JP2011068025A - Inkjet recording medium and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording medium that has superior absorbency and prevents the occurrence of curling and bronzing of an image under low humidity environment. <P>SOLUTION: The inkjet recording medium includes: a porous resin layer that has holes in order from a supporter on the supporter and contains an inorganic particle and resin whose volume average particle size is 0.20 μm or less; and an ink absorbing layer with thickness of 6-20 μm that contains the inorganic particle, water-soluble resin and mordant. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink jet recording medium suitable for recording with ink ejected by an ink jet method, and a method for manufacturing the same.

  2. Description of the Related Art In recent years, inkjet recording methods have been widely used because they can be recorded on various recording materials, the hardware (device) is relatively inexpensive, compact, and quiet.

  Accompanying this, the resolution of ink jet printers has been increased, and in recent years, so-called photographic-like high-quality images have been obtained. The characteristics required of a recording medium for ink-jet recording for obtaining a high-quality image include quick drying (ink absorption speed), dot uniformity (bleed resistance), granularity, color density, saturation, and other various performances. It is necessary to meet. For example, as an ink jet recording medium with improved cracking, density, and gloss, the ink receiving layer contains inorganic fine particles, a water-soluble resin, and a boron compound, and a basic solution having a pH of 8 or higher is (1) simultaneously with the application of the receiving layer. An ink jet recording medium formed by (2) reducing-rate drying of the receiving layer or (3) applying the receiving layer after coating and drying is disclosed (for example, see Patent Document 1).

  On the other hand, when trying to reduce the thickness of the ink receiving layer for receiving ink in order to improve productivity and reduce curling in a low-humidity environment, the ink absorbability necessary for image recording is insufficient. The bronzing and glossiness of the image deteriorates.

  In relation to the above, an inkjet recording sheet having a porous film layer having an average pore diameter of 20 to 30 nm containing a hydrophilic substance between a support and a colorant receiving layer containing fine particles and a water-soluble resin. It is disclosed (for example, see Patent Document 2). Also disclosed is an ink jet recording paper in which an ink absorbing layer having a porous hydrophobic resin layer and a void layer containing fine particles is provided on a water-absorbing support (see, for example, Patent Document 3).

JP 2003-191607 A JP 2004-174747 A JP 11-291623 A

  However, in the above conventional technique, when the thickness of the ink receiving layer is reduced, the curling property under a low humidity environment is deteriorated, and the bronzing property of the recorded image is deteriorated.

  The present invention has been made in view of the above, and an object of the present invention is to provide an ink jet recording medium excellent in ink absorptivity, in which the occurrence of curling and image bronzing in a low humidity environment is suppressed, and a method for producing the same. It is an object to achieve the object.

Specific means for achieving the above object are as follows.
<1> A porous resin layer containing inorganic fine particles and a resin having pores and having a volume average particle diameter of 0.20 μm or less, an inorganic fine particle, a water-soluble resin, and a mordant in that order from the support side. An ink jet recording medium having an ink receiving layer having a thickness of 6 to 20 μm.

  <2> The ink receiving layer is formed by applying a coating liquid containing at least inorganic fine particles, a water-soluble resin, and a mordant on the porous resin layer, and (1) simultaneously with the coating or (2) formed by the coating. When the applied layer is in the middle of drying and before the coated layer exhibits reduced-rate drying, a basic solution containing a basic compound is applied to the coated layer, and the coating solution and the base The ink jet recording medium according to <1>, wherein the ink-jet recording medium is formed by including a crosslinking agent in at least one of the functional solutions and curing by crosslinking.

  <3> A resin layer forming step for forming a porous resin layer containing inorganic fine particles having a pore and a volume average particle size of 0.20 μm or less on the support, and a resin, inorganic fine particles, a water-soluble resin, and a mordant The coating liquid containing the coating is applied so as to be disposed on the porous resin layer, and (1) at the same time as the coating, or (2) during the drying of the coating layer formed by the coating, At any time before the layer shows reduced-rate drying, a basic solution containing a basic compound is applied to the coating layer, and at least one of the coating solution and the basic solution is crosslinked with a crosslinking agent. A receiving layer forming step of forming a cured ink receiving layer having a thickness of 6 to 20 μm.

  <4> In the resin layer forming step, at least a volume average particle size of 0.20 μm or less of inorganic fine particles and a resin are mixed, formed into a film by melt extrusion, and cooled and solidified. The method for producing an ink jet recording medium according to <3>, wherein the porous resin layer having a thickness of 5 to 30 μm is formed by stretching.

  According to the present invention, it is possible to provide an ink jet recording medium excellent in ink absorbability and suppressed in curling and image bronzing in a low humidity environment, and a method for manufacturing the same.

Hereinafter, the ink jet recording medium of the present invention and the manufacturing method thereof will be described in detail.
In the inkjet recording medium of the present invention, a porous resin layer containing inorganic fine particles having a volume average particle size of 0.20 μm or less and a resin is provided on a support, and the inorganic fine particles, water-soluble resin, And a mordant, and an ink receiving layer having a thickness of 6 to 20 μm is provided.

  In the present invention, when an ink receiving layer for receiving an ink and recording an image on a support is formed with a thin thickness of 6 to 20 μm, the volume average particle diameter is 0.20 μm in advance on the support. By providing a porous resin layer containing the following inorganic fine particles and a resin and providing an ink receiving layer thereon, the ink absorption speed can be ensured while the ink receiving layer is thin, and low humidity is achieved. It is possible to suppress the occurrence of curling and image bronzing under the environment. Further, the glossiness on the image recording surface is also improved. As a result, it is possible to provide a recorded matter with excellent image quality while suppressing deterioration in quality due to deformation.

-Porous resin layer-
The porous resin layer in the present invention includes at least inorganic fine particles having a volume average particle diameter of 0.20 μm or less and a resin, and can be configured using other components as necessary. The porous resin layer in the present invention is preferably in the form of a porous film layer in which pores are provided in at least a part of the layer. In this case, for example, a resin composition containing inorganic fine particles having a specific particle size and a resin is formed into a film by melt extrusion, cooled, solidified, and then stretched to suitably form a porous resin layer. Can do.

  By disposing this porous resin layer between the support and the ink receiving layer, the surface of the porous resin layer is smooth and contributes to gloss improvement, and ink absorption when the ink receiving layer is thinned Transmission is enhanced, and curling and image bronzing can be suppressed in a low-humidity environment.

  As thickness of a porous resin layer, 5-50 micrometers is preferable and 10-30 micrometers is more preferable. When the thickness of the porous resin layer is 5 μm or more, it is possible to obtain a good porous resin layer by preventing breakage that easily occurs during stretching, and when it is 50 μm or less, the ink absorbability is good.

The porosity in the porous resin layer is preferably 35% or more. When the porosity is 35% or more, the ink absorbability is excellent, and the generation of low-humidity curling and bronzing can be suppressed. The porosity of the porous resin layer can be obtained by the following formula.
Porosity = 100 × {1- (ρE / ρA)}
[ΡE: apparent density, ρA: absolute density of sample]

The porous resin layer in the present invention can be formed as follows.
First, a compound containing a thermoplastic resin and inorganic fine particles having a volume average particle size of 0.20 μm or less is prepared, and the obtained compound is extruded in at least one layer by a melt casting method. The film is prestretched with a chill roll. A prestretched film prestretched with a chill roll is cooled and solidified, and the solidified film is stretched at an appropriate temperature to form a porous film. When the film is formed, the interface between the inorganic fine particles contained in the compound and the heat-fusible resin is peeled off to form holes. At this time, as the longitudinal stretching of the solidified film, the film is stretched to the above thickness at a stretch ratio of 1.5 to 10 from the viewpoint of pore formation using inorganic fine particles having a volume average particle diameter of 0.20 μm or less. It is preferable that the film is stretched to the thickness of 2 to 6. The porous film may be stretched laterally as necessary.

