was stirred and used after appropriately adding a 5% aqueous sodium hydroxide solution until the pH of the ink-receiving layer coating solution 1 reached 6. A glossy ink jet recording sheet of the present invention was obtained.

<Ink-receiving layer coating liquid 8>
237.5 parts of aluminum oxide (Cabot Specialty Chemicals Inc. CAB-O-SPERSE PG003 primary particle size 20 nm, average secondary particle size 150 nm, solid content concentration 40%) as inorganic ultrafine particles, 10% polyvinyl alcohol (Saponification degree 88%, polymerization degree 2400) 60 parts aqueous solution, 12.5 parts 4% boric acid aqueous solution, polyolefin particle dispersion (Mitsui Chemicals, Inc. Chemipearl W310, particle size 9.5 μm, solid content concentration 40%) 12 .5 parts was mixed, and a necessary amount of pure water was added to prepare an ink-receiving layer coating solution 8 having a solid content concentration of 15.4% and a pH of 3.9. The ratio of aluminum oxide, which is inorganic ultrafine particles, to polyolefin particles is 95/5.

  A glossy inkjet recording sheet of the present invention was obtained in the same manner as in Example 9 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 8.

<Gas phase silica dispersion>
While adding 25 kg of gas phase method silica (Tokuyama Corporation, BET specific surface area 300 m ² / g) having an average primary particle size of 7 nm to 131.25 kg of 5% aqueous solution of cationic polymer (diallyldimethylammonium chloride, molecular weight 9000), 2 Using a shaft disperser (container diameter 550 mm, sawtooth blade diameter 150 mm for each shaft), the peripheral speed of the sawtooth blade was dispersed at 30 m / sec for 60 minutes to obtain a coarse dispersion of vapor phase method silica. Next, the vapor phase silica coarse dispersion obtained in the primary dispersion step was emulsified and dispersed three times by a high pressure homogenizer under the conditions of a throughput of 40 l / hour and a pressure of 19.6 MPa to obtain a vapor phase silica dispersion. The resulting dispersion was stored at 60 ° C. for 1 hour with a propeller blade-type disperser while stirring at low speed to obtain a vapor phase method silica dispersion. The solid concentration was measured and found to be 21%. In addition, the average secondary particle diameter of the vapor phase method silica fine particles measured by a laser light diffraction / scattering method was 200 nm.

<Ink-receiving layer coating liquid 9>
Vapor phase silica dispersion 476 parts, 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400) aqueous solution 150 parts, 4% boric acid aqueous solution 12.5 parts are mixed, and the required amount of pure water is added. Thus, an ink receiving layer coating solution 9 having a solid concentration of 18.1% and a pH of 3.8 was prepared.

Prepare high-quality paper with a basis weight of 102 g / m ² as a water-absorbing support, and apply a pigment bar coating solution 7 prepared in Example 9 on one side with a wire bar so that the dry coating amount is 12 g / m ^2. Applied and dried. Next, the ink receiving layer coating liquid 9 prepared above was applied onto the pigment layer with a wire bar so that the dry coating amount was 8 g / m ^2, and dried. Further, the ink receiving layer coating liquid 1 prepared in Example 1 was applied with a wire bar so that the dry coating amount was 9 g / m ² and dried, followed by a soft calendering process. Obtained.

  A glossy inkjet recording sheet of the present invention was obtained in the same manner as in Example 21 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 8.

(Comparative Example 1)
<Pigment layer coating solution 10>
100 parts of synthetic amorphous silica (average secondary particle size 0.8 μm, secondary particle size 1.2 to 15 μm inorganic particle ratio: 20% by volume) is dispersed in 400 parts of pure water using a homogenizer. A pigment layer coating solution 10 having a solid content concentration of 16.7% and a pH of 5.9 was prepared by mixing 250 parts of an aqueous solution of 10% polyvinyl alcohol (completely saponified, degree of polymerization 1700).

  An ink jet recording sheet was obtained in the same manner as in Example 1 except that the pigment layer coating solution 1 was changed to the pigment layer coating solution 10.

(Comparative Example 2)
<Pigment layer coating solution 11>
100 parts of synthetic amorphous silica (average proportion of inorganic particles having a secondary particle diameter of 20 μm, secondary particle diameter of 1.2 to 15 μm: 30% by volume) is dispersed in 400 parts of pure water using a homogenizer, and 10 parts thereof are dispersed. A pigment layer coating solution 11 having a solid content of 16.7% and a pH of 5.9 was prepared by mixing 250 parts of a% polyvinyl alcohol (completely saponified, degree of polymerization 1700) aqueous solution.

  An ink jet recording sheet was obtained in the same manner as in Example 1 except that the pigment layer coating solution 1 was changed to the pigment layer coating solution 11.

(Comparative Example 3)
An ink jet recording sheet was obtained in the same manner as in Example 21 except that the pigment layer coating solution 7 was changed to the pigment layer coating solution 10.

(Comparative Example 4)
An ink jet recording sheet was obtained in the same manner as in Example 21 except that the pigment layer coating solution 7 was changed to the pigment layer coating solution 11.

(Comparative Example 5)
<Ink-Receiving Layer Coating Liquid 10>
Using the above dispersion of 16% ultrafine alumina hydrate, 625 parts of the alumina hydrate dispersion, 60 parts of 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400) aqueous solution 4 parts, 12.5 parts of an aqueous boric acid solution was mixed, and a necessary amount of pure water was added to prepare an ink-receiving layer coating solution 10 having a solid content concentration of 15.4% and pH 4.0.

