JP2005262603A - Manufacturing method of inkjet recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing an inkjet recording material which does not have a defective coating of an ink acceptance layer or cracks on the surface of the ink acceptance layer, and is excellent in glossiness. <P>SOLUTION: When this inkjet recording material is manufactured by applying a coating liquid on a support, the coating liquid is formed by mixing an inorganic particle dispersion liquid and a hydrophilic binder solution. In this case, the hydrophilic binder solution is added while being kept at a temperature of 55°C or higher to the inorganic particle dispersion liquid. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing an ink jet recording material, and more particularly to a method for efficiently producing an ink jet recording material excellent in glossiness without application defects of an ink receiving layer and cracks on the surface of an ink receiving layer.

  As a recording material used in the inkjet recording system, a porous ink receiving layer comprising a pigment such as amorphous silica and a water-soluble binder such as polyvinyl alcohol on a support called ordinary paper or inkjet recording paper. Recording materials provided are known.

  For example, JP-A Nos. 55-51583, 56-157, 57-107879, 57-107880, 59-230787, 62-160277, 62-184879, 62-183382 And a recording material obtained by applying a silicon-containing pigment such as silica to a paper support together with an aqueous binder has been proposed. JP-A-9-286165 (Patent Document 1) and JP-A-10-181190 disclose the use of silica fine particles obtained by pulverizing precipitated silica aggregates to 10 to 300 nm by mechanical means.

  JP-B-3-56552, JP-A-2-188287, JP-A-10-81064, JP-A-10-100377, JP-A-10-119423, JP-A-10-203006, etc. Ink jet recording materials using synthetic silica fine particles obtained by the method (hereinafter referred to as gas phase method silica) have been proposed.

  Vapor phase silica is fine particles having an average primary particle size of several nanometers to several tens of nanometers. Generally, solid vapor phase silica fine particles are added to water and dispersed with a homogenizer or the like, and then polyvinyl alcohol. A manufacturing method is known in which a coating solution prepared by adding a binder such as an aqueous solution is applied on a support and then dried.

  However, an inkjet recording material manufactured by dispersing solid fine particles such as vapor-phase method silica has an advantage that high gloss is easily obtained. On the other hand, repelling and streak-like coating defects often occur during coating and drying. In addition, there is a problem that an ink jet recording material that is easily cracked and has high gloss cannot be produced stably.

  In addition, as a water-soluble binder, a hydrophilic polymer having a high degree of polymerization and high water resistance is increasingly used in order to increase physical strength with a small amount, but it has poor solubility and requires a lot of production time. To do. In addition, undissolved material is generated and causes cracking.

As a method for solving such a problem, JP 2003-113596 A (Patent Document 2) discloses a hydrophilic polymer dissolution method, and JP 2003-276303 A (Patent Document 3) discloses an inorganic fine particle dispersion as a water-soluble solution. The manufacturing method which mixes, after mixing for 30 minutes or more and less than 5 hours at 30 degreeC or more and less than 50 degreeC before mixing with a conductive polymer is disclosed. However, even with the technique disclosed herein, it has not been possible to sufficiently avoid application defects of the ink receiving layer and cracks on the surface of the ink receiving layer.
JP-A-9-286165 (pages 2 to 5) JP 2003-113596 A (2nd to 5th pages) JP 2003-276303 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently producing an ink jet recording material which is excellent in glossiness and free from coating defects in the ink receiving layer and cracks on the surface of the ink receiving layer.

  1. In producing an inkjet recording material by applying a coating liquid on a support, the coating liquid is formed by mixing an inorganic fine particle dispersion and a hydrophilic binder aqueous solution, and the hydrophilic binder aqueous solution is at a temperature of 55 ° C. or higher. A method for producing an ink jet recording material, which is added to the inorganic fine particle dispersion.

  2. 2. The method for producing an inkjet recording material according to 1 above, wherein the support is a water-resistant support.

  3. 3. The method for producing an inkjet recording material according to 1 or 2 above, wherein the inorganic fine particles are silica fine particles having an average secondary particle diameter of 500 nm or less.