(resin)
The porous resin layer in the present invention contains at least one kind of resin. The resin is preferably a hydrophobic resin, particularly a hydrophobic thermoplastic resin, in terms of dimensional stability against moisture and ease of forming a porous material.

Here, the “hydrophobic resin” refers to a resin in which the resin itself in a case where no pore is opened exhibits liquid hardly permeable or non-permeable. Here, a poorly permeable to impermeable, after the liquid (e.g., ink) was added dropwise 10 ml / m ² on the resin surface, the liquid amount permeated after lapse of 30 seconds is 1 ml / m ² or less Say.

  Examples of the hydrophobic resin include polyolefin resin, acetate resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyester resin, acrylic resin, polyurethane resin, polycarbonate resin, nylon, and mixtures thereof. A publicly known hydrophobic resin can be mentioned. Among these, polyethylene and polyethylene terephthalate are preferable from the viewpoint of film formability and ease of forming a porous layer, and low density polyethylene (LDPE) is particularly preferable.

Low density polyethylene, JIS 6899-1: those defined in 2000: a (JIS K 6748 1995 Density 910 kg / m ³ or more 930 kg / m ³ less than one), a radical polymerization catalyst of ethylene under high pressure It is manufactured by polymerization.

(Inorganic fine particles)
The porous resin layer in the present invention contains at least one kind of inorganic fine particles having a volume average particle diameter of 0.20 μm or less.

The volume average particle diameter of the inorganic fine particles is 0.20 μm or less. By setting the volume average particle diameter of the inorganic fine particles contained in the porous resin layer located below the ink receiving layer to 0.20 μm or less, the flatness of the surface of the porous resin layer is increased and the glossiness is increased. In addition, the occurrence of curling and bronzing in a low humidity environment can be suppressed. That is, when the volume average particle diameter exceeds 0.20 μm, the glossiness decreases, and curling and bronzing occur under low humidity.
A preferable range of the volume average particle diameter of the inorganic fine particles is 0.010 to 0.20 μm, more preferably 0.05 to 0.20 μm, for the same reason as described above.

  The volume average particle diameter is a value calculated from the diameters of primary particles obtained for 500 particles randomly selected from an electron microscope observation image.

Examples of the inorganic fine particles contained in the porous resin layer include calcium carbonate, calcium sulfate, barium sulfate, kaolin, mica, zinc oxide, dolomite, glass fiber, hollow glass microbeads, chalk, talc, pigment, silicon dioxide, bentonite. And particles such as clay and diatomaceous earth, and the inorganic fine particles may be either sintered or unsintered. Among these, calcium carbonate particles are preferable in terms of uniformity of particle diameter, dispersion stability, and stability of density after ink jet recording.
Inorganic fine particles may be included singly or in combination of two or more.

  The content of the inorganic fine particles in the porous resin layer is preferably 40 to 80% by mass and more preferably 50 to 70% by mass with respect to the total solid content. When the content of the inorganic fine particles is 40% by mass or more, the ink absorption and permeability are improved, and when the content is 80% by mass or less, the film is not easily broken during stretching after melt extrusion. It is.

(Other ingredients)
The porous resin layer in the present invention may contain, for example, a color pigment, an ultraviolet absorber, an antioxidant, a release agent, and other components as long as the effects of the present invention are not impaired.

-Ink receiving layer-
The ink receiving layer in the present invention includes at least inorganic fine particles, a water-soluble resin, and a mordant, and can be configured using other components as necessary. While including inorganic fine particles and a resin to make a porous material, the combined use of a mordant can prevent ink absorption and transmission from being inhibited.

  The thickness of the ink receiving layer in the present invention is in the range of 6 to 20 μm in terms of dry layer thickness. When the thickness of the ink receiving layer is less than 6 μm, the ink absorbability is insufficient and the ink receiving layer is easily peeled off from the support. On the other hand, when the thickness of the ink receiving layer exceeds 20 μm, the productivity improvement effect is small. In particular, the thickness of the ink receiving layer is preferably in the range of 8 to 15 μm from the viewpoint of maintaining the ink absorbency and suppressing the occurrence of bronzing and low-humidity curl.

(Inorganic fine particles)
The ink receiving layer in the present invention contains at least one kind of inorganic fine particles. The inorganic fine particles form a porous structure when the ink receiving layer is formed, and have a role of improving the ink absorption performance.

  Examples of the inorganic fine particles include vapor phase silica, hydrous silica fine particles, colloidal silica, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, boehmite, Pseudo boehmite etc. are mentioned. These may be used alone or in combination of two or more.

  Among these, from the viewpoint of forming a porous structure, gas phase method silica is preferable. When the vapor phase silica and other inorganic fine particles are used in combination, the content of the vapor phase silica in all the inorganic fine particles is preferably 90% by mass or more, and more preferably 95% by mass or more.

  Silica fine particles are generally roughly classified into wet method particles and dry method (gas phase method) particles according to the production method. In the wet method, active silica is produced by acid decomposition of silicate, and the method is mainly polymerized and agglomerated and precipitated to obtain hydrous silica. On the other hand, in the vapor phase method, the high temperature of silicon halide is obtained. The mainstream method is to obtain anhydrous silica by a method using gas phase hydrolysis (flame hydrolysis method) and a method in which silica sand and coke are heated and reduced and vaporized by arc in an electric furnace and oxidized with air (arc method). It is. The gas phase method silica is anhydrous silica fine particles obtained by a gas phase method.

Vapor phase method silica is different from hydrous silica in terms of the density of silanol groups on the surface, presence or absence of vacancies, and the like, and is suitable for forming a three-dimensional structure having a high porosity. The reason for this is not clear, but in the case of hydrous silica, the density of silanol groups on the fine particle surface is large at 5 to 8 / nm ² and the silica fine particles tend to aggregate (aggregate) easily. Has a low density of 2 to 3 silanol groups / nm ² on the surface of the fine particles, so that it is presumed that the structure becomes sparsely soft agglomerated (flocculate), resulting in a structure with a high porosity.

  Vapor phase silica has a particularly large specific surface area, so it has high ink absorption and retention efficiency, and low refractive index. Therefore, if it is dispersed to an appropriate particle size, it will provide transparency to the ink receiving layer. And high color density and good color developability can be obtained. The fact that the ink receiving layer is transparent can provide high color density, good color developability, and gloss even when applied to photo glossy paper as well as applications that require transparency such as OHP.

  The average primary particle size of the vapor phase silica is preferably 20 nm or less, more preferably 10 nm or less, and most preferably 3 nm to 10 nm. Vapor phase silica is easy to adhere to each other by hydrogen bonding due to silanol groups, so that a structure having a large porosity can be formed when the average primary particle diameter is 20 nm or less.

The content of the inorganic fine particles in the ink receiving layer is preferably 50% by mass or more, and more preferably exceeds 60% by mass. When the amount of the inorganic fine particles is in the range of 50% by mass or more, and more than 60% by mass, it is possible to form a more favorable porous structure and to produce an ink jet recording medium excellent in ink absorbability. be able to.
The content of the inorganic fine particles in the ink receiving layer is an amount calculated based on solid components other than water in the composition forming the ink receiving layer.

(Water-soluble resin)
The ink receiving layer in the invention contains at least one water-soluble resin.
Examples of water-soluble resins include polyvinyl alcohol (PVA), polyvinyl acetal, cellulose resins [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), etc.], chitins, and chitosans. , Starch; resins having ether bond, polypropylene oxide (PPO), polyethylene glycol (PEG), polyvinyl ether (PVE); polyacrylamide (PAAM), resin having amide group or amide bond, polyvinyl pyrrolidone (PVP) And polyacrylates, maleic resins, alginates, gelatins and the like having a carboxyl group as a dissociable group. These water-soluble resins may be used alone or in combination of two or more.

