JP2009209025A - Composite fine particle, method for producing the same and inkjet recording body using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite fine particle for inkjet recording body which materializes quality at a high level required for an ink acceptance layer of silver salt photographic toned gloss inkjet recording body and excellent in productivity with small burden on installation when producing thereof. <P>SOLUTION: The composite particle comprises a composite of ultrafine particles having a coating layer including an amino group and a M-O-Si linkage, wherein M represents a ≥divalent metal atom, in at least a part of the surface of the core particle and an inorganic pigment. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to composite fine particles useful as a material for an ink receiving layer of a silver salt photographic glossy ink jet recording material, a method for producing the same, and an ink jet recording material using the same. More specifically, the composite fine particles of the present invention are easy to produce, and the ink jet recording material using the composite fine particles of the present invention for the ink receiving layer not only has excellent coating surface quality and image quality, but also has excellent ink fixing properties. Since it is excellent, it has a feature that there is little deterioration in image quality even when continuous printing is performed under high temperature and high humidity.

  Various output systems such as a wire dot recording system, a thermal coloring recording system, a melt thermal transfer recording system, a sublimation recording system, an electrophotographic system, and an ink jet recording system have been developed so far. Above all, the inkjet recording method is recognized as a recording method suitable for personal use because of the fact that plain paper can be used as a recording sheet, the running cost is low, and the hardware is compact and inexpensive. Has stretched to. With the widespread use of hardware, full-color, high-speed, and high-quality images have rapidly advanced, so output applications can be expanded from simple monochrome text output to digital image output that can replace silver halide photography. However, inevitably, the quality required for the recording paper side has become stricter.

  Among commercially available ink jet recording papers, the sales volume of glossy paper is rapidly increasing as a medium capable of outputting a silver salt photographic full color image in recent years. In the production of glossy paper, how to “get close to a silver salt photograph” is an important key, and not only “print image quality” but also “can maintain the obtained image quality for a long time” is required. With regard to “print image quality”, recording that enables further improvement within the scope of demands for improvement in ink absorption speed, which became more severe as the printing speed of printers increased, and restrictions on raw material costs due to lower prices for glossy paper Body material development is needed. Among them, “image light resistance and ozone resistance”, which was greatly inferior to silver salt photography, has been improved to some extent by recent improvements in ink, but the image fixability reproducibility and sharpness are still unclear. There are aspects that need improvement. Ink jet printer ink has dye or pigment dye dissolved or dispersed in a solvent. In order to sufficiently fix the dye after printing on the recording paper, it is necessary to remove the ink solvent by means such as vaporization. However, when trying to output a plurality of photographic images easily, glossy paper after printing will be in a state of being sequentially stacked (soon after the ink solvent is dried) on the printer's discharge tray. It is difficult to evaporate the solvent. If the ink solvent is confined in the recording paper, the dye that is not sufficiently fixed diffuses in the receiving layer as the ink solvent diffuses.Therefore, the sharpness of the printed image and blurring tend to occur. It is. In particular, a stronger ink fixing property is required in order to keep the skin color that is visually sensitive and the uniformity of the dark solid portion well even under severe output conditions.

  In order to obtain a vivid output image and retain it, a stable combination is required even when the ink solvent remains in a state that is highly reactive with the dye that is a dye or pigment contained in the ink. It is necessary to include a “cationic fixing agent” that can be formed in the inkjet recording medium on the receiving side. It is important that such a fixing agent can be quickly bonded and insolubilized when ink is printed. Currently, in many commercially available ink jet recording materials, a water-soluble cationic resin is generally used as the fixing agent. For example, as disclosed in JP-A-60-61887 (see Patent Document 1), polyallylamines that have long been known to have excellent ink fixing ability, and JP-A-2004-122769. A “water-soluble cationic resin containing a primary amine structure” such as a cationic resin containing a 5-membered ring amidine structure, which is disclosed in (Patent Document 2) and has good image storage stability of a dye ink, is suitable. However, recent high-quality ink for inkjet printers is a mixture made by combining multiple color components composed of various dyes or pigments with various structures, so it can fix a full-color image with a single fixing agent. It is a very difficult situation. Even if the fixing ability is improved simply by increasing the amount of the cationic resin, the effect cannot be expected so much, and there is a high possibility that the ink absorption, which is a capillary phenomenon, will be inhibited. Furthermore, these cationic resins are easy to absorb moisture and may move relatively easily in the ink receiving layer, and may be relatively deteriorated by changes in external environment and stimuli such as high temperature and high humidity, light and ozone. This is easy and may cause deterioration of image storability and blank sheet storability, so care must be taken when setting the addition amount. From the above background, development of fixing agents other than cationic resins has been desired.

  Representative examples of fixing agents other than the existing cationic resins include water-soluble compounds containing aluminum or elements of Group 4A of the periodic table described in JP-A-2000-309157 (see Patent Document 3). Aluminum oxide compounds, titanium and zirconium compounds are exemplified as suitable. However, if these are used alone as the fixing agent, the ink fixing ability is insufficient, and therefore the combined use of a cationic resin is being studied in order to obtain a clear image. However, in this case, deterioration of storage stability derived from the cationic resin is inevitable. In JP-A-4-7189 (see Patent Document 4), a zirconium oxychloride-based active inorganic polymer has been proposed as a zirconium compound, but this also failed to obtain a sufficient fixing ability by itself. .

  JP-A-2006-160539 (see Patent Document 5) and JP-A-2006-224432 (see Patent Document 6) propose silica fine particles coated with a transition metal oxide such as titanium or zirconium. However, they are intended to increase the gloss of the coating film due to the high refractive index of the transition metal oxide while maintaining the good ink absorbability obtained from the silica fine particles. A uniform oxide coating layer is obtained by hydrolyzing the transition metal oxide precursor such as metal acetylacetonate only on the silica surface layer where crystal water is present. Under these conditions, the highly reactive transition metal precursor is sufficiently hydrolyzed to form an oxide layer, and the cationic properties of titanium and zirconium are poor, so that the effect of improving the ink fixing ability cannot be obtained.

  In order to ensure the fixing ability while reducing the amount of the cationic resin used, Japanese Patent Application Laid-Open No. 2001-10209 (see Patent Document 7) proposes to use a silane coupling agent in combination with a cationic resin as a fixing agent. In particular, it is clearly stated that it is preferable to use a silane coupling agent having a cationic quaternary ammonium structure. The silane coupling agent itself is a material that has been used for a long time as a surface treatment agent for pigments used in ink jet recording materials, as described in JP-A No. 62-178384 (see Patent Document 8). When a cationic silane coupling agent is used as the fixing agent of the ink receiving layer, the cationic group is bonded or adsorbed to the surface of the pigment, which is the main component of the ink receiving layer, more strongly than the cationic resin, so that it can resist external stimuli. It is expected that the resistance is increased and the ink absorbability and the image storage stability are improved. However, even if this cationic silane coupling agent was used alone as an ink fixing agent, sufficient ink fixing ability could not be obtained, so the quality of the image tends to be inferior particularly in a high temperature and high humidity environment. there were.

  Japanese Unexamined Patent Publication No. 2006-110770 (see Patent Document 9) proposes a combination of a water-soluble polyvalent metal compound in order to compensate for the insufficient fixing ability of the cationic silane coupling agent. In the ink jet recording material shown here, an ink receiving layer containing silica fine particles pulverized and dispersed in the presence of a silane coupling agent as a main component contains a water-soluble polyvalent metal compound. The silane coupling agent has a cationic property, and the water-soluble polyvalent metal compound is preferably an aluminum compound or a zirconium compound, and the water-soluble polyvalent metal compound is preferably added immediately before coating. The As a result of this improvement, a certain degree of improvement in the ink fixing ability was confirmed as compared with the case where the cationic silane coupling agent was used alone, but the binding strength of the water-soluble polyvalent metal compound itself to the ink receiving layer was insufficient. Because of this, not only image water resistance was deteriorated, but also the glossiness of the paint film and the print density, which are the most important indicators of image quality deterioration in normal environments, were reduced, so further improvement is necessary. Met.

JP-A-60-61887 JP, 2004-122769, A Claim 1 JP, 2000-309157, A Claims 1 and 2. Japanese Patent Laid-Open No. 4-7189 JP, 2006-160539, A Claims 1 and 2 JP, 2006-224432, A Claims 1-3 JP, 2001-10209, A Claims 1 and 2 JP, 62-178384, A Claim 1 JP, 2006-110770, A Claims 1, 3, 4

  On the other hand, the present inventors examined a polymer having a Zr—O—Si bond obtained by polymerizing an amino group-containing silane coupling agent and a zirconium compound as a novel ink fixing agent capable of overcoming these drawbacks. The composite fine particles composed of this polymer and inorganic pigment have been confirmed to exhibit better ink fixing ability, but there is a step of redispersing the aqueous slurry aggregated by mixing the inorganic pigment and polymer in the production process. In this treatment, a high-speed slurry mixture that has passed through the orifice at a high pressure is preferably collided oppositely, or dispersed or pulverized by colliding with a fixed wall. However, these distributed facilities do not have a very high processing capacity per unit time, and diamonds are required in the central part to prevent wear inside the disperser, which has a large impact on productivity and facilities. The improvement was called for.

  The present invention provides a composite fine particle for an ink jet recording material that realizes the quality that the ink receiving layer of the above-described silver salt photographic glossy ink jet recording material should have at a high level, has good productivity, and has less burden on facilities. It is what. In addition, a preferred method for producing the composite fine particles and an ink jet recording material using the composite fine particles are disclosed.

  The present inventors proceeded to improve a cationic polymer in which an amino group-containing silane coupling agent and a zirconium compound were appropriately polymerized in advance in an aqueous solvent, and both were integrated via a Zr—O—Si bond. It was. When this polymer is used, a water-soluble polyvalent metal compound such as a zirconium compound can be combined with an inorganic pigment as it is, so that aggregation at the time of compounding is reduced, so that a coating with higher transparency can be obtained. Met. However, the improvement effect due to the use of this polymer is not always sufficient, and particularly when a high specific surface area gas phase method silica having a strong cohesive force is used as the inorganic pigment, the dispersion power is strong due to the redispersion treatment. However, it was essential to use a high-pressure disperser that was inferior in production efficiency. The present researchers estimated that the cause of this strong aggregation is that the particle size of the polymer, which can be regarded as ultrafine particles, is too small.

  Therefore, an attempt was made to reduce the energy required for the “redispersion process” that increases the particle size of the ultrafine particles to alleviate aggregation during compounding, resulting in deterioration of productivity and cost increase. However, if an attempt is made to extend the polymerization time or adjust the temperature or pH with the intention of promoting the polymerization of the amino group-containing silane coupling agent and the zirconium compound in order to simply increase the particle size, coloring due to alteration of the amino group may occur. , Because the hydrolysis of zirconium proceeds too much and the cation ratio having the ink fixing ability decreases, the ink fixing ability deteriorates, or the particle diameter of the resulting ultrafine particles varies, resulting in coating film defects on the ink jet recording body. Many problems occurred, such as the generation of coarse particles that could be the cause.

Next, we attempted to increase the particle size of the ultrafine particles exhibiting a cationic property by introducing particles serving as nuclei during the polymerization of the amino group-containing silane coupling agent and the zirconium compound. Ultrafine particles were obtained without generation of particles. This is presumably because the polymerization reaction by hydrolysis of the amino group-containing silane coupling agent and the zirconium compound proceeds promptly and uniformly on the surface of the core particles. In other words, this ultrafine particle is “covered at least a part of the core particle by a coating layer composed of a polymer containing an amino group and a M—O—Si bond (M represents a divalent or higher metal atom)”. It has a structure.
Since these ultrafine particles have core particles as nuclei, they are produced with a larger appropriate particle size. Therefore, as described above, gas phase method silica having a high cohesive force and high specific surface area is used as an inorganic pigment. Even in the case of complexing, it was possible to reduce the load required for redispersion of the resulting composite fine particles without causing excessive aggregation. The ink jet recording material using the composite fine particles showed excellent quality equivalent to the case where the core particles were not used. In this connection, the composite means that ultrafine particles are bonded to at least a part of the periphery of the inorganic pigment.

  Since the core particles used here are not expected to function as an ink fixing agent, they can be used regardless of their composition as long as they can hold a coating layer as an active ingredient. In addition, it is good even if a metal compound having a valence of 2 or more other than the starting zirconium compound is used as a raw material for the coating layer of the ultrafine particles, because the polymerization of the coating layer can proceed rapidly by the introduction of the core particles. A high quality ink jet recording material was obtained. In particular, when a zirconium compound, a titanium compound, an aluminum compound, or a zinc compound was used, an ink jet recording body with particularly excellent quality was obtained. However, the color of ink when forming an image differs slightly depending on the type of metal ion. Therefore, diversifying the types of metal ions that can be used is very preferable from the viewpoint of facilitating the adjustment of the color tone of an image, and other metal compounds are also effectively used.

  In addition, the present inventors also described the above “ultrafine particles comprising a coating layer containing amino groups and M—O—Si bonds (M represents a divalent or higher-valent metal atom) and core particles” and an inorganic pigment in an aqueous medium. When complexing, if a hydrophilic polymer capable of forming a chelate with the metal ion of M is present, the excessive hydrolysis of the M ion is suppressed, or the stability of the composite fine particle sol is improved, The present invention has been completed.