  4). 4. The method for producing an inkjet recording material according to any one of 1 to 3, wherein the hydrophilic binder is polyvinyl alcohol having a polymerization degree of 3000 or more.

  5). 5. The method for producing an inkjet recording material according to any one of 1 to 4, wherein the hydrophilic binder aqueous solution is added to the inorganic fine particle dispersion at a temperature of 60 ° C. or higher.

  According to the present invention, it is possible to efficiently produce an ink jet recording material having excellent glossiness without application defects of the ink receiving layer and cracks on the surface of the ink receiving layer.

Hereinafter, the present invention will be described in detail.
Supports used in the present invention include polyethylene, polypropylene, polyvinyl chloride, diacetate resin, triacetate resin, cellophane, acrylic resin, polyethylene terephthalate, polyethylene naphthalate and other water-resistant supports such as resin-coated paper, and high quality Water-absorbing supports such as paper, art paper, coated paper and cast coated paper are used. A water resistant support is preferably used. In particular, the thickness of these supports is preferably about 50 to 250 μm.

  Amorphous synthetic silica can be broadly classified into gas phase method silica, wet method silica and others depending on the production method. Vapor phase silica is also called a dry method, and is generally produced by flame hydrolysis. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, and is commercially available as Aerosil from Nippon Aerosil Co., Ltd. and QS type from Tokuyama Co., Ltd.

  Wet process silica is further classified into precipitation process silica and gel process silica according to the production method. Precipitated silica is produced by reacting sodium silicate and sulfuric acid under alkaline conditions, and the silica particles that have grown are agglomerated and settled, and are then commercialized through the steps of filtration, washing, drying, pulverization and classification. The silica secondary particles produced by this method become loosely agglomerated particles, and particles that are relatively easy to grind are obtained. Precipitated silica is commercially available, for example, as a nip seal from Tosoh Silica Co., Ltd., as a Toku Seal from Tokuyama Co., Ltd., and as a fine seal. Gel silica is produced by reacting sodium silicate and sulfuric acid under acidic conditions. In this case, the small silica particles dissolve during ripening and reprecipitate so as to bond the primary particles between the primary particles of the large particles, so that the distinct primary particles disappear and are relatively hard agglomerates with an internal void structure Form particles. For example, it is commercially available as Mizusukacil from Mizusawa Chemical Industry Co., Ltd. and as a silo jet from Grace Japan Co., Ltd.

  The wet method silica particles that can be used in the present invention have an average primary particle diameter of 50 nm or less, preferably 3 to 40 nm, and precipitation method silica particles are particularly preferable. The oil absorption of the wet process silica in the present invention is preferably in the range of 120 to 210 ml / 100 g, more preferably in the range of 160 to 210 ml / 100 g. The oil absorption is measured based on the description of JIS K-5101.

  The ink receiving layer of the present invention can contain wet-process silica that has been pulverized until the average secondary particle size is 500 nm or less. Since the wet process silica produced by a normal method has an average secondary particle diameter of 1 μm or more, it is used after being finely pulverized. As a pulverization method, a wet dispersion method in which silica dispersed in an aqueous medium is mechanically pulverized can be preferably used. As the wet disperser, a media mill such as a ball mill, a bead mill, and a sand grinder, a pressure disperser such as a high pressure homogenizer, and an ultra high pressure homogenizer, an ultrasonic disperser, and a thin film winding disperser can be used. In the present invention, it is particularly preferable to use a media mill such as a bead mill.

  The pulverization of the wet process silica is preferably performed in the presence of a cationic compound. When a cationic compound is added to silica dispersed in water, agglomerates are often generated, but by pulverizing this, it becomes possible to disperse at a higher concentration than when dispersed only in water, resulting in improved dispersion efficiency. It rises and can be pulverized into finer particles. Further, the use of the high concentration dispersion liquid has an advantage that the concentration of the coating liquid can be increased at the time of preparing the coating liquid, and the production efficiency is improved. In particular, the use of wet-process silica having an average secondary particle diameter of 5 μm or more is further advantageous because an increase in viscosity due to the initial generation of aggregates is suppressed and dispersion at a higher concentration is possible. The upper limit of the average secondary particle diameter is not particularly limited, but the average secondary particle diameter of the wet process silica is usually 200 μm or less.