  Among these, polyvinyl alcohol is preferable. When polyvinyl alcohol and another water-soluble resin are used in combination, the content of polyvinyl alcohol in the total water-soluble resin is preferably 90% by mass or more, and more preferably 95% by mass or more.

  Examples of the polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, and other polyvinyl alcohol derivatives in addition to polyvinyl alcohol (PVA).

  PVA has a hydroxyl group in its structural unit, and this hydroxyl group and the silanol group on the surface of the silica fine particle form a hydrogen bond, thereby making it easy to form a three-dimensional network structure in which the secondary particle of the silica fine particle is a chain unit. . By forming a three-dimensional network structure in this way, it is considered that an ink receiving layer having a porous structure with a high porosity is formed. The porous ink receiving layer formed in this manner can absorb ink rapidly by capillary action, and can suppress the occurrence of ink bleeding and form dots with good roundness.

  The content of the water-soluble resin in the ink receiving layer is to prevent the film strength from being reduced and cracking during drying due to the excessive content, and the excessive content causes the voids to be blocked by the resin. From the viewpoint of preventing the ink absorbency from being lowered by decreasing the porosity, the amount is preferably 9 to 40% by mass, more preferably 12 to 33% by mass with respect to the total solid content of the ink receiving layer. .

  The water-soluble resin preferably has a number average polymerization degree of 1800 or more, more preferably 2000 or more, from the viewpoint of preventing cracking of the ink receiving layer. Among them, from the viewpoint of glossiness and image density, PVA having a saponification degree of 88% or more is preferable, PVA having a saponification degree of 89 to 97.5% is more preferable, and PVA having a saponification degree of 91 to 96% is particularly preferable.

-Content ratio of inorganic fine particles and water-soluble resin-
The content ratio of inorganic fine particles (for example, vapor phase silica; i) and water-soluble resin (for example, PVA; p) [PB ratio (i: p), mass of inorganic fine particles relative to 1 part by mass of water-soluble resin] is: The film structure of the ink receiving layer is also greatly affected. That is, as the PB ratio increases, the porosity, pore volume, and surface area (per unit mass) increase. Specifically, as the PB ratio (i: p), the film strength is reduced due to the PB ratio being too large, and cracking during drying is prevented. Further, the PB ratio is too small, The ratio of 1.5: 1 to 10: 1 is preferable from the viewpoint of preventing the void from being easily blocked by the water-soluble resin and preventing the ink absorbency from being lowered due to the decrease in the void ratio. For example, a coating solution in which anhydrous silica fine particles having an average primary particle diameter of 20 nm or less and a water-soluble resin are completely dispersed in an aqueous solution at a PB ratio of 2: 1 to 5: 1 is coated on a support, and the coating layer is formed. When dried, a three-dimensional network structure is formed with the secondary particles of silica fine particles as chain units, the average pore diameter is 30 nm or less, the porosity is 50% to 80%, the pore specific volume is 0.5 ml / g or more, A translucent porous film having a specific surface area of 100 m ² / g or more can be easily formed.

(mordant)
The ink receiving layer in the invention contains at least one mordant.
As the mordant, either an organic mordant or an inorganic mordant can be used. As the organic mordant, a polymer mordant containing a primary to tertiary amino group or a quaternary ammonium base as a cationic group is preferable. Cationic non-polymer mordants may also be used. As the inorganic mordant, a water-soluble metal compound or the like is preferable.

  Examples of the polymer mordant include a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base (mordant monomer), the mordant monomer and another monomer (non-mordant). Those obtained as copolymers or condensation polymers with monomers) are preferred. These polymer mordants can be used in any form of a water-soluble polymer or water-dispersible latex particles.

  Specific examples of the mordant monomer include compounds described in paragraph numbers [0069] to [0075] of JP-A No. 2002-274024.

  Further, as a polymer mordant, polydiallyldimethylammonium chloride, polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride, polyallylamine hydrochloride, polyamide-polyamine resin, cationized starch, dicyandiamide formalin condensate, dimethyl-2-hydroxypropyl Ammonium salt polymers are also preferred.

  Among these, from the viewpoint of suppressing bleeding, cationic polyurethanes and cationic polyacrylates described in JP-A No. 2004-167784 are preferable, and cationic polyurethanes are more preferable. As the cationic polyurethane, for example, “Superflex 650”, “F-8564D”, “F-8570D” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., “Neofix IJ” manufactured by Nikka Chemical Co., Ltd. are commercially available. -150 "and the like.

  The molecular weight of the polymer mordant is preferably 2000 to 300,000 in terms of weight average molecular weight. When the molecular weight is within the above range, water resistance and aging resistance are improved.

As the inorganic mordant, a water-soluble polyvalent metal compound is suitable.
Examples of the water-soluble polyvalent metal compound include water-soluble salts of metals selected from calcium, barium, manganese, copper, cobalt, nickel, aluminum, iron, zinc, zirconium, chromium, tungsten, and molybdenum. The “water-soluble” of the water-soluble metal compound means that 1% by mass or more dissolves in 20 ° C. water.

  Among the water-soluble metal compounds, trivalent or higher polyvalent metal compounds are preferable, aluminum compounds or compounds containing Group 4A metals of the periodic table (for example, zirconium, titanium) are preferable, aluminum compounds are more preferable, and water-soluble is particularly preferable. It is an aluminum compound.

Examples of the water-soluble aluminum compound include aluminum chloride or a hydrate thereof (eg, aluminum chloride hexahydrate), aluminum sulfate or a hydrate thereof, ammonium alum, aluminum sulfite, aluminum thiosulfate, aluminum nitrate nine water Japanese hydrates, aluminum acetate, aluminum lactate, basic aluminum thioglycolate and the like are known. Furthermore, basic polyaluminum hydroxide compounds (hereinafter also referred to as “basic polyaluminum chloride” and “polyaluminum chloride”), which are inorganic aluminum-containing cationic polymers, are known and preferably used. The basic polyaluminum hydroxide compound is represented by the following formula 1, formula 2 or formula 3, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ , [Al ₂₁ (OH) ₆₀ ] ³⁺ , and the like, which are water-soluble polyaluminum hydroxides that stably contain basic and high-molecular polynuclear condensed ions.
[Al ₂ (OH) _n Cl _6-n ] _m Formula 1
[Al (OH) ₃ ] _n AlCl ₃ Formula 2
Al _n (OH) _m Cl _{(3 nm)} [0 <m <3n] Formula 3
These are water treatment agents under the name of polyaluminum chloride (PAC) from Taki Chemical Co., Ltd., under the name of polyaluminum hydroxide (Paho) from Asada Chemical Co., Ltd. It is named -25 by Daiming Chemical Co., Ltd., and is also marketed by other manufacturers for the same purpose, and various grades are easily available.

  The content of the mordant in the ink receiving layer is preferably 1 to 20% by mass and more preferably 3 to 15% by mass with respect to the total mass of the ink receiving layer. When the content of the mordant is within the above range, it is possible to effectively prevent the ink from being absorbed and transmitted. The ink image-receiving layer is either (1) simultaneously with the application of the coating liquid for forming the ink-receiving layer, or (2) during the drying of the coating layer formed by the coating, and before the coating layer exhibits reduced-rate drying, In any of the cases, when forming by a method (wet-on-wet method) of applying a basic solution containing a basic compound to the coating layer, it is contained in the coating solution for forming the ink receiving layer. The amount of the mordant preferably occupies 95% by mass or more of the total amount of the mordant contained in the finally obtained ink receiving layer. When the amount of the mordant contained in the coating liquid is within the above range, bronzing can be effectively prevented.