Accordingly, this application includes the following inventions:
(1) An inorganic pigment, a core layer and a polymer layer containing an amino group and M-O-Si bond (M represents a divalent or higher metal atom) covering at least a part of the surface of the core particle. Composite fine particles comprising ultrafine particles having the fine particles bonded to at least a part of the periphery of the inorganic pigment.
(2) A polymer containing an amino group and a M—O—Si bond (M represents a divalent or higher-valent metal atom) in the molecule, and a hydrophilic polymer capable of forming a chelate with the M ion. The composite fine particles according to (1), wherein at least some of them are coordinated with each other.
(3) In an aqueous solvent containing core particles, an amino group-containing silane coupling agent and a divalent or higher valent metal compound are polymerized to cover at least a part of the surface of the core particles and M-O Composite fine particles obtained by obtaining an aqueous dispersion of ultrafine particles having a polymer layer with a Si bond (M represents a divalent or higher-valent metal atom), and dispersing an inorganic pigment in the aqueous dispersion.
(4) The composite fine particle according to any one of (1) to (3), wherein the core particle is colloidal silica having a particle diameter of 4 to 30 nm.
(5) The composite microparticle according to (2) or (4), wherein the hydrophilic polymer capable of forming a chelate with the M ion is polyallylamine.
(6) The composite microparticle according to (2), (4) or (5), wherein the hydrophilic polymer capable of forming a chelate with the M ion has a weight average molecular weight of 5,000 to 50,000.
(7) The composite fine particles according to any one of (1) to (6), wherein the inorganic pigment is gas phase method silica having an average particle diameter of 1 μm or less.
(8) The composite particle according to any one of (1) to (7), wherein M is at least one metal atom selected from the group consisting of zirconium, aluminum, titanium, and zinc.
(9) The ultrafine particles are formed by polymerization of an amino group-containing silane coupling agent and a divalent or higher metal compound in an aqueous solvent containing core particles (1) The composite fine particle according to any one of to (8).
(10) The amino group-containing silane coupling agent includes 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, and N-2 (aminoethyl). The composite microparticle according to (9), which is at least one selected from the group consisting of 3-aminopropyltriethoxysilane or a hydrolyzate and polymer thereof.
(11) The composite fine particles according to (9) or (10), wherein the divalent or higher valent metal compound is at least one selected from a zirconium compound, an aluminum compound, a titanium compound, and a zinc compound.
(12) The solid content ratio of the inorganic pigment and the ultrafine particles is 2 to 20 parts by mass of the ultrafine particles with respect to 100 parts by mass of the inorganic pigment, according to any one of (1) to (11) Composite fine particles.
(13) The solid content ratio of the inorganic pigment, the ultrafine particles and the hydrophilic polymer is 2 to 20 parts by mass of the ultrafine particles and 0.5 to 5 parts by mass of the hydrophilic polymer with respect to 100 parts by mass of the inorganic pigment. The composite fine particles according to any one of (2) to (12), wherein
(14) An ink jet recording material comprising the composite fine particles according to any one of (1) to (13).
(15) In an aqueous solvent containing core particles, amino group-containing silane coupling agent and divalent or higher valent metal compound are polymerized to cover at least a part of the surface of the core particles and M-O An aqueous dispersion of ultrafine particles having a polymer layer containing a -Si bond (M represents a divalent or higher-valent metal atom) is obtained, and an inorganic pigment and, if necessary, dilution water are added to the aqueous dispersion to disperse And a composite fine particle production method, wherein the composite fine particles are combined.
(16) In an aqueous solvent containing core particles, an amino group-containing silane coupling agent and a divalent or higher-valent metal compound are polymerized to cover at least a part of the surface of the core particles and M-O An aqueous dispersion of ultrafine particles having a polymer layer containing a -Si bond (M represents a divalent or higher-valent metal atom) is obtained, and hydrophilicity capable of forming a chelate with the M ion in the aqueous dispersion A method for producing composite fine particles, comprising adding a polymer and an inorganic pigment, and dispersing and compositing.

  The composite microparticles of the present invention can be prepared with a relatively simple dispersion because the aggregation between the microparticles generated in the composite process during production is gentle. Therefore, productivity is also good, and there is little burden on the facility side during the production. The silver salt photographic glossy inkjet recording material using the composite fine particles of the present invention for the ink receiving layer not only has excellent coating surface quality and image quality, but also has excellent ink fixing properties, so it can be continuously printed at high temperature and high humidity. Even when this is performed, there is a feature that there is little deterioration in image quality.

(Preparation of composite fine particles)
The composite fine particle of the present invention is a nuclear particle comprising a polymer layer containing an amino group and a M—O—Si bond (M represents a divalent or higher-valent metal atom, preferably Zr, Al, Ti, Zn, etc.). The ultrafine particles having a structure in which at least a part, preferably all, of the surface is coated with an inorganic pigment, more preferably a hydrophilic polymer capable of forming a chelate with the M ion. The conditions and preparation methods for the ultrafine particles, the hydrophilic polymer, and the inorganic pigment that are the raw materials for the composite fine particles are shown below.

(Preparation of ultrafine particles composed of a coating layer containing amino groups and M-O-Si bonds and core particles)
“Ultra-fine particles composed of a coating layer containing an amino group and an M—O—Si bond (M represents a divalent or higher-valent metal atom, preferably Zr, Al, Ti, Zn, etc.) and a core particle for preparation and production of composite fine particles ”As long as a coating layer containing an amino group and a M—O—Si bond is formed on at least a part of the surface of the core particle, and each distribution state and preparation method are not particularly limited. An example of such a preparation method is a method in which an amino group-containing silane coupling agent and a hydrolyzable divalent or higher metal compound are polymerized in a solvent containing core particles. Further, in this polymerization, it is preferable from the viewpoint of the quality stability of the composite fine particles obtained when the “hydrophilic polymer capable of forming a chelate with the M ion” is coexistent, but this will be described later.

The core of the ultrafine particles only needs to be able to form a “coating layer containing an amino group and M—O—Si bond (M represents a divalent or higher-valent metal atom)” on at least a part of the surface. The material is not particularly limited as long as it is a material that can be firmly bonded to the coating layer. For example, various inorganic pigments described later can be used as the material of the ink receiving layer. Among these, in order to quickly form the coating layer, an anionic material that is easily bonded to the cationic coating layer or a material that can form a M-O-Si bond with the coating layer component by hydrolysis is preferable. . As a material that meets these requirements, colloidal silica can be exemplified as the most preferable core particle material. As the colloidal silica, commercially available chemical products (for example, manufactured by NISSAN CHEMICAL INDUSTRY CO., LTD .: Snowtex series, manufactured by Catalytic Chemical Industry Co., Ltd .: Cataloid series, etc.) may be used as they are. The core particles may be prepared by a technique, for example, a technique of adding an appropriate acid or aqueous alkali solution to an alkoxysilane dissolved in a solvent to cause hydrolysis. In order to avoid excessive aggregation when forming the coating layer, it is preferable to use a sol with good dispersibility (so-called monodisperse). In addition, if the particle size is too small, the effect of introducing the core particles cannot be obtained, and if it is too large, there is a possibility that the ink receiving layer of the ink jet recording body may have a surface layer defect or a decrease in transparency. The particle diameter is preferably 2 to 50 nm, and more preferably 4 to 30 nm. However, the optimum value varies depending on the type and formulation of the core particles and the coating layer, and is not limited thereto.
Here, the average particle size is a particle size (value obtained by cumulant method) measured by a dynamic light scattering method using a commercially available particle size measuring device. Since the above-mentioned fine particles have a very small particle diameter, it is preferable to use an apparatus having a measurable lower limit range of 1 nm or less in order to ensure measurement accuracy.

The amino group-containing silane coupling agent that is suitably used as a material for the ultrafine particle coating layer generates silanol groups by hydrolysis when dissolved in a solvent containing water, and some silanol groups are condensed to form Si. -O-Si bond is formed. At this time, if a divalent or higher-valent metal compound having hydrolyzability is present, a part of the silanol group is bonded to the metal ion of the metal compound through the M—O—Si bond. The silane coupling agent usually has 2 or 3 silanol-forming groups, and as a result of the progress of generation of Si—O—Si bonds and M—O—Si, a three-dimensional polymer, coating in the present invention A layer is generated.
The specific structure of the amino group-containing silane coupling agent is not particularly limited, but 3-aminopropyltrimethoxysilane (CAS number 4369-14-6), 3-aminopropyltriethoxysilane (CAS number 21142). -29-0), N-2 (aminoethyl) 3-aminopropyltrimethoxysilane (CAS number 1760-24-3), N-2 (aminoethyl) 3-aminopropyltriethoxysilane (CAS number 5089-72). -5), N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane (CAS number 3069-29-2), N-phenyl-3-aminopropyltrimethoxysilane (CAS number 3086-76-6), 3 -Triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, etc. Illustration can, Shin-Etsu Chemical Co., Ltd., GE Toshiba Silicone Co., Dow Corning Toray Co., Ltd. and the like, sold under the name of the silane coupling agent from the company. Among them, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, and N-2 (aminoethyl) 3-aminopropyltriethoxysilane are amino acids. Among the group-containing silane coupling agents, since the molecular weight per amino group is small, the cationic property is high, and since there are many alkoxyl groups that become silanol groups, the polymerization reactivity is high, and it is suitably used.

The amino group-containing silane coupling agent is preferably hydrolyzed in advance in order to convert the alkoxyl group into a silanol group. In the case where the silanol-forming group is a methoxy group, the hydrolysis rate is fast, so that the operation of hydrolysis in advance can be omitted. Hydrolysis can be performed by a conventionally known method, for example, a method of reacting with water in a solvent and adding a catalyst such as acid or alkali as necessary.
The solvent for the hydrolysis is not particularly limited as long as the silane coupling agent after hydrolysis can be uniformly dissolved, but water that is an essential component of the reaction is most preferable. If the concentration of the amino group-containing silane coupling agent at the time of hydrolysis is too low, the polymerization reaction with the metal compound will hardly proceed, and if it is too high, the amino group-containing silane coupling agent alone will not be allowed to react with the metal compound. Since excessive polymerization proceeds, it is preferably 1 to 50% by mass, more preferably 5 to 45% by mass, and most preferably 10 to 40% by mass. Moreover, when diluting an amino group containing silane coupling agent in a solvent in order to suppress generation | occurrence | production of the gel-like substance which is an excessive polymer, it is good to add it gradually in the state which stirred the solvent.

  When an acid is added at the time of hydrolysis, effects such as enhancing the stability of the silanol groups produced and suppressing excessive polymerization while promoting the hydrolysis reaction of the amino group-containing silane coupling agent can be expected. The acid may be added in advance to a solvent before the silane coupling agent is dropped, or may be mixed later into the solution after dropping. The type of acid is not particularly limited, but representative examples include hydrofluoric acid, hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, propionic acid, glycolic acid, lactic acid, oxalic acid, Citric acid, malic acid, phthalic acid, etc. can be exemplified. In addition, various kinds of inorganic acids, organics described in “Chemical Handbook Basic Edition, Revised 5th Edition (Chemical Society of Japan, published by Maruzen Co., Ltd.) Chapter 11” Acid can be used.

  Among various acids, a monovalent acid is preferably used because of a small increase in viscosity when forming composite fine particles prepared from ultrafine particles. Further, since the generation of coarse particles during preparation of the ultrafine particle dispersion is small and the particle size control is relatively easy, carboxylic acid is preferable, and among these, hydroxycarboxylic acid having a hydroxyl group is most preferably used. Specifically, it can be said that α-lactic acid and glycolic acid are optimum materials in terms of price and performance.

If the amino group-containing silane coupling agent is added dropwise or acid is added, heat of dilution or heat of reaction is generated, which may promote inappropriate polymerization between the silane coupling agents. Therefore, the liquid temperature of the solution is preferably controlled so as not to rise excessively. However, as long as the reactivity with the metal compound can be maintained, the polymerization of the amino group-containing silane coupling agents may be intentionally progressed to some extent.
As described above, an amino group-containing silane coupling agent solution is prepared, but instead of or mixed with, a commercially available hydrolysis solution of an amino group-containing silane coupling agent (for example, trade name: KBP- 90, manufactured by Shin-Etsu Chemical Co., Ltd .: 32% aqueous solution) or a polymer solution of an amino group-containing silane coupling agent (for example, Silaace S-330, Silaace S-320, manufactured by Chisso Corporation) or the like. good.

On the other hand, as a metal compound that can be used as a source of “M” that is a divalent or higher metal atom in the coating layer, any metal compound that is hydrolyzable or higher can be used without particular limitation. From the viewpoint of ink fixing ability, zirconium compounds, titanium compounds, aluminum compounds, and zinc compounds can be preferably used. In particular, a zirconium compound can be most suitably used.
Zirconium chloride (ZrCl ₄ ), zirconium oxychloride (ZrOCl ₂ · nH ₂ O), zirconium sulfate (Zr (SO ₄ ) ₂ · nH ₂ O), zirconium oxysulfate (ZrOSO ₄ · nH ₂ O) , Zirconium nitrate (Zr (NO ₃ ) ₄ .nH ₂ O), zirconium oxynitrate (ZrO (NO ₃ ) ₂ .nH ₂ O), zirconium diacetate (Zr (CH ₃ COO) ₂ ), zirconium tetraacetate (Zr) (CH ₃ COO) ₄ ), zirconium oxyacetate (ZrO (CH ₃ COO) ₂ ), zirconium carbonate ammonium ((NH ₄ ) ₂ ZrO (CO ₃ ) ₂ ), various zirconium salts, zirconium alkoxides, etc. Illustrated. However, among the zirconium compounds, zirconium alkoxides are very fast in hydrolysis and polymerization reaction, so the reaction is difficult to control. In particular, as the number of alkoxyl groups increases, coarse zirconium hydroxide precipitates due to rapid polymerization. Be careful because it tends to be easy to do. In view of solubility in water, which is the most preferable solvent, pH of the compound itself, cost, and the property of exhibiting cationic property that bears ink fixing ability when it is made into ultrafine particles, it has a unit of ZrO in the chemical formula. Zirconium salts, that is, oxyzirconium salts are preferred, and among them, zirconium oxychloride (also known as zirconyl chloride, zirconium oxide chloride) is most preferred. This zirconium oxychloride can be purchased, for example, from Daiichi Rare Element Chemical Co., Ltd. as product names: zirconium oxychloride, zircozole ZC, zircozole ZC-20.