  As the cationic compound, a cationic polymer or a water-soluble metal compound can be used. As the cationic polymer, polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymer, JP-A-59-20696, JP-A-59-33176, JP-A-59-33177, JP-A-59-155088, Sho 60-11389, Sho 60-49990, Sho 60-83882, Sho 60-109894, Sho 62-198493, Sho 63-49478, Sho 63-115780, Shosho 63-280681, No. 1-40371, No. 6-234268, No. 7-125411, No. 10-193976, etc. The polymer having is preferably used. In particular, diallylamine derivatives are preferably used as the cationic polymer. The molecular weight of these cationic polymers is preferably about 2,000 to 100,000, and particularly preferably about 2,000 to 30,000. A molecular weight greater than 100,000 is not preferred because the dispersion becomes too viscous.

  Examples of the water-soluble metal compound include water-soluble polyvalent metal salts. Examples thereof include water-soluble salts of metals selected from calcium, barium, manganese, copper, cobalt, nickel, aluminum, iron, zinc, titanium, zirconium, chromium, magnesium, tungsten, and molybdenum. Specifically, for example, calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, chloride chloride Dicopper, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel sulfate Ammonium hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate, ferrous bromide, ferric chloride Ferrous, ferric chloride, ferrous sulfate, ferric sulfate, zinc bromide, zinc chloride, zinc nitrate six Japanese products, zinc sulfate, zinc p-phenolsulfonate, titanium chloride, titanium sulfate, titanium lactate, zirconium acetate, zirconium chloride, zirconium chloride octahydrate, zirconium zirconium chloride, chromium acetate, chromium sulfate, magnesium sulfate, chloride Magnesium hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphate n A hydrate etc. are mentioned.

  Among the above water-soluble polyvalent metal compounds, compounds made of aluminum or a Group 4A metal (for example, zirconium or titanium) of the periodic table are preferable. Particularly preferred is a water-soluble aluminum compound. As a water-soluble aluminum compound, for example, as an inorganic salt, aluminum chloride or a hydrate thereof, aluminum sulfate or a hydrate thereof, ammonium alum and the like are known. Furthermore, a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer is known and preferably used.

The basic polyaluminum hydroxide compound has a main component represented by the following general formula 1, 2, or 3, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ , [Al ₂₁ (OH) ₆₀ ] ³⁺ , etc. is there.

[Al ₂ (OH) _n Cl _6-n ] _m General formula 1
[Al (OH) ₃ ] _n AlCl ₃ general formula 2
Al _n (OH) _m Cl _(3n-m) 0 <m <3n General formula 3

  These are water treatment agents from Taki Chemical Co., Ltd. under the name of polyaluminum chloride (PAC), from Asada Chemical Co., Ltd. under the name of polyaluminum hydroxide (Paho), and from Riken Green Co., Ltd. It is marketed under the name of Purachem WT and from other manufacturers for the same purpose, and various grades can be easily obtained.

  As the water-soluble compound containing a Group 4A element of the periodic table that can be used in the present invention, a water-soluble compound containing titanium or zirconium is more preferable. Examples of the water-soluble compound containing titanium include titanium chloride and titanium sulfate. Examples of water-soluble compounds containing zirconium include zirconium acetate, zirconium chloride, zirconium oxychloride, hydroxy zirconium chloride, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium lactate, zirconium carbonate / ammonium, zirconium carbonate / potassium, zirconium sulfate. And zirconium fluoride compounds. In the present invention, the term “water-soluble” means that 1% by mass or more dissolves in water at room temperature and normal pressure.