(Other ingredients)
In addition to the above components, the ink receiving layer in the invention may contain other components such as a crosslinking agent such as a boron compound, a surfactant, a cationic resin, and an organic solvent.

-Crosslinking agent-
The ink receiving layer can contain a crosslinking agent that crosslinks and cures the water-soluble resin in terms of suppressing cracking and improving image density and glossiness.

A preferable example of the crosslinking agent is a boron compound. Examples of the boron compound include borax, boric acid, borates (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , diboric acid. Salt (eg, Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ ), metaborate (eg, LiBO ₂ , Ca (BO ₂ ) ₂ , NaBO ₂ , KBO ₂ ), tetraborate (eg, Na ₂ B ₄ O ₇ · 10H ₂ O), pentaborate (for example, KB ₅ O ₈ · 4H ₂ O, Ca ₂ B ₆ O ₁₁ · 7H ₂ O, CsB ₅ O ₅ ), etc. Among them, water-soluble. Alkaline metal salts of boric acid, boric acid, and boric acid salt are preferred from the viewpoint of causing a rapid crosslinking reaction with a resin (particularly polyvinyl alcohol), among which sodium tetraborate, borax, and boric acid are more preferred, and borax, boric acid. The most preferred.
Boron compounds may be used alone or in combination of two or more.

  Glyoxal, melamine / formaldehyde (for example, methylol melamine, alkylated methylol melamine), methylol urea, resol resin, polyisocyanate, epoxy resin, and the like may be used in combination with the boron compound as a water-soluble resin crosslinking agent.

  When gelatin is used as the water-soluble resin, examples of gelatin hardeners include aldehyde compounds such as formaldehyde, glyoxal, and glutaraldehyde; ketone compounds such as diacetyl and cyclopentanedione; bis (2-chloroethylurea). ) Active halogen compounds such as 2-hydroxy-4,6-dichloro-1,3,5-triazine, 2,4-dichloro-6-S-triazine sodium salt; divinylsulfonic acid, 1,3-vinylsulfonyl Active vinyl compounds such as 2-propanol, N, N′-ethylenebis (vinylsulfonylacetamide), 1,3,5-triacryloyl-hexahydro-S-triazine; dimethylolurea, methyloldimethylhydantoin, etc. N-methylol compound; 1,6-hexamethylene diiso Isocyanate compounds such as anate; Aziridine compounds described in US Pat. Nos. 3,017,280 and 2,983,611; Carboximide compounds described in US Pat. No. 3,100,704; Epoxys such as glycerol triglycidyl ether Compounds; ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; dioxane such as 2,3-dihydroxydioxane Compounds such as chromium alum, potash alum, zirconium sulfate, chromium acetate and the like can be used.

  The content of the crosslinking agent in the ink receiving layer is preferably 5 to 40 parts by mass, more preferably 8 to 30 parts by mass with respect to 100 parts by mass of the water-soluble resin, from the viewpoint of improving the film strength and preventing cracking.

-Surfactant-
As the surfactant, a nonionic or amphoteric surfactant is preferable. Nonionic surfactants include polyoxyalkylene alkyl ethers and polyoxyalkylene alkyl phenyl ethers (for example, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene Nonylphenyl ether, etc.), oxyethylene / oxypropylene block copolymers, sorbitan fatty acid esters (eg, sorbitan monolaurate, sorbitan monooleate, sorbitan trioleate, etc.), polyoxyethylene sorbitan fatty acid esters (eg, polyoxyethylene sorbitan) Monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trio Polyoxyethylene sorbitol fatty acid esters (for example, polyoxyethylene sorbitol tetraoleate), glycerin fatty acid esters (for example, glycerol monooleate), polyoxyethylene glycerin fatty acid esters (polystearic acid poly, etc.) Oxyethylene glycerin, polyoxyethylene glyceryl monooleate, etc.), polyoxyethylene fatty acid esters (polyethylene glycol monolaurate, polyethylene glycol monooleate, etc.), polyoxyethylene alkylamine, etc., and polyoxyalkylene alkyl ethers Is preferred.

  Examples of amphoteric surfactants include amino acid type, carboxyammonium betaine type, sulfoneammonium betaine type, ammonium sulfate betaine type, imidazolium betaine type, and the like. For example, US Pat. No. 3,843,368, Those described in JP-A-59-49535, JP-A-63-236546, JP-A-5-303205, JP-A-8-262742, and JP-A-10-282619 are suitable. As the amphoteric surfactant, an amino acid type amphoteric surfactant is preferable. As the amino acid-type amphoteric surfactant, those derived from, for example, amino acids (glycine, glutamic acid, histidine acid, etc.) described in JP-A-5-303205 are preferable, and N-in which a long chain acyl group is introduced. Aminoacyl acid and its salt are mentioned.

  The content of the nonionic or amphoteric surfactant in the first liquid is preferably 0.01 to 1% by mass, particularly preferably 0.03 to 0.6% by mass. Surfactant may be used individually by 1 type and may use 2 or more types together. Further, an amphoteric surfactant and a nonionic surfactant may be used in combination.

-High boiling point organic solvent-
A high boiling point organic solvent may be contained together with the nonionic or amphoteric surfactant. By containing a high boiling point organic solvent together with the surfactant, curling of the ink jet recording medium can be prevented and flatness can be maintained.
A high boiling point organic solvent refers to an organic solvent having a boiling point of 150 ° C. or higher under atmospheric pressure.

  The high boiling point organic solvent is preferably a water-soluble one. Examples of water-soluble high-boiling organic solvents include polyhydric alcohols (ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 1 , 2,4-pentanetriol, 1,2,6-hexanetriol, thiodiglycol, polyethylene glycol (weight average molecular weight 400 or less), polyhydric alcohol ethers (diethylene glycol monobutyl ether (DEGmBE), triethylene glycol) Monobutyl ether, glycerin monomethyl ether, etc.), alcohol amines having a plurality of hydroxyl groups (triethanolamine, etc.), polyhydric alcohol ethers are preferred, and diethylene glycol is more preferred. Roh is a butyl ether (DEGmBE).

  The content of the high-boiling organic solvent in the ink-receiving layer is preferably 0.05 to 1% by mass, particularly preferably 0.1 to 0.6% by mass, based on the total solid content.

-Other additives-
The ink receiving layer in the invention may contain other additives such as various ultraviolet absorbers, surfactants, antioxidants, and anti-fading agents such as singlet oxygen quenchers, as necessary. The details of these additives can be referred to the descriptions in paragraphs [0081] to [0090] of JP-A-2007-98657.

(Support)
The ink jet recording medium in the present invention is configured by providing a support.
A base paper is preferably used as the support. As the base paper, wood pulp is used as a main raw material, and paper is made using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp as necessary. As the above-mentioned wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, NUKP can be used, but more LBKP, NBSP, LBSP, NDP, LDP with more short fibers are used. preferable.

  The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities, and a pulp having a whiteness improved by bleaching is also useful.

  In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength enhancing agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, polyethylene glycols A water retaining agent such as a dispersant, a softening agent such as a quaternary ammonium, and the like can be appropriately added.

The basis weight of ^the base paper ^is preferably from ^{30g / m 2 ~250g / m 2} , particularly preferably ^{50g / m 2 ~200g / m 2} . The thickness of the base paper is preferably 40 μm to 250 μm. The base paper can be given a high smoothness by calendering at the paper making stage or after paper making.
The density of base paper is ^{0.7g / cm 3 ~1.2g / cm 3} (JIS P-8118) it is generally used.
The stiffness of the base paper, ²⁰ under conditions specified in JIS P-8143 (L 3/ 100) ~200 (L 3/100) are preferred.
The pH of the base paper is preferably 5 to 9 when measured by a hot water extraction method defined in JIS P-8113.

