JP2005238480A - Inorganic fine particle dispersion, its manufacturing method and image recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable an inorganic fine particle to be uniformly dispersed with the low level consumption of energy by restraining the thickening of the inorganic fine particle during its dispersion. <P>SOLUTION: In the method for manufacturing the inorganic fine particle dispersion, the process to add the inorganic fine particle and a dispersant to an aqueous medium under the addition conditions that the ratio (Dt/It) of the addition amount Dt of the dispersant to the addition amount It of the inorganic fine particle, is lower than the ratio (D/I) of the final addition amount D of the dispersant to the final addition amount I of the inorganic fine particle, is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention uses an inorganic fine particle dispersion that can be prepared with energy saving, a method for producing the same, and a liquid ink such as an aqueous or oily ink, a solid ink that is a solid at room temperature and melted and liquefied, and is used for recording. The present invention relates to an image recording material suitable for ink jet recording, recording using a colored composition or colored toner that is used for transfer recording, and the like.

  In recent years, with the rapid development of the information technology (IT) industry, various information processing systems have been developed, and a recording method and a recording apparatus suitable for each information processing system have been developed and put into practical use. Examples of recording methods that have been put to practical use include silver salt photography, inkjet recording, electrophotography, thermal recording, sublimation transfer, and thermal transfer.

  Among the above recording methods, for example, the inkjet recording method is capable of recording on various types of recording materials, the hardware (device) is relatively inexpensive, is compact, has excellent quietness, and the like. Of course, it has been widely used in so-called home use. In recent years, with the increase in resolution of ink jet printers and the development of hardware (devices), various types of ink jet recording media have been developed, making it possible to obtain so-called photographic-like high-quality recorded matter. .

  The ink jet recording medium is prepared by, for example, applying a prepared liquid (for example, a coating liquid for forming an ink receiving layer) prepared by dispersing inorganic fine particles such as silica fine particles in an aqueous medium onto a supporting substrate such as paper. Can be produced. In this case, it is desirable that the inorganic fine particles are in a good dispersion state in the liquid in which the inorganic fine particles are dispersed.

  For example, there is an ink jet recording medium in which an ink receiving layer containing fine inorganic fine particles and a water-soluble resin and having a high porosity is provided on a support (see, for example, Patent Documents 1 and 2). These recording media, particularly ink jet recording media having an ink receiving layer having a porous structure using silica as inorganic fine particles, have excellent ink absorbability and high ink receiving performance capable of forming high-resolution images. Yes.

  As described above, for example, silica fine particles are one of suitable particles for reasons such as high color density, good color developability, and gloss, and the smaller the particle size, the better. The viscosity increases when agglomerated, and the degree of thickening increases especially as the diameter decreases.Therefore, it takes a long time to uniformly disperse in the aqueous medium due to the increase in viscosity, and high energy is required. In other words, energy efficiency is low in manufacturing, and there are problems in terms of energy saving and cost reduction. Moreover, the application after preparation may be hindered, and the applied surface may be deteriorated.

In addition, the characteristics required for ink jet recording media generally include (1) fast drying (high ink absorption speed) and (2) proper and uniform ink dot diameter (similarity). (3) Good graininess, (4) High dot roundness, (5) High color density, (6) High saturation (no blurring) ), (7) The light resistance, gas resistance and water resistance of the print area are good, (8) the whiteness of the recording surface is high, and (9) the storage stability of the recording medium is good (for long-term storage) No yellowing coloring, long-term image does not bleed), (10) good deformation and good dimensional stability (curl is small enough), (11) good hard running And so on. In addition, the recorded material can be said to be a so-called photographic-like high-quality image. In addition to having the above-mentioned characteristics, not only can the photographic-like high-quality image be recorded, but also image stability that does not cause ink bleeding during long-term storage after recording. It is required to have sex.
In addition, the above-described other recording methods other than the ink jet recording method are required to obtain a sharp and vivid color image and to obtain a photographic-like high-quality image.
JP 10-119423 A Japanese Patent Laid-Open No. 10-217601

  As described above, although various proposals have been made on recording media that can form photographic-like high-quality images in recent years, energy consumption is reduced in the preparation process of inorganic fine particle dispersions related to the production of recording media, thereby reducing costs. The technology to achieve this has not been established and established. In particular, an inkjet recording medium is still insufficient in terms of preventing ink bleeding over time (hereinafter referred to as “time bleeding”) in order to enable photographic-like image formation.

  The present invention has been made in view of the above, and a method for producing an inorganic fine particle dispersion that suppresses thickening during dispersion of inorganic fine particles and enables uniform dispersion of inorganic fine particles with low energy consumption. An image recording material (especially inkjet recording) that is easy to manufacture, has a good surface shape for receiving ink, and has little image change such as bleeding over time. It is an object of the present invention to provide a medium) and to achieve the object.

  In the present invention, when the dispersant and the inorganic fine particles are added to the aqueous medium, the addition ratio of the dispersant to the inorganic fine particles is added before or after the addition of the inorganic fine particles or simultaneously with the addition of the inorganic fine particles. The knowledge that it is effective to reduce the energy consumption while suppressing the thickening during preparation and improving the dispersibility by providing a time zone that does not exceed the content ratio of the dispersant and inorganic fine particles of And have been achieved based on such findings. Specific means for solving the above problems are as follows.

<1> In the aqueous medium, the ratio (Dt / It) of the addition amount Dt of the dispersant and the addition amount It of the inorganic fine particles is the ratio of the final addition amount D of the dispersant and the final addition amount I of the inorganic fine particles ( D / I) A method for producing an inorganic fine particle dispersion, comprising the step of adding the inorganic fine particles and the dispersant under an addition condition smaller than D / I).
<2> The method for producing an inorganic fine particle dispersion according to <1>, wherein the inorganic fine particles are silica fine particles.
<3> The method for producing an inorganic fine particle dispersion according to <1> or <2>, wherein the dispersant is a cationic polymer dispersant.
<4> The method for producing an inorganic fine particle dispersion according to any one of <1> to <3>, wherein the inorganic fine particle dispersion further contains a hardening agent.
<5> The method for producing an inorganic fine particle dispersion according to any one of <1> to <4>, wherein the inorganic fine particle dispersion further contains a water-soluble metal salt.
<6> An inorganic fine particle dispersion obtained by the method for producing an inorganic fine particle dispersion according to any one of <1> to <5>.
<7> An image recording material formed by applying a coating liquid using the inorganic fine particle dispersion according to <6>. <8> At least inorganic fine particles and a water-soluble resin on a support. The image recording material according to <7> (that is, an ink jet recording medium) having an ink receptive recording layer.

  According to the present invention, a method for producing an inorganic fine particle dispersion that suppresses thickening during dispersion of inorganic fine particles and enables uniform dispersion of inorganic fine particles with low energy consumption, and low viscosity in which inorganic fine particles are uniformly dispersed. An inorganic fine particle dispersion can be provided. In addition, it is possible to provide an image recording material (particularly an ink jet recording medium) that is easy to manufacture, has a good surface shape for receiving ink, and has little image change such as bleeding over time.

  Hereinafter, the method for producing the inorganic fine particle dispersion of the present invention and the ink jet recording medium will be described in detail, and the details of the image recording material other than the inorganic fine particle dispersion of the present invention and the ink jet recording medium will be described.

  The method for producing an inorganic fine particle dispersion according to the present invention is a process for preparing an inorganic fine particle dispersion by adding inorganic fine particles and a dispersant to an aqueous medium. The ratio (Dt / It) between the added amount of inorganic fine particles and the added inorganic fine particles is the final added amount D (total amount) of the dispersant finally added until the preparation is completed and the final added amount I (total amount) of the inorganic fine particles. ) And the ratio (D / I) smaller than the ratio (D / I).

  For example, when the ratio D / I of the amount of dispersant (ie, final addition amount D) and the amount of inorganic fine particles (ie, final addition amount I) in the prepared inorganic fine particle dispersion is 1/1, the addition starts Until the end of the addition, the ratio (Dt / It) between the added amount Dt of the added dispersant and the added amount It of the inorganic fine particles is smaller than 1/1 (= 1). That is, the dispersant and the inorganic fine particles are added to the aqueous medium so that there is a process in which the amount Dt of the inorganic fine particles is larger than the amount It of the dispersant.

  Further, for example, in the case where the final addition amount D of the dispersant in the prepared inorganic fine particle dispersion is 150 parts, the final addition amount I of the inorganic fine particles is 750 parts, and the ratio D / I is 0.2. , The ratio belonging to the area on the right side (in the direction of the arrow) of the straight line Q (for example, the ratio 0.1 at the point S) can be obtained as shown by the thick solid line P shown in FIG. The dispersant and the inorganic fine particles are added to the aqueous medium at such an addition ratio that the region R is formed. In addition, the long broken line T in a figure is a case where the whole quantity of a dispersing agent is added previously before addition of inorganic fine particles like the past.

  Addition of the dispersant and the inorganic fine particles to the aqueous medium may be carried out in any manner of adding in a divided manner or continuously, while having the above-described ratio relationship from the start of addition. It is sufficient that the addition process at the above ratio exists in any part of the process. In particular, it is preferable that the inorganic fine particles are added so that the hatched region R shown in FIG. 1 is formed from the initial addition stage to the intermediate stage when the addition amount It is less than ½ of the final addition quantity I. The lower limit value of Dt / It is not particularly limited, but it is more preferable that the value of (Dt / It) / (D / I) be 0.4 or more.

  In this way, the dispersant and inorganic fine particles are added, and particularly by reducing the amount of the dispersant added at the initial stage of preparation of the inorganic fine particle dispersion, the increase (thickening) of the liquid viscosity is suppressed and low energy consumption is achieved. In addition, it is possible to uniformly disperse and obtain a low-viscosity inorganic fine particle dispersion. Also, using this inorganic fine particle dispersion, a preparation liquid (particularly a coating liquid for forming an ink receiving layer) for forming a recording layer for recording an image (particularly an ink receiving layer for receiving an ink to form an image) is prepared. In the case where an image recording layer (particularly an ink jet recording medium) is finally produced by coating, for example, an image recording material (particularly an ink jet recording medium) having a recording layer (particularly an ink receiving layer) with good surface properties. ) Can be provided.

Next, the inorganic fine particles and the dispersant according to the present invention will be described in detail.
-Inorganic fine particles-
Examples of the inorganic fine particles include silica fine particles, colloidal silica, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, pseudoboehmite, zinc oxide, and hydroxide. Examples thereof include zinc, alumina, aluminum silicate, calcium silicate, magnesium silicate, zirconium oxide, zirconium hydroxide, cerium oxide, lanthanum oxide, and yttrium oxide. Among these, when forming a recording layer, particularly an ink receiving layer as described later, silica fine particles, colloidal silica, alumina fine particles, or pseudoboehmite is preferable from the viewpoint of forming a good porous structure. Particulates are particularly preferred.