  As a specific method for obtaining wet method silica fine particles having an average secondary particle diameter of 500 nm or less preferably used in the present invention, first, at least one of silica and a cationic polymer and / or a cationic metal compound is added to water. The preliminary dispersion is obtained using at least one of a dispersing device such as a sawtooth blade type disperser, a propeller blade type disperser, or a rotor stator type disperser. If necessary, an appropriate low boiling point solvent may be added. The amount of the cationic polymer or water-soluble metal compound is 0.5 to 20% by mass, preferably 2 to 10% by mass, based on silica. By setting it in this range, the viscosity of the silica preliminary dispersion does not become too high, and the solid content concentration can be increased. The silica pre-dispersion of the present invention preferably has a higher solid content, but if the concentration is too high, it becomes impossible to disperse, so a preferable range is 20 to 60% by mass, and more preferably 30 to 50% by mass.

  The silica predispersion obtained by the above method is pulverized by a bead mill. A bead mill is a process in which beads are placed in a container having a stirring device inside, a liquid material is placed in the container, the stirring device is rotated and the beads collide with each other to give a shearing force to the liquid material. Device. The particle size of the beads is generally 0.1 to 10 mm, preferably 0.2 to 1 mm, more preferably 0.3 to 0.6 mm. The beads include glass beads, ceramic beads, metal beads and the like, but zirconia beads are preferred from the viewpoint of wear resistance and dispersion efficiency. The filling rate of beads in the container is generally 40 to 80% by volume, preferably 55 to 80% by volume. Under the above dispersion conditions, the silica dispersion can be efficiently pulverized to have an average secondary particle diameter of 500 nm or less without remaining coarse particles or generating aggregates. In the case where the preliminary dispersion is continuously processed, if coarse particles are likely to remain after one pass, it is preferable to perform the treatment twice or more. In the present invention, it is preferable that the concentration is high in the range where coarse particles cannot be formed because the concentration of the coating liquid can be increased. A preferable range of the solid content concentration of the silica dispersion of the present invention is 20 to 60% by mass, and more preferably 30 to 50% by mass. Examples of commercially available bead mills include nano mills manufactured by Asada Tekko Co., Ltd., ultra visco mills manufactured by Imex, and Amueller type OB mills manufactured by Matsubo, and dyno mills manufactured by Shinmaru Enterprises.

  In addition to the above-described wet process silica, vapor phase process silica can also be used for the ink receiving layer of the present invention. The average primary particle diameter of the vapor phase method silica used in the present invention is preferably 50 nm or less, more preferably 5 to 30 nm. When using vapor phase silica in the ink-receiving layer, it is preferable to make the aggregated particle size finer to 300 nm using a high-pressure homogenizer or a media mill.

  Further, the inorganic fine particles of the present invention may be alumina fine particles in addition to the silica particles. The alumina-based fine particles are aluminum oxide or a hydrate thereof, and may be crystalline or amorphous, and those having an amorphous shape, a spherical shape, a plate shape, or the like are used. Either of them may be used or may be used in combination.

  As the aluminum oxide that can be used in the present invention, γ-alumina, which is a γ-type crystal of aluminum oxide, is preferable, and δ group crystal is particularly preferable. Although γ-alumina can reduce the primary particles to about 10 nm, usually, secondary particles of several thousand to several tens of thousands of nanometers are mixed with ultrasonic waves, high-pressure homogenizers, counter-impact type jet crushers, etc. What grind | pulverized to about 300 nm can be used preferably.

The aluminum oxide hydrate that can be used in the present invention is represented by a constitutional formula of Al ₂ O ₃ .nH ₂ O (n = 1 to 3). The case where n is 1 represents an alumina hydrate having a boehmite structure, and the case where n is greater than 1 and less than 3 represents an alumina hydrate having a pseudo boehmite structure. It can be obtained by a known production method such as hydrolysis of an aluminum alkoxide such as aluminum isopropoxide, neutralization of an aluminum salt with an alkali, or hydrolysis of an aluminate.

  The average particle diameter of the primary particles of silica, alumina, and alumina hydrate that can be used in the present invention is the projected area of each of 100 particles existing within a certain area by electron microscope observation of the dispersed particles. The diameter of an equal circle is determined as the particle size. The average particle size of the secondary particles of silica, alumina, and alumina hydrate of the present invention can be obtained by measuring a dilute dispersion with a laser diffraction / scattering particle size distribution analyzer.