  An ink jet recording sheet was obtained in the same manner as in Example 5 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 10.

(Comparative Example 6)
A glossy inkjet recording sheet was obtained in the same manner as in Example 21 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 10.

(Comparative Example 7)
<Ink-Receiving Layer Coating Liquid 11>
Using the above dispersion of 16% ultrafine alumina hydrate, 594 parts of the alumina hydrate dispersion, 60 parts of an aqueous solution of 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400), 4 parts 12.5 parts of an aqueous boric acid solution and 5 parts of wheat starch particles (particle size: 20.0 μm) are mixed, and a necessary amount of pure water is added to form an ink receiving layer coating solution having a solid content of 15.4% and a pH of 4.0 11 was prepared. The ratio of alumina hydrate, which is inorganic ultrafine particles, to wheat starch is 95/5.

  An ink jet recording sheet was obtained in the same manner as in Example 1 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 11.

(Comparative Example 8)
<Ink receiving layer coating liquid 12>
Using the above dispersion of 16% ultrafine alumina hydrate, 594 parts of the alumina hydrate dispersion, 60 parts of an aqueous solution of 10% polyvinyl alcohol (saponification degree 88%, polymerization degree 2400), 4 parts 12.5 parts of 1% aqueous boric acid solution and 12.5 parts of ethylene vinyl acetate copolymer resin particle dispersion (Mitsui Chemicals, Inc. Chemipearl V100, particle size 12.0 μm, solid content concentration 40%) Pure water was added to prepare an ink receiving layer coating solution 12 having a solid content concentration of 15.4% and a pH of 4.0. In addition, the ratio of the alumina hydrate which is inorganic ultrafine particles to the ethylene vinyl acetate copolymer resin particles is 95/5.

  An ink jet recording sheet was obtained in the same manner as in Example 1 except that the ink receiving layer coating liquid 1 was changed to the ink receiving layer coating liquid 12.

<Test method>
(1) Print Part Scratch Resistance The ink jet recording sheets prepared in Examples and Comparative Examples were cut into A4 size, and black (Bk) using an ink jet printer using pigment ink (Canon, Inc., imagePROGRAF W6200 mode; photo glossy paper). ), Cyan (C), magenta (M), and yellow (Y) 100% solid printing. After leaving for 24 hours after printing, the printed part is rubbed strongly with a corner of a 4 cm × 4 cm × 0.5 cm vinyl chloride plate, and the degree of ink peeling is visually observed. ◎ If the ink is not peeled off and there is no trace of rubbing, ◎ If the ink is not peeled off but the rubbing trace is known by gloss difference, ○ Even if the ink is slightly peeled off and attached to the plate It was determined that the part that was not visible to the ground in the part was Δ, and that the part that was clearly visible to the ground was ×. Practically, it needs to be ◎ or ○.

(2) Color development After the inkjet recording sheets prepared in Examples and Comparative Examples were cut into A4 size, an inkjet printer using pigment ink (Canon, Inc., imagePROGRAF W6200 mode; photo glossy paper), black (Bk), cyan (C ), 100% solid printing of each color of magenta (M) and yellow (Y) was performed, and the density of the printed portion was measured with Macbeth RD919. Larger values indicate higher print density and better printability.

(3) Surface gloss The surface gloss was measured at an incident reflection angle of 75 degrees using a digital gloss meter GM-26D manufactured by Murakami Color Research Laboratory according to JIS P8142. If the glossiness is 50% or more, the visibility is good as a posting and an image that looks good can be printed.

  As is apparent from Tables 1 and 2, the glossy ink jet recording sheet of the present invention has high scratch resistance at the printed portion, and good color development and glossiness. It is effective as an ink jet recording sheet.

Claims (5)

  In an inkjet recording sheet in which a pigment layer and at least one or more ink-receiving layers are sequentially laminated on one surface of the water-absorbent support, the average secondary particle diameter of the pigment contained in the pigment layer is 1 μm or more and 5 μm or less, and 50% by volume or more of the total volume of the pigment has a secondary particle diameter of 1.2 μm or more and 15 μm or less, and the first ink-receiving layer directly applied on the pigment layer has at least inorganic ultrafine particles and hydrophilic binders. A glossy ink jet recording sheet comprising an agent, boric acid or borate, and the ink receiving layer located on the outermost surface contains at least polyolefin particles and inorganic ultrafine particles.   2. The glossy ink jet recording sheet according to claim 1, wherein the mass ratio of the inorganic ultrafine particles and the polyolefin particles contained in the ink receiving layer located on the outermost surface is 98/2 to 90/10.   The pH of the coating liquid of the pigment layer is 8 or more and 11 or less, and the pH of the coating liquid of the first ink receiving layer in contact with the pigment layer is 3 or more and 5 or less. Glossy inkjet recording sheet.   The glossy ink jet recording sheet according to any one of claims 1 to 3, wherein the inorganic ultrafine particles contained in the ink receiving layer located on the outermost layer are alumina hydrate and / or aluminum oxide.   Inorganic ultrafine particles contained in the first ink-receiving layer in contact with the pigment layer, having two or more ink-receiving layers, are vapor phase silica and contained in the ink-receiving layer located on the outermost layer The glossy inkjet recording sheet according to any one of claims 1 to 4, wherein the inorganic ultrafine particles to be formed are alumina hydrate and / or aluminum oxide.