  When forming an ink receiving layer of an ink jet recording medium as described later using the inorganic fine particle dispersion of the present invention, a porous structure is obtained by containing inorganic fine particles, thereby improving ink absorption performance. To do. In particular, when the solid content of the inorganic fine particles in the ink receiving layer is 50% by mass or more, more preferably more than 60% by mass, it becomes possible to form a more favorable porous structure, and sufficient ink absorptivity. This is preferable because an ink jet recording medium having the above can be obtained. Here, the solid content in the ink receiving layer of the inorganic fine particles is a content calculated based on components other than water in the composition constituting the ink receiving layer.

  In addition, since the silica fine particles have a particularly large specific surface area, when an ink receiving layer of an ink jet recording medium is formed as described later, the ink absorbability and retention efficiency are high, and the refractive index is low. Dispersing to a fine particle diameter has the advantage that transparency can be imparted to the ink receiving layer, and high color density and good color development can be obtained. The transparent layer means not only the use of transparency such as OHP, but also a high color density and good color development and gloss when applied to recording sheets such as photo glossy paper. More important.

  The average primary particle size of the inorganic fine particles is preferably 20 nm or less, more preferably 15 nm or less, and particularly preferably 10 nm or less. When the average primary particle diameter is 20 nm or less, when an ink receiving layer of an ink jet recording medium is formed as will be described later, the ink absorption characteristics can be effectively improved, and at the same time, the surface of the ink receiving layer can be improved. Glossiness can also be enhanced.

  In particular, the silica fine particle has a silanol group on the surface thereof, and the particles are likely to adhere to each other due to the hydrogen bond of the silanol group, and because of the adhesion effect between the particles via the silanol group and the water-soluble resin, As described above, when the average primary particle size is 20 nm or less, the ink receiving layer has a high porosity and a highly transparent structure can be formed, and the ink absorption characteristics can be effectively improved.

  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, a method in which activated silica is produced by acid decomposition of a silicate, which is appropriately polymerized and coagulated and precipitated to obtain hydrous silica is the mainstream. On the other hand, the gas phase method is a method by high-temperature gas phase hydrolysis of silicon halide (flame hydrolysis method), a method in which silica sand and coke are heated and reduced by an arc in an electric furnace and oxidized with air. The method of obtaining anhydrous silica by the (arc method) is the mainstream, and “gas phase method silica” means anhydrous silica fine particles obtained by the gas phase method. As the silica fine particles in the present invention, gas phase method silica fine particles are particularly preferable.

Vapor phase silica is different from hydrous silica in terms of the density of silanol groups on the surface, the presence or absence of vacancies, etc., and exhibits different properties, but is suitable for forming a three-dimensional structure with a high porosity. The reason for this is not clear, but in the case of hydrous silica, the density of silanol groups on the surface of the fine particles is as high as 5 to 8 / nm ^2, and the silica fine particles tend to aggregate closely (aggregate). In this case, since the density of silanol groups on the surface of the fine particles is as small as ² to 3 / nm ² , it is estimated that a structure having a high porosity is obtained as a result of sparse soft agglomeration. .

  Silica fine particles may be used in combination with other inorganic fine particles other than silica fine particles. When other fine particles and vapor phase method silica are used in combination, the content of vapor phase method silica in all inorganic fine particles is preferably 30% by mass or more, and more preferably 50% by mass or more.

As the inorganic fine particles, alumina fine particles, alumina hydrate, a mixture or a composite thereof are also preferable. Of these, alumina hydrate is preferable because it can absorb and fix ink well, and pseudoboehmite (Al ₂ O ₃ .nH ₂ O) is particularly preferable. Alumina hydrate can be used in various forms, but it is preferable to use sol boehmite because a smooth layer can be easily obtained.

  About the pore structure of pseudo boehmite, it is preferable that the average pore radius is 1-30 nm, and it is more preferable that it is 2-15 nm. The pore volume is preferably 0.3 to 2.0 cc / g, more preferably 0.5 to 1.5 cc / g. Here, the pore radius and the pore volume are measured by a nitrogen adsorption / desorption method, and can be measured using, for example, a gas adsorption / desorption analyzer (for example, Omni Soap 369 (trade name), manufactured by Coulter). .

  Among the alumina fine particles, vapor-phase method alumina fine particles are preferable in terms of a large specific surface area. The average primary particle diameter of the vapor-phase process alumina fine particles is preferably 30 nm or less, and more preferably 20 nm or less.

  The content of the inorganic fine particles in the inorganic fine particle dispersion is not particularly limited, but is preferably 5 to 25% by mass of the total mass of the inorganic fine particle dispersion in consideration of the preparation of the coating liquid for the ink receiving layer described later. 8-20 mass% is more preferable.

-Dispersant-
The inorganic fine particle dispersion of the present invention is added with a dispersant for favorably dispersing the inorganic fine particles. The dispersant also has a function as a mordant. For example, when an ink jet recording medium having an ink receiving layer is prepared as described later, the water resistance and bleeding over time of a recorded image are improved. In other words, the presence of the dispersant in the ink receiving layer stabilizes the color material by interacting with the liquid ink having the anionic dye as the color material, and the recorded image has water resistance and aging resistance. Can be improved.

  The dispersant according to the present invention includes an organic dispersant and an inorganic dispersant. In particular, a cationic polymer (cationic polymer dispersant) which is an organic dispersant is preferable. As the dispersant, one type of organic or inorganic dispersant can be used alone, or two or more types can be used in combination, or an organic dispersant and an inorganic dispersant can be used in combination.

  As the cationic polymer dispersant, a polymer dispersant having a primary to tertiary amino group or a quaternary ammonium base as a cationic group is generally used. Cationic non-polymeric dispersants may also be used.

  As the polymer dispersant, a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base (mordanting monomer), or the mordanting monomer and another monomer (non-mordanting) And monomers obtained as a copolymer or a condensation polymer. These polymer dispersants can be used in any form of a water-soluble polymer or water-dispersible latex particles.

  Examples of the monomer (mordanting monomer) include trimethyl-p-vinylbenzylammonium chloride, trimethyl-m-vinylbenzylammonium chloride, triethyl-p-vinylbenzylammonium chloride, triethyl-m-vinylbenzylammonium chloride, N , N-dimethyl-N-ethyl-Np-vinylbenzylammonium chloride, N, N-diethyl-N-methyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-Nn-propyl-N -P-vinylbenzylammonium chloride, N, N-dimethyl-Nn-octyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-benzyl-Np-vinylbenzylammonium chloride, N, N-die Ru-N-benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N- (4-methyl) benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-phenyl-N -P-vinylbenzylammonium chloride;

Trimethyl-p-vinylbenzylammonium bromide, trimethyl-m-vinylbenzylammonium bromide, trimethyl-p-vinylbenzylammonium sulfonate, trimethyl-m-vinylbenzylammonium sulfonate, trimethyl-p-vinylbenzylammonium acetate, trimethyl-m-vinyl Benzylammonium acetate, N, N, N-triethyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N, N-triethyl-N-2- (3-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride Tate;

N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N- Methyl chloride, ethyl chloride, methyl bromide of dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide , Quaternized products of ethyl bromide, methyl iodide or ethyl iodide, or sulfonates, alkyl sulfonates, acetates or alkyl carboxylates substituted for their anions.

  Specific examples include monomethyldiallylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium chloride, triethyl-2- (methacryloyloxy) ethylammonium chloride, trimethyl-2- (acryloyloxy) ethylammonium chloride, triethyl-2 -(Acryloyloxy) ethylammonium chloride, trimethyl-3- (methacryloyloxy) propylammonium chloride, triethyl-3- (methacryloyloxy) propylammonium chloride, trimethyl-2- (methacryloylamino) ethylammonium chloride, triethyl-2- ( Methacryloylamino) ethylammonium chloride, trimethyl-2- (acryloylamino) ethyla Monium chloride, triethyl-2- (acryloylamino) ethylammonium chloride, trimethyl-3- (methacryloylamino) propylammonium chloride, triethyl-3- (methacryloylamino) propylammonium chloride, trimethyl-3- (acryloylamino) propylammonium chloride Triethyl-3- (acryloylamino) propylammonium chloride;

N, N-dimethyl-N-ethyl-2- (methacryloyloxy) ethylammonium chloride, N, N-diethyl-N-methyl-2- (methacryloyloxy) ethylammonium chloride, N, N-dimethyl-N-ethyl- 3- (acryloylamino) propylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium bromide, trimethyl-3- (acryloylamino) propylammonium bromide, trimethyl-2- (methacryloyloxy) ethylammonium sulfonate, trimethyl-3- And (acryloylamino) propylammonium acetate.
In addition, examples of copolymerizable monomers include N-vinylimidazole and N-vinyl-2-methylimidazole.

  The non-mordant monomer does not contain a basic or cationic moiety such as a primary to tertiary amino group and salt thereof, or a quaternary ammonium base, and does not interact with the dye in the inkjet ink, or It is a monomer having a substantially small interaction.

  Examples of non-mordant monomers include (meth) acrylic acid alkyl esters; (meth) acrylic acid cycloalkyl esters such as cyclohexyl (meth) acrylate; (meth) acrylic acid aryl esters such as phenyl (meth) acrylate; Aralkyl esters such as meth) benzyl acrylate; aromatic vinyls such as styrene, vinyltoluene and α-methylstyrene; vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatate; allyl esters such as allyl acetate; And halogen-containing monomers such as vinylidene chloride and vinyl chloride; vinyl cyanide such as (meth) acrylonitrile; olefins such as ethylene and propylene.

The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl moiety, such as methyl (meth) acrylate, ethyl (meth) acrylate, (meth) Propyl acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, Examples include 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like.
Of these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and hydroxyethyl methacrylate are preferable. The non-mordant monomers can also be used singly or in combination of two or more.

  Further, as the polymer dispersant, polydiallyldimethylammonium chloride, polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride, polyethyleneimine, polyallylamine and its modified product, polyallylamine hydrochloride, polyamide-polyamine resin, cationization Starch, dicyandiamide formalin condensate, dimethyl-2-hydroxypropylammonium salt polymer, polyamidine, polyvinylamine, or JP-A-10-264511, JP-A-2000-43409, JP-A-2000-343811, JP-A Cationic acrylic emulsion of acrylic silicon latex as described in JP 2002-120452A (Aquabrid series manufactured by Daicel Chemical Industries, Ltd., for example, AS -781, ASi-784, ASi-578, ASi-903, etc.) and the like can also be mentioned as preferable examples. Acrylic cationic polymers such as Chemist 7005 (manufactured by Sanyo Kasei Kogyo Co., Ltd.) and Charol DC-902P Particularly preferred are dimethyldiallylammonium chloride homopolymers (Daiichi Kogyo Seiyaku Co., Ltd.) and the like, and copolymers of cationic monomers and nonionic monomers described in JP-A-11-20306.