  In the present invention, as the hydrophilic binder used together with inorganic fine particles such as wet method silica, gas phase method silica, alumina, and alumina hydrate, various known binders can be used. A hydrophilic binder capable of obtaining high permeability is preferably used. When using a hydrophilic binder, it is important that the hydrophilic binder does not swell during the initial penetration of the ink and block the voids. From this point of view, a hydrophilic binder having a relatively low swellability around room temperature is preferable. Used. Particularly preferred hydrophilic binders are fully or partially saponified polyvinyl alcohol or cation-modified polyvinyl alcohol.

  Particularly preferred among the polyvinyl alcohols are those having a degree of saponification of 80% or more or those completely saponified. Those having an average degree of polymerization of 200 to 5000 are preferred, with 3000 to 5000 being particularly preferred.

  Examples of the cation-modified polyvinyl alcohol include primary to tertiary amino groups and quaternary ammonium groups as described in JP-A No. 61-10383, for example, in the main chain or side chain of polyvinyl alcohol. It has polyvinyl alcohol.

  The hydrophilic binder used by this invention can be melt | dissolved by a well-known method according to the kind of hydrophilic binder. In the case of polyvinyl alcohol having an average degree of polymerization of 3000 or more, which is particularly preferably used in the present invention, in order to avoid Mamako generally, it is poured into water at a low temperature of 25 ° C. or lower with good stirring, and high temperature with sufficient stirring. Dissolve at about 95 ° C. Although a well-known method can be used for the stirring means, the stirring means corresponding to high viscosity is preferable. The dissolution time is generally about 60 minutes after reaching 95 ° C.

  In the present invention, the aqueous hydrophilic binder solution is mixed with the inorganic fine particle dispersion at a temperature of 55 ° C. to 95 ° C., particularly preferably 60 ° C. to 80 ° C. When mixed with the inorganic fine particle dispersion at a temperature lower than 55 ° C., coating defects occur and the object of the present invention cannot be achieved. The temperature of the hydrophilic binder aqueous solution should just be 55 degreeC or more, and the temperature of an inorganic fine particle dispersion liquid is not restrict | limited. The reason is not clear, but when the hydrophilic binder is mixed in the inorganic fine particle dispersion at a high temperature, it can come into contact with the inorganic fine particles in a relatively low viscosity state and can be uniformly distributed among the inorganic fine particles. It is considered possible. It is estimated that contact with inorganic fine particles in a state of less than 55 ° C. causes uneven distribution and locally generates seeds of coating defects. In the present invention, the temperature of the inorganic fine particle dispersion at the time of mixing and the storage temperature of the coating liquid before coating are not limited, but generally, the inorganic fine particle dispersion is 30 to 55 ° C. and the temperature of the coating liquid due to handling problems. Is 30-45 ° C.

  In the present invention, a crosslinking agent (hardener) can be used. Specific examples of the crosslinking agent include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedione, bis (2-chloroethylurea), 2-hydroxy-4,6-dichloro-1, 3,5-triazine, a compound having a reactive halogen as described in US Pat. No. 3,288,775, divinylsulfone, a compound having a reactive olefin as described in US Pat. No. 3,635,718, N-methylol compounds as described in Japanese Patent No. 2,732,316, isocyanates as described in US Pat. No. 3,103,437, US Pat. Nos. 3,017,280 and 2,983,611 described Aziridine compounds such as US Pat. No. 3,100,704, carbodiimide compounds, US Epoxy compounds such as those described in allowed 3,091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane, chromium alum, zirconium sulfate, boric acid, borate, inorganic cross-linking agents such as borax, etc. These can be used alone or in combination of two or more. Among these, boric acid, borax or borate is particularly preferable. Examples of the boric acid used in the present invention include orthoboric acid, metaboric acid, and hypoboric acid. Examples of the boric acid salt include sodium salt, potassium salt, and ammonium salt.