Zirconium compounds are known to hydrolyze in solution to form polynuclear ions ("Inorganic Chemistry" by JD LEEE, Tokyo Kagaku Dojin, 1982, p. 321) and amino group-containing silanes. Prior to reacting with the coupling agent, the zirconium compound may be intentionally hydrolyzed to increase the content of polynuclear ions. Moreover, you may utilize the commercially available zirconium compound (For example, brand name: Zircosol ZC-2, the 1st rare element chemical industry company make) which raised content of a polynuclear ion.
Similar to the amino group-containing silane coupling agent, these are uniformly dissolved in an appropriate solvent and then used for preparation of ultrafine particles. The preferred solvent and concentration for dissolution are the same as those for the amino group-containing silane coupling agent.

On the other hand, aluminum compounds include aluminum chloride, tetrachloroaluminate (eg, sodium salt), aluminum bromide, tetrabromoaluminate (eg, potassium salt), aluminum iodide, aluminate (eg, Sodium salt, potassium salt, calcium salt, etc.), aluminum fluoride, hexafluoroaluminic acid (eg, potassium salt), aluminum sulfate, basic aluminum sulfate, potassium aluminum sulfate (alum), ammonium aluminum sulfate (ammonium alum), sulfuric acid Sodium aluminum, aluminum phosphate, aluminum nitrate, aluminum hydrogen phosphate, aluminum carbonate, polysulfuric acid aluminum silicate, aluminum formate, aluminum acetate, aluminum lactate, aluminum oxalate In addition to the various aluminum salts and the like, aluminum alkoxides and the like. Moreover, like a zirconium compound, the high molecular weight product (for example, the product made from Taki Chemical Co., Ltd., polyaluminum chloride: brand name PAC, highly basic aluminum chloride: Trade name tachyvine, highly basic aluminum lactate: trade name taxanelam, etc.) can also be preferably used.
Titanium compounds include titanium tetrachloride, titanium sulfate, basic titanium lactate, titanium lactate ammonium salt, various titanium salts, titanium alkoxides, etc., and zinc compounds include zinc chloride, zinc ammonium chloride, zinc sulfate, Various zinc salts such as zinc acetate, zinc nitrate, zinc pyrophosphate, zinc citrate, and zinc lactate are exemplified.
The above metal compounds may be used singly or in combination of two or more, and metal compounds other than the exemplified compounds may be used.

  The amino group-containing silane coupling agent solution prepared as described above and the metal compound solution are mixed and polymerized in the presence of the core particles to prepare the ultrafine particles of the present invention. When the solution pH when mixing the amino group-containing silane coupling agent solution and the metal compound solution is too high, coarse particles of the metal oxide that lead to deterioration of the quality of the ink jet recording material are likely to be precipitated. It is preferable to keep it acidic. Since the solution pH of the amino group-containing silane coupling agent is usually 7 or more, addition of an acid is also desired from the viewpoint of pH adjustment. Further, when the pH of the metal compound aqueous solution is also high, an acid may be added before mixing. As a method for adding the core particles, a method of sequentially adding an amino group-containing silane coupling agent solution and a metal compound solution in an aqueous medium containing the core particles in advance is not particularly limited, The amino group-containing silane coupling agent solution, the metal compound solution, or both may be mixed in advance.

  The average particle diameter of the ultrafine particles having the coating structure should naturally be larger by the “thickness of the coating layer × 2” than the diameter of the ultrafine particles used as the core particles, but occurs during the coating process. Since the particles aggregate due to the agglomeration, the particle diameter measured by dynamic light scattering often increases greatly. In this case, in order to confirm the thickness of the intended coating layer, after applying a high degree of dispersion treatment to the ultrafine particles after coating treatment, images are taken with a transmission electron microscope, and the particle size of each particle is measured by its projected area. Can be calculated by calculating the diameter when assuming a circle equal to the diameter of the untreated core particles, but in practice, even if ultrafine particles are associated to some extent at this point, Since it is dispersed and homogenized during the compounding step with the pigment, there is no problem. However, in order to obtain a higher dispersion state, the coated ultrafine particle dispersion may be subjected to a dispersion treatment using various dispersion equipments described later.

As described above, the average particle size of the ultrafine particles after the coating treatment is not particularly limited due to the influence of the association, but is preferably 3 to 500 nm, more preferably 10 to 300 nm, and further 20 to Most preferred is 200 nm.
If the average particle size is too large, not only will the print density decrease due to the glossiness or transparency of the ink-receiving layer, but also there is a risk of hindering the binding force with the inorganic pigment when making composite fine particles. is there. However, as long as the surface quality of the ink receiving layer is not affected, even if a small amount of coarse particles are mixed, the function as a fixing agent is not affected.

The particle size of the ultrafine particles after the coating treatment is most affected by the particle size of the core particles, but also varies depending on the type and ratio of the amino group-containing silane coupling agent and the metal compound as the raw material. It is possible to control to some extent by mixing order, pH, temperature and time, or stirring conditions.
The polymerization reaction is promoted at a higher solution temperature. However, the reactivity of the raw material is relatively high, and in order to increase the cationic property of the resulting ultrafine particles, it is necessary not to proceed excessively with hydrolysis of metal ions. For reasons such as being preferable, the polymerization reaction is preferably allowed to proceed under relatively mild conditions. Also, in order to avoid yellowing of the solution due to amino group modification, the reaction temperature should not be too high, and the reaction temperature is 5 to 90 ° C., except when it is desired to complete the polymerization in a short time. More preferably, it is 10-80 degreeC, Most preferably, 20-70 degreeC is good. In other words, if a certain amount of reaction time can be secured, the polymerization reaction can be allowed to proceed slowly even if the components are sufficiently mixed and then the mixture is kept at room temperature (aging) without any particular heating. it can. In particular, when using a material that has a high hydrolysis rate and is easy to react (for example, a methoxy-type amino group-containing silane coupling agent), depending on the formulation, a desired polymer may be obtained even if each material is mixed for several minutes at room temperature. Obtainable.
In addition, in order to suppress the formation of a coarse polymer, it is desirable to stir the solution during the polymerization reaction from the time of solution mixing. It is not necessary to always stir.

Confirmation of the M—O—Si bond generated by polymerization of the intended amino group-containing silane coupling agent and a divalent or higher-valent metal compound was carried out by measuring an infrared absorption spectrum.
Although the ratio varies depending on the type and ratio of the material, it is considered that Si—O—Si bonds, M—O—Si bonds, and M—O—M bonds are mixed in the coating layer. Usually, the infrared absorption spectrum of a compound having a Si—O—SI bond shifts to some extent when a cyclic structure is formed by condensation, but the stretching vibration of the Si—O—Si bond is around 1100 cm ^−1. Absorption from origin. If a divalent or higher-valent metal ion is introduced there, the cyclic structure is distorted, so that the absorption peak of the stretching vibration of the M—O—Si bond has a wavelength different from that of the Si—O—SiI bond (around 1000 cm ⁻¹ ). Appears in For example, in the reference document “Inorganic Polymer I” (supervised by Naruyuki Sugawara, published by Sangyo Tosho Co., Ltd. in 1992), Zr—O—Si bond of polyzirconosiloxane and Ti—O—Si bond of polytitanosiloxane. A peak at about 1000 cm ⁻¹ showing can be confirmed in the vicinity of the Si—O—Si bond peak.

  The mixing ratio of the amino group-containing silane coupling agent and the divalent or higher metal compound, which is a raw material for the coating layer containing an amino group and M-O-Si bond (M represents a divalent or higher metal atom), is Since it varies greatly depending on the type of component, specifically the number of amino groups and alkoxyl groups of the amino group-containing silane coupling agent, the type of metal compound, etc., there is no particular limitation. However, if the mixing ratio of the metal compound is too large, the image fixing ability tends to be deteriorated because it is difficult for the two to be combined. Also, if one of them is too small, the effect of using both is not obtained, which is not preferable. As a specific mixing ratio, taking a Zr compound as an example, it is preferable to mix 0.01 to 5 mol of Zr compound with respect to 1 mol of amino group-containing silane coupling agent, more preferably 0.1 to 1 mol. Are preferred.

  Similarly, the optimum value varies depending on the composition and formulation of the component and cannot be specified, but the coating layer material containing an amino group and M—O—Si bond (M represents a divalent or higher metal atom) and The ratio of the compound to the core particles is not preferable if the number of core particles is too small, and the effect of introduction is reduced, and if the amount is too large, a coating layer cannot be stably formed. As a specific mixing ratio, as a solid content ratio, the core particles are 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, and most preferably 100 parts by mass of the total amount of the compounds as raw materials for the coating layer. 20-30 mass parts is illustrated.

  In addition to the amino group-containing silane coupling agent, the divalent or higher-valent metal compound, and the acid, various materials may be used as necessary as the constituent component of the ultrafine particles. One example is a hydrophilic polymer capable of forming a chelate with the M ion shown below.

(Hydrophilic polymer that can form chelates with metal ions)
“Composite fine particles in which an ultrafine particle comprising a coating layer containing an amino group and a M—O—Si bond (M represents a metal atom having a valence of 2 or more) and a core particle and an inorganic pigment are combined” For example, a “hydrophilic polymer capable of forming a chelate with the M ion” may be introduced as necessary. The hydrophilic polymer has an effect of stably maintaining a high ink fixing ability by coordinating to M ions having an ink fixing effect contained in the ultrafine particles and suppressing excessive hydrolysis. When stability is important, it is preferable to add. Therefore, the timing of mixing for coordination to the ultrafine particles is preferably after the polymerization of the amino group-containing silane cup agent and the metal compound having a valence of 2 or more has proceeded appropriately. For example, the heating for promoting the polymerization is completed. If it is a prescription with relatively mild reactivity, it may be just before compounding with inorganic pigments, etc., but the optimum time varies depending on the composition and mixing ratio of ultrafine particles and hydrophilic polymer, so it is limited to this However, it may be mixed in the above-mentioned preparation step of the ultrafine particles.

  The hydrophilic polymer capable of forming a chelate with a metal ion only needs to contain a structure having electron donating groups at regular intervals that are easy to coordinate with the metal ion. As a specific example of the structure, β-diketone Structure, polyamine structure, iminodiacetic acid structure, sarcosine structure, ethanol amino acid structure, glycine structure, xanthogenic acid structure, amidoxime structure, amine structure, pyridine structure, imidazole structure, phosphonic acid structure, phosphinic acid structure, phosphoric acid structure, Schiff base structure , An oxime structure, a hydroxam structure, an aminopolycarboxylic acid structure, a thiol structure, a polythioalcohol structure, a 2-pyrrolidone structure, and a 2-oxazolidone structure, but are not limited thereto.

  The preferred molecular weight of the hydrophilic polymer varies depending on the composition and particle size of the hydrophilic polymer and the ultrafine particles to be coordinated, and is not particularly limited. However, if it is too low, it is difficult to maintain an appropriate chelate structure. If it is too much, the viscosity of the composite fine particle dispersion increases. Therefore, although not particularly limited, the weight average molecular weight is 1,000 to 400,000, more preferably 3000 to 100,000, and most preferably 5000 to 50,000.

  If this hydrophilic polymer capable of forming a chelate with a metal ion has a cationic group having ink fixing ability, an amino group derived from a silane coupling agent or an ink fixing component different from the cationic component of the metal ion may be used. Since it can introduce | transduce, it is very preferable. Normally, when a cationic resin is used as an ink fixing agent, it tends to cause a decrease in light resistance and ozone resistance, but when a cationic resin is added in a state of forming a chelate structure as described above, these qualities are not deteriorated, It has been found that only the ink fixing ability is improved. This is presumed to be because the movement of the cationic resin is restricted on the ultrafine particles incorporated in the composite fine particles due to chelate formation. Among them, polyallylamine and a copolymer containing the structure, or a derivative thereof can be suitably used.

  The ratio of the hydrophilic polymer to be coordinated with the ultrafine particles is not particularly limited because the optimum value varies depending on the type, but if the amount of the polymer to be coordinated is too small, the effect becomes insufficient, and if it is too large Since there is a possibility of inhibiting the ink fixing ability of the ultrafine particles, the polymer is 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, most preferably 20 to 30 parts by mass with respect to 100 parts of the ultrafine particles. A mass part is considered appropriate.