  The molecular weight of the organic dispersant is preferably 2000 to 300000, more preferably 2000 to 50000 in terms of mass average molecular weight. When the molecular weight is within this range, water resistance and aging resistance can be further improved. Also, if the molecular weight is too small, the water resistance and aging resistance may deteriorate, and if the molecular weight is too large, the liquid viscosity increases and the workability deteriorates, and the gloss of the coated film after drying becomes poor. Detrimental effects such as lowering may occur.

  As the cationic polymer dispersant which is an organic dispersant, an acrylic cationic polymer and a derivative thereof are particularly preferable from the viewpoint of dispersion of inorganic fine particles.

In addition to organic dispersants, inorganic dispersants can also be used. Examples of inorganic dispersants include polyvalent water-soluble metal salts and hydrophobic metal salt compounds. This inorganic dispersant can be contained as a metal salt described later.
Specific examples of inorganic dispersants include magnesium, aluminum, calcium, scandium, titanium, vanadium, manganese, iron, nickel, copper, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, indium, barium, lanthanum, cerium And salts or complexes of metals selected from praseodymium, neodymium, samarium, europium, gadolinium, dysproprosium, erbium, ytterbium, hafnium, tungsten, and bismuth.

  Specific examples include 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 Cupric, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, sulfuric acid Nickel ammonium hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum alum, basic polyaluminum hydroxide, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate Japanese, ferrous bromide, ferrous chloride, ferric chloride Ferrous sulfate, ferric sulfate, zinc phenolsulfonate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, titanium tetrachloride, tetraisopropyl titanate, titanium acetylacetonate, titanium lactate, zirconium acetyl Acetonate, zirconyl acetate, zirconyl sulfate, ammonium zirconium carbonate, zirconyl stearate, zirconyl octylate, zirconyl nitrate, zirconium oxychloride, zirconium hydroxychloride, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, citric acid Magnesium nonahydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphoric acid n hydrate, gallium nitrate , Strontium nitrate, strontium nitrate, yttrium acetate, yttrium chloride, yttrium nitrate, indium nitrate, lanthanum nitrate, lanthanum chloride, lanthanum acetate, lanthanum benzoate, cerium chloride, cerium sulfate, cerium octylate, praseodymium nitrate, neodymium nitrate, nitric acid Examples include samarium, europium nitrate, gadolinium nitrate, dysprosium nitrate, erbium nitrate, ytterbium nitrate, hafnium chloride, and bismuth nitrate.

As the inorganic dispersant, an aluminum-containing compound, a titanium-containing compound, a zirconium-containing compound, and a metal compound (salt or complex) of Group IIIB series of the Periodic Table of Elements are preferable.
The amount of the dispersant in the inorganic fine particle dispersion is preferably 3 to 15% by mass, more preferably 5 to 10% by mass, based on the mass of the inorganic fine particles described above. In the case where an ink receiving layer of an ink jet recording medium is formed as described later, the amount of the dispersant in the ink receiving layer is preferably 0.01 to 5 g / m ² , and preferably 0.1 to ³ g / m. ² is more preferable.

  In addition to the dispersant and the inorganic fine particles described above, a hardening agent, a water-soluble metal salt, and other components as necessary can be added to the inorganic fine particle dispersion of the present invention. These will be described in detail below.

-Hardener-
In addition to the inorganic fine particles and the dispersant described above, a hardening agent (crosslinking agent) can be added to the inorganic fine particle dispersion of the present invention. For example, when an ink jet recording medium having an ink receiving layer as described later is prepared, the hardener is contained so that the ink receiving layer includes a coating layer containing a water-soluble resin described later together with inorganic fine particles and a dispersant. Furthermore, the aspect comprised by the porous layer hardened | cured by the crosslinking reaction of a hardener and water-soluble resin including the hardener which can bridge | crosslink this water-soluble resin is preferable.

For the hardener according to the present invention, a boron compound may be mentioned as one suitable. 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} ), can be mentioned five borate _{(e.g., KB 5 O 8 · 4H 2} O, Ca 2 B 6 O 11 · 7H 2 O, CsB 5 O 5) or the like. of these, Borax, boric acid and borates are preferred, and boric acid is particularly preferred in that a crosslinking reaction can be promptly caused.

  Moreover, the following compounds other than a boron compound can also be used. For example, aldehyde compounds such as formaldehyde, glyoxal, and glutaraldehyde; ketone compounds such as diacetyl and cyclopentanedione; bis (2-chloroethylurea) -2-hydroxy-4,6-dichloro-1,3,5- Active halogen compounds such as triazine and 2,4-dichloro-6-S-triazine sodium salt; divinylsulfonic acid, 1,3-vinylsulfonyl-2-propanol, N, N′-ethylenebis (vinylsulfonylacetamide) ), Active vinyl compounds such as 1,3,5-triacryloyl-hexahydro-S-triazine; N-methylol compounds such as dimethylolurea and methyloldimethylhydantoin; melamine resins (for example, methylolmelamine, alkylated methylolmelamine) ;Epoxy resin;

Isocyanate compounds such as 1,6-hexamethylene diisocyanate; Aziridine compounds described in US Pat. Nos. 3,017,280 and 2,983,611; Carboximide compounds described in US Pat. No. 3,100,704; Glycerol triglycidyl Epoxy compounds such as ether; Ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; Halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; 2,3-dihydroxy Dioxane compounds such as dioxane; metal-containing compounds such as titanium lactate, aluminum sulfate, chromium alum, potash alum, zirconyl acetate, chromium acetate, polyamine compounds such as tetraethylenepentamine, hydrazide compounds such as adipic acid dihydrazide, A low molecule or polymer containing two or more oxazoline groups.
In addition, a hardening agent may be used individually by 1 type or in combination of 2 or more types.

When forming the ink receiving layer, the hardening of the layer (crosslinking curing) is performed by preparing a coating liquid (first liquid) containing a hardening agent, inorganic fine particles and a dispersant, a water-soluble resin, and the like, and (1) At the same time when the coating solution is applied to form a coating layer, or (2) before the coating layer is dried by applying the coating solution and before the coating layer exhibits reduced-rate drying. At any time, it can be suitably performed by applying a basic solution (second liquid) having a pH of 7.1 or higher to the coating layer.
When adding said hardener, 1-50 mass% is preferable with respect to the water-soluble resin mentioned later as its quantity, and 5-40 mass% is more preferable.

-Metal salt-
In addition to the inorganic fine particles, the dispersant, and the hardener, a metal salt (preferably a water-soluble metal salt) can be suitably added to the inorganic fine particle dispersion of the present invention. This metal salt can further improve the dispersibility of the inorganic fine particles. Further, for example, when an ink jet recording medium having an ink receiving layer is prepared as described later, the recording image bleeds over time due to the action of the metal cation of the metal salt. Can be more effectively prevented. Thus, it is possible to provide an ink jet recording medium having a photographic-like image recording property while realizing low energy consumption and low cost during production.

The metal salts include both water-soluble metal salts and hydrophobic metal salts. Specific examples of the metal salt include compounds similar to the specific examples listed as the inorganic dispersant described above.
The metal salt is desirably contained in the following range. That is, the content of the metal salt in the inorganic fine particle dispersion is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass with respect to the mass of the inorganic fine particles described above. When this content is within the above range, thickening during dispersion of the inorganic fine particles is effectively suppressed. As a result, energy consumption during preparation can be further reduced, and a low-viscosity inorganic fine particle dispersion can be obtained. It is possible to obtain.

  Note that “water-soluble” in a water-soluble metal salt means that 1% by mass or more is dissolved in water at 20 ° C., and “hydrophobic” in a hydrophobic metal salt is a solution corresponding to the above “water-soluble”. It means no sex.

  As the metal salt, a water-soluble metal salt is particularly preferable, and a zirconium compound is more preferable. Examples of the water-soluble compound containing zirconium include zirconium acetylacetonate, zirconyl acetate, zirconyl sulfate, ammonium zirconium carbonate, zirconyl stearate, zirconyl octylate, zirconyl nitrate, zirconium oxychloride, and zirconium zirconium hydroxychloride.

  As described above, the metal salt has a function as a mordant when used as an aqueous medium.

  In addition to the above-described components, other components described later, for example, various additives such as an ultraviolet absorber and a surfactant can be further added.

  The inorganic fine particle dispersion of the present invention is prepared by the above-described method for producing the inorganic fine particle dispersion of the present invention, and contains a dispersant and inorganic fine particles in an aqueous medium, preferably further a hardener or metal. It comprises a salt and is prepared using other ingredients as required.

  A preferred embodiment and use of the inorganic fine particle dispersion of the present invention are not particularly limited, and high-quality images having weather resistance, recording surface smoothness, clear vividness, and sharpness (sharpness). Can be suitably used for various image recording material applications, such as inkjet recording media to be described later, electrophotographic image receiving materials, thermosensitive color recording materials, sublimation transfer image receiving materials, It is suitable for applications that require dispersion of inorganic fine particles, such as thermal transfer image receiving materials, silver salt photographic light-sensitive materials, and printing paper.

The image recording material of the present invention can be composed of a support and a recording layer using the inorganic fine particle dispersion of the present invention described above on the support, and other image recording materials can be used depending on the image recording material. Further layers can be provided. In consideration of the component structure required for the image recording material to be produced, at least one recording layer can be provided directly on the support or via another layer.
The image recording material of the present invention includes various recording materials such as an ink jet recording medium, an electrophotographic image receiving material, a heat sensitive color recording material, a sublimation transfer image receiving material, a thermal transfer image receiving material, and a silver salt photographic light sensitive material.

Hereinafter, among the image recording materials, an ink jet recording medium will be described in detail.
The ink jet recording medium can be composed of a support and at least one ink receiving recording layer (hereinafter referred to as “ink receiving layer”) provided on the support. It may have a layer. The ink receiving layer is prepared by applying a coating liquid for forming an ink receiving layer (hereinafter, also referred to as “ink receiving layer coating liquid”) prepared using the inorganic fine particle dispersion of the present invention described above, for example, on a support. It can be produced by coating directly or through another layer.

  As described above, the ink receiving layer can be constituted by containing a water-soluble resin together with inorganic fine particles and a dispersant, and optionally a hardening agent, a metal salt, and the like. Moreover, it can also comprise using another component as needed.