  A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, a sizing agent similar to the size that can be added to the base paper can be used. Further, a pigment may be applied or a smoothing treatment may be performed.

  A back coat layer may be provided on the support. A white pigment, an aqueous binder, and other components can be used for the backcoat layer. Examples of white pigments include 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, and silicic acid. Magnesium, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrohalloysite, magnesium carbonate, magnesium hydroxide, white inorganic pigments, styrene plastic pigment, acrylic plastic Examples thereof include organic pigments such as pigments, polyethylene, microcapsules, urea resins, and melamine resins. Examples of the aqueous binder include styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose, and hydroxyethylcellulose. Water-soluble polymers such as polyvinylpyrrolidone, water-dispersible polymers such as styrene butadiene latex and acrylic emulsion, and the like. Examples of other components include antifoaming agents, antifoaming agents, dyes, fluorescent whitening agents, preservatives, and water resistance agents.

-Inkjet recording medium manufacturing method-
The inkjet recording medium of the present invention can be produced by any method as long as it can be formed on the support in a configuration in which the porous resin layer and the ink receiving layer are provided in order from the support side. May be.

  Preparation of the inkjet recording medium of the present invention includes, for example, a resin layer forming step of forming a porous resin layer containing inorganic fine particles having a volume average particle diameter of 0.20 μm or less and a resin, at least inorganic fine particles, a water-soluble resin, And a receiving layer forming step for forming an ink receiving layer having a thickness of 6 to 20 μm, including the mordant, so that the porous resin layer and the ink receiving layer are arranged in this order from the support side. The porous resin layer and the ink receiving layer may be formed by a sequential multi-layer method in which an ink receiving layer is formed on a previously formed porous resin layer by coating or the like.

  In the resin layer forming step for forming the porous resin layer, for example, a resin composition in which inorganic fine particles having a volume average particle diameter of 0.20 μm or less and a resin are mixed is formed into a film by melt extrusion, cooled and solidified. Thereafter, the porous resin layer can be suitably formed by stretching.

  In addition to the following wet-on-wet method, the receiving layer forming step for forming the ink receiving layer forms a coating layer by applying a coating liquid containing at least inorganic fine particles, a water-soluble resin, and a mordant on the support. A step, a step of cooling the formed coating layer so as to be lowered by 5 ° C. or more with respect to the temperature of the coating solution at the time of coating, and a step of drying the cooled coating layer to form an ink receiving layer. The ink receiving layer can be formed in a form having a (set drying method).

  As a method of cooling the coating layer, a method of cooling the support on which the coating layer is formed in a cooling zone maintained at 0 to 10 ° C. for 5 to 30 seconds is preferable. In the process of cooling, it is preferable to cool so that it may fall 0-10 degreeC, and it is more preferable to cool so that it may fall 0-5 degreeC or more. The temperature of the coating layer is measured by measuring the temperature of the film surface.

  The inkjet recording medium of the present invention includes a resin layer forming step of forming a porous resin layer containing inorganic fine particles and a resin having a volume average particle size of 0.20 μm or less on a support, and at least inorganic fine particles and a water-soluble resin. And a coating liquid containing a mordant is applied so as to be disposed on the porous resin layer, and (1) at the same time as the coating, or (2) during the drying of the coating layer formed by the coating. Before the coating layer exhibits reduced rate drying, a basic solution containing a basic compound is applied to the coating layer (wet-on-wet method), A receiving layer forming step of forming an ink receiving layer having a thickness of 6 to 20 μm that is crosslinked and cured by including a crosslinking agent in at least one of the coating solution and the basic solution (for the inkjet recording medium of the present invention). Manufacturing method) It can be suitably performed.

-Resin layer formation process-
In the resin layer forming step, a porous resin layer having pores and containing inorganic fine particles having a volume average particle diameter of 0.20 μm or less and a resin is formed on the support.

The porous resin layer is a layer having pores, and a resin composition obtained by mixing and kneading inorganic fine particles having a volume average particle size of 0.20 μm or less and a kneaded resin is formed into a film by melt extrusion, cooled and solidified. After stretching, the porous resin layer can be suitably formed by adhering to the support through the adhesive layer. Specifically, a compound containing a hydrophobic thermoplastic resin and inorganic fine particles having a volume average particle size of 0.20 μm or less is prepared, and the obtained compound is extruded in at least one layer by a melt casting method and extruded. The obtained resin film is pre-stretched with a chill roll. And it can form by cooling and solidifying the prestretched film | membrane prestretched with the chill roll, extending | stretching the solidified film | membrane at appropriate temperature, and shape | molding a porous film.
The details of the inorganic fine particles and the resin are as described above.

  The adhesive layer is not particularly limited as long as it can adhere the film-like porous resin layer and the support. For example, a solution containing a water-soluble resin and inorganic fine particles can be applied to the support or the film-like porous layer. It can be provided by applying on the resin layer and drying it after the film-like porous resin layer or support is stacked while it is in a wet state. Examples of the water-soluble resin include those described in the description of the water-soluble resin of the ink-receiving layer. Examples of the inorganic fine particles include those described in the description of the inorganic fine particles of the ink image-receiving layer. Prior to bonding, the surface of the film-like porous resin layer is preferably hydrophilized by corona treatment or the like.

-Receptive layer formation process-
The receiving layer forming step includes a coating liquid (hereinafter referred to as “ink receiving layer forming step”) containing at least inorganic fine particles, a water-soluble resin, and a mordant so as to be positioned on the porous resin layer formed in the resin layer forming step. And (1) at the same time as the coating, or (2) during the drying of the coating layer formed by the coating and before the coating layer exhibits reduced-rate drying. At that time, a basic solution containing a basic compound is applied to the coating layer to form an ink receiving layer having a thickness of 6 to 20 μm. At this time, the ink receiving layer is crosslinked and cured by including a crosslinking agent in one or both of the coating solution and the basic solution.

Details of the components contained in the ink-receiving layer-forming coating solution, specifically, the inorganic fine particles, the water-soluble resin, the mordant, and, if necessary, other components such as a crosslinking agent are as described above.
The ink-receiving layer-forming coating liquid contains, for example, gas phase method silica (inorganic fine particles), PVA (water-soluble resin), mordant, boric acid (crosslinking agent), nonionic or amphoteric surfactant, and high-boiling organic solvent. In this case, the preparation method is shown as an example. That is,
First, vapor phase silica is added to water, and a mordant is further added, followed by dispersion with a high-pressure homogenizer, a sand mill, or the like. Thereafter, boric acid is added to this, an aqueous PVA solution (for example, PVA having a mass of about 1/3 of that of vapor phase method silica) is added, and a nonionic or amphoteric surfactant and a high boiling point organic solvent are further added. And can be prepared by stirring. The obtained coating solution is a uniform sol, and a porous layer having a three-dimensional network structure can be formed by coating this on a support by the following coating method.

  Moreover, partial gelatinization of PVA can be prevented by adding PVA after thinning boric acid as described above. A crosslinking agent such as boric acid may be added in addition to or added to the basic solution described later, in addition to or in addition to the ink receiving layer forming coating solution.

In dispersing the inorganic fine particles, a form in which a cationic resin is added together with the inorganic fine particles and the inorganic fine particles are dispersed in the cationic resin is preferable.
Although there is no restriction | limiting in particular in cationic resin, A water-soluble or aqueous emulsion type etc. can be used conveniently. Examples of the cationic resin include a dicyan cationic resin represented by a dicyandiamide-formalin polycondensate, a polyamine cationic resin represented by a dicyanamide-diethylenetriamine polycondensate, an epichlorohydrin-dimethylamine addition polymer, and dimethyldiallylammonium chloride. -SO ₂ copolymer, diallylamine salt -SO ₂ copolymer, dimethyl diallyl ammonium chloride polymer, polymer of allylamine salt, dialkylaminoethyl (meth) acrylate quaternary salt polymer, acrylamide - diallylamine salt copolymer Polycationic cationic resins such as dimethyldiallylammonium chloride, monomethyldiallylammonium chloride and polyamidine are preferred. Ammonium chloride, and monomethyl diallyl ammonium chloride are particularly preferred. A cationic resin may be used individually by 1 type, and may use 2 or more types together.