(Inorganic pigment)
As an inorganic pigment which is another material of the composite fine particles, those having an average particle diameter of 1 μm or less are preferable, and by using a fine pigment having a particle diameter of 500 nm or less, it is excellent in ink absorbability, transparency and gloss. An excellent receptor layer can be obtained, but is not limited thereto. Types are not limited, but commercially available pigments such as silica, aluminosilicate, kaolin, clay, calcined clay, zinc oxide, tin oxide, aluminum hydroxide, boehmite, pseudoboehmite, alumina, calcium carbonate, satin white, aluminum silicate, smectite, Various inorganic pigments known in the field of general coated paper or ink jet recording material, such as magnesium silicate, magnesium carbonate, magnesium oxide, and diatomaceous earth, can be used. Among these fine pigments, silica, aluminum hydroxide, boehmite, pseudoboehmite, and alumina are particularly suitable because they have a large pore volume and excellent ink absorbability.

  In order to obtain a highly glossy and highly transparent ink-receiving layer, as a fine pigment, primary particles having an average particle diameter of 3 to 40 nm aggregate to form secondary particles having an average particle diameter of 500 nm or less. Is preferably used. In particular, the particle diameter of the secondary particles is preferably 8 to 400 nm, more preferably 10 to 300 nm. Such secondary particles have a large pore volume because of voids inside the secondary particles. Furthermore, since the voids between the secondary particles can also be used for ink absorption, the ink absorption capability is high. In addition, since the primary particles are sufficiently smaller than the wavelength of light, there are advantages in that the light scattering ability is small and the transparency of the ink receiving layer is high as compared with pigments not forming secondary particles. If the primary particle size or the secondary particle size of the pigment is too small, it becomes difficult to form voids that contribute to ink absorption, so that the ink absorbability of the ink receiving layer may be inferior. On the other hand, if the primary particle size or the secondary particle size is too large, the transparency of the ink receiving layer is lowered, and it may be difficult to obtain a high print density. On the other hand, if the secondary particle size is too large, not only the gloss of the ink receiving layer is lowered, but also the surface may be roughened or the powder may fall off. In addition, all the primary particle diameters of the pigment as used in the field of this invention are the particle diameters (Martin diameter) observed with the electron microscope (SEM and TEM) (refer to "fine particle handbook", Asakura Shoten, p52). The secondary particle diameter is a particle diameter measured by a dynamic light scattering method.

  In order to obtain an ink-receiving layer having a high ink absorption capacity, the fine pigment preferably has a high pore volume, but the fine pigment suitably used in the present invention has a pore volume of 0.4-2. 5 ml / g. Preferably it is 0.4-2.0 ml / g, More preferably, it is 0.6-1.9 ml / g, Most preferably, it is 0.7-1.8 ml / g. The pore volume is a value obtained using a specific surface area / pore distribution measuring device by a gas adsorption method. In the present invention, the pore volume is the total pore volume of pores having a pore diameter of 100 nm or less.

  The method for producing these fine pigments is not particularly limited, and as one of the means, there is a method obtained by pulverizing and dispersing a commercially available pigment (several μm) by applying a strong force by mechanical means. That is, it can be obtained by the breaking down method (a method of subdividing the bulk material). Examples of the mechanical means include mechanical techniques such as a high-speed rotary homogenizer, a pressure homogenizer, an ultrasonic homogenizer, a roll mill, a ball mill, a vibration mill, a bead mill, a sand grinder, and a jet mill. The fine pigment obtained may be colloidal or slurry. Other preferable methods for producing fine pigments include hydrolysis by metal alkoxides disclosed in JP-A-5-32413 and JP-A-7-76161.

Among the inorganic pigments as described above, silica is particularly preferable because of its large pore volume. Silica includes wet-process silica using alkali silicate as a raw material, vapor-phase process silica produced by a dry process that decomposes volatile silicon compounds such as silicon tetrachloride in a flame, and mesoporous silica. Is also preferable. Vapor phase silica is a very bulky silica that can be easily made into an aqueous dispersion, and when used in an ink-receiving layer, has excellent ink absorbency, gloss, and coating transparency. Various products with different surface areas are commercially available. Therefore, gas phase method silica having an average particle diameter of 1 μm or less is most preferably used in the present invention. The average particle size of the aqueous dispersion varies depending on the method for producing the dispersion, but is in the range of about 100 nm to 900 nm. When the aqueous dispersion was dried to measure the specific surface area and pore volume by the nitrogen adsorption method is about a specific surface area of 50m ² / g~400m ² / g, a pore volume of 0.6ml / g~1.8ml / G.

The specific surface area by the "nitrogen adsorption method is described in JP 2001-354408 is at 300m ² / g~1000m ² / g, pore volume is 0.4ml / g~2.0ml / g A liquid in which silica particles are colloidally dispersed is used as a seed solution. After adding alkali to the seed solution, a feed solution consisting of at least one selected from an aqueous solution of active silicate and alkoxysilane is added to the seed solution little by little. to wherein the growing silica particles, specific surface area measured by the nitrogen adsorption method 100m ² / g~400m ² / g, average secondary particle diameter of 20 nm to 300 nm, and a pore volume of 0.5 ml / g Fine silica produced by the “method for producing a silica fine particle dispersion in which silica fine particles of up to 2.0 ml / g are colloidally dispersed” can also be preferably used.

The method based on the condensation of active silicic acid disclosed in JP-A-2001-354408 can directly produce fine silica having the above particle diameter and pore volume without using mechanical means, and has a particle size distribution. Since it is narrow, it becomes a coating layer with good transparency and gloss, so that it can be preferably used. Here, the activated silicic acid refers to an aqueous silicic acid solution having a pH of 4 or less obtained by ion exchange treatment of an aqueous alkali metal silicate solution with a hydrogen cation exchange resin, for example. Preferably 1-6 wt% as SiO ₂ concentration, aqueous active silicic acid is preferable and more preferably and 2-5% by weight pH 2 to 4. The alkali metal silicate may be a commercially available industrial product, and more preferably a sodium water glass having a SiO ₂ / M ₂ O (where M represents an alkali metal atom) molar ratio of about 2 to 4. It is preferable to use it. As a method for condensing active silicic acid, an aqueous solution of active silicic acid is added dropwise to hot water, or the aqueous solution of active silicic acid is heated to produce seed particles. Before the dispersion liquid precipitates or gels, an alkali is added. to stabilize the seed particles was added and then in terms of SiO ₂ with respect to SiO ₂ 1 mole contained the active silicic acid solution to the seed particle while maintaining the stable state from 0.001 to 0.2 mol / min It is preferable that each primary particle constituting the seed particle is grown by adding at a rate of 5%. The average secondary particle size is 1 μm or less, preferably 20 nm to 800 nm, and most preferably 30 nm to 700 nm. The average secondary particle diameter is a value measured by a particle size meter employing a dynamic light scattering method and analyzed by a cumulant method.

(Preparation method and conditions of composite fine particles)
An inorganic pigment is combined with an ultrafine particle composed of a coating layer containing an amino group and a M-O-Si bond and a core particle, and a hydrophilic polymer capable of forming a chelate with the M ion introduced as necessary. There are no particular restrictions on the means to be used, and the detailed conditions differ depending on the characteristics of each material. However, as a suitable example, a slurry obtained by mixing and thickening a mixture of components is mechanically dispersed and pulverized again. And a method of adjusting the secondary particle diameter of the aggregate to a desired particle diameter. Alternatively, a strong mechanical solution in an aqueous solvent containing a coating layer containing an amino group and an M—O—Si bond and ultrafine particles composed of core particles and, if necessary, a hydrophilic polymer capable of forming a chelate with M ions. This can also be achieved by gradually adding and dispersing inorganic pigment while giving a share. By passing through this means, ultrafine particles or ultrafine particles coordinated with a hydrophilic polymer are stabilized in a state of wrapping around the inorganic pigment, and a highly stabilized composite fine particle dispersion can be obtained. Bonds between ultrafine particles or ultrafine particles coordinated with a polymer and an inorganic pigment may be ionic bonds, hydrogen bonds, or covalent bonds, but regardless of the type of bond, the ultrafine particles or the ultrafine particles coordinated with the polymer are inorganic. If the pigment moves as a whole and the potential of the composite fine particle surface (zeta potential) is positive as a whole, the composite is achieved.
In order to sufficiently obtain this effect, if the amount of ultrafine particles or ultrafine particles coordinated with a hydrophilic polymer is too small relative to the inorganic pigment, the periphery of the inorganic pigment cannot be stably surrounded. There is a concern that the stability of the slurry and paint after conversion may be lowered. On the other hand, if the amount is too large, the ink absorptivity may be hindered or the quality such as light resistance and ozone resistance may be deteriorated. Specifically, the preferable amount of ultrafine particles with respect to 100 parts by mass of the inorganic pigment is 0.5 to 30 parts by mass, more preferably 2 to 20 parts by mass, most preferably 5 to 15 parts by mass, and further hydrophilic. In the case of introducing the functional polymer, the preferred amount is about 0.3 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and most preferably 1 to 3 parts by mass. Since the optimum amount varies depending on the type (composition), molecular weight, and shape of the pigment, ultrafine particles, and polymer, it is not limited to this range.

  The above-mentioned composite fine particles are greatly aggregated and thickened in the process of compositing, compared with the case where no core particles are used or when a general water-soluble polyvalent metal compound exemplified by a water-soluble zirconium salt is used. However, some aggregation / thickening occurs. In order to form a silver salt photographic glossy inkjet recording material, it is desirable to disperse and pulverize the agglomerated and thickened mixed slurry again to a mean secondary particle size of 1 μm or less by a mechanical method. However, since aggregation and thickening are alleviated, depending on the formulation, the desired degree of dispersion can be sufficiently achieved even with dispersion equipment such as a simple rotary homomixer with low dispersion power. However, for example, when using vapor phase silica having a high cohesive force and a high specific surface area, a pressure-type dispersion type dispersion facility having a strong dispersion force may be used. A preferred specific example of this method is a method of pulverizing by passing a narrow orifice under high pressure on a slurry mixture of raw materials, the treatment pressure is preferably 10 to 250 MPa, more preferably 20 to 200 MPa, More preferably, it is 30-100 Mpa, and it can disperse | distribute with a low pressure compared with the case where a nucleus particle is not used. By performing the above treatment, good dispersion or pulverization can be achieved. This type of device is called a high pressure homogenizer. Furthermore, it is more preferable to use a system in which a high-speed slurry mixture that has passed through the orifice at high pressure collides with each other or is dispersed or pulverized by colliding with a fixed wall. In the method of opposing collision, the dispersion is pressurized and guided to the inlet side, the dispersion is branched into two passages, the flow path is further narrowed by the orifice, the flow velocity is accelerated, and the opposing collision occurs, thereby causing the particles to collide. Disperse and crush by colliding. As a material constituting the portion where the dispersion is accelerated or collided, diamond is preferably used for the reason of suppressing wear of the material.

  As the high-pressure type homogenizer, a microfluidizer (manufactured by Microfluidics), an optimizer (manufactured by Sugino Machine Co., Ltd.), a homogenizer (manufactured by Sanwa Machine Co., Ltd.), and a nanomizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) are used. In particular, a microfluidizer and a nanomizer are preferable as the opposing collision type homogenizer. The composite fine particles thus subjected to the composite treatment are generally obtained as an aqueous dispersion (slurry or colloid) having a solid content concentration of 5 to 40% by mass, more preferably 10 to 30% by mass.

  The composite fine particles prepared as described above can be suitably used as a material for an ink receiving layer of an ink jet recording material. The ink jet recording material to which the composite fine particles are applied is shown below.

(Base material)
Various substrates can be used for the ink jet recording material containing the composite fine particles of the present invention as long as a coating layer serving as an ink receiving layer can be applied. For example, fine paper, art paper, coated paper, paperboard, cardboard, plastic film, non-woven fabric, metal foil, glass and the like can be exemplified. In particular, when a base material having air permeability of Oken type air permeability of less than 500 seconds / 100 ml is used, a so-called cast treatment can be performed in which the coating layer is dried by a glossy roll in which the outermost layer of the recording body is heated. Therefore, a highly glossy recording material can be obtained. In addition, the air-permeable base material has a relatively low specific gravity and is generally highly liquid-absorbing, and the base material is suitable in that it can contribute to ink absorption. Because of expansion, there is a side surface where wrinkles and unevenness are likely to occur. When troubles occur in this respect, it is effective to apply an undercoat layer or a back layer. Moreover, a low air permeability or a non-air-permeable base material can be used conveniently at the point which does not need to worry about these.

In the present invention, the low-permeability or non-permeability base material is such that the Oken type air permeability is 500 seconds / 100 ml or more, preferably 800 seconds / 100 ml or more, more preferably 1000 seconds / 100 ml or more. It means a substrate. When such a base material is used, it is possible to prevent the penetration of water vapor or moisture into the base material itself, and it is possible to easily obtain an ink jet recording material having a photographic texture with reduced cockling and the like.
The base material that can be used is, for example, a so-called resin-coated paper in which polyethylene resin is coated on both sides of a paper base material, YUPO (trade name: manufactured by YUPO Corporation), which has been subjected to special processing by stretching polypropylene. So-called synthetic paper, cellophane (registered trademark), polyethylene, polypropylene, soft polyvinyl chloride, hard polyvinyl chloride, polyester (such as PET), films such as polystyrene, metallized paper, papers with controlled air permeability, etc. Is mentioned. Of these, the use of resin-coated paper, synthetic paper, and film is preferred.