-Water-soluble resin-
Examples of water-soluble resins include polyvinyl alcohol resins that are resins having a hydroxy group as a hydrophilic structural unit [polyvinyl alcohol (PVA), acetoacetyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl. Alcohol, polyvinyl acetal, etc.], cellulose resins [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.], chitins, chitosans, starch , Resin having an ether bond [polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene Glycol (PEG), poly ether (PVE)], and resins having carbamoyl groups [polyacrylamide (PAAM), polyvinyl pyrrolidone (PVP), polyacrylic acid hydrazide, etc.] and the like. Moreover, the polyacrylic acid salt which has a carboxyl group as a dissociable group, maleic acid resin, alginate, gelatins, etc. can be mentioned.
Of these, polyvinyl alcohol resins are particularly preferable.

  The polyvinyl alcohol-based resin (particularly PVA) has a number average degree of polymerization of preferably 1800 or more, more preferably 2000 or more, from the viewpoint of preventing cracks. When combined with silica fine particles, the type of water-soluble resin is important from the viewpoint of transparency. In particular, when anhydrous silica is used, PVA is preferably used as the water-soluble resin, and among them, PVA having a saponification degree of 70 to 99% is more preferable.

  In addition to polyvinyl alcohol (PVA), polyvinyl alcohol resins include cation-modified PVA, anion-modified PVA, silanol-modified PVA, and other polyvinyl alcohol derivatives. Polyvinyl alcohol can be used individually by 1 type or in combination of 2 or more types.

  The polyvinyl alcohol-based resin has a hydroxyl group in its structural unit, and since this hydroxyl group and the surface silanol group of the silica fine particle form a hydrogen bond, a three-dimensional network having a secondary particle of the silica fine particle as a network chain unit. It becomes easy to form a structure. By forming this three-dimensional network structure, it is considered that an ink receiving layer having a porous structure with a high porosity and sufficient strength is formed. In ink-jet recording, the ink receiving layer having a porous structure obtained as described above absorbs ink rapidly by capillarity, and forms dots with good roundness without ink bleeding. Can do.

The content of the water-soluble resin in the ink-receiving layer prevents the film strength from being reduced and cracks during drying due to the excessive content, and the excessive content causes the voids to be easily clogged with the resin. From the viewpoint of preventing the ink absorbability from being lowered due to the decrease in 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 (mass) of the ink receiving layer. .
The inorganic fine particles and the water-soluble resin that mainly constitute the ink receiving layer may be a single material or a mixed system of a plurality of materials.

<Content ratio of inorganic fine particles and water-soluble resin>
The mass content ratio [PB ratio (x / y)] of the inorganic fine particles (x) and the water-soluble resin (y) greatly affects the film structure and film strength of the ink receiving layer. That is, as the PB ratio (x / y) increases, the porosity, pore volume, and surface area (per unit mass) increase, but the density and strength tend to decrease. Therefore, specifically, the PB ratio (x / y) in the ink receiving layer according to the present invention prevents a decrease in film strength and cracks during drying caused by the PB ratio being too large, and When the PB ratio is too small, the voids are easily blocked by the resin, and from the viewpoint of preventing the ink absorbency from being lowered due to the decrease in the void ratio, 1.5 to 10 is preferable.

  In addition, since stress may be applied to the ink jet recording medium when passing through the transport system of the ink jet printer, the ink receiving layer needs to have sufficient film strength and is cut into a sheet shape. In addition, the ink receiving layer needs to have sufficient film strength from the viewpoint of preventing the ink receiving layer from cracking or peeling. In consideration of these, the PB ratio is more preferably 5 or less, and more preferably 2 or more from the viewpoint of ensuring high-speed ink absorbability in an inkjet printer.

For example, a coating solution in which gas phase method silica fine particles having an average primary particle size of 20 nm or less and a water-soluble resin are completely dispersed in an aqueous solution at a PB ratio (x / y) of 2 to 5 is applied on a support and dried. In this case, a three-dimensional network structure in which the secondary particles of silica fine particles are network chains is formed, the average pore diameter is 25 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.

-Other ingredients-
For an ink jet recording medium (for example, an ink receiving layer), if necessary, various other known additives such as anti-fading agents such as ultraviolet absorbers and antioxidants, fluorescent whitening agents, monomers, polymerization initiators, polymerization Inhibitors, anti-bleeding agents, preservatives, viscosity stabilizers, antifoaming agents, surfactants, antistatic agents, matting agents, anti-curling agents, water-resistant agents, water-soluble organic solvents and the like can be contained.

  Examples of the ultraviolet absorber include cinnamic acid derivatives, benzophenone derivatives, benzotriazolylphenol derivatives, and the like. For example, α-cyano-phenyl cinnamate butyl, o-benzotriazole phenol, o-benzotriazole-p-chlorophenol, o-benzotriazole-2,4-di-t-butylphenol, o-benzotriazole-2,4 -Di-t-octylphenol etc. are mentioned. A hindered phenol compound can also be used as an ultraviolet absorber, and specifically, a phenol derivative in which at least one of 2-position or 6-position is substituted with a branched alkyl group is preferable.

  Moreover, a benzotriazole type ultraviolet absorber, a salicylic acid type ultraviolet absorber, a cyanoacrylate type ultraviolet absorber, an oxalic acid anilide type ultraviolet absorber, etc. can be used. For example, JP-A-47-10537, 58-111942, 58-21284, 59-19945, 59-46646, 59-109055, 63-53544. No. 36, Japanese Patent Publication No. 36-10466, No. 42-26187, No. 48-30492, No. 48-31255, No. 48-41572, No. 48-54965, No. 50-10726. No. 2,719,086, US Pat. No. 3,707,375, US Pat. No. 3,754,919, US Pat. No. 4,220,711, and the like. .

  A fluorescent brightening agent can also be used as an ultraviolet absorber, and examples thereof include a coumarin fluorescent brightening agent. Specifically, it is described in Japanese Patent Publication Nos. 45-4699 and 54-5324.

  Examples of the antioxidant include European Patent Publication No. 223739, Publication No. 309401, Publication No. 309402, Publication No. 310551, Publication No. 310552, Publication No. 4594416, German Publication No. 3435443, No. 54-48535, No. 60-107384, No. 60-107383, No. 60-125470, No. 60-125471, No. 60-125472, No. 60-287485, 60-287486, 60-287487, 60-287488, 61-160287, 61-185483, 61-2111079, 62-146678, 62-146680, 62-146679, 6 No. 282885, No. 62-262047, No. 63-05174, No. 63-89877, No. 63-88380, No. 66-88381, No. 63-113536, No. 63- No. 163351, No. 63-203372, No. 63-224989, No. 63-251282, No. 63-267594, No. 63-182484, JP-A-1-239282, and JP-A-2 -262654, 2-71262, 3-121449, 4-291865, 4-291684, 5-611166, 5-119449, 5- 188687, 5-188686, 5-110490, 5-1108437 Broadcast, the 5-170361, JP-Sho 48-43295, JP-same 48-33212, JP-U.S. Patent No. 4814262, the first 4980275 Pat, etc. include those described in.

  Specifically, 6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2-dihydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2-dihydroquinoline 6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2,3 4, -tetrahydroquinoline, nickel cyclohexane acid, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -2-ethylhexane, 2-methyl-4-methoxy-diphenylamine, Examples include 1-methyl-2-phenylindole.

  The anti-fading agents such as the ultraviolet absorbers and antioxidants described above may be used in combination of two or more in addition to being used alone. The anti-fading agent may be water-solubilized, dispersed, or emulsified, and can also be used by being encapsulated in microcapsules. The addition amount of the anti-fading agent is preferably 0.01 to 10% by mass with respect to the mass of the ink receiving layer coating solution.

  The ink receiving layer preferably contains a high boiling point organic solvent for curling prevention. The water-soluble high-boiling organic solvent is preferable as the high-boiling organic solvent. Examples of the water-soluble high-boiling organic solvent include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerin, diethylene glycol monobutyl ether (DEGMBE), and triethylene glycol. Monobutyl ether, glycerin monomethyl ether, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,4-pentanetriol, 1,2,6-hexanetriol, thiodiglycol, triethanolamine And alcohols such as polyethylene glycol (weight average molecular weight of 400 or less). Diethylene glycol monobutyl ether (DEGMBE) is preferred.

The content of the high-boiling organic solvent in the ink-receiving layer coating solution is preferably 0.05 to 1% by mass, particularly preferably 0.1 to 0.6% by mass.
Moreover, an acid, an alkali, etc. may be included as a pH adjuster. Furthermore, for the purpose of suppressing surface frictional charge or peeling charge, the metal oxide fine particles having electronic conductivity may contain various matting agents for the purpose of reducing the surface frictional characteristics.

In addition, the ink receiving layer coating liquid preferably includes a surfactant. As the surfactant, any of cationic, anionic, nonionic, amphoteric, fluorine, and silicone surfactants can be used.
Examples of the nonionic surfactant include polyoxyalkylene alkyl ethers and polyoxyalkylene alkyl phenyl ethers (eg, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene Ethylene nonylphenyl ether), oxyethylene / oxypropylene block copolymer, sorbitan fatty acid esters (for example, sorbitan monolaurate, sorbitan monooleate, sorbitan trioleate, etc.), polyoxyethylene sorbitan fatty acid esters (for example, polyoxyethylene) Sorbitan monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitant Oleate, etc.), polyoxyethylene sorbitol fatty acid esters (eg, polyoxyethylene sorbitol tetraoleate), glycerin fatty acid esters (eg, glycerol monooleate), polyoxyethylene glycerin fatty acid esters (polyoxymonostearate) Ethylene glycerol, monooleic acid polyoxyethylene glycerin, etc.), polyoxyethylene fatty acid esters (polyethylene glycol monolaurate, polyethylene glycol monooleate, etc.), polyoxyethylene alkylamine, acetylene glycols (eg, 2, 4, 7) , 9-tetramethyl-5-decyne-4,7-diol, and ethylene oxide adducts and propylene oxide adducts of the diols). Of these, polyoxyalkylene alkyl ethers are preferred. The nonionic surfactant may be contained in any one of the ink receiving layer coating solution (first solution) and the basic solution (second solution), and may be used alone or in combination of two or more. You can also.

  Examples of the amphoteric surfactant include amino acid type, carboxyammonium betaine type, sulfoammonium 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 can be suitably used. As the amphoteric surfactant, an amino acid type amphoteric surfactant is preferable, and as the amino acid type amphoteric surfactant, as described in JP-A-5-303205, for example, an amino acid (glycine, glutamic acid, Histidine acid etc.) and N-aminoacyl acids and salts thereof into which long chain acyl groups have been introduced. These can be used alone or in combination of two or more.

Examples of the anionic surfactant include fatty acid salts (for example, sodium stearate, potassium oleate), alkyl sulfate esters (for example, sodium lauryl sulfate, triethanolamine lauryl sulfate), and sulfonates (for example, sodium dodecylbenzenesulfonate). Alkyl sulfosuccinate (for example, sodium dioctyl sulfosuccinate), alkyl diphenyl ether disulfonate, alkyl phosphate, and the like.
Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, pyridinium salts, imidazolium salts, and the like.