  The content of the cationic resin in the ink receiving layer is preferably 1 to 30 parts by mass, more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the inorganic fine particles. As a mode of addition of the cationic resin, a small amount may be added before pulverization and dispersion, and after pulverization and dispersion until a desired particle size is obtained, it may be further added.

  The coating solution for forming the ink receiving layer is preferably an acidic solution, and its pH is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less. The pH can be adjusted by selecting the type and amount of mordant. Moreover, you may adjust by adding an organic or inorganic acid. When the pH is 5.0 or less, the crosslinking reaction of the water-soluble resin by a crosslinking agent such as a boron compound can be suppressed.

  The coating can be performed by a known coating method such as an extrusion die coater, an air doctor coater, a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, or a bar coater.

The coating amount of the ink receiving layer coating solution is preferably ^{10~200g / m 2, 15~150g / m} 2 is more preferable.

  The basic solution is preferably a solution having a pH of 7.1 or more, and more preferably a solution having a pH of 7.5 or more. When the pH is 7.1 or more, the dura mating reaction of the ink receiving layer becomes good and scratches are less likely to occur. The pH of the basic solution can be adjusted by adding a basic substance. Examples of the basic substance include amine compounds having a molecular weight of 700 or less. For example, ammonia, primary amine (ethylamine etc.), secondary amine (dimethylamine etc.), tertiary amine (N-ethyl- N-methylbutylamine, triethylamine, etc.), hydroxides of alkali metals and alkaline earth metals and / or salts thereof (preferably ammonium salts). In addition, other polyvalent amines such as ethylenediamine may be added.

  Among basic substances, at least one selected from ammonia and primary to tertiary amines having a molecular weight of 700 or less is preferable from the viewpoint of improving performance such as scratch resistance, wet heat bleeding, and storage stability of the ink receiving layer. Furthermore, ammonia and an ammonium salt having a molecular weight of 700 or less are preferable.

  The basic solution may contain a crosslinking agent such as a boron compound with or without being contained in the ink receiving layer forming coating solution. In addition, the basic solution may contain a mordant component such as a cationic mordant in order to further improve the water resistance and aging resistance of the image. Details of the crosslinking agent and mordant component are as described above.

  “Before the coating layer shows reduced-rate drying” usually refers to several minutes immediately after coating of the coating solution, and during this time, the content of the solvent in the coated layer decreases in proportion to the time. The phenomenon is constant rate drying. About the time which shows this constant rate drying, it describes in chemical engineering handbook (pp.707-712, Maruzen Co., Ltd. issue, October 25, 1980).

  The coating layer formed by coating the coating liquid for forming the ink receiving layer is dried until it shows reduced rate drying. In this case, the drying is generally performed at 40 ° C. to 180 ° C. for 0.5 minutes to 10 minutes. (Preferably, 0.5 to 5 minutes). The drying time naturally varies depending on the coating amount, but the above range is appropriate.

  As a method of applying the basic solution before the coating layer formed by applying the coating solution for forming the ink receiving layer shows reduced drying, (i) applying the basic solution for forming the ink receiving layer (Ii) a method in which a basic solution is sprayed by a method such as spraying, (iii) a coating solution for forming an ink-receiving layer is applied in the basic solution. Examples include a method of immersing the support on which the coating layer is formed. In addition, as a method to apply in the method (i), for example, known methods such as curtain flow coater, extrusion die coater, air doctor coater, bread coater, rod coater, knife coater, squeeze coater, reverse roll coater, bar coater, etc. Application methods may be mentioned. Among them, a method in which the coater does not contact an existing coating layer such as an extrusion die coater, a curtain flow coater, or a bar coater is preferable.

As a provision amount of a basic solution, 0.1-40 g / m < ² > is preferable and 0.5-30 g / m < ² > is more preferable.

  In addition, when the application of the basic solution is performed simultaneously with the application of the ink-receiving layer-forming coating solution, the ink-receiving layer-forming coating solution and the basic solution are stacked in the order in which the ink-receiving layer-forming coating solution contacts the support. Then, it can be simultaneously applied (multilayer application) on the support and dried and cured.

  Simultaneous coating (multilayer coating) can be performed by a coating method using, for example, an extrusion die coater or a curtain flow coater. After the simultaneous coating, the formed coating layer is dried. In this case, drying is generally performed by heating the coating layer at 40 ° C. to 150 ° C. for 0.5 minutes to 10 minutes, preferably 40 ° C. to It is carried out by heating at 100 ° C. for 0.5 to 5 minutes. When using a boron compound, it is preferable to heat at 60 to 100 ° C. for 5 to 20 minutes.

  When simultaneous coating (multi-layer coating) is performed by, for example, an extrusion die coater, two types of coating liquid discharged simultaneously are formed in the vicinity of the discharge port of the extrusion die coater, that is, before moving onto the support, In this state, it is coated on the support in a multilayer manner. Since the two coating liquids that have been layered before coating are likely to undergo a crosslinking reaction at the interface between the two liquids when transferred to the support, the two liquids discharged near the discharge port of the extrusion die coater are mixed and increased. It may become sticky and may interfere with the coating operation. Therefore, in the case of simultaneous application, simultaneously with the application of the ink receiving layer forming application liquid and the basic solution, a barrier liquid prepared from a material that does not react with the cross-linking agent is interposed between the two liquids and applied simultaneously in three layers. It is preferable.

  The barrier liquid can be selected without particular limitation as long as it can form a liquid film without reacting with the boron compound. For example, an aqueous solution containing a trace amount of a water-soluble resin that does not react with a boron compound, water, or the like can be given. The water-soluble resin is used in consideration of coating properties for the purpose of a thickener, and examples thereof include polymers such as hydroxypropylmethylcellulose, methylcellulose, hydroxyethylmethylcellulose, polyvinylpyrrolidone, and gelatin. It is done. The barrier liquid may contain a mordant.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” is based on mass.

Example 1
−Preparation of base paper−
Wood pulp consisting of 100 parts of LBKP was beaten to 300 ml of Canadian freeness with a double disc refiner, to which 0.5 part of epoxidized behenamide, 1.0 part of anionic polyacrylamide, 0.1 part of polyamide polyamine epichlorohydrin, and cationic poly 0.5 parts of acrylamide (both dry-mass ratio to pulp) was added and weighed with a long paper machine to make a base paper of 170 g / m ² .

-Formation of porous resin layer-
Low-density polyethylene (LDPE) 38.5 parts, calcium carbonate (Vigot-15, manufactured by Shiroishi Kogyo Co., Ltd., volume average particle size 0.15 μm) 60 parts, calcium stearate 1 part, and Irganox 1010, After kneading 5 parts, the film obtained by extrusion from a die by melt extrusion at 220 ° C. was cooled and solidified on a chill roll. Thereafter, the film was stretched in the longitudinal direction at 90 ° C. at a stretching ratio of 5 to obtain a porous film having a thickness of 10 μm.

  The obtained porous film was bonded to the above base paper through an adhesive layer to form a porous resin layer. For the formation of the adhesive layer, an adhesive solution containing 10% by mass of polyvinyl alcohol (PVA-124, manufactured by Kuraray Co., Ltd.) and 5% by mass of silica is used. Discharge treatment was performed, and an adhesive solution was applied to the corona discharge treatment surface to adhere to the base paper.