  In particular, a resin-coated paper obtained by coating polyethylene on which the titanium oxide is kneaded on the paper surface is preferably used because the finished appearance is equivalent to that of a photographic printing paper. 3-50 micrometers is preferable and, as for the thickness of a polyethylene coating layer, 5-30 micrometers is more preferable. When the thickness of the polyethylene coating layer is less than 3 μm, defects such as holes in the polyethylene resin tend to increase during resin coating, and there are many cases where it is difficult to control the thickness, and smoothness is difficult to obtain. Conversely, if it exceeds 50 μm, the effect obtained is small and uneconomical for an increase in cost. In order to enhance the adhesion of an undercoat layer or ink receiving layer described later, it is preferable to subject the surface of the coating layer to corona discharge treatment or to provide a subcoat layer such as gelatin.

  As the paper base material used for the resin-coated paper, a paper base manufactured using wood pulp as a main material is used. As the wood pulp, various chemical pulps, mechanical pulps, regenerated pulps and the like can be used as appropriate, and these pulps can be adjusted in the beating degree by a beating machine in order to adjust paper strength, smoothness, papermaking suitability, and the like. The beating degree is not particularly limited, but generally about 250 to 550 ml (CSF: JIS-P-8121) is a preferable range. Also, chlorine-free pulp such as so-called ECF and TCF pulp can be preferably used. Moreover, a pigment can be added as needed. As the pigment, talc, calcium carbonate, clay, kaolin, calcined kaolin, silica, zeolite and the like are preferably used. Opacity and smoothness can be increased by adding a pigment, but if added excessively, paper strength may be reduced, and the amount of pigment added is preferably about 1 to 20% by mass with respect to wood pulp.

  Moreover, if a plastic film with excellent transparency such as polyethylene terephthalate, polyvinyl chloride, polycarbonate, polyimide, cellulose triacetate, cellulose diacetate, polyethylene, polypropylene is used as the base material, light transmission of back prints, OHP sheets, etc. An ink jet recording material that can be used as a recording medium can be produced. Since the ink receiving layer obtained in the present invention is highly transparent, it can be suitably used for these media.

The thickness of the substrate is preferably 50 to 500 μm in consideration of the paper passing property of the printer. In particular, in the case of a water-absorbing substrate, if the substrate is too thin, there is a concern that the strength and dimensional stability when wet are reduced, so a relatively thick 100 to 500 μm is desirable.
Further, a back layer can be provided on the side of the substrate opposite to the ink receiving layer in order to suppress curling of the ink jet recording material and to improve the transportability. In particular, when a base material having high air permeability or high water absorption is used, it is desirable to coat the back layer in order to make the hand feeling closer to the silver salt photograph. The composition of the back surface layer and the easy adhesion treatment of the back surface of the base material sheet accompanying it can be selected according to the application, and are not particularly limited. However, in view of coating properties and cost, the pigment and the hydrophilic resin It is preferable to provide a back surface layer containing as a main component. However, if the water absorption of the back layer is too high, it is not preferable because the recording medium laminated after printing is stuck or sticky. Moreover, the base material which provided the resin coating of the resin coating paper only on the back surface side instead of a back surface layer is used suitably.
Furthermore, assuming double-sided printing, a coating layer including an ink-receiving layer may be provided on both sides, and the back surface may be subjected to adhesive processing so as to correspond to a label or seal application.

(Formation of undercoat layer)
In the ink jet recording material containing the composite fine particles of the present invention, an undercoat layer containing a pigment and a binder may be formed between the substrate and the ink receiving layer. The undercoat layer can be provided with functions such as correcting the dimensional stability, smoothness, and color tone of the substrate, and quickly absorbing the solvent in the inkjet ink component. A colorant, that is, a dye in the ink-jet ink component that could not be fixed by the ink receiving layer may be fixed. In particular, when a water-absorbing substrate is used, it is desirable to coat an undercoat layer from the viewpoint of wet strength and dimensional stability as described above.

  Examples of the pigment used for the undercoat layer include transparent or white pigments such as colloidal silica, amorphous silica, alumina, aluminum hydroxide, magnesium carbonate, calcium carbonate, kaolin, and calcined kaolin. Pigments used in the ink receiving layer and the gloss layer such as composite fine particles of the present invention described later can also be used. Of these, an especially preferred pigment is amorphous silica.

  When amorphous silica is used, the amorphous silica preferably has an average primary particle diameter of 3 to 70 nm and an average secondary particle diameter of 20 μm or less, an average primary particle diameter of 10 to 40 nm, and an average of 2 Those having a secondary particle size of 15 μm or less are more preferred. The average secondary particle diameter of the amorphous silica used for the undercoat layer is preferably larger than the average secondary particle diameter of the amorphous silica used for the ink receiving layer. When the average secondary particle diameter of the amorphous silica used for the undercoat layer is smaller than the average secondary particle diameter of the amorphous silica used for the ink receiving layer, the ink absorbability may be lowered.

The binder resin for the undercoat layer includes proteins such as casein, gelatin and soybean protein, various starches such as starch, oxidized starch and processed starch, and modified polyvinyl alcohols such as polyvinyl alcohol, cationic polyvinyl alcohol and silyl-modified polyvinyl alcohol. Polyvinyl alcohols containing, cellulose derivatives such as carboxymethyl cellulose and methyl cellulose, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, acrylic polymer latex, ethylene-vinyl acetate copolymer, etc. Conventionally known binders generally used for coated paper, such as vinyl polymer latex, are used singly or in combination of several kinds.
The blending ratio of the pigment and binder in the undercoat layer is generally adjusted in the range of 1 to 100 parts by weight, preferably 2 to 50 parts by weight with respect to 100 parts by weight of the pigment.

  A cationic compound that is an ink fixing agent is added to the undercoat layer as necessary in order to catch ink penetrating from the ink receiving layer, fix the dye, impart water resistance, and improve the recording density. be able to.

Examples of the cationic compound to be added include the “ultrafine particle comprising a coating layer containing an amino group and a M—O—Si bond (M represents a divalent or higher-valent metal atom) and a core particle” of the present invention. A cationic resin may be used. However, as described above, since the cationic resin may impair image storage stability other than fixing, it is desirable to suppress the amount used.
Polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, (meth) acrylate polymers having primary to tertiary amino groups and quaternary ammonium groups, primary to tertiary amino groups and quaternary ammonium (Meth) acrylamide derivative polymer having a group, vinylamine polymer or derivative thereof, allylamine polymer or derivative thereof, diallylamine polymer, diallylmethylamine polymer, diallyldimethylammonium chloride polymer, diallylamine-sulfur dioxide copolymer, Representative examples include diallyldimethylammonium chloride-sulfur dioxide copolymer, acrylamide-diallylamine copolymer, acrylamide-diallyldimethylammonium chloride copolymer, and dicyandiamide-formalin polycondensate. Cations such as dicyanic cation resin, polyamine cation resin represented by dicyandiamide-diethylenetriamine polycondensate, epichlorohydrin-dimethylamine addition polymer, hydrolyzate of acrylonitrile and N-vinylformamide copolymer, polyvinylamidine resin, etc. Resin can be illustrated and you may use individually or in combination of several types.
From the viewpoint of ink fixing ability, a polymer containing a 5-membered ring amidine structure such as the aforementioned polyallylamine (PAA-15C manufactured by Nittobo Co., Ltd.), Himax SC-700M manufactured by Hymo Co., Ltd., or polyvinylamine. Is preferred.

  In addition to the above components, the coating liquid for forming the undercoat layer further includes a dispersant, a thickener, an antifoaming agent, an antistatic agent, an antiseptic, a fluorescent dye used in the production of general coated paper. Various auxiliary agents such as a colorant are appropriately added.

The coating amount of the undercoat layer is about 0.5 to 30 g / m ² and can be formed by various known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a die coater, and a curtain coater. . In particular, the air knife coater is preferably used because it can deal with a wide range of paint properties and coating amounts. In addition, a die coater and a curtain coater are excellent in uniformity of coating amount, and are therefore preferable coating methods particularly for glossy ink jet recording materials for the purpose of high-definition recording.

(Formation of ink receiving layer)
The composite fine particles of the present invention may be used for the above-mentioned undercoat layer, but the performance can be maximized by using it as a main component of the porous ink receiving layer which is essential for ink absorption and fixing in the ink jet recording medium. Demonstrate to the limit.
The other materials for forming the porous ink receiving layer are shown below.

  The porous ink receiving layer includes a fine pigment and a binder resin required for film formation as essential components. Examples of the fine pigment include the composite fine particles of the present invention, inorganic pigments exemplified as raw materials for the composite fine particles, organic pigments such as styrene-based plastic pigments, urea resin-based plastic pigments, and benzoguanamine-based plastic pigments, and general coated papers or Various pigments known in the field of ink jet recording materials can be used alone or in combination. However, it is most desirable to use the composite fine particles alone from the viewpoint of coating stability, and even when other pigments are mixed, the addition amount is in a range that does not interfere with the quality of the composite fine particles. In addition, various pigments may be pretreated before preparing the paint.

  The binder resin component of the ink receiving layer of the ink jet recording material of the present invention is not particularly limited, but various resins exemplified as the material for the undercoat layer may be used alone or in combination.

  Among these, polyvinyl alcohol or a derivative thereof is most preferably used from the viewpoints of miscibility with the pigment as the main component, coating suitability, and quality of the obtained ink jet recording material. The degree of saponification is not particularly limited and can be appropriately used in the range of 70 to 99.9 mol%. However, if the degree of saponification is too low, the hydrophilicity is lowered, and if too high, there is a possibility of fibrillation, etc. Preferably it is 75-99.9%, More preferably, it is 78-99.8%. Also, the polymerization degree can be suitably used at 200 to 4500, but if it is too low, the paint viscosity may be too low or cracks may not be suppressed, and if it is too high, the paint viscosity will be too high. Therefore, Preferably it is 1000 or more, More preferably, it is 1000-4500.

  In order to change the color tone with time after printing, it is also effective to use a resin having a high affinity with the hydrophilic high-boiling solvent contained in the ink alone or in combination. The hydrophilic high-boiling solvents contained in the ink include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, diethylene glycol monomethyl ether, 2-pyrrolidone, thiodiglycol, triethylene glycol mono Examples of resins having high affinity with these solvents include butyl ether, 1,5-pentanediol, etc., but include, but are not limited to, polyvinylpyrrolidone, polyacryloylmorpholine, polyhydroxyalkyl acrylate, and hydroxypropylcellulose. Is not to be done.

  Since the composite fine particles used in the present invention have a high ink fixing ability, it is basically unnecessary to use another ink fixing agent in combination. However, water-soluble cationic resins exemplified as undercoat layer materials, emulsion-type cationic resins, and many kinds of cationic compounds are used as long as they do not impede the performance of the composite fine particles with intentions other than fixing ability such as color tone adjustment. From various cationic inorganic salts such as a valent metal salt compound, etc., one or a combination of several kinds may be added as required. However, in this case, the amount of the cationic compound to be added is the minimum amount, and the addition means is to multilayer the ink receiving layer or laminate the ink fixing agent separately in order to suppress the opacification of the coating layer to the maximum. A configuration such as coating is desirable.

  The ink receiving layer in the ink jet recording material of the present invention is preferably adjusted to be porous, specifically, the pore volume is in the range of 0.2 to 2.0 ml / g. It can be adjusted within this range by selecting the pore volume of the fine pigment and by appropriately adjusting the amount of the hydrophilic resin added. When the pore volume is less than 0.2 ml / g, the ink cannot be absorbed unless the coating amount is increased, so that the manufacturing cost of the ink jet recording body is increased. On the other hand, a pore volume exceeding 2.0 ml / g is not preferable because the mechanical strength of the ink receiving layer is lowered, and the ink receiving layer is easily scratched, peeled off or cracked. The pore volume of the present invention is the total pore volume of pores having a pore diameter of 100 nm or less.

  The suitable solid content concentration of the water-based paint used in the present invention varies greatly depending on the paint composition, but it is preferably a higher concentration within a range where the water-based paint can be stably and coated. This is because the higher the concentration of the water-based paint, the lighter the drying load. The solid content concentration of the water-based paint is preferably 3 to 40% by mass, more preferably 5 to 25% by mass.

  In addition to the main component, without significantly deteriorating the coating properties of the water-based paint, while maintaining the pores necessary for ink absorption, within the range that does not significantly reduce the water resistance of the ink receiving layer, Other components can also be added to the ink receiving layer. Examples thereof include fluorescent whitening agents that have the effect of increasing the whiteness of ink jet recording materials and boron compounds such as boric acid and / or borates that have the effect of suppressing cracks in porous receptor layers that are prone to cracking. .

Examples of boric acid include orthoboric acid, metaboric acid, hypoboric acid, tetraboric acid, and pentaboric acid. Moreover, these sodium salt, potassium salt, and ammonium salt may be sufficient. Among these, orthoboric acid and disodium tetraborate are preferable. The sodium salt of boric acid is often called borax, but its composition is usually Na ₂ B ₄ O ₇ .10H ₂ O.

  The addition means is not only pre-added in advance to the water-based paint as described above, but also can be applied to the substrate or the undercoat layer before applying the ink receiving layer, or the ink receiving surface can be applied as long as the coated surface is not disturbed. You may laminate | stack on the water-based paint application layer before drying after application | coating of a layer, It does not specifically limit to these. In terms of uniform mixing, a method of internally adding to a water-based paint is preferable. When the boron compound is added by a method other than the internal addition to the water-based paint, the boron compound is internally added to the undercoat layer for the purpose of diffusion to the ink receiving layer, or the solution containing the boron compound and the ink receiving layer Alternatively, the aqueous paint may be laminated and applied by wet-on-wet, or a solution containing a boron compound may be laminated and applied to the aqueous paint using a technique such as lamination and spraying. The type of the solvent for dissolving the boron compound is not particularly limited, but water is most preferable from the viewpoints of cost and handling.