  Examples of the fluorosurfactant include compounds derived via an intermediate having a perfluoroalkyl group using a method such as electrolytic fluorination, telomerization, or oligomerization. Examples thereof include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl trialkyl ammonium salts, perfluoroalkyl group-containing oligomers, and perfluoroalkyl phosphate esters.

  The silicone surfactant is preferably a silicone oil modified with an organic group, and can have a structure in which a side chain of a siloxane structure is modified with an organic group, a structure in which both ends are modified, or a structure in which one end is modified. Examples of the organic group modification include amino modification, polyether modification, epoxy modification, carboxyl modification, carbinol modification, alkyl modification, aralkyl modification, phenol modification, and fluorine modification.

  The content of the surfactant in the ink receiving layer coating solution is preferably 0.001 to 2.0%, more preferably 0.01 to 1.0%. Further, when coating is performed using two or more liquids as the ink receiving layer coating liquid, it is preferable to add a surfactant to each coating liquid.

In addition, the ink receiving layer coating liquid preferably contains a water-soluble organic solvent for the purpose of improving the coating liquid stability and the handleability due to a decrease in liquid viscosity. As the water-soluble organic solvent, a volatile solvent is preferable. However, the water-soluble organic solvent is preferable in that it can exhibit an anti-curl effect when used with the high-boiling organic solvent.
Examples of the water-soluble organic solvent include alcohols such as methanol, ethanol, propanol and butanol; cyclic alcohols such as cyclohexanol; ketones such as acetone, methyl ethyl ketone and diethyl ketone; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and the like Cellosolves; esters such as ethyl acetate, methyl acetate, propyl acetate; cellosolv esters such as ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate; other propylene glycol monomethyl ether, propylene glycol monoethyl ether, dimethylformamide, Dimethyl sulfoxide, 2-pyrrolidone, N-methylpyrrolidone, tetrahydrofuran, acetonitrile, Common organic solvents such as ene. Among these, alcohols such as methanol and ethanol are preferable from the viewpoint of handleability. The amount of water-soluble organic solvent added is preferably 0.1 to 15% by mass, more preferably 0.5 to 5% by mass, based on the total mass of the ink receiving layer coating solution.

-Support-
As the support, either a transparent support made of a transparent material such as plastic or an opaque support made of an opaque material such as paper can be used. In order to make use of the transparency of the ink receiving layer, it is preferable to use a transparent support or a highly glossy opaque support. Further, a read-only optical disk such as a CD-ROM or DVD-ROM, a write-once optical disk such as a CD-R or DVD-R, or a rewritable optical disk can be used as a support, and an ink receiving layer can be provided on both sides of the label. .

The material that can be used for the transparent support is preferably a material that is transparent and can withstand radiant heat when used in an OHP or a backlight display. Examples of the material include polyesters such as polyethylene terephthalate (PET); polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide and the like. Of these, polyesters are preferable, and polyethylene terephthalate is particularly preferable.
Although there is no restriction | limiting in particular as thickness of the said transparent support body, 50-200 micrometers is preferable at the point which is easy to handle.

  As the highly glossy opaque support, one having a glossiness of 40% or more on the surface on which the ink receiving layer is provided is preferable. The glossiness is a value determined according to the method described in JIS P-8142 (75-degree specular gloss test method for paper and paperboard). Specifically, the following supports are mentioned.

  For example, high gloss paper support such as art paper, coated paper, cast coated paper, baryta paper used for silver salt photographic support, etc .; polyesters such as polyethylene terephthalate (PET), nitrocellulose, cellulose acetate , Cellulose esters such as cellulose acetate butyrate, and plastic films such as polysulfone, polyphenylene oxide, polyimide, polycarbonate, and polyamide are made opaque by adding a white pigment or the like (surface calendering may be applied). Glossy film; or a support in which a polyolefin coating layer containing or not containing a white pigment is provided on the surface of a highly glossy film containing the various paper supports, the transparent support or the white pigment. Etc. A white pigment-containing foamed polyester film (for example, foamed PET containing polyolefin fine particles and forming voids by stretching) can also be suitably exemplified. Furthermore, resin-coated paper used for silver salt photographic printing paper is also suitable.

  Although there is no restriction | limiting in particular also about the thickness of the said opaque support body, 50-300 micrometers is preferable at the point of handleability.

  The surface of the support may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, etc. in order to improve wettability and adhesion.

Next, a base paper used for a paper support such as resin-coated paper will be described in detail.
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 fibers such as nylon or polyester in addition to wood pulp as necessary. As the wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, NUKP can be used, but it is preferable to use more LBKP, NBSP, LBSP, NDP, LDP with a lot of short fibers. preferable. However, the ratio of LBSP and / or LDP is preferably 10% by mass or more and 70% by mass or less.

  As the pulp, chemical pulp (sulfate pulp or sulfite pulp) with few impurities is suitably used, and a pulp having a whiteness improved by performing a bleaching treatment 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 freeness of the pulp used for papermaking is preferably 200 to 500 ml as defined by CSF, and the fiber length after beating is a 24 mesh residual mass% and a 42 mesh residual as defined in JIS P-8207. 30 to 70% of the sum with the mass% of is preferable. In addition, it is preferable that the mass% of 4 mesh remainder is 20 mass% or less.

The basis weight of the base paper is preferably 30 to 250 g, and particularly preferably 50 to 200 g. The thickness of the base paper is preferably 40 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 the base paper is generally 0.7 to 1.2 g / m ² (JIS P-8118).
Furthermore, the base paper stiffness is preferably 20 to 200 g under the conditions specified in JIS P-8143.

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.
The pH of the base paper is preferably 5 to 9 when measured by a hot water extraction method defined in JIS P-8113.

  The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but some other LLDPE, polypropylene, etc. can also be used.

  In particular, the polyethylene layer on the side on which the ink receiving layer is formed is obtained by adding rutile or anatase type titanium oxide, fluorescent whitening agent, ultramarine to polyethylene, as is widely done in photographic paper. Those having improved whiteness and hue are preferred. Here, as a titanium oxide content, about 3-20 mass% is preferable with respect to polyethylene, and 4-13 mass% is more preferable. Although the thickness of a polyethylene layer does not have limitation in particular, 10-50 micrometers is suitable for both front and back layers. Further, an undercoat layer can be provided on the polyethylene layer in order to provide adhesion to the ink receiving layer. As the undercoat layer, aqueous polyester, gelatin and PVA are preferable. Moreover, as thickness of this undercoat layer, 0.01-5 micrometers is preferable.

  Polyethylene-coated paper can be used as glossy paper, or when it is melt-extruded onto the surface of the base paper and coated, the matte surface or silky surface that can be obtained with ordinary photographic printing paper by so-called molding Can also be used.

A back coat layer can be provided on the support, and examples of components that can be added to the back coat layer include a white pigment, an aqueous binder, and other components.
Examples of white pigments contained in the backcoat layer include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, and aluminum silicate. , Diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, white inorganic pigment, styrene And organic pigments such as polyethylene plastic pigments, acrylic plastic pigments, polyethylene, microcapsules, urea resins, and melamine resins.

Examples of the aqueous binder used in the backcoat layer include styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxy Examples thereof include water-soluble polymers such as methyl cellulose, hydroxyethyl cellulose, and polyvinyl pyrrolidone, and water-dispersible polymers such as styrene butadiene latex and acrylic emulsion.
Examples of other components contained in the backcoat layer include an antifoaming agent, an antifoaming agent, a dye, a fluorescent brightening agent, a preservative, and a water-proofing agent.

Next, a method for producing an inkjet recording medium will be described in detail.
The ink jet recording medium of the present invention can be produced by applying an ink receiving layer forming coating liquid (ink receiving layer coating liquid) on a support and drying it to form an ink receiving layer. The layer coating solution is most preferably prepared by using the inorganic fine particle dispersion of the present invention obtained by adding inorganic fine particles and a dispersant to an aqueous medium. In addition, the inorganic fine particle dispersion is prepared by adding the dispersion of the inorganic fine particles to (1) the aqueous medium by dividing the dispersant and the inorganic fine particles into two or more portions, or (2) in the aqueous medium. In addition, the dispersant and the inorganic fine particles can be prepared by continuously adding them.

  In any of the above methods (1) and (2), after adding at least a part of the inorganic fine particles and / or at least a part of the dispersant, or simultaneously and continuously adding the inorganic fine particles and the dispersant. In this case, the addition ratio of the dispersing agent and the inorganic fine particles is added so that a process (time zone) to be added exists under the relationship as described above, that is, Dt / It <D / I. And, when the number of times is infinite, it becomes the method of (2) above, but the addition amount in this case is the addition amount per hour, and at the initial stage of addition, the addition ratio of the inorganic fine particles to the dispersant is increased. It is preferable to adjust the ratio so that the addition ratio of the dispersant to the inorganic fine particles increases in the latter half of the addition. Thereby, the viscosity of the liquid is kept low.

  As the aqueous medium, water or a mixed solvent of water and a water-miscible solvent (for example, an organic solvent) can be used. The water includes distilled water, ion exchange water and the like. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, i-propanol, and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate, and toluene.

It is preferable to add the dispersant and the inorganic fine particles while stirring the aqueous medium with a dissolver or the like. Moreover, it is preferable to continue stirring with a dissolver even after completion of these additions, and to perform atomization with a sand grinder if necessary. In this way, an inorganic fine particle dispersion liquid uniformly dispersed with a low viscosity is obtained.
In addition to the dispersant and the inorganic fine particles, when a hardening agent, a metal salt or the like is further added, it may be added at any stage before or after the addition of the dispersant and the inorganic fine particles.

An ink receiving layer coating liquid (first liquid) can be prepared by adding and mixing a water-soluble resin aqueous solution such as an aqueous polyvinyl alcohol solution, a surfactant and other optional components to the inorganic fine particle dispersion. Furthermore, by containing a metal salt (preferably a water-soluble metal salt), bleeding with time can be further improved.
The obtained coating liquid (first liquid) is in a uniform sol state, and this is applied to a support, for example, by a known coating method and dried to dry the porous ink having a three-dimensional network structure. A receiving layer can be formed.

  When an ink jet recording medium is produced, the ink receiving layer constituting the medium is coated with an ink receiving layer prepared using the inorganic fine particle dispersion of the present invention so as to contain at least inorganic fine particles and a water-soluble resin. A liquid (first liquid) is applied onto a support to form a coating layer, and (1) at the same time as the coating liquid (first liquid) is applied, or (2) the coating liquid (first liquid). The basic solution (second liquid) having a pH of 7.1 or higher is either during the drying of the coating layer formed by coating the coating layer and before the coating layer exhibits reduced-rate drying. It can form suitably by the method (Wet on Wet method) which gives to a coating layer and carries out the crosslinking hardening of the said coating layer. Providing the ink-receptive layer thus crosslinked and cured is preferable in terms of ink absorbability and prevention of film cracking.