The dry coating amount of the ink receiving layer of the present invention is 12 to 45 g / m ² , preferably 15 to 30 g / m ² . The above range is preferable in terms of ink absorbability and ink receiving layer strength.

  The ink receiving layer of the present invention preferably further contains a cationic compound for the purpose of improving water resistance. Examples of the cationic compound include the cationic polymer and the water-soluble metal compound mentioned in the description of the pulverization of the wet process silica. In particular, a compound composed of a cationic polymer having a molecular weight of about 5,000 to 100,000 and aluminum or a group 4A metal (for example, zirconium or titanium) in the periodic table is preferable. One type of cationic compound may be used, or a plurality of compounds may be used in combination.

  In the present invention, in addition to the surfactant and the hardener, the ink receiving layer of each layer further includes a coloring dye, a coloring pigment, a fixing agent for the ink dye, an ultraviolet absorber, an antioxidant, a dispersant for the pigment, Various known additives such as foaming agents, leveling agents, preservatives, optical brighteners, viscosity stabilizers, and pH adjusters can also be added.

In the present invention, a layer other than the ink receiving layer may be provided. In that case, it is necessary that the layer does not impair ink permeability. For example, for the purpose of improving scratch resistance, a protective layer mainly composed of colloidal silica may be provided on the ink receiving layer so as not to lower the ink absorbability, and at a solid content of about 5 g / m ² or less. The average primary particle diameter of colloidal silica is about 5 to 100 nm, and it is preferable from the viewpoint of ink absorption that secondary particles having an average particle diameter of about 10 to 500 nm are formed. Examples of commercially available spherical products include Nissan Chemical Industries, Snowtex 20, etc., Catalyst Kasei Kogyo Co., Ltd., Cataloid USB, etc., and examples of chain-shaped products include Nissan Chemical Corporation, Snowtex UP, etc., Pearl Necklace For example, Snowtex PS-M manufactured by Nissan Chemical Co., Ltd. can be used. Further, colloidal silica in which the surface of the colloidal silica is modified to be cationic can be preferably used, and in particular, the surface is preferably modified to be cationic with an aluminum compound. Examples of the alumina-modified colloidal silica include Nissan Chemical Industries, Snowtex AK-L, Snowtex AK-UP, and Snowtex PS-M-AK.

  In the present invention, a known coating method can be used as a coating method of each layer constituting the ink receiving layer. For example, there are a slide bead method, a curtain method, an extrusion method, an air knife method, a roll coating method, a rod bar coating method, and the like.

  When the coating liquid for the ink receiving layer is applied to the film support or the resin-coated paper, corona discharge treatment, flame treatment, ultraviolet irradiation treatment, plasma treatment or the like is preferably performed prior to coating.

  In the present invention, when using a support, particularly a film or resin-coated paper which is a water-resistant support, a primer layer mainly composed of a natural polymer compound or a synthetic resin is provided on the surface on which the ink receiving layer is provided. Is preferred. The ink receiving layer containing the inorganic fine particles of the present invention is coated on the primer layer, and then cooled and dried at a relatively low temperature, whereby the transparency of the ink receiving layer is further improved.

  The primer layer provided on the support is mainly composed of natural polymer compounds such as gelatin and casein and synthetic resins. Examples of such synthetic resins include acrylic resins, polyester resins, vinylidene chloride, vinyl chloride resins, vinyl acetate resins, polystyrene, polyamide resins, polyurethane resins, and the like.

  The primer layer is provided on the support with a film thickness (dry film thickness) of 0.01 to 5 μm. Preferably it is the range of 0.05-5 micrometers.

  Various back coat layers can be coated on the support in the present invention for writing properties, antistatic properties, transport properties, anticurling properties and the like. An inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, latex, a pigment, a curing agent, a surfactant, and the like can be appropriately combined in the backcoat layer.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not restricted to an Example. In addition, a part and% show a mass part and the mass%.