  Further, a surfactant may be blended in order to improve workability during coating by mixing an antifoaming agent, or to improve the wettability of the substrate and obtain a uniform ink receiving layer. High pore volume fine pigment-based paints suitably used in the present invention tend to increase viscosity with time and increase thixotropy and often have poor coating suitability. In that case, it is preferable to add a certain amount of a surfactant to the coating because the coating suitability is improved. The addition amount is not particularly specified, but 0.001 to 5 parts by mass, and more preferably 0.01 to 1 part by mass is preferable with respect to 100 parts by mass of the fine pigment that is the main component of the paint. If the addition amount of the surfactant is too small, the above-mentioned paint appropriateness improving effect cannot be obtained sufficiently, which is inappropriate. On the other hand, if the amount added is too large, problems such as blocking and transfer to the back surface caused by the excessive amount of surfactant oozing out from the coated film become unsuitable.

The surfactant to be added may be any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant.
Examples of anionic surfactants include sulfate ester salts, sulfonate salts, phosphate ester salts, and the like. Examples of the cationic surfactant include amine salt type and quaternary ammonium salt type. Nonionic surfactants include, for example, acetylene glycols, polyethylene glycols (higher alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, alkylphenol ethylene oxide adducts, polypropylene glycol ethylene oxide adducts, higher aliphatic amines and fatty acids. Amide ethylene oxide adducts), polyhydric alcohols (fatty acid esters of glycerin and pentaerythritol, fatty acid esters of sorbitol and sorbitan, fatty acid esters of sucrose, ethylene oxide adducts of polyhydric alcohols, fatty acid alkanolamides, etc.) Can be mentioned.

  Among the above surfactants, nonionic surfactants are preferred because of their high affinity with ink for ink jet printers. Furthermore, among nonionic surfactants, acetylene glycol surfactants are preferred. The acetylene glycol-based surfactant is nonionic and has a very strong polarity because oxygen atoms are bonded to adjacent carbon atoms that form an acetylenic triple bond in the molecule. Therefore, even when added in a small amount, the surface activity effect is high, and the wettability of the aqueous coating liquid with respect to the support can be improved. In general, a surfactant has a strong bubble forming property, which causes a problem of foaming. However, an acetylene glycol surfactant has a defoaming property and can suppress foaming. Among these, an addition reaction product of an alkynylene glycol compound and ethylene oxide is preferable.

  In addition, various additives may be added for the purpose of improving the quality of the ink jet recording material. Specifically, coloring dyes or pigments for color tone preparation, image preservability improving agents such as light stabilizers and ultraviolet absorbers, and the like are not limited thereto. In particular, it is preferable to add a blue color pigment to the water-based paint as a color tone adjusting agent together with the fluorescent whitening agent, because the whiteness of the recording medium is visually enhanced by a synergistic effect.

  As a method for adding these additives, they may be mixed in advance with the composite fine particle sol, or may be mixed during the preparation of the paint. Moreover, after forming a coating layer first, you may add the solution containing an additive later by methods, such as top-coating, spraying, and impregnating with a well-known coating means.

  As a coating method of the water-based paint used as the ink receiving layer, the above-described known coating apparatus, for example, bar coater, roll coater, blade coater, air knife coater, gravure coater, die coater, curtain coater, etc. can be used. It is not restricted to these. Moreover, you may implement multilayer coating using simultaneous multilayer coating apparatuses, such as a multilayer slot die coater, a multilayer slide die coater, a multilayer curtain coater.

The coating amount is preferably about 1~60g / m ² as the mass after drying, more preferably about 3 to 50 g / m ^2. If the amount is less than 1 g / m ² , ink absorption tends to be insufficient, and if it is more than 60 g / m ² , curling tends to occur and the cost increases, which is not preferable. Two or more ink receiving layers may be formed. When it has two or more layers, the color scheme may be different.

  In addition, the active energy ray-curable material is mixed in advance with the coating layer to be the ink receiving layer, and the coating layer is gelated by irradiating the active energy ray to the coating layer before drying, You may suppress the crack of the coating layer which is easy to produce. The active energy ray to be used is not particularly limited, and examples thereof include α rays, β rays, γ rays, X rays, ultraviolet rays, and electron beams. However, it is preferable to use ultraviolet rays and electron beams which are easy to handle and are widely used. For ultraviolet rays, it is necessary to use a photopolymerization initiator or a specific hydrophilic resin having an active group, but it is preferable that the irradiation equipment is inexpensive. Alternatively, an electron beam that can form a hydrogel with many of general-purpose hydrophilic resins as described above can be most suitably used without adding an initiator or the like to the water-based paint. In addition, when an air-permeable substrate is used, the ink receiving layer can be subjected to a casting process in which the ink receiving layer is pressed against a heated gloss roll and dried while the ink receiving layer is in a wet state.

(Glossy layer formation)
The ink jet recording material of the present invention may form a gloss layer containing a fine pigment as a main component, if necessary. In the case where the cost is important or the gloss sufficient for the application is obtained, it is not necessary to form the gloss layer. However, in the case of photographic printing, it is preferable to coat a glossy layer. The glossy layer may be formed during the drying of the porous ink receiving layer or after the drying. Further, simultaneous multilayer coating with the ink receiving layer may be performed.

  The coating liquid for glossy layer contains arbitrary other components such as a fine pigment, a binder resin, and a cationic compound. The coating solution for forming the gloss layer is prepared by dispersing these components in a dispersion medium.

  Examples of the fine pigment used in the gloss layer include colloidal silica, amorphous silica, alumina, boehmite, aluminum hydroxide, magnesium carbonate, calcium carbonate, kaolin, calcined kaolin, and other transparent or white pigments. It is not limited and organic pigments can also be used. The composite fine particles of the present invention may be used. Among these, colloidal silica, alumina, or amorphous silica is preferable because glossiness is particularly improved. When using colloidal silica or alumina, the average primary particle size is preferably 5 to 100 nm, more preferably 10 to 80 nm. More preferably, it is 20-70 nm. When the average particle diameter is less than 5 nm, the ink absorbability may be reduced, and when the average particle diameter exceeds 100 nm, the transparency tends to decrease and the print density tends to decrease.

  When amorphous silica is used, one having an average primary particle diameter of 5 to 100 nm, more preferably 5 to 40 nm is used. Amorphous silica preferably has an average secondary particle diameter of 1 μm or less, more preferably 10 to 700 nm.

When the binder resin component is added to enhance the adhesion of the fine pigment, the type is not particularly limited, but the above-mentioned various water-soluble resins and emulsion type hydrophilic resins are preferably used. When using an emulsion type hydrophilic resin, the average particle size is preferably in the range of 20 to 150 nm. If the average particle size is less than 20 nm, the ink absorbency may be reduced, and if it exceeds 150 nm, the glossiness is reduced. There is a case. These glass transition temperatures are preferably in the range of 50 to 150 ° C. When the glass transition temperature is lower than 50 ° C., the gloss layer is excessively formed at the time of drying, and the porosity of the gloss layer is lowered and the ink absorbability may be lowered. When the temperature is higher than 150 ° C., film formation is insufficient, and gloss and strength may be insufficient.
In addition to the above, the gloss layer includes various dispersants and thickeners used in the production of organic and inorganic coarse particles and generally coated paper to prevent paper feeding suitability and blocking. Various auxiliary agents such as an antifoaming agent, a colorant, an antistatic agent, an antiseptic and a preservative may be added as appropriate.

The coating amount of the glossy layer is preferably 0.01 to 10 g / m ² as dry mass, more preferably 0.1-5 g / m ^2, more preferably 0.3 to 3 g / m ^2. When the coating amount is less than 0.01 g / m ² , it is advantageous for ink absorbability and recording density, but it is difficult to form a sufficient gloss layer, so that the glossiness tends to be low. On the other hand, when the coating amount exceeds 10 g / m ² , glossiness can be easily obtained, but ink absorbability and recording density tend to be lowered. The thickness of the gloss layer varies greatly depending on the pore state of the ink receiving layer. Therefore, it is difficult to unconditionally define the thickness of the gloss layer, but it is preferably 5 nm to 5 μm, more preferably 10 nm to 3 μm, and most preferably 20 nm to 1 μm. In order to obtain a sufficient gloss on the surface of the coating layer, it is most desirable that the gloss layer coating completely covers the surface of the ink receiving layer while maintaining the pores. It becomes equal to the diameter of the fine pigment used for the glossy layer paint. On the other hand, when the thickness of the glossy layer exceeds 5 μm, it is not preferable because there is a possibility that the ink absorbability and the strength of the coating film may be hindered.

The gloss layer can be produced by a known coating apparatus similar to the ink receiving layer. Multi-layer coating may be performed simultaneously with the ink receiving layer. Further, in order to further improve the gloss, in the case of a gas permeable substrate, a method of drying using a heated gloss roll (so-called casting treatment) is used, and in the case of a low gas permeable or non-air permeable substrate, WO2003 / It is possible to employ a method disclosed in Japanese Patent No. 039881 and the like, in which coating is performed while applying pressure at the nip portion between a heated gloss roll and a press roll, and drying is performed in the next step.
In addition, a release agent can be added to the coating liquid for forming the gloss layer in order to smoothly and stably peel the surface of the formed coating liquid layer from the gloss roll.
Release agents include fatty acids such as stearic acid, oleic acid, and palmitic acid, and salts thereof such as sodium, potassium, calcium, zinc, ammonium, stearic acid amide, ethylene bis stearic acid amide, and methylene bis stearic acid amide. Fatty acid amides such as, aliphatic hydrocarbons such as microcrystalline wax, paraffin wax and polyethylene wax, higher alcohols such as cetyl alcohol and stearyl alcohol, fats and oils such as funnel oil and lecithin, lipids, fluorine-containing surface activity Examples thereof include various surfactants such as agents, and fluorine-based polymers such as tetrafluoroethylene polymer and ethylene-tetrafluoroethylene polymer.

  Of these, aliphatic hydrocarbons or derivatives or modified products thereof, fatty acids or salts thereof, and lipids are particularly preferable. Among them, polyethylene wax is used as the aliphatic hydrocarbon, stearic acid or oleic acid is used as the fatty acid, and lipids are used. More preferably, lecithin is used.

  The surface temperature of the gloss roll is preferably in the range of 40 to 130 ° C., more preferably in the range of 70 to 120 ° C., more preferably in the range of 70 to 120 ° C., from the operational properties such as drying conditions, the adhesion to the ink receiving layer, and the gloss of the gloss layer surface. A range of 110 ° C. is more preferred. When the surface temperature of the gloss roll is less than 40 ° C., the coating strength due to insufficient indentation of the pigment may decrease or the gloss may decrease. When the surface temperature exceeds 130 ° C., the coating may crack. .

  Note that, instead of the fine pigment in the gloss layer, a pigment having an average particle diameter of more than 1 μm can be used as a matting agent to control the gloss low.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example are a mass part and the mass%, respectively.

Example 1
<< Preparation of treatment liquid >>
To 7.88 g of ion-exchanged water stirred at 3000 rpm using a propeller-type stirring blade, 14.19 g of colloidal silica (Nissan Chemical Industry Co., Ltd., Snowtex OXS, aqueous dispersion concentration 15%) having a particle size of about 5 nm is obtained. After adding 19.16 g of a 20% aqueous lactic acid solution, 7.66 g of 3-aminopropyltrimethoxysilane (amino group-containing silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd., product number: LS-1420) was added dropwise. After stirring for 10 minutes, further, zirconium oxychloride octahydrate (Kanto Chemical Co., reagent name: zirconium oxide octahydrate chloride, chemical formula: ZrOCl ₂ · 8H ₂ O) Ion-exchanged water 7.66g of An aqueous solution dissolved in 43.43 g was added, and the mixture was heated at 50 ° C. for 2 hours with stirring to obtain a treatment liquid a which was an acidic ultrafine particle dispersion. The average particle size of the ultrafine particles contained in this solution was 48 nm, and it was confirmed by infrared absorption spectrum measurement that an absorption peak corresponding to the Zr—O—Si bond was present. The average particle diameter and infrared absorption spectrum were measured as follows.

(Measurement method of average particle size of ultrafine particles)
The obtained ultrafine particle aqueous dispersion was used as a sample solution, and the average particle size was measured using a fiber optical dynamic light scattering photometer (manufactured by Otsuka Electronics Co., Ltd., FDLS-3000, measurable range: 0.5 nm to 5 μm). did. As the average particle size, a value calculated from an analysis using a cumulant method was used.

(Measurement of infrared absorption spectrum of ultrafine particles)
10 g of each ultrafine particle dispersion was dried with hot air at 105 ° C., and the solvent was evaporated to dryness to obtain a glassy residue. A KBr tablet was prepared using a fine powder obtained by pulverizing this in a mortar as a sample, and an infrared absorption spectrum in a wavelength range of 400 to 4000 cm ⁻¹ was measured with a Fourier transform infrared spectrometer (NEXUS670, manufactured by Nicorey). . From the obtained spectrum, the presence or absence of an absorption peak corresponding to the Zr—O—Si bond appearing in the vicinity of 1000 cm ⁻¹ was confirmed.