  Moreover, a basic solution (2nd liquid) can be prepared as follows, for example. That is, a mordant (for example, 0.1 to 5.0% by mass) necessary for ion-exchanged water and a surfactant (for example, 0.01 to 1.0% by mass in total) are added and sufficiently stirred. The pH of the second liquid is preferably 7.1 or higher, and pH adjustment is appropriately performed using ammonia water, sodium hydroxide, calcium hydroxide, amino group-containing compounds (ethylamine, ethanolamine, diethanolamine, polyallylamine, etc.) and the like. Can be done.

  When the mordant is added to the second liquid, it is present in a predetermined part of the ink receiving layer, so that the color material of the ink-jet ink is sufficiently mordanted, color density, bleeding over time, gloss of the printed part, and water resistance of characters and images after printing. And ozone resistance are preferred.

  The ink receiving layer coating solution is applied by a known coating method using, for example, an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, a bar coater, or the like. Can do.

  The second liquid (basic solution) is applied to the coated layer at the same time as or after the first liquid (ink-receiving layer coating liquid) is applied. It may be applied before the coating layer exhibits reduced rate drying. That is, after the application liquid for the ink-receiving layer is applied, the basic solution is preferably introduced while the applied layer exhibits constant rate drying. This second liquid may contain a mordant.

  Here, “before the coating layer comes to show reduced drying” usually refers to a process for several minutes immediately after the coating of the coating liquid for the ink-receiving layer. This shows a phenomenon of “constant rate drying” in which the content of the solvent (dispersion medium) of the ink decreases in proportion to time. About the time which shows this "constant rate drying", it describes in chemical engineering handbook (p.707-712, Maruzen Co., Ltd. issue, October 25, 1980), for example.

  As described above, after the application of the first liquid, the coating layer is dried until the coating layer exhibits reduced-rate drying. This drying is generally performed at 40 to 180 ° C. for 0.5 to 10 minutes (preferably, 0.00. 5-5 minutes). The drying time naturally varies depending on the coating amount, but the above range is usually appropriate.

  As a method of applying the second liquid before becoming reduced drying, (i) a method of further applying the second liquid on the coating layer, (ii) a method of spraying by a method such as spraying, (iii) ) A method of immersing the support on which the coating layer is formed in the second liquid.

  In the method (i), the application method for applying the second liquid is, for example, curtain flow coater, extrusion die coater, air doctor coater, bread coater, rod coater, knife coater, squeeze coater, reverse roll coater, bar A known coating method using a coater or the like can be used. However, it is preferable to use a method in which the coater does not directly contact the already formed first coating layer, such as an extrusion die coater, a curtain flow coater, a bar coater or the like.

The application amount of the second liquid, 5 to 50 g / m ² is generally, 10 to 30 g / m ² is preferred.

  After application of the second liquid, it is generally heated at 40 to 180 ° C. for 0.5 to 30 minutes, and dried and cured. Especially, it is preferable to heat at 40-150 degreeC for 1 to 20 minutes.

  Further, when the basic solution (second liquid) is applied simultaneously with the application of the ink receiving layer coating liquid (first liquid), the first liquid and the second liquid are brought into contact with the support. Thus, the ink receiving layer can be formed by simultaneously coating (multilayer coating) on the support, followed by drying and curing.

  The 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, the drying is generally performed by heating the coating layer at 40 to 150 ° C. for 0.5 to 10 minutes, preferably 40 to 100. It is carried out by heating at a temperature of 0.5 to 5 minutes.

  When the simultaneous application (multilayer application) is performed by, for example, an extrusion die coater, the two types of liquid discharged simultaneously are in the vicinity of the discharge port of the extrusion die coater, that is, before being transferred onto the support. In that state, it is coated on the support in multiple layers. Since the two-layer coating liquid layered before coating is likely to cause a cross-linking reaction at the interface between the two liquids when transferred to the support, the two liquids to be ejected are mixed in the vicinity of the discharge port of the extrusion die coater. As a result, thickening is likely to occur, which may hinder the application operation. Therefore, when applying simultaneously as mentioned above, it is preferable to apply a simultaneous triple layer with the barrier liquid (intermediate liquid) interposed between the two liquids together with the application of the first liquid and the second liquid.

  The barrier layer solution can be selected without particular limitation. For example, an aqueous solution containing a trace amount of water-soluble resin, water, and the like can be given. The water-soluble resin is used in consideration of applicability for the purpose of a thickener and the like. For example, a cellulose resin (for example, hydroxypropylmethylcellulose, methylcellulose, hydroxyethylmethylcellulose) And polymers such as polyvinylpyrrolidone and gelatin. The barrier layer liquid may contain the mordant.

  The ink receiving layer coating liquid can also be applied by so-called set drying. In this case, the ink receiving layer coating liquid is heated to a temperature of 40 ° C. or higher and applied onto the support, and then cooled to a temperature of 15 ° C. or lower to gel the coating liquid applied on the support. The porous film can be formed by (setting) and evaporating and drying a solvent such as water by spraying a drying air of 50 ° C. or less to this. In drying, from the viewpoint of preventing cracking of the porous membrane, it is preferable to adjust the relative humidity to about 50% in the final drying step. Since the drying time varies depending on the coating amount and the drying air amount, there is no particular limitation, but the drying time is generally 1 to 15 minutes.

  After forming the ink receiving layer on the support, the ink receiving layer is subjected to, for example, supercalendering, gloss calendering, etc., and calendering through the roll nip under heat and pressure, so that surface smoothness, glossiness, It is possible to improve transparency and coating strength. However, the calendering process may cause a decrease in the porosity (that is, the ink absorbability may be decreased), so it is necessary to set the conditions under which the decrease in the porosity is small.

  As roll temperature in the case of performing a calendar process, 30-150 degreeC is preferable and 40-100 degreeC is more preferable. Moreover, as a linear pressure between rolls at the time of a calendar process, 50-400 kg / cm is preferable and 100-200 kg / cm is more preferable.

In the case of ink jet recording, the thickness of the ink receiving layer needs to have an absorption capacity sufficient to absorb all the droplets, and therefore needs to be determined in relation to the porosity in the layer. For example, if the ink amount is 8 nL / mm ² and the porosity is 60%, a film having a layer thickness of about 15 μm or more is required. Considering this point, in the case of ink jet recording, the layer thickness of the ink receiving layer is preferably 10 to 50 μm.

  The pore diameter of the ink receiving layer is preferably 0.005 to 0.030 μm, more preferably 0.01 to 0.025 μm in terms of median diameter. The porosity and the median diameter of the pores can be measured using a mercury porosimeter (trade name “Bore Sizer 9320-PC2” manufactured by Shimadzu Corporation).

  In addition, the ink receiving layer is preferably excellent in transparency, as a guide, the haze value when the ink receiving layer is formed on a transparent film support is preferably 30% or less, More preferably, it is 20% or less. The haze value can be measured using a haze meter (HGM-2DP: manufactured by Suga Test Instruments Co., Ltd.).

  A polymer fine particle dispersion may be added to a constituent layer (for example, an ink receiving layer or a back layer) of the ink jet recording medium of the present invention. This polymer fine particle dispersion is used for the purpose of improving film properties such as dimensional stabilization, curling prevention, adhesion prevention, and film cracking prevention. The polymer fine particle dispersion is described in JP-A Nos. 62-245258, 62-1316648, and 62-110066. When a polymer fine particle dispersion having a low glass transition temperature (40 ° C. or lower) is added to a layer containing a mordant, cracking and curling of the layer can be prevented. Further, even when a polymer fine particle dispersion having a high glass transition temperature is added to the back layer, curling can be prevented.

Next, image recording materials other than the above-described ink jet recording medium will be described.
-Image receiving material for electrophotography-
The electrophotographic image-receiving material has a support and at least one toner image-receiving layer (recording layer) provided on at least one surface of the support, and other layers appropriately selected as necessary, for example, surface protection A layer, an intermediate layer, an undercoat layer, a cushion layer, a charge control (prevention) layer, a reflective layer, a tint control layer, a storage stability improving layer, an adhesion prevention layer, an anti-curl layer, a smoothing layer, and the like. Each of these layers may have a single layer structure or a laminated structure.

-Silver salt photographic material-
As a silver salt photographic light-sensitive material, for example, it has a structure in which a photosensitive layer (recording layer) that develops at least YMC color is provided on a support, and is passed through a plurality of processing tanks after being sequentially exposed after printing exposure. Examples thereof include materials used in silver halide photographic systems in which color development, bleach-fixing, washing with water and drying are performed to obtain an image.

-Thermal transfer image receiving material-
The thermal transfer image receiving material has, for example, a configuration in which at least an image receiving layer (recording layer) is provided on a support, and the thermal transfer material having at least a heat-meltable ink layer provided on the support is heated and melted by a thermal head. Examples include materials used in a method for melting and transferring ink from a conductive ink layer.

-Thermosensitive color recording material-
As a thermosensitive color recording material, for example, a thermoauto having a structure in which at least a thermochromic layer (recording layer) is provided on a support, and heat-colored by repeated heating with a thermal head and fixing with ultraviolet rays, etc., is formed. Examples include materials used for the chrome method (TA method).

-Sublimation transfer image receiving material-
The sublimation transfer image receiving material has, for example, a structure in which at least an image receiving layer (recording layer) is provided on a support, and sublimation in which an ink layer containing at least a heat diffusible dye (sublimation dye) is provided on the support. Examples include materials used in a sublimation transfer method in which a transfer material is heated by a thermal head to transfer a heat diffusible dye from an ink layer.

  The electrophotographic image-receiving material, heat-sensitive color-recording recording material, sublimation transfer image-receiving material, thermal transfer image-receiving material, or silver salt photographic light-sensitive material has at least a recording layer (toner image-receiving layer, heat-coloring layer) corresponding to each material. , An image receiving layer, or a photosensitive layer) on a support by a method similar to the above-described method for producing an ink jet recording medium using a prepared liquid prepared using the inorganic fine particle dispersion of the present invention. Can be produced.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In this embodiment, an ink jet recording sheet provided with an ink receiving layer is prepared as an example of an image recording material (ink jet recording medium). In the examples, “%” is based on mass unless otherwise specified.

-Production of support-
Wood pulp composed of 100 parts of LBKP is beaten to 300 ml Canadian freeness with a double disc refiner, 0.5 parts of epoxidized behenamide, 1.0 part of anionic polyacrylamide, 0.1 part of polyamide polyamine epichlorohydrin, 0.5 part of cationic polyacrylamide All the parts were added at an absolute dry weight ratio to the pulp, and weighed with a long net paper machine to make a base paper of 170 g / m ² . Subsequently, in order to adjust the surface size of the base paper, 0.04% of a fluorescent whitening agent (Whitetex BB, manufactured by Sumitomo Chemical Co., Ltd.) was added to a 4% aqueous solution of polyvinyl alcohol, and this was converted into an absolute dry weight. The base paper was impregnated to 0.5 g / m ² , dried, and then calendered to obtain a base paper having a density adjusted to 1.05 g / cc.