-Formation of ink receiving layer-
(Preparation of the first liquid)
Vapor phase silica fine particles are mixed with ion-exchanged water having the following composition, and Charol DC-902P and ZA-30 are further mixed with this, and 500 kg / m ² using Nanomizer LA31 (manufactured by Nanomizer Co., Ltd.). The treatment was carried out twice at the pressure of Thereafter, stirring was performed for 60 minutes, and an aqueous boric acid solution (5% by mass) was added while stirring. In addition, a 5% by weight aqueous solution of polyvinyl alcohol having the following composition is added with stirring, polyoxyethylene lauryl ether and diethylene glycol monobutyl ether are added, and ion exchange water is further added to adjust the total amount to 1000.0 kg. Thus, a first liquid was prepared. The mass ratio of the inorganic fine particles to the water-soluble resin (inorganic fine particles: water-soluble resin) was 4.9: 1.

<Composition of the first liquid>
・ Ion-exchanged water ... 400.0kg
・ Vapor phase silica fine particles (inorganic fine particles) 86.0 kg
(AEROSIL300SF75, manufactured by Nippon Aerosil Co., Ltd.)
・ Charol DC-902P (51.5% aqueous solution) 7.0 kg
(Cationic resin, mordant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
・ ZA-30 ... 5.0kg
(Mordant, zirconyl acetate, manufactured by Daiichi Rare Element Chemical Co., Ltd.)
・ Boric acid aqueous solution (5% by mass) ... 63.0 kg
・ Polyvinyl alcohol 5 mass% aqueous solution 353.0kg
(JM-33, degree of saponification 94.3 mol%, degree of polymerization 3300, manufactured by Nihon Azuma Bi-Poval)
・ Polyoxyethylene lauryl ether ... 52.0kg
(2% by weight aqueous solution of Emulgen 109P, manufactured by Kao Corporation; nonionic surfactant)
・ Diethylene glycol monobutyl ether ... 3.0kg
(DEGmBE; high boiling point organic solvent)
・ Ion-exchanged water: the total amount is 1000.0 kg

(Formation of ink receiving layer)
The surface of the porous resin layer bonded to the base paper is subjected to corona discharge treatment, and the first liquid having the above composition is applied to the corona discharge treatment surface with an extrusion die coater so that the wet coating amount is 35 g / m ^2. The coating layer formed by coating was dried with a hot air drier at 80 ° C. (wind speed of 3 to 8 m / sec) until the solid content concentration of the layer became 20% by mass. During this time, the coating layer formed with the first liquid exhibited constant rate drying. Immediately thereafter, this coating layer was immersed in a second liquid (basic solution) having the following composition for 30 seconds, and a wet coating amount of 2.5 g / m ² was deposited on the coating layer (decreasing rate). Application of basic solution before drying). Then, it was further dried at 80 ° C. for 10 minutes.
As described above, an ink jet recording medium having an ink receiving layer formed on a porous resin layer on a support was produced.

<Composition of the second liquid (basic solution)>
・ Ion exchange water ... 70.0kg
・ Boric acid ... 0.65kg
・ Polyoxyethylene lauryl ether ... 5.0kg
(Nonionic surfactant: 10% by weight aqueous solution of Emulgen 109P, manufactured by Kao Corporation)
・ Ammonium carbonate ... added to pH 7.3 ・ Ion-exchanged water ... Amount to make the total amount 100.0 kg

-Evaluation-
The following evaluation was performed about the obtained inkjet recording medium. The evaluation results are shown in Table 1 below.

(1) Low-humidity curl The ink-jet recording medium was cut into 148 mm x 100 mm sample pieces and laid flat on a flat surface with the coated surface of the image-receiving layer facing up, and the humidity was adjusted for one day in an environment of 23 ° C and 50% RH. did. Further, in a 23 ° C., 50% RH environment, the sample pieces were stacked and sandwiched between two flat plates, and a 500 g weight was placed thereon and left for 10 days to flatten the sample pieces. After that, in a 25 ° C., 35% RH environment, the sample piece was laid flat on a flat surface with the image-receiving layer coating surface facing up and conditioned for 1 day, and then placed with the corners raised from the flat surface. The lift distance from the plane was measured for the four corners and averaged. The case where it floated on the image-receiving layer application surface side was designated as a positive curl, and the case where it floated on the opposite side was designated as a negative curl. The curl behavior was evaluated according to the following evaluation criteria using the average value obtained as an index.
<Evaluation criteria>
AA: The average absolute value of the lifting distance (curl) was 3 mm or more and less than 5 mm.
A: The average absolute value of the lifting distance (curl) was 5 mm or more and less than 10 mm.
B: The average absolute value of the lifting distance (curl) was 10 mm or more and less than 15 mm.
C: The average absolute value of the lifting distance (curl) was 15 mm or more.

(2) Bronzing After the inkjet recording medium was allowed to stand at 25 ° C. and 70% RH for 24 hours, a solid image was recorded with cyan ink using an inkjet printer MP-960 (manufactured by Canon Inc.). . The obtained cyan image was visually observed, and the presence or absence of metallic luster was evaluated according to the following evaluation criteria.
<Evaluation criteria>
AAA: No metallic luster was observed.
AA: A slight metallic luster was observed, but it was slight enough to be noticed when pointed out.
A: Although a slight metallic luster was observed, there was no practical problem.
B: Although a metallic luster was observed, it was acceptable to practical use.
C: A metallic luster was remarkably recognized.

(3) Glossiness A solid black image was recorded on an inkjet recording medium using an inkjet printer A820 (manufactured by Seiko Epson Corporation) in an environment of 23 ° C. and 50% RH. The 60 ° glossiness at the outermost surface of the ink image-receiving layer was measured with a digital variable glossiness meter (UGV-50DP, manufactured by Suga Test Instruments Co., Ltd.) and evaluated according to the following criteria.
<Evaluation criteria>
AAA: Glossiness of 58 or more AA: Glossiness of 55 or more and less than 58 A: Glossiness of 52 or more and less than 55 B: Glossiness of 45 or more and less than 52 C: Glossiness of less than 45

(4) Ink Absorption Time until a black solid image is recorded on an ink jet recording medium using an ink jet printer MP-960 (manufactured by Canon Inc.), and after the recording is finished, the recording portion is lightly rubbed with a fingertip until no dirt is left. Was measured and evaluated according to the following evaluation criteria.
<Evaluation criteria>
A: The ink absorption speed was less than 3 seconds.
B: The ink absorption speed was 3 seconds or more and less than 7 seconds.
C: The ink absorption speed was 7 seconds or more, which was practically hindered.

(Example 2)
In Example 1, the wet coating amount of the first liquid was changed from 35 g / m ² to 55 g / m ² , and the wet coating amount of the second liquid was changed from 2.5 g / m ² to 4.5 g / m ² . An ink jet recording medium was produced and evaluated in the same manner as in Example 1 except that the change was made. The evaluation results are shown in Table 1 below.

(Example 3)
In Example 1, the wet coating amount of the first liquid was changed from 35 g / m ² to 100 g / m ² , and the wet coating amount of the second liquid was changed from 2.5 g / m ² to 8.0 g / m ² . An ink jet recording medium was produced and evaluated in the same manner as in Example 1 except that the change was made. The evaluation results are shown in Table 1 below.

Example 4
In Example 1, calcium carbonate (Vigot-15, manufactured by Shiroishi Kogyo Co., Ltd., volume average particle size 0.15 μm) used for forming the porous resin layer was converted to calcium carbonate (Shiraka Hana CCR, Shiraishi Kogyo Co., Ltd.) Volume average particle diameter 0.08 μm), the wet coating amount of the first liquid is changed from 35 g / m ² to 100 g / m ² , and the wet coating amount of the second liquid is 2.5 g / m ^2. An ink jet recording medium was prepared and evaluated in the same manner as in Example 1 except that the amount was changed from 8.0 to 8.0 g / m ² . The evaluation results are shown in Table 1 below.