<Preparation of composite fine particle sol>
To a high-speed stirrer (manufactured by Primix Co., Ltd., TK Robotics), stirring section: homodisper 2.5 type was attached, and 362.7 g of ion-exchanged water stirred at 3000 rpm was charged with processing solution a: 42.7 g. Subsequently, 90.9 g of a commercially available specific surface area of 200 m ² / g gas phase method silica (trade name: Leorociol QS-102, average primary particle size 12 nm, manufactured by Tokuyama Corporation) was gradually added. The mixture was dispersed in the above-described high-speed stirrer, and a stirring unit: homomixer 2.5 type was attached, and dispersion treatment was performed at 15000 rpm for 30 minutes to prepare a composite fine particle sol A having a solid content concentration of 20%. The resultant composite fine particles A ′ had a pore volume of 1.4 ml / g and an average secondary particle size of 148 nm. The average secondary particle diameter and pore volume were measured as follows.

(Measuring method of average secondary particle size of agglomerated fine particles such as composite fine particles)
Place 100 ml of the fine particle aqueous dispersion in a 500 ml stainless steel cup, and perform dispersion treatment at 3000 rpm for 5 minutes using the above-described high-speed disperser (stirring section: Homodisper 2.5 type). Of tertiary particles were dispersed. The dispersion after treatment is sufficiently diluted with distilled water to obtain a sample solution, and averaged using a laser particle size meter by dynamic light scattering method (manufactured by Otsuka Electronics, FPAR-1000, measurable range: 3 nm to 5 μm). Secondary particle size was measured. As the average secondary particle size, a value calculated from an analysis using a cumulant method was used.

(Method for measuring pore volume of agglomerated fine particles such as composite fine particles)
The fine particle dispersion was dried at 105 ° C. as it was, and was measured after vacuum degassing at 200 ° C. for 2 hours as a pretreatment using a nitrogen gas adsorption specific surface area / pore distribution measuring device (SA3100 plus type manufactured by Coulter). As the pore volume, the value of the total pore volume (nitrogen relative pressure 0.9814) having a pore diameter of 100 nm or less was used.

<< Preparation of coated substrate >>
Conifer bleached kraft pulp (NBKP) beaten to CSF (JIS P-8121) to 250 ml and hardwood bleached kraft pulp (LBKP) beaten to CSF to 250 ml are mixed at a mass ratio of 2: 8, and the concentration is 0. A 5% pulp slurry was prepared. In this pulp slurry, cationized starch 2.0%, alkyl ketene dimer 0.4%, anionized polyacrylamide resin 0.1% and polyamide polyamine epichlorohydrin resin 0.7% are added to the pulp dry weight. The mixture was sufficiently stirred and dispersed.
The pulp slurry having the above composition was made with a long net machine and passed through a dryer, a size press, and a machine calendar to produce a base paper having a basis weight of 180 g / m ² and a density of 1.0 g / cm ³ . The size press solution used in the size press step was prepared by mixing carboxyl-modified polyvinyl alcohol and sodium chloride at a mass ratio of 2: 1, adding this to water and dissolving it by heating, and adjusting the concentration to 5%. A total of 25 ml / m ^{2 of} this size press solution was applied to both sides of the paper to obtain a base material A (air permeability: 1000 seconds).

After applying corona discharge treatment to both sides of the base paper of the base material A, the following polyolefin resin composition 1 mixed and dispersed by a Banbury mixer is applied to the felt surface side of the base material A so that the coating amount is 25 g / m ^2. Further, the polyolefin resin composition 2 was applied to the wire side of the substrate A with a melt extruder (melting temperature: 320 ° C.) having a T-die so that the coating amount was 20 g / m ^2, and felt. The surface side is cooled and solidified with a mirror surface cooling roll and the wire surface side is cooled with a rough surface cooling roll, smoothness (Oken type, J.TAPPI No. 5B) is 6000 seconds, and opacity (JIS P8138) is 93%. Of the resin. Then, after corona discharge treatment was performed again on the side coated with the polyolefin resin composition 1, a 1% hot aqueous solution of commercially available photographic gelatin (manufactured by Miyagi Chemical Co., Ltd., product name: P-487) was reduced to a dry mass of 0.00. Coating was carried out to 3 g / m ² and drying with hot air at 60 ° C. gave substrate B.

Polyolefin resin composition 1
Long chain type low density polyethylene resin (density 0.926 g / cm ³ , melt index 20 g / 10 min) 35 parts, low density polyethylene resin (density 0.919 g / cm ³ , melt index 2 g / 10 min) 50 parts, anatase Type titanium dioxide (trade name: A-220, manufactured by Ishihara Sangyo Co., Ltd.) 15 parts, zinc stearate 0.1 part, antioxidant (trade name: Irganox 1010, manufactured by Ciba Geigy) 0.03 parts, ultramarine (trade name) : Aoguchi Ultramarine NO.2000, manufactured by Daiichi Kasei Co., Ltd.) 0.09 part, fluorescent whitening agent (trade name: UVITEX OB, manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.3 part, and polyolefin resin composition 1 It was.

Polyolefin resin composition 2
65 parts of high density polyethylene resin (density 0.954 g / cm ³ , melt index 20 g / 10 min) and 35 parts of low density polyethylene resin (density 0.919 g / cm ³ , melt index 2 g / 10 min) are melt mixed. A polyolefin resin composition 2 was obtained.

《Coating》
To the above-mentioned composite fine particle sol A 60 g, ion-exchange water 8.76 g, boric acid 0.48 g, 0.1% aqueous solution of acetylene glycol surfactant (trade name: Olphine E1004, manufactured by Nissin Chemical Industry Co., Ltd.) 6.00 g After mixing, 24.00 g of a 9% aqueous solution of partially saponified polyvinyl alcohol (trade name: PVA-224, polymerization degree = 2400, saponification degree = about 88%, manufactured by Kuraray Co., Ltd.) is mixed, and the coating composition has a solid content concentration of 15%. Was prepared.
On the side of the substrate B on which the polyolefin resin composition 1 is laminated, the above-mentioned coating material is applied with a die coater so that the coating amount is 24 g / m ² in dry mass, and dried with hot air at 110 ° C. for 10 minutes to perform inkjet. A record was obtained.

Example 2
25.81 g of colloidal silica (Nissan Chemical Industry Co., Ltd., Snowtex NXS, aqueous dispersion concentration 15%) having a particle size of about 5 nm was added to 3.35 g of ion-exchanged water stirred at 3000 rpm using a propeller type stirring blade. After adding 17.42 g of 20% aqueous lactic acid solution, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane (amino group-containing silane coupling agent, manufactured by Shin-Etsu Chemical Co., Ltd., product number: LS-2480) 97 g was added dropwise. After stirring for 10 minutes, an aqueous solution in which 6.97 g of zirconium oxychloride octahydrate was dissolved in 39.48 g of ion-exchanged water was added, and the mixture was heated at 50 ° C. for 2 hours with stirring. Then, a microfluidizer (Microfluidics, Inc.) was added. The pulverization dispersion process (30 Mpa) by a product, model number: M110 / EH) was performed once, and the process liquid b which is an acidic ultrafine particle dispersion liquid was obtained. The average particle diameter of the ultrafine particles contained in this solution was 64 nm, and the presence of an absorption peak corresponding to the Zr—O—Si bond was confirmed by infrared absorption spectrum measurement.
A composite fine particle sol B was prepared in the same manner as in Example 1 except that 366.5 g of ion-exchanged water was charged with 46.5 g of the treatment liquid b and then gradually added 90.1 g of Leorociol QS-102. An ink jet recording material was prepared from the paint. The obtained composite fine particles B ′ had a pore volume of 1.5 ml / g and an average secondary particle size of 149 nm.

Example 3
Example 2 except that in the preparation step of the composite fine particle sol, the above-described pulverization dispersion treatment (30 MPa) using the microfluidizer was performed once instead of the dispersion treatment of 15000 rpm for 30 minutes using the homomixer 2.5 type. In the same manner as above, a composite fine particle sol C was prepared, and an ink jet recording material was prepared from the paint. The obtained composite fine particles C ′ had a pore volume of 1.4 ml / g and an average secondary particle size of 138 nm.

Example 4
20.51 g of an aqueous solution of polyallylamine (PAA-15C manufactured by Nittobo Co., Ltd., average molecular weight ≈ 15000, solid content concentration 15%) was mixed with 79.49 g of the ultrafine particle dispersion prepared in Example 2 with stirring, at room temperature. The treatment liquid d was obtained by leaving it for 24 hours.
A composite fine particle sol D was prepared in the same manner as in Example 1 except that 357.5 g of ion-exchanged water was charged with 57.5 g of the treatment liquid b and then gradually added with Leorociol QS-102: 88.5 g. An ink jet recording material was prepared from the paint. The composite fine particles D ′ thus obtained had a pore volume of 1.5 ml / g and an average secondary particle size of 146 nm.

Example 5
An ink jet recording material was prepared in the same manner as in Example 4 except that the base material A was used in place of the base material B as the coating base material.

Example 6
100 g of commercially available gel method silica (trade name: Silojet P612, manufactured by Grace Devison) was added to 400 g of ion-exchanged water, preliminarily dispersed by sand grinder grinding, and then ground by a microfluidizer in the same manner as in Example 3. Dispersion treatment was performed to obtain a 20% silica sol aqueous dispersion.
A composite fine particle sol E was prepared in the same manner as in Example 1 except that 57.5 g of the treatment liquid b was added to 442.5 g of this silica sol, and an ink jet recording material was prepared from the paint. The obtained composite fine particles E ′ had a pore volume of 1.1 ml / g and an average secondary particle size of 293 nm.

Example 7
A composite fine particle sol F was prepared in the same manner as in Example 4 except that the dispersion treatment of the composite fine particle sol was performed with a microfluidizer in the same manner as in Example 3, and an ink jet recording material was prepared from the paint. The resulting composite fine particles F ′ had a pore volume of 1.4 ml / g and an average secondary particle size of 137 nm.

Example 8
Instead of 20.51 g of the polyallylamine aqueous solution (PAA-15C), 15.38 g of the same PAA-05 (manufactured by Nittobo Co., Ltd., average molecular weight≈5000, solid content concentration 20%) was diluted with 5.13 g of ion-exchanged water. The use of an aqueous solution and the use of gas phase method silica having a specific surface area of 300 m ² / g (trade name: Leorociol QS-30, average primary particle size 7 nm, manufactured by Tokuyama Corporation) instead of Leorociol QS-102 Except for the above, a treatment liquid g and a composite fine particle sol G were prepared in the same manner as in Example 4, and an ink jet recording material was prepared from the paint. The obtained composite fine particles G ′ had a pore volume of 1.5 ml / g and an average secondary particle size of 152 nm.

Example 9
A composite fine particle sol H was prepared in the same manner as in Example 8 except that the dispersion treatment of the composite fine particle sol was performed with a microfluidizer in the same manner as in Example 3, and an ink jet recording material was prepared from the paint. The obtained composite fine particles H ′ had a pore volume of 1.4 ml / g and an average secondary particle size of 137 nm.

Example 10
Snowtex NXS: Instead of 25.81 g, an aqueous dispersion obtained by diluting 12.91 g of zirconia sol (Nissan Chemical Industries, Nanouse ZR-30AL, solid content concentration 30%) with the same amount of ion-exchanged water is used. Except that, an acidic ultrafine particle dispersion was obtained in the same manner as in Example 2. The average particle diameter of the ultrafine particles contained in this solution was 83 nm, and the presence of an absorption peak corresponding to the Zr—O—Si bond was confirmed by infrared absorption spectrum measurement.
A treatment liquid j and a composite fine particle sol J were prepared in the same manner as in Example 4 except that this ultrafine particle dispersion was used, and an ink jet recording material was prepared from the paint. The resulting composite fine particles J ′ had a pore volume of 1.3 ml / g and an average secondary particle size of 160 nm.

Example 11
An acidic ultrafine particle dispersion was obtained in the same manner as in Example 2 except that aluminum lactate (manufactured by Kanto Chemical Co., Ltd., reagent) was used instead of zirconium oxychloride. The average particle diameter of the ultrafine particles contained in this solution was 81 nm, and the presence of an absorption peak corresponding to the Al—O—Si bond was confirmed by infrared absorption spectrum measurement.
While stirring an aqueous solution obtained by dissolving 3.08 g of Goosephimer Z-220 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., acetoacetylated PVA) in 17.43 g of ion-exchanged water, 79.49 g of this ultrafine particle dispersion was stirred. The mixture was mixed and allowed to stand at room temperature for 24 hours to obtain a treatment liquid k.
A composite fine particle sol K was prepared in the same manner as in Example 4 except that the treatment liquid k was used, and an ink jet recording material was prepared from the paint. The obtained composite fine particles K ′ had a pore volume of 1.4 ml / g and an average secondary particle size of 162 nm.

Example 12
Zirconyl acetate (manufactured by Daiichi Rare Elemental Chemical Co., Ltd., chemical formula: ZrO (C ₂ H ₃ O ₂ ) ₂ instead of an aqueous solution in which 6.97 g of zirconium oxychloride octahydrate is dissolved in 39.48 g of ion-exchanged water, An acidic ultrafine particle dispersion was obtained in the same manner as in Example 2 except that 46.45 g (ZrO conversion≈15%) was used. The average particle diameter of the ultrafine particles contained in this solution was 112 nm, and it was confirmed by infrared absorption spectrum measurement that an absorption peak corresponding to the Zr—O—Si bond was present.
A treatment liquid m and a composite fine particle sol M were prepared in the same manner as in Example 4 except that this ultrafine particle dispersion was used, and an ink jet recording material was prepared from the paint. The resultant composite fine particles M ′ had a pore volume of 1.4 ml / g and an average secondary particle size of 166 nm.