After the corona discharge treatment was performed on the wire surface (back surface) side of the obtained base paper, high-density polyethylene was coated to a thickness of 19 μm using a melt extruder to form a resin layer composed of a mat surface. (Hereinafter, this resin layer surface is referred to as “back surface”). After the corona discharge treatment is further applied to the resin layer on the back surface, aluminum oxide (alumina sol 100, manufactured by Nissan Chemical Industries, Ltd.) and silicon dioxide (Snowtex O, manufactured by Nissan Chemical Industries, Ltd.) as antistatic agents are produced. ) Was dispersed in water at a mass ratio of 1: 2 so that the dry weight was 0.2 g / m ² .

  Furthermore, after the corona discharge treatment is applied to the felt surface (surface) side where the resin layer is not provided, anatase-type titanium dioxide 10%, a trace amount of ultramarine blue, and a fluorescent whitening agent 0.01% (vs. polyethylene) Low-density polyethylene containing MFR (melt flow rate) 3.8 is melt-extruded to a thickness of 29 μm using a melt extruder to form a high-gloss thermoplastic resin layer on the surface side of the base paper (Hereinafter, this highly glossy surface is referred to as a “front side”) and used as a support.

(Example 1)
-Preparation of silica dispersion-
The following compositions were mixed as follows to prepare a silica dispersion of the present invention.
Add (1) ion-exchanged water and (2) boric acid to a stainless steel pot with an inner diameter of 26 cm. Stir at a rotation speed of 1500 rpm using a dissolver (blade φ6 cm diameter) until uniformly dissolved, and finally add to this (3) Corresponding to 1/3 of the total amount to be added (3) Chemistat 7005 is added to set the rotational speed to 3500 rpm, and it corresponds to 2/3 of the final amount to be added (4) Leoroseal QS-30 for 5 minutes And evenly added. At this time, the ratio Dt / It between the addition amount Dt of (3) and the addition amount It of (4) is 0.1.

  Thereafter, unadded (5) chemistat 7005 corresponding to 2/3 of the total amount was added, and then unadded (6) Leolosil QS-30 corresponding to 1/3 of the total amount was added evenly over 15 minutes. Added. Here, the liquid viscosity immediately after the addition was measured as shown in the following evaluation (measurement of liquid viscosity 1). (6) After completion of the addition of Leolosil QS-30, stirring was further performed for 120 minutes to prepare a silica dispersion of the present invention. Here, the liquid viscosity after stirring was measured as shown in the following evaluation (measurement of liquid viscosity 2). As described above, the final addition amount D of Chemistat 7005 (dispersing agent) is 150 g, the final addition amount I of Leoroseal QS-30 (silica fine particles) is 750 g, and the ratio D / I thereof is 0.2. It is.

[composition]
(1) Ion exchange water: 4644.00 g
(2) Boric acid (hardener) ... 30.49 g
(3) Chemistat 7005 (40% aqueous solution) 50.00 g
(Sanyo Chemical Industries, Ltd .; acrylic cationic polymer)
(4) Leoroseal QS-30 ... 500.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)
(5) Chemistat 7005 (40% aqueous solution) 100.00 g
(Sanyo Chemical Industries, Ltd .; acrylic cationic polymer)
(6) Leoroseal QS-30 ... 250.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)

-Measurement and evaluation of silica dispersion-
In the process of preparing the silica dispersion, the following measurements and evaluations were performed. The results of measurement and evaluation are shown in Table 1 below.
a) Measurement of liquid viscosity 1
The liquid viscosity (30 ° C.) immediately after the addition of Leolosil QS-30 (silica fine particles) to be the final addition amount I was measured using a B-type viscometer (manufactured by Toki Co., Ltd.). That is, a smaller liquid viscosity is effective in reducing energy consumption required for stirring.
b) Measurement of liquid viscosity 2
The liquid viscosity (30 ° C.) immediately after stirring for 120 minutes after the addition of Leolosil QS-30 (silica fine particles) to be the final addition amount I was measured using a B-type viscometer (manufactured by Toki Co., Ltd.). That is, a smaller liquid viscosity is effective in reducing energy consumption required for stirring.
c) Foaming of liquid The state of foaming during the addition of Leolosil QS-30 (silica fine particles) was evaluated silently according to the following criteria.
○: Although slightly recognized, the occurrence of foaming was suppressed approximately.
Δ: Some occurrence of foaming was observed.
X: A large amount of foaming was observed.

-Preparation of coating solution for ink receiving layer-
The silica dispersion obtained above was finely dispersed with Dynomil KDL-PILOT. The fine dispersion treatment is performed twice in a batch process while cooling with 5 ° C. cooling water under the conditions of a filling ratio of φ0.65 mm zirconia beads of 70%, a peripheral speed of 8 m / min, and a flow rate of 590 g / min. Was done. The silica dispersion thus obtained was stored at 30 ° C. for 24 hours, and then 95.7 g of ion-exchanged water was added to 986.5 g of this silica dispersion, and 430.8 g of the following (7) water-soluble resin aqueous solution ( 8) Surfactant 12.67g and (9) Surfactant 7.7g were mixed to prepare an ink-receiving layer coating solution.

(7) Water-soluble resin aqueous solution After mixing the following composition, the mixture was heated at 95 ° C for 180 minutes and cooled to 30 ° C to obtain a water-soluble resin aqueous solution.
・ Ion exchange water: 1367.17 g
・ Polyoxyethylene oleyl ether: 1.28g
(Emulgen 109P, manufactured by Kao Corporation; surfactant)
・ Diethylene glycol monobutyl ether ... 16.65g
・ Polyvinyl alcohol: 100.75g
(PVA124, manufactured by Kuraray Co., Ltd.)
・ Hydroxypropylcellulose: 5.67g
(HPC-SSL, Nippon Soda Co., Ltd.)
(8) Polyoxyethylene oleyl ether (Emulgen 109P, manufactured by Kao Corporation; surfactant)
(9) Megafuck F-1405 (10% solution)
(Dainippon Ink Chemical Co., Ltd .; fluorine surfactant)

-Preparation of inkjet recording sheet-
After the corona discharge treatment is applied to the front surface of the support, the obtained ink receiving layer coating solution is applied to the front surface of the support at a coating amount of 170 ml / m ^{2 using} an extrusion die coater. It was dried with a dryer at a temperature of 40 ° C. (wind speed 5 m / sec) until the solid content concentration of the coating layer reached 18%. During this time, the coating layer showed constant rate drying. Immediately after that, it was immersed in a basic solution (pH 9.6) having the following composition to deposit 20 g / m ² on the coating layer, and further dried at a temperature of 80 ° C. for 10 minutes. Thus, an inkjet recording sheet of the present invention provided with an ink receiving layer having a dry film thickness of 35 μm was obtained.

[Composition of basic solution]
・ Boric acid (crosslinking agent, 100%): 6.5 g
・ Ion exchange water: 723.5g
・ Basic mordant: 150g
(PAA-03 (20% aqueous solution); manufactured by Nittobo Co., Ltd.)
・ Surface pH adjuster (ammonium chloride, 100%): 1.0 g
・ Surface pH adjuster (p-toluenesulfonic acid, 100%) 18.0 g
・ Polyoxyethylene oleyl ether (2% solution)… 100.0g
(Emulgen 109P, manufactured by Kao Corporation; surfactant)
・ Megafuck F-1405 (100%) ... 2.0g
(Dainippon Ink Chemical Co., Ltd .; fluorine surfactant)

  As described above, the ink jet recording sheet obtained by using the silica dispersion having good dispersibility of the silica fine particles had a good surface shape in which no flaws were observed on the coated surface. Further, the image receiving sheet had high gloss and a high maximum density Dm at which a black density after ink jet recording was sufficiently obtained. By improving the dispersibility of the inorganic fine particles, it is possible to further reduce the diameter of the inorganic fine particles to be used, and to further improve the surface condition.

(Example 2)
In “Preparation of silica dispersion” in Example 1, addition of silica fine particles and a dispersant was performed as follows: (3) Addition amount Dt of Chemistat 7005 and (4) Addition amount It of Leoroseal QS-30 A silica dispersion was prepared in the same manner as in Example 1 except that the ratio Dt / It was changed to 0.15, and the same evaluation was performed. And an inkjet recording sheet were prepared. The results of measurement and evaluation are shown in Table 1 below.

-Preparation of silica dispersion-
Add (1) ion-exchanged water and (2) boric acid to a stainless steel pot with an inner diameter of 26 cm. Stir at a rotation speed of 1500 rpm using a dissolver (blade φ6 cm diameter) until uniformly dissolved, and finally add to this (3) Corresponding to 1/2 of the total amount to be added (3) Chemistat 7005 is added to set the rotational speed to 3500 rpm, and it corresponds to 2/3 of the total amount finally added (4) Leoroseal QS-30 for 5 minutes And evenly added. At this time, the ratio Dt / It is 0.15. Thereafter, unadded (5) chemistat 7005 corresponding to 1/2 of the total amount was added, and then unadded (6) Leolosil QS-30 corresponding to 1/3 of the total amount was added evenly over 15 minutes. Added. (6) After completion of the addition of Leolosil QS-30, stirring was further performed for 120 minutes to prepare a silica dispersion of the present invention. In the above, the liquid viscosity immediately after addition and the liquid viscosity after stirring were measured. The final addition amount D of Chemistat 7005 (dispersing agent) is 150 g, the final addition amount I of Leoroseal QS-30 (silica fine particles) is 750 g, and the ratio D / I is 0.2.

(1) Ion exchange water: 4644.00 g
(2) Boric acid (hardener) ... 30.49 g
(3) Chemistat 7005 (40% aqueous solution) ... 75.00 g
(Sanyo Chemical Industries, Ltd .; acrylic cationic polymer)
(4) Leoroseal QS-30 ... 500.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)
(5) Chemistat 7005 (40% aqueous solution) ... 75.00 g
(Sanyo Chemical Industries, Ltd .; acrylic cationic polymer)
(6) Leoroseal QS-30 ... 250.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)

  Further, the obtained ink jet recording sheet had a good surface shape in which no defects on the coated surface were observed. Further, the image receiving sheet was highly glossy and had a high Dm with which black density after ink jet recording was sufficiently obtained. With the improvement of the dispersibility of the inorganic fine particles, it is possible to further reduce the diameter and improve the surface state of the inorganic fine particles used.