<Preparation of polyolefin resin-coated paper support>
A 1: 1 mixture of hardwood bleached kraft pulp (LBKP) and softwood bleached sulfite pulp (NBSP) was beaten to 300 ml with Canadian Standard Freeness to prepare a pulp slurry. As a sizing agent, 0.5% by mass of alkyl ketene dimer with respect to pulp, 1.0% by mass of polyacrylamide with respect to pulp as a strengthening agent, 2.0% by mass of cationized starch with respect to pulp, and polyamide epichlorohydrin resin 0.5% by mass of pulp was added and diluted with water to give a 1% slurry. This slurry was made with a long paper machine to a basis weight of 170 g / m ² , dried and conditioned to obtain a polyolefin resin-coated paper base paper. A polyethylene resin composition in which 10% by mass of anatase-type titanium is uniformly dispersed with respect to 100% by weight of low-density polyethylene having a density of 0.918 g / cm ³ is melted at 320 ° C. at 320 ° C. It was extrusion-coated so as to have a thickness of 35 μm per minute, and extrusion-coated using a cooling roll having a finely roughened surface to obtain a surface. Melted at similarly 320 ° C. The blend resin composition of the low density polyethylene resin parts by weight of a density 0.962 g / cm high-density polyethylene resin 70 parts by weight of ³ and a density 0.918 g / cm ³ on the other side, Extrusion coating was carried out so as to have a thickness of 30 μm, and a back surface was formed by extrusion coating using a cooling roll having a rough surface.

The polyolefin resin-coated paper surface was subjected to high-frequency corona discharge treatment, and then a primer layer having the following composition (solid content) was applied and dried so that the gelatin was 50 mg / m ² to prepare a support.

<Underlayer>
Lime-processed gelatin 100 parts Sulfosuccinic acid-2-ethylhexyl ester salt 2 parts Chromium alum 10 parts Add water and solid content concentration 1% by mass

<Silica dispersion 1>
Dimethyldiallylammonium chloride homopolymer (molecular weight 9,000, 4 parts) and gas phase method silica (average primary particle diameter 7 nm, 100 parts) are added to water, and a sawtooth blade type disperser (blade peripheral speed 30 m / second) ) Was used to make a preliminary dispersion. Next, the obtained preliminary dispersion was passed once through a pressure homogenizer under the condition of 40 MPa to obtain a silica dispersion 1 having a solid content concentration of 20% by mass and an average secondary particle diameter of 150 nm. The temperature of the dispersion was 35 ° C.

The ink receiving layer coating solution having the following composition (solid content) was applied to the support with a slide bead coating device so that the dry coating amount was 23 g / m ² and dried. Polyvinyl alcohol was poured into water at 20 ° C. with good stirring and then heated with sufficient stirring. After reaching 95 ° C., stirring was continued for 60 minutes to dissolve. The solid content concentration was 7% by mass. After dissolution, the mixture was kept warm so that the temperature at the time of addition was 55 ° C. After completion of the coating solution, the coating solution was kept at 40 ° C. until coating. The drying conditions after the coating were 30 ° C. for 30 seconds, and the total solid content was dried at 45 ° C. and 10% RH until the total solid concentration was 90% by mass, and then dried at 35 ° C. and 10% RH.

<Ink-receiving layer coating solution>
Silica dispersion 1 20 parts polyvinyl alcohol aqueous solution 4.5 parts (saponification degree 88%, average polymerization degree 3500)
Boric acid 1 part Surfactant 0.01 parts Add water and solid content 12% by mass

  The following evaluation was performed about the inkjet recording sheet produced as mentioned above. The results are shown in Table 1.

<Applied surface evaluation>
○: No coating failure was observed at all.
Δ: Slight repelling is observed.
X: Partial failure of repelling and thin streaky coating is observed.

<Glossiness of white paper part>
The glossiness of the blank paper before printing on the recording material was observed obliquely and evaluated according to the following criteria.
A: Glossiness as high as that of color photographic paper.
○: High glossiness but slightly inferior to ◎.
Δ: Glossiness similar to art and coated paper.
X: There is a lustrous luster similar to that of fine paper.