(Example 5)
An ink jet recording medium was produced and evaluated in the same manner as in Example 2 except that in Example 2, the formation of the ink receiving layer was changed to the following method. The evaluation results are shown in Table 1 below.
~ Formation of ink receiving layer ~
The surface of the porous resin layer adhered to the base paper is subjected to corona discharge treatment, and a third liquid having the following composition is applied to the corona discharge treatment surface with an extrusion die coater so that the wet coating amount is 48 g / m ^2. After cooling at 5 ° C. for 20 seconds, it was dried at 40 ° C. and 10% RH. Thus, an ink jet recording medium in which an ink receiving layer was formed on a porous resin layer on a support was produced.

<Composition of the third liquid>
・ Ion-exchanged water ... 400.0kg
・ Vapor phase silica fine particles (inorganic fine particles) 86.0 kg
(AEROSIL300SF75, manufactured by Nippon Aerosil Co., Ltd.)
・ Charol DC-902P (51.5% aqueous solution) 7.0 kg
(Cationic resin, mordant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
・ ZA-30 ... 5.0kg
(Mordant, zirconyl acetate, manufactured by Daiichi Rare Element Chemical Co., Ltd.)
・ Boric acid aqueous solution (5% by mass) ... 63.0 kg
・ Polyvinyl alcohol 7 mass% aqueous solution ・ ・ ・ 252.0kg
(JM-33, degree of saponification 94.3 mol%, degree of polymerization 3300, manufactured by Nihon Azuma Bi-Poval)
・ Polyoxyethylene lauryl ether ... 5.0kg
(100% by weight aqueous solution of Emulgen 109P, manufactured by Kao Corporation; nonionic surfactant)
・ Diethylene glycol monobutyl ether ... 3.0kg
(DEGmBE; high boiling point organic solvent)
・ Ion-exchanged water: the total amount is 852.0kg

(Example 6)
In Example 2, the inkjet recording medium was prepared in the same manner as in Example 2 except that the film obtained by extrusion from the die by melt extrusion was cooled and solidified on a chill roll, and the stretch ratio was changed from 5 to 10. Fabricated and evaluated. The evaluation results are shown in Table 1 below.

(Example 7)
In Example 2, an ink jet recording medium was produced and evaluated in the same manner as Example 2 except that the thickness of the porous resin layer was changed from 10 μm to 40 μm. The evaluation results are shown in Table 1 below.

(Example 8)
In Example 2, 38.5 parts of low density polyethylene (LDPE) used for forming the porous resin layer was changed to 53.5 parts, and calcium carbonate (Vigot-15, manufactured by Shiroishi Kogyo Co., Ltd., volume average particle) An ink jet recording medium was prepared and evaluated in the same manner as in Example 2 except that 60 parts (diameter 0.15 μm) were changed to 45 parts. The evaluation results are shown in Table 1 below.

(Comparative Example 1)
In Example 2, 38.5 parts of low density polyethylene (LDPE) used for forming the porous resin layer was changed to 98.5 parts, and calcium carbonate (Vigot-15, manufactured by Shiroishi Kogyo Co., Ltd., volume average particle) An ink jet recording medium was prepared and evaluated in the same manner as in Example 2 except that 60 parts (diameter 0.15 μm) were not used. The evaluation results are shown in Table 1 below.

(Comparative Example 2)
In Example 1, the wet coating amount of the first liquid was changed from 35 g / m ² to 17 g / m ² , and the wet coating amount of the second liquid was changed from 2.5 g / m ² to 1.3 g / m ² . An ink jet recording medium was produced in the same manner as in Example 1 except for the change. The ink jet recording medium thus obtained could not be evaluated because the ink image-receiving layer was cracked and peeled off.

(Comparative Example 3)
In Example 1, calcium carbonate (Vigot-15, manufactured by Shiraishi Kogyo Co., Ltd., volume average particle size 0.15 μm) used for forming the porous resin layer was converted into calcium carbonate (Softon 1800, Bihoku Flour Industry Co., Ltd.). ), Volume average particle diameter 1.2 μm), the composition of the second liquid (basic solution) is changed as follows, and the wet coating amount of the first liquid is changed from 35 g / m ² to 200 g / m ^2. change in m ^2, except that the wet coating amount of the second liquid is changed from 2.5 g / m ² to 15 g / m ^2, in the same manner as in example 1, to produce an inkjet-recording medium for comparison Evaluation was performed. The evaluation results are shown in Table 1 below.

<Composition of the second liquid (basic solution)>
・ Ion exchange water: 570.0 kg
・ Boric acid: 6.5kg
・ Polyoxyethylene lauryl ether ... 100.0kg
(Nonionic surfactant: 2% by weight aqueous solution of Emulgen 109P, manufactured by Kao Corporation)
・ Polyallylamine “PAA-10C” 20% aqueous solution 300.0 kg
(Mordant, manufactured by Nittobo Co., Ltd., weight average molecular weight 15000)
・ Ammonium carbonate ... added to pH 7.3 ・ Ion-exchanged water ... Amount that makes the total amount 1000.0 kg

(Comparative Example 4)
In Example 2, calcium carbonate (Vigot-15, manufactured by Shiroishi Kogyo Co., Ltd., volume average particle size 0.15 μm) used for forming the porous resin layer was replaced with calcium carbonate (MP-555 powder product, Maruo calcium). A comparative ink jet recording medium was prepared and evaluated in the same manner as in Example 2 except that the volume average particle diameter was changed to 0.25 μm. The evaluation results are shown in Table 1 below.

As shown in Table 1, in Examples, while having good ink absorbability, the occurrence of low-humidity curling and bronzing was suppressed, and glossy images could be recorded.
On the other hand, in the comparative example, the ink absorption and transmission were inferior, low humidity curling and bronzing could not be prevented, and the glossiness of the image was insufficient.

Claims (4)

  A porous resin layer containing pores and having a volume average particle size of 0.20 μm or less and containing inorganic fine particles and a resin, an inorganic fine particle, a water-soluble resin, and a mordant in order from the support side, and having a thickness. An ink-jet recording medium having an ink receiving layer of 6 to 20 μm.   The ink receiving layer is formed by applying a coating liquid containing at least inorganic fine particles, a water-soluble resin, and a mordant on the porous resin layer, and (1) the coating formed simultaneously with the coating or (2) the coating formed by the coating. At any time during the drying of the layer and before the coating layer exhibits reduced-rate drying, a basic solution containing a basic compound is applied to the coating layer, and the coating solution and the basic solution The inkjet recording medium according to claim 1, wherein the inkjet recording medium is formed by including a crosslinking agent in at least one and crosslinking and curing. A resin layer forming step of forming a porous resin layer containing inorganic fine particles and a resin having pores and a volume average particle diameter of 0.20 μm or less on the support;
A coating liquid containing inorganic fine particles, a water-soluble resin, and a mordant is applied so as to be disposed on the porous resin layer. (1) Simultaneously with the coating or (2) A coating layer formed by the coating At any time during the drying of the coating layer and before the coating layer exhibits reduced-rate drying, a basic solution containing a basic compound is applied to the coating layer, and at least one of the coating solution and the basic solution A receiving layer forming step of forming an ink receiving layer having a thickness of 6 to 20 μm, which is crosslinked and cured by adding a crosslinking agent to
A method for producing an ink jet recording medium comprising:   In the resin layer forming step, inorganic fine particles having a volume average particle diameter of 0.20 μm or less and a resin are mixed, formed into a film by melt extrusion, cooled and solidified, and then stretched at a stretch ratio of 2 to 6. The method for producing an ink jet recording medium according to claim 3, wherein a porous resin layer having a thickness of 10 to 30 μm is formed.