Comparative Example 1
After adding 21.60 g of a 20% aqueous lactic acid solution to 12.16 g of ion-exchanged water stirred at 3000 rpm using a propeller type stirring blade, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane: 8.64 g Was dripped. After stirring for 10 minutes, an aqueous solution in which 8.64 g of zirconium oxychloride octahydrate was dissolved in 48.96 g of ion-exchanged water was further added, and the mixture was heated at 50 ° C. for 2 hours with stirring. A certain processing solution n was prepared. The average particle diameter of the ultrafine particles contained in this solution was 2.2 nm, and it was confirmed by infrared absorption spectrum measurement that an absorption peak corresponding to a Zr—O—Si bond was present.
Preparation of composite fine particle sol N was carried out in the same manner as in Example 2, except that 370.0 g of ion-exchanged water was mixed with 38.2 g of treatment liquid n and then gradually added Leorociol QS-102: 91.7 g. An ink jet recording material was prepared from the paint. The resulting composite fine particles N ′ had a pore volume of 1.4 ml / g and an average secondary particle size of 170 nm.

Comparative Example 2
24.24 g of an aqueous polyallylamine solution (PAA-15C manufactured by Nittobo Co., Ltd., average molecular weight≈15000, solid content concentration 15%) was mixed with 75.76 g of the ultrafine particle dispersion prepared in Comparative Example 1 at room temperature. The treatment liquid p was obtained by leaving it for 24 hours.
The composite fine particle sol P was prepared in the same manner as in Example 1 except that the treatment liquid p: 49.5 g was added to 360.4 g of ion-exchanged water, and then leorosiol QS-102: 90.1 g was gradually added. An ink jet recording material was prepared from the paint. The resulting composite fine particles P ′ had a pore volume of 1.5 ml / g and an average secondary particle size of 172 nm.

Comparative Example 3
PAA-15C: Instead of 20.51 g, an aqueous solution obtained by diluting PAA-05: 15.38 g with 5.13 g of ion-exchanged water was used, except that Leorociol QS-30 was used instead of Leorociol QS-102. In the same manner as in Comparative Example 2, a treatment liquid q and composite fine particle sol Q were prepared, and an ink jet recording material was prepared from the paint. The obtained composite fine particles Q ′ had a pore volume of 1.4 ml / g and an average secondary particle size of 188 nm.

Comparative Example 4
A composite fine particle sol R was prepared in the same manner as in Comparative Example 3 except that the dispersion treatment of the composite fine particle sol was performed with a microfluidizer in the same manner as in Example 3, and an ink jet recording material was prepared from the paint. The obtained composite fine particles R ′ had a pore volume of 1.4 ml / g and an average secondary particle size of 182 nm.

(Evaluation methods)
The ink jet recording materials obtained in Examples and Comparative Examples were evaluated by the following methods. The production conditions of each recording material were shown in Table 1, and the evaluation results were shown in Table 2.

(Coating surface quality)
The coated surface of the obtained ink jet recording material was evaluated in the following five stages by visual evaluation.
5 points: High visual glossiness and smooth surface quality. There are no flaws such as cracks or bumps.
4 points: Glossy that looks like a photo-like texture level. There are no flaws such as cracks or bumps.
3 points: Although slightly, the surface of the coating layer is defective as a photographic ink jet recording paper, and the visual glossiness is slightly inferior.
Two points: The surface of the coating layer is defective as a photographic ink jet recording paper.
1 point: Due to a defect, the coating surface quality is extremely inferior.

(Paint gloss)
The coated surface of the obtained ink jet recording material was measured based on ISO 8254-1 using a gloss meter (GM-26 PRO / AUTO) of Murakami Color Research Laboratory.

(Print density measurement)
Super photo paper recommended setting mode of Canon printer: PIXUS-iP8600 (machine installed with dye ink) in an environment of 23 ° C. and 50% humidity (ISO environment) on each sample cut to L size (89 mm × 127 mm) 100% black solid was printed with the setting (no matching), and was dried in an ISO environment for 24 hours. This printed portion was measured using a black filter of a Macbeth reflection densitometer (manufactured by Macbeth, RD-914). The numbers shown in the table are average values of five measurements.

(Continuous printing evaluation test under high temperature and high humidity)
Samples were cut to L size (89 mm x 127 mm), and each two sheets were conditioned for 24 hours in an environment of 30 ° C and 80% humidity, then Canon Inc. inkjet printer: PIXUS-iP4200 Super Photo Paper recommended setting, JIS -X9201 "High-definition color digital standard image CMYK / SCID" Image identification number: N1 was printed in succession. The sample after printing was immediately sandwiched between two L-sized glass plates having a thickness of 5 mm and left in the same environment. After 24 hours, the print sample output on the first sheet (the one on which the second sheet was laminated) was taken out and dried in an environment of 23 ° C. and 50% humidity for 2 hours. As a normal image for comparison, a print sample was prepared after humidity control was performed in an environment of 23 ° C. and 50% humidity, followed by printing and drying without stacking. Similarly, instead of the N1 image, a pattern image “a pattern in which 100% red, green, and blue of 1 cm ² squares are connected horizontally and arranged in three rows vertically with an interval of 1 mm and 0.5 mm” is also used. A normal print sample was prepared. The color tone was mainly confirmed from the N1 image, and the blur was mainly confirmed from the pattern image, and was evaluated in five levels based on the following indices.

《Color tone evaluation index》
5 points: Even an image laminated by continuous printing under severe conditions of high temperature and high humidity has a clear color tone equivalent to that of a normal image.
4 points: Although the color tone is slightly different from that of a clear normal image, the layered image has a clear color tone with no unnaturalness when viewed alone.
3 points: The normal image is clear, but the color of the layered image is sunk, and there is an unnatural impression alone.
2 points: The sharpness of the normal image is slightly inferior, and the layered image has a more unnatural impression because the color further sinks.
1 point: The color tone of the normal image is clearly unnatural.

《Budget evaluation index》
5 points: There is no blur even in images laminated by continuous printing under severe conditions of high temperature and high humidity.
4 points: Although there is a slight blur at the printing boundary portion (solid portion to white paper, or solid portion to solid portion) of the laminated image, it is at a level with no problem.
3 points: There is blurring that can be discriminated at the printing boundary of the laminated image.
2 points: The laminated image is clearly blurred, but the normal image is not blurred.
1 point: Normal image is also blurred.

  In the table, as abbreviations, APTMS represents 3-aminopropyltrimethoxysilane, and AEAPTMS represents N-2 (aminoethyl) 3-aminopropyltrimethoxysilane.

  As is clear from Examples 1 to 12 in Tables 1 and 2, the composite fine particles of the present invention can be prepared with a relatively light dispersion load, and the composite fine particles are used as the main component of the ink receiving layer. The ink jet recording medium included in the present invention has a particularly high ink fixing ability, so that it has a high printing density and can obtain a clear image that does not differ from the normal environment even if it is kept in a laminated state by continuous printing. there were. Inkjet printers are now widely used as simple output devices including general households, so it is fully assumed that multiple photos are output in a high-temperature and high-humidity environment and stored in a stacked state. Environment. Even under these harsh conditions, the ink jet recording material using the composite fine particles of the present invention can contain core particles (Examples 1, 2, 10 and 12) and Si compounds having amino groups (components of ultrafine particles as raw materials). Examples 1 and 2), types of various metal compounds (Examples 1, 11, and 12), polymerization degree and types of hydrophilic polymers to be coordinated (Examples 4, 8, and 11), types of inorganic pigments (implementation) Even when Examples 1 and 6) were changed, a good ink jet recording material could always be obtained. In particular, when polyallylamine having a cationic property is coordinated as a hydrophilic polymer (Examples 4 to 11), or a paper base material is used as a base material (Example 6), the ink fixing property is very good. Therefore, good image quality without blurring was obtained even under severe conditions. These qualities were obtained even with the composite fine particles subjected to the light dispersion treatment, but when the composite fine particles subjected to the stronger dispersion treatment were used, the coating film gloss and the print density were further improved (Examples 3 and 7). . In addition, as the inorganic pigment, since the primary particle size is small, transparency of the coating leading to high printing density can be expected, but even when silica with high specific surface area with strong cohesion is used, it is relatively dispersible with mild dispersion. (Example 8), and in combination with a strong dispersion treatment, an extremely high quality ink jet recording material could be obtained (Example 9).

  On the other hand, as shown in Comparative Example 1, in the ultrafine particles prepared without using the core particles and the composite microparticles obtained by using the inorganic pigment, the aggregation generated during the compositing is a light load equivalent to that in Example 2. Since it could not be redispersed completely, the surface quality and gloss of the coating film were insufficient. This ink-receiving layer was not only low in printing density but also poor in fixing of ink because the pores contributing to ink absorption were non-uniform and the transparency of the coating film was lowered. When polyallylamine having excellent ink fixing ability was introduced, the ink fixing property was slightly improved, but the dispersibility of the composite fine particles was insufficient, so that the quality of the coating film was inferior. Moreover, when the high specific surface area silica similar to Example 8 was used as an inorganic pigment, the coating quality was inferior due to its strong cohesiveness (Comparative Example 3). Further, even when combined with the strong dispersion treatment, it was not possible to obtain the same quality as the composite fine particles into which the core particles of the present invention were introduced (Comparative Example 4).

Claims (16)

  Ultrafine particles having an inorganic pigment, a core layer, and a polymer layer including an amino group and M-O-Si bond (M represents a divalent or higher valent metal atom) covering at least a part of the surface of the core particle A composite fine particle comprising at least a part of the periphery of the inorganic pigment bonded to the ultrafine particle.   At least a part of a polymer containing an amino group and a M-O-Si bond (M represents a divalent or higher-valent metal atom) in the molecule, and a hydrophilic polymer capable of forming a chelate with the ion of M The composite fine particles according to claim 1, wherein are coordinated with each other.   In an aqueous solvent containing core particles, an amino group-containing silane coupling agent and a divalent or higher valent metal compound are polymerized to cover at least a part of the surface of the core particles and an M—O—Si bond. Composite fine particles obtained by obtaining an aqueous dispersion of ultrafine particles having a polymer layer containing (M represents a divalent or higher-valent metal atom) and dispersing an inorganic pigment in the aqueous dispersion.   The composite fine particle according to any one of claims 1 to 3, wherein the core particle is colloidal silica having a particle diameter of 4 to 30 nm.   5. The fine composite particle according to claim 2, wherein the hydrophilic polymer capable of forming a chelate with the M ion is polyallylamine.   The composite fine particles according to claim 2, 4 or 5, wherein the hydrophilic polymer capable of forming a chelate with the M ion has a weight average molecular weight of 5,000 to 50,000.   The composite fine particle according to any one of claims 1 to 6, wherein the inorganic pigment is gas phase method silica having an average particle diameter of 1 µm or less.   The composite particle according to any one of claims 1 to 7, wherein M is at least one metal atom selected from the group consisting of zirconium, aluminum, titanium, and zinc.   9. The ultra fine particles are formed by polymerization of an amino group-containing silane coupling agent and a divalent or higher metal compound in an aqueous solvent containing core particles. The composite fine particle according to any one of the above.   The amino group-containing silane coupling agent is selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, and N-2 (aminoethyl) 3- The composite fine particle according to claim 9, which is at least one selected from the group consisting of aminopropyltriethoxysilane or a hydrolyzate and a polymer thereof.   11. The composite fine particle according to claim 9, wherein the divalent or higher-valent metal compound is at least one selected from the group consisting of a zirconium compound, an aluminum compound, a titanium compound, and a zinc compound.   The composite fine particles according to any one of claims 1 to 11, wherein the solid content ratio of the inorganic pigment and the ultrafine particles is 2 to 20 parts by mass with respect to 100 parts by mass of the inorganic pigment.   The solid content ratio of the inorganic pigment, the ultrafine particles and the hydrophilic polymer is such that the ultrafine particles are 2 to 20 parts by mass and the hydrophilic polymer is 0.5 to 5 parts by mass with respect to 100 parts by mass of the inorganic pigment. The composite fine particle according to any one of claims 2 to 12, which is characterized by the following.   An ink jet recording material comprising the composite fine particles according to claim 1.   In an aqueous solvent containing core particles, an amino group-containing silane coupling agent and a divalent or higher valent metal compound are polymerized to cover at least a part of the surface of the core particles and an M—O—Si bond. An aqueous dispersion of ultrafine particles having a polymer layer containing (M represents a divalent or higher-valent metal atom) is obtained, and an inorganic pigment and dilution water as necessary are added to the aqueous dispersion and dispersed to form a composite. A method for producing composite fine particles, characterized in that   In an aqueous solvent containing core particles, an amino group-containing silane coupling agent and a divalent or higher valent metal compound are polymerized to cover at least a part of the surface of the core particles and an M—O—Si bond. An aqueous dispersion of ultrafine particles having a polymer layer containing (M represents a divalent or higher-valent metal atom), and a hydrophilic polymer capable of forming a chelate with the M ions in the aqueous dispersion; A method for producing composite fine particles, comprising adding an inorganic pigment and dispersing and compositing.