<Surface property>
◎: No problem at all ○: Slightly defective but no cracks △: Many cracks ×: Many defects including cracks cannot be used

  The inkjet recording material of Example 2 was obtained in the same manner as in Example 1 except that the addition temperature of polyvinyl alcohol was adjusted to 60 ° C. when adjusting the ink receiving layer coating solution. The evaluation results are shown in Table 1.

  The inkjet recording material of Example 3 was obtained in the same manner as in Example 1 except that the addition temperature of polyvinyl alcohol when adjusting the ink receiving layer coating solution was changed to 65 ° C. The evaluation results are shown in Table 1.

Comparative Example 1
The ink jet recording material of Comparative Example 1 was obtained in the same manner as in Example 1 except that the addition temperature of the polyvinyl alcohol at the time of adjusting the ink receiving layer coating solution was changed to 45 ° C. The evaluation results are shown in Table 1.

Comparative Example 2
The inkjet recording material of Comparative Example 2 was obtained in the same manner as in Example 1 except that the addition temperature of polyvinyl alcohol was adjusted to 40 ° C. when adjusting the ink receiving layer coating solution. The evaluation results are shown in Table 1.

Comparative Example 3
The inkjet recording material of Comparative Example 3 was obtained in the same manner except that the addition temperature of polyvinyl alcohol in adjusting the ink receiving layer coating liquid in Example 1 was changed to 35 ° C. The evaluation results are shown in Table 1.

  An inkjet recording material of Example 4 was obtained in the same manner except that the silica dispersion 1 of Example 2 was replaced with the following silica dispersion 2. The evaluation results are shown in Table 1.

<Silica dispersion 2>
Dimethyldiallylammonium chloride homopolymer (molecular weight 9,000, 4 parts) and precipitated silica (average primary particle diameter 15 nm, average secondary particle diameter 18 μm, oil absorption 180 ml / 100 g, 100 parts) are added to water and sawtooth A pre-dispersion was prepared using a blade-type disperser (blade peripheral speed 30 m / sec). Next, the obtained preliminary dispersion was passed once through a bead mill under the conditions of a zirconia bead having a diameter of 0.3 mm, a filling rate of 80 vol%, and a disk peripheral speed of 10 m / sec. A silica dispersion 2 having a secondary particle size of 200 nm was obtained.

Comparative Example 4
The inkjet recording material of Comparative Example 4 was obtained in the same manner except that the addition temperature of the polyvinyl alcohol at the time of preparing the ink receiving layer coating solution was changed to 35 ° C. in Example 4. The evaluation results are shown in Table 1.

  From the above results, it can be seen that the ink-jet recording materials of Examples 1 to 4 have no coating defects, good blank section glossiness, and few cracks. In particular, Examples 2 and 3 in which an aqueous polyvinyl alcohol solution was added at 60 ° C. or higher were preferable results. In Comparative Examples 1 to 3, a coating failure occurred, and the glossiness of the blank paper portion and the surface property were deteriorated. In particular, Comparative Examples 3 and 4 to which an aqueous polyvinyl alcohol solution was added at 35 ° C. caused coating defects and markedly deteriorated surface properties.

Claims (5)

  In producing an inkjet recording material by applying a coating liquid on a support, the coating liquid is formed by mixing an inorganic fine particle dispersion and a hydrophilic binder aqueous solution, and the hydrophilic binder aqueous solution is at a temperature of 55 ° C. or higher. A method for producing an ink jet recording material, which is added to the inorganic fine particle dispersion.   The method for producing an inkjet recording material according to claim 1, wherein the support is a water-resistant support.   The method for producing an inkjet recording material according to claim 1, wherein the inorganic fine particles are silica fine particles having an average secondary particle diameter of 500 nm or less.   The method for producing an inkjet recording material according to any one of claims 1 to 3, wherein the hydrophilic polymer is polyvinyl alcohol having a degree of polymerization of 3000 or more.   The method for producing an inkjet recording material according to claim 1, wherein the hydrophilic polymer aqueous solution is added to the inorganic fine particle dispersion at a temperature of 60 ° C. or higher.