(Example 3)
After preparing the dispersant mixture as described below, in Example 1 “-Preparation of silica dispersion”, the addition of the silica fine particles and the dispersant was performed using the dispersant mixture as described below. A silica dispersion was prepared in the same manner as in Example 1 except that the measurement was performed so that / It was 0.1. Further, the same evaluation was performed, and the preparation of the ink receiving layer coating liquid and the inkjet recording sheet were performed. Was made. The results of measurement and evaluation are shown in Table 1 below.

-Preparation of dispersant mixture-
Chemistat 7005 (40% aqueous solution, Sanyo Chemical Industries, Ltd .; acrylic cationic polymer) 525.00 g and Zircosol ZA-30 (Daiichi Rare Element Chemical Industries, Ltd .; zirconium ammonium carbonate [water-soluble metal salt]) 164.00 g was mixed to prepare a dispersant mixture.

-Preparation of silica dispersion-
Add (1) ion-exchanged water and (2) boric acid to a stainless steel pot with an inner diameter of 26 cm. Stir at a rotation speed of 1500 rpm using a dissolver (blade φ6 cm diameter) until uniformly dissolved, and finally add to this (3) Addition of the above dispersant mixture (chemistat 7005 amount is 50.00 g) to 3500 rpm, and finally corresponds to 2/3 amount of the total amount to be added (4) Reolosil QS-30 was added evenly over 5 minutes. At this time, the ratio Dt / It between the addition amount Dt of (3) and the addition amount It of (4) is 0.1. Thereafter, unadded (5) the above-mentioned dispersant mixed liquid corresponding to 2/3 of the total amount (chemistat 7005 amount is 100.00 g) is added, and then the unadded (6 ) Reolosil QS-30 was added evenly over 15 minutes. (6) After completion of the addition of Leolosil QS-30, stirring was further performed for 120 minutes to prepare a silica dispersion of the present invention. In the above, the liquid viscosity immediately after addition and the liquid viscosity after stirring (30 ° C.) were measured. The final addition amount D of Chemistat 7005 (dispersing agent) is 150 g (total amount of dispersing agent mixture 196.86 g), the final addition amount I of Leoroseal QS-30 (silica fine particles) is 750 g, and the ratio D / I is 0.2.

(1) Ion exchange water: 4447.65g
(2) Boric acid (hardener) ... 30.49 g
(3) The above dispersant mixture liquid: 65.62 g
(4) Leoroseal QS-30 ... 500.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)
(5) Mixture of the above dispersants ... 131.24 g
(6) Leoroseal QS-30 ... 250.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)

  Further, the obtained ink jet recording sheet had a good surface shape in which no defects on the coated surface were observed. Further, the image receiving sheet was highly glossy and had a high Dm with which black density after ink jet recording was sufficiently obtained. With the improvement of the dispersibility of the inorganic fine particles, it is possible to further reduce the diameter and improve the surface state of the inorganic fine particles used.

(Comparative Example 1)
In “Preparation of silica dispersion” in Example 1, addition of silica fine particles and a dispersant was performed as follows: (3) Addition amount Dt of Chemistat 7005 and (4) Addition amount It of Leoroseal QS-30 A silica dispersion was prepared and evaluated in the same manner as in Example 1 except that the ratio Dt / It was changed to 0.2 (= D / I). The results of measurement and evaluation are shown in Table 1 below. Also, an ink receiving layer coating solution was prepared in the same manner as in Example 1 to prepare an ink jet recording sheet.

-Preparation of silica dispersion-
Add (1) ion-exchanged water and (2) boric acid to a stainless steel pot with an inner diameter of 26 cm. Stir at a rotation speed of 1500 rpm using a dissolver (blade φ6 cm diameter) until uniformly dissolved, and finally add to this (3) Corresponding to 2/3 of the total amount to be added (3) Chemistat 7005 is added to set the rotational speed to 3500 rpm, and further equivalent to 2/3 of the total amount to be finally added (4) Leorosil QS-30 for 5 minutes And evenly added. At this time, the ratio Dt / It is 0.2. Thereafter, unadded (5) chemistat 7005 corresponding to 1/3 of the total amount was added, and then unadded (6) Leolosil QS-30 corresponding to 1/3 of the total amount was added evenly over 15 minutes. Added. (6) After completion of the addition of Leoroseal QS-30, the mixture was further stirred for 120 minutes to prepare a silica dispersion. In the above, the liquid viscosity immediately after addition and the liquid viscosity after stirring were measured. The ratio D / I is 0.2 as in the first embodiment.

(1) Ion exchange water: 4644.00 g
(2) Boric acid (hardener) ... 30.49 g
(3) Chemistat 7005 (40% aqueous solution) 100.00 g
(Sanyo Chemical Industries, Ltd .; acrylic cationic polymer)
(4) Leoroseal QS-30 ... 500.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)
(5) Chemistat 7005 (40% aqueous solution) 50.00g
(Sanyo Chemical Industries, Ltd .; acrylic cationic polymer)
(6) Leoroseal QS-30 ... 250.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)

(Comparative Example 2)
In “Preparation of silica dispersion liquid” in Example 1, the addition of the silica fine particles and the dispersant was added in the following manner without adding the dispersant in a divided manner as described below. A silica dispersion was prepared and evaluated in the same manner as in Example 1 except that the addition was performed. The results of measurement and evaluation are shown in Table 1 below. Also, an ink receiving layer coating solution was prepared in the same manner as in Example 1 to prepare an ink jet recording sheet.

-Preparation of silica dispersion-
(1) Ion-exchanged water and (2) boric acid are added to a stainless steel pot with an inner diameter of 26 cm, and stirred at a rotational speed of 1500 rpm using a dissolver (blade φ6 cm diameter) until uniformly dissolved, and then (3) chemistat. 7005 (total amount of final added amount) is added and the number of revolutions is set to 3500 rpm, and further corresponds to 2/3 of the final added amount. (4) Leorosil QS-30 is evenly distributed over 5 minutes Added. At this time, the ratio Dt / It is 0.3. Thereafter, the remaining (5) Leolosil QS-30 corresponding to 1/3 of the total amount was added uniformly over 15 minutes. (6) After completion of the addition of Leoroseal QS-30, the mixture was further stirred for 120 minutes to prepare a silica dispersion. In the above, the liquid viscosity immediately after addition and the liquid viscosity after stirring were measured. The ratio D / I is 0.2 as in the first embodiment.

(1) Ion exchange water: 4644.00 g
(2) Boric acid (hardener) ... 30.49 g
(3) Chemistat 7005 (40% aqueous solution): 150.00 g
(Sanyo Chemical Industries, Ltd .; acrylic cationic polymer)
(4) Leoroseal QS-30 ... 500.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)
(5) Leoroseal QS-30 ... 250.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)

(Comparative Example 3)
In Example 3, the addition of the silica fine particles and the dispersant mixed liquid in the preparation of the silica dispersion was added in the following manner before the addition of the silica fine particles without adding the dispersant mixed liquid separately, and then the silica fine particles were added. A silica dispersion was prepared and evaluated in the same manner as in Example 3 except that the addition was performed. The results of measurement and evaluation are shown in Table 1 below. Also, an ink receiving layer coating solution was prepared in the same manner as in Example 1 to prepare an ink jet recording sheet.

-Preparation of silica dispersion-
(1) Ion-exchanged water and (2) boric acid are added to a stainless steel pot with an inner diameter of 26 cm, and stirred at a rotational speed of 1500 rpm using a dissolver (blade φ6 cm diameter) until uniformly dissolved. Add the dispersant mixture (total amount of the total amount to be finally added; among them, Chemistat 7005 is 150 g), and after setting the rotation speed to 3500 rpm, it corresponds to 2/3 of the total amount finally added (4) Leolosil QS-30 was added evenly over 5 minutes. At this time, the ratio Dt / It is 0.3. Thereafter, the remaining (5) Leolosil QS-30 corresponding to 1/3 of the total amount was added uniformly over 15 minutes. (6) After completion of the addition of Leoroseal QS-30, the mixture was further stirred for 120 minutes to prepare a silica dispersion. In the above, the liquid viscosity immediately after addition and the liquid viscosity after stirring were measured. The ratio D / I is 0.2 as in the first embodiment.

(1) Ion exchange water: 4447.65g
(2) Boric acid (hardener) ... 30.49 g
(3) The above dispersant mixture liquid: 196.86 g
(4) Leoroseal QS-30 ... 500.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)
(5) Leoroseal QS-30 ... 250.00g
(Average primary particle diameter 7 nm, manufactured by Tokuyama Corporation; silica fine particles)

As shown in Table 1 above, the addition rate (Dt / It) of the dispersant and silica fine particles at the time of addition is less than the ratio (D / I) of the total amount of the dispersant and silica fine particles finally added In the examples in which the silica dispersion was prepared with an addition process as a condition, the viscosity of the preparation liquid could be drastically reduced, and the preparation could be easily performed while suppressing energy consumption. It was. Moreover, the occurrence of foaming during preparation could be suppressed to a small level. The surface properties of the ink receiving layer (application surface) were also good.
On the other hand, in the comparative example in which the ratio Dt / It was added under the addition conditions not lower than the ratio D / I, the increase in the liquid viscosity was large, inferior to the examples in terms of energy consumption, and the degree of foaming was also large. . Also, the surface properties of the ink receiving layer (application surface) were inferior to those of the examples.

FIG. 6 is a relationship diagram for explaining an addition condition in which an addition ratio Dt / It of the dispersant and inorganic fine particles at the time of dispersion is smaller than a ratio D / I of the dispersant and inorganic fine particles finally added.

Claims (8)

  In the aqueous medium, the ratio (Dt / It) of the addition amount Dt of the dispersant and the addition amount It of the inorganic fine particles is the ratio (D / I) of the final addition amount D of the dispersant and the final addition amount I of the inorganic fine particles. ) A method for producing an inorganic fine particle dispersion, comprising the step of adding the inorganic fine particles and the dispersant under a smaller addition condition to produce an inorganic fine particle dispersion.   The method for producing an inorganic fine particle dispersion according to claim 1, wherein the inorganic fine particles are silica fine particles.   The method for producing an inorganic fine particle dispersion according to claim 1, wherein the dispersant is a cationic polymer dispersant.   The method for producing an inorganic fine particle dispersion according to any one of claims 1 to 3, wherein the inorganic fine particle dispersion further contains a hardening agent.   The method for producing an inorganic fine particle dispersion according to any one of claims 1 to 4, wherein the inorganic fine particle dispersion further contains a water-soluble metal salt.   An inorganic fine particle dispersion obtained by the method for producing an inorganic fine particle dispersion according to any one of claims 1 to 5.   An image recording material formed by applying a coating liquid using the inorganic fine particle dispersion according to claim 6.   The image recording material according to claim 7, further comprising an ink receptive recording layer containing at least inorganic fine particles and a water-soluble resin on the